Plaxis 3D Tutorial

PLAXIS 3D FOUNDATION Tutorial Manual Version 2

TABLE OF CONTENTS TABLE OF CONTENTS 1

Introduction............. .............. ............... .............. .............. ............... .............1-1

2

Getting started .............. .............. .............. ............... .............. .............. ........2-1 2.1 Installation .............................................................................................2-1 2.2 General modelling aspects ..................................................................... 2-1 2.3 Input procedures ....................................................................................2-3 2.3.1 Input of geometry objects ..........................................................2-4 2.3.2 Input of text and values..............................................................2-4 2.3.3 Input of selections ......................................................................2-4 2.3.4 Structured input..........................................................................2-6 2.4 Starting the program ..............................................................................2-7 2.4.1 General settings..........................................................................2-7 2.4.2 Creating a model ........................................................................2-8

3

Foundation in overconsolidated clay (Lesson 1) ............ .............. .............3-1 3.1 Geometry ...............................................................................................3-2 3.2 Case A: Rigid foundation.......................................................................3-2 3.2.1 Geometry input ..........................................................................3-3 3.2.2 Performing calculations ...........................................................3-15 3.2.3 Viewing output results .............................................................3-20 3.3 Case B: Raft foundation.......................................................................3-23 3.3.1 Geometry input ........................................................................3-24

3.3.2 Performing calculations ...........................................................3-32 3.3.3 Viewing output results .............................................................3-35 3.4 Case C: Pile-raft foundation.................................................................3-37 3.4.1 Geometry input ........................................................................3-37 3.4.2 Performing calculations ...........................................................3-40 3.4.3 Viewing output results .............................................................3-41 4

Excavation pit (Lesson 2) .............. .............. .............. .............. .............. ......4-1 4.1 Geometry input ......................................................................................4-2 4.2 Performing calculations .......................................................................4-10 4.3 Viewing output results .........................................................................4-14

5

Load capaci ty of a suction pile (Lesson 3) .............. .............. .............. .......5-1 5.1 Geometry ...............................................................................................5-2 5.2 Calculations ...........................................................................................5-7 5.3 Viewing output results ...........................................................................5-9

6

Safety analysis of an embankment (Lesson 4) ........... ........... ........... .......... 6-1 6.1 Geometry input ......................................................................................6-2 6.2 Calculations ...........................................................................................6-5 6.3 Viewing output results ...........................................................................6-7

Appendix A – Menu Tree

i

TUTORIAL MANUAL

ii

PLAXIS 3D FOUNDATION

INTRODUCTION 1

INTRODUCTION

PLAXIS 3D FOUNDATION is a three-dimensional finite element program especially developed for the analysis of foundation structures, including off-shore foundations. It combines simple graphical input procedures, which allow the user to automatically generate complex finite element models, with advanced output facilities and robust calculation procedures. The program is designed such that a user can analyse complex constructions after only a few hours of training. This Tutorial Manual is designed to help new users get acquainted with the program. The lessons deal with a number of different constructions, which gradually introduce the various features of the program and show some of its possible applications. Users are expected to have a basic understanding of soil mechanics and should be able to work with a Windows environment. It is helpful, but not required, that users are familiar with the standard PLAXIS (2D) deformation analysis program, as many of the interface objects are similar. It is recommended that the lessons are made in the order in which they appear in the manual. The input files and results of the lessons are also available from the examples folder of the PLAXIS 3D FOUNDATION program directory and can be used to check your results. The Tutorial Manual does not provide theoretical background information on the finite element method, nor does it explain the details of the various soil models available in the program. The latter can be found in the Material Models Manual, as included in the full manual, whereas theoretical background is given in the Scientific Manual. For detailed information on the available program features, the user is referred to the Reference Manual. In addition to the full set of manuals, short courses are organised on a regular basis at several places in the world to provide hands-on experience and background information on the use of the program.

The examples and corresponding material data sets used in the Tutorial Manual are based on fictitious projects in fictitious soils, and purely meant to train new users in becoming familiar with the features of the 3D Foundation package. Although it is attempted to create realistic Tutorial examples with realistic soil properties for the situation as described, the examples and material data sets may NOT be considered directly applicable or sufficiently accurate to model real projects. Users should realise this, and remain fully responsible for the modelling of their own projects based on corresponding project related data and local soil conditions.

1-1

TUTORIAL MANUAL

1-2


GETTING STARTED 2

GETTING STARTED

This chapter describes some of the notation and basic input procedures that are used in the PLAXIS 3D FOUNDATION program. In the manuals, text buttons on the screen, menu items or windows specific items are printed in Italics. Whenever keys on the keyboard need to be pressed, this is indicated by the name of the key in brackets (for example the key).

2.1

INSTALLATION

For the installation procedure the user is referred to the General Information section in this manual.

2.2

GENERAL MODELLING ASPECTS

For each new 3D project to be analysed it is important to create a geometry model first. A geometry model is a representation of a real three-dimensional problem and is defined by work planes and boreholes. A geometry model should include a representative division of the subsoil into distinct soil layers, structural objects, construction stages and loadings. The model must be sufficiently large so that the boundaries do not influence the results of the problem to be studied. The two components of a geometry model are described below in more detail.

Boreholes Boreholes are objects in the geometry model, defining the ground surface, soil layers and the water table at a certain location. Multiple boreholes can be used to define the stratigraphy of the soil for the project. During 3D mesh generation, the position of soil layers is interpolated between boreholes and the mesh is generated such that the boundaries between soil layers always coincide with the boundaries of elements.

Work planes Work planes are horizontal planes, with different y-coordinates, presenting a top-view of the geometry model at the specified vertical level. They are used to create the loads and structures in the model. Each work plane holds the same geometry lines, but the distance between work planes may vary, as defined by the input of y-coordinates. Work planes may be used to activate or deactivate point loads, line loads, distributed loads or structural elements. Within work planes, points, lines and clusters can be used to describe a 2D geometry model. These three components are described below.

2-1

TUTORIAL MANUAL

Points Points form the start and end of lines. Points can also be used for the positioning of springs and point loads and for local refinements of the finite element mesh.

Lines Lines are used to define the physical boundaries of the geometry, contours of structures and discontinuities in the geometry such as walls or beams, or excavation areas. A line can have several functions or properties.

Clusters Clusters are areas that are fully enclosed by lines. P LAXIS automatically recognises clusters based on the input of geometry lines. Within a cluster the properties are homogeneous. Hence, clusters can be regarded as homogeneous parts of a structure or soil layer. Actions related to clusters apply to all elements in the cluster. After the creation of the 2D geometry model in a work plane, a 2D finite element mesh composed of 6-node triangles can automatically be generated, based on the composition of clusters and lines in the geometry model. If the 2D mesh is satisfactory, an extension into the third dimension can be made. In a 3D finite element mesh three types of components can be identified, as described below (see also the Scientific Manual).

Elements During the generation of the mesh, the geometry is divided into 15-node wedge elements. These elements are composed of the 6-node triangular faces in the work planes, as generated by the 2D mesh generation, and 8-node quadrilateral faces in y-direction. In addition to the volume elements, which are generally used to model the soil, compatible 2-node or 3-node line elements, 6-node or 8node plate elements and 16-node interface elements may be generated to model structural behaviour and soil-structure interaction respectively.

Nodes The wedge elements as used in the 3D Foundation program consist of 15 nodes. The distribution of nodes over the elements is shown in Figure 2.1. Adjacent elements are connected through their common nodes. During a finite element calculation, displacements (ux, uy and uz) are calculated at the nodes. Nodes may be selected for the generation of load-displacement curves.

2-2


GETTING STARTED

Stress points In contrast to displacements, stresses and strains are calculated at individual Gaussian integration points (or stress points) rather than at the nodes. A 15node wedge element contains 6 stress points as indicated in Figure 2.1. Stress points may be selected for the generation of stress and strain diagrams. 3

12

1

9

8

6

1

η

4

7 10

2

15

ζ

14

5

6

4

2

3

ξ

11

13 5

Figure 2.1 Distribution of nodes (●) and stress points (×) in a 15-node wedge element

2.3

INPUT PROCEDURES

In P LAXIS, input is specified by using the mouse and also by keyboard input. In general, four types of input may be identified:

•

Input of geometry objects (e.g. drawing a geometry line)

•

Input of text

(e.g. entering a project name)

• •

Input of values

(e.g. entering the soil unit weight)

Input of selections

(e.g. choosing a soil model)

The mouse is generally used for drawing and selection purposes, whereas the keyboard is used to enter text and values.

2-3

TUTORIAL MANUAL 2.3.1

INPUT OF GEOMETRY OBJECTS

The creation of a geometry model is based on the input of points and lines. This is done by means of a mouse pointer in the draw area. Several geometry objects are available from the menu or from the toolbar. The input of most of the geometry objects is based on a line drawing procedure. In any of the drawing modes, lines are drawn by clicking on the left mouse button in the draw area. As a result, a first point is created. On moving the mouse and left clicking with the mouse again, a new point is created together with a line from the previous point to the new point. The line drawing is finished by clicking the right mouse button, or by pressing the key on the keyboard. 2.3.2

INPUT OF TEXT AND VALUES

As for any software, some input of values and text is required. The required input is specified in the edit boxes. Multiple edit boxes for a specific subject are grouped in windows. The desired text or value can be typed on the keyboard, followed by the key or the key. As a result, the value is accepted and the next input field is highlighted. In some countries, like The Netherlands, the decimal dot in floating point values is represented by a comma. The type of representation that occurs in edit boxes and tables depends on the country setting of the operating system. Input of values must be given in accordance with this setting. Many parameters have default values. These default values may be used by pressing the key without other keyboard input. In this manner, all input fields in a window can be entered until the OK button is reached. Pressing the OK button confirms all values and closes the window. Alternatively, selection of another input field, using the mouse, will result in the new input value being accepted. Input values are confirmed by left clicking the OK button with the mouse. Pressing the key or left clicking the Cancel button will cancel the input and restore the previous or default values before closing the window. The spin edit feature is shown in Figure 2.2. Just like a normal input field a value can be entered by means of the keyboard, but it is also possible to left-click on the ▲ or ▼ arrows at the right side of each spin edit or by using the <↑> and <↓> keys on the keyboard to increase or decrease its value by a predefined amount.

Figure 2.2 Spin edits

2.3.3

INPUT OF SELECTIONS

Selections are made by means of radio buttons, check boxes or combo boxes as described below. 2-4


GETTING STARTED

Figure 2.3 Radio buttons

Figure 2.4 Check boxes

Figure 2.5 Combo boxes

Radio buttons In a window with radio buttons only one item may be active. The active selection is indicated by a black dot in the white circle in front of the item. Selection is made by clicking the left mouse button in the white circle or by using the <↑> and <↓> keys on the keyboard. When changing the existing selection to one of the other options, the 'old' selection will be deselected. An example of a window with radio buttons is shown in Figure 2.3. According to the selection in Figure 2.3 the project that will be opened is set to a New project.

Check boxes In a window with check boxes more than one item may be selected at the same time. The selection is indicated by a black tick mark in a white square. Selection is made by clicking the left mouse button in the white square or by pressing the space bar on the keyboard. Another click on a pre-selected item will deselect the item. An example of check boxes is shown in Figure 2.4.

Combo boxes A combo box is used to choose one item from a predefined list of possible choices. An example of a window with combo boxes is shown in Figure 2.5. As soon as the ▼ arrow at the right hand side of the combo box is left clicked with the mouse, a pull down list occurs that shows the possible choices. It is also possible to switch between these items by using the <↑> and <↓> keys on the

2-5

TUTORIAL MANUAL keyboard. A combo box has the same functionality as a group of radio buttons but it is more compact. 2.3.4

STRUCTURED INPUT

The required input is organised in a way to make it as logical as possible. The Windows environment provides several ways of visually organising and presenting information on the screen. To make the reference to typical Windows elements in the next chapters easier, some types of structured input are described below.

Page control and tab sheets An example of a page control with three tab sheets is shown in Figure 2.6. In this figure the second tab sheet for the input of the model parameters of the Mohr-Coulomb soil model is active. Tab sheets are used to handle large amounts of different types of data which do not all fit in one window. Tab sheets can be activated by left-clicking on the corresponding tab or using on the keyboard.

Group boxes Group boxes are rectangular boxes with a title. They are used to cluster input items that have common features. In Figure 2.6, the active tab sheet contains three group boxes named Stiffness, Strength and Alternatives.

Figure 2.6 Page control and tab sheets

2-6


GETTING STARTED 2.4

STARTING THE PROGRAM

It is assumed that the program has been installed using the procedures described in the General Information part of the manual. It is advisable to create a separate directory in which data files are stored. The P LAXIS 3D FOUNDATION program can be started by selecting the PLAXIS 3D FOUNDATION Input icon in the PLAXIS 3D FOUNDATION program group. The user is asked whether to define a new problem or to retrieve a previously defined project. If the latter option is chosen, the program lists four of the most recently used projects from which a direct choice can be made. Choosing the item <> that appears first in this list will give a file requester from which the user can choose any previously defined project for modification. 2.4.1

GENERAL SETTINGS

If a new project is to be defined, the General Settings window as shown in Figure 2.7 appears. This window consists of two tab sheets. In the first tab sheet miscellaneous settings for the current project have to be given. A filename has not been specified here; this can be done when saving the project.

Figure 2.7 General Settings - Project tab sheet The user can enter a brief description of the problem as the title of the project as well as a more extended description in the Comments box. The title is proposed as the default filename and appears on output plots. The Comments box is simply a convenient place to store information about the analysis. Also, the magnitude of the standard earth gravity and the unit weight of water can be specified here.

2-7

TUTORIAL MANUAL The second tab sheet is shown in Figure 2.8. In addition to the basic units of Length, Force and Time, the minimum dimensions of the draw area must be given here, such that the geometry model will fit the draw area.

Figure 2.8 General Settings - Dimensions tab sheet The general system of axes is such that the x-axis points to the right and the z-axis points downwards in the draw area. Xmin is the lowest x-coordinate of model, Xmax the highest x-coordinate, Zmin the lowest z-coordinate and Zmax the highest z-coordinate of the model. Y-coordinates are not entered in the General Settings dialog, but during the input of bore holes and work planes. In practice, the draw area resulting from the given values of Xmin, Xmax, Zmin and Zmax will be larger than the values given in the four spin edits. This is partly because PLAXIS will automatically add a small margin to the dimensions and partly because of the difference in the width/height ratio between the specified values and the screen. 2.4.2

CREATING A MODEL

When the general settings are entered and the OK button is clicked, the main window appears. This main window is shown in Figure 2.9. The most important parts of the main window are indicated and briefly discussed below. For a more extensive description the reader is referred to the Reference Manual.

2-8


GETTING STARTED

Main Menu

Tool bars

Tool bars

Origin

Switch Switch between between Model Model mode mode and and Calculation Calculation mode mode

Draw area Ruler R

Manual input

Cursor position indicator

Figure 2.9 Main window of the Input program

Input menu The Input menu contains all input items and operation facilities of the Input program. Most items are also available as buttons in the toolbar.

Toolbar (File) This toolbar contains buttons for file operations, corresponding with the options in the File menu. It also contains buttons to start the other sub-program of the PLAXIS 3D FOUNDATION package (Output).

Toolbar (Edit) This toolbar contains buttons for editing operations, corresponding with the options in the Edit menu.

Toolbar (View) This toolbar contains buttons for viewing operations such as zooming into a particular part of the draw area. The buttons correspond with the options in the View menu.

2-9

TUTORIAL MANUAL

Toolbar (General) This toolbar contains buttons for functionalities that apply to the Model mode as well as to the Calculation mode, among which the use of the selection tool and the selection of a work plane.

Toolbar (Model) This toolbar contains buttons related to the creation of a geometry model, such as Boreholes, Geometry lines, Beams, Floors, Walls, Piles, Embedded piles, Ground anchors, Springs, Line fixities and Loads, as well as options for 2D and 3D mesh generation.

Toolbar (Calculation) This toolbar contains buttons related to the definition of calculation phases.

Rulers At both the left and the top of the draw area, rulers indicate the physical coordinates, which enables a direct view of the geometry dimensions.

Draw area The draw area is the drawing sheet on which the geometry model is created. The draw area can be used in the same way as a conventional drawing program. The grid of small dots in the draw area can be used to snap to regular positions.

Origin If the physical srcin is within the range of given dimensions, it is represented by a small circle, with an indication of the x- and z-axes.

Manual input If drawing with the mouse does not give the desired accuracy, then the Manual input line can be used. Values for x- and z-coordinates can be entered here by typing the corresponding values separated by a space. The manual input can also be used to assign new coordinates to a selected point.

Cursor position indicator The cursor position indicator gives the current position of the mouse cursor both in physical units and screen pixels. Some of the objects mentioned above can be removed by deselecting the corresponding item from the View menu.

2-10


GETTING STARTED ew Save (Ctrl+N) (Ctrl+S)

Print

View table

Go to Output Program Open (Ctrl+O) Zoom in Zoom out

Geometry line

Horiz. beam Vert. beam

Distributed load ((horiz. planes)

Select

Undo

Copy

Distributed load ((vert. planes)

Materials

Workplanes

Generate 2D mesh

Next phase

Wall

Phases

Generate 3D mesh

Pile

Vert. line fixity Hor. line Borehole Embedded pile Ground anchor fixity Hor. line load Floor

Active workplane

Spring

Phase list

Preview

Point load Vert. line load

Select points for curves

Figure 2.10 Toolbars For both toolbars, the name and function of the buttons is shown after positioning the mouse cursor on the corresponding button and keeping the mouse cursor still for about a second; a hint will appear in a small yellow box below the button. The available hints for both toolbars are shown in Figure 2.10. In this Tutorial Manual, buttons will be referred to by their corresponding hints. For detailed information on the creation of a complete finite element model, the reader is referred to the various lessons that are described in this Tutorial Manual.

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TUTORIAL MANUAL

2-12


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) 3

FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1)

In the previous chapter some general aspects and basic features of the P LAXIS 3D FOUNDATION program were presented. In this chapter a first application is considered, namely the settlement of a foundation in clay. This is the first step in becoming familiar with the practical use of the program. The general procedures for the creation of a geometry, the generation of a finite element mesh, the execution of a finite element calculation and the evaluation of the output results are described here in detail. The information provided in this chapter will be utilised in later lessons. Therefore, it is important to complete this first lesson before attempting any further tutorial examples.

18.0 m 75.0 m

75.0 m building y=0 y=-2

40.0 m

y clay

x

y=-40

z

x z

Figure 3.1 Geometry of a square building on a raft foundation

3-1

TUTORIAL MANUAL 3.1

GEOMETRY

This exercise deals with the construction and loading of a foundation of a square building in a lightly overconsolidated Lacustrine Clay. Below the clay layer there is a stiff rock layer that forms a natural boundary for the considered geometry. The rock layer is not included in the geometry; instead an appropriate boundary condition is applied at the bottom of the clay layer. The purpose of the exercise is to find the settlement of the foundation. The building consists of a basement level and 5 floors above ground level (see Figure 3.1). To reduce calculation time, only one-quarter of the building is modelled, using symmetry boundary conditions along the lines of symmetry. To enable any possible mechanism in the clay and to avoid any influence of the outer boundary, the model is extended in both horizontal directions to a total width of 75.0 m.

3.2

CASE A: RIGID FOUNDATION

In the first calculation, the building is considered to be very stiff and rough. In this calculation the basement is simulated by means of non-porous linear elastic volume elements. The total weight of the basement corresponds to the total permanent and variable load of the building. This approach leads to a very simple model and is therefore used as a first exercise, but it also has some disadvantages. For example, it does not give any information about the structural forces in the foundation. The second part this lesson deals with a raft foundation existing structural is a moreofadvanced modelling approach. In the third part ofofthis lesson elements, embeddedwhich piles will be added to the raft foundation to decrease the settlement of the foundation. Objectives: • Starting a new project • Adding work planes • Creating a borehole • Defining drained Mohr-Coulomb soil material • Defining non-porous linear elastic material • Creating a mesh • Mesh refinement of a cluster • Rotating the model in Output • Using K0 procedure to generate initial stresses • Adding calculation phases

• • • • • • 3-2

Changing material of volume elements Preview option Viewing deformed mesh Viewing total displacements Changing presentation of the results Viewing output at work planes Scaling of results PLAXIS 3D FOUNDATION

FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) 3.2.1

GEOMETRY INPUT

Start the PLAXIS 3D FOUNDATION Input program. A Create/Open Project dialog box will appear in which you can select an existing project or create a new one. Choose New project and click the OK button (see Figure 3.2). Now the General Settings window appears, consisting of the two tab sheets Project and Dimensions (see Figure 3.3 and Figure 3.4).

Figure 3.2 Create/Open Project dialog box

General Settings The first step in every analysis is to set the basic parameters of the finite element model. This is done in the General Settings window. These settings include the description of the problem, units and the sizefollow of thethese drawsteps: area. To enter the appropriate settings for thethe raftbasic foundation calculation

Figure 3.3 Project tab sheet of the General Settings window 3-3

TUTORIAL MANUAL

•

In the Project tab sheet, enter ‘Lesson 1’ in the Description box and type ‘Settlements of a foundation’ in the Comments box.

•

The General box indicates a fixed gravity of 1.0 G, in the vertical direction downward (-Y). Also, the value of the acceleration of gravity (1.0 G) can be entered in the Earth gravity box. This should be kept to the default value of 9.8 m/s2 for this exercise.

•

In the γwater box the unit weight of water can be entered. Keep this to the default value of 10 kN/m3. Click the Next button below or click the Dimensions tab sheet.

Figure 3.4 Dimensions tab sheet of the General Settings window

•

In the Dimensions tab sheet, keep the default units in the Units box (Unit of Length = m; Unit of Force = kN; Unit of Time = day).

•

In the Geometry Dimensions box the size of the required draw area must be entered. When entering the upper and lower coordinate values of the geometry to be created, a small margin is automatically added so that the geometry will fit well within the draw area. Enter 0, 75, -75 and 0 for Xmin, Xmax, Zmin and Zmax respectively.

•

The Grid box contains the settings for the grid spacing. The grid provides a matrix of dots on the screen that can be used as reference points. It may also be used for snapping to regular points during the creation of a geometry. The distance between the dots is determined by the Spacing value. The spacing of snapping points can be further divided into smaller intervals by the Number of intervals value. Enter 1.0 for the spacing and 1 for the intervals.

3-4



•

Click the OK button to confirm the settings. Now the draw area appears in which the geometry model can be drawn. The draw area shows a top view of the geometry model. Hint: In the case of a mistake or for any other reason that the general settings need to be changed, you can access the General Settings window by selecting the General Settings option from the File menu.

Once the general settings have been completed, the draw area appears with an indication of the srcin and direction of the system of axes. The x-axis is pointing to the right and the z-axis is pointing downwards on the screen. The y-axis is perpendicular to the draw area, pointing towards the user. A first cluster (area that is fully enclosed by geometry lines) with dimensions equal to the dimensions entered in the General Settings window is also automatically created. A geometry model can be created in this draw area, which will be considered later on. First, we will consider the soil stratigraphy and ground surface level by defining a borehole.

Borehole Information on the soil layers and the water table is entered in so called boreholes. Boreholes are locations in the draw area at which the information on the location of soil layers and the water table is given. If multiple boreholes are defined, P LAXIS 3D FOUNDATION will automatically interpolate between the boreholes, and derive the position of the soil layers from the borehole information. Hint: PLAXIS 3D FOUNDATION can also deal with layers that are discontinuous, i.e. only locally present in the model area. In such cases, so called degenerated elements are used. See Section 3.3.1 of the Reference Manual for more information.

In the current example, only one soil layer is present, and only a single borehole is needed to define the soil layer. In order to define the borehole, follow these steps: Select the Borehole tool from the Model toolbar.

•

Click at a location in the cluster that represents the soil. It is suggested to click on (0.0, -75.0).

•

This borehole location (0.0, -75.0) and opens the Borehole (see places Figure a3.5). The attop and bottom boundaries of the borehole window will be determined automatically. They correspond to y = 0.0 m and to y = -3.0 m. For this exercise, the level of the bottom boundary has to be changed.

•

Click in the table on the y-coordinate of the bottom layer boundary. Enter a value of -40.0 m for this layer boundary.

3-5

TUTORIAL MANUAL

•

In the Water level box, set the water level to y = -2.0 m. Do not close the window as the properties of the soil layer still need to be defined.

Figure 3.5 The Borehole window

Material Data Sets In order to simulate the behaviour of the soil, a suitable material model and appropriate material parameters must be assigned to the geometry. In PLAXIS, soil properties are collected in material data sets and the various data sets are stored in a material database. From the database, a data set can be assigned to one or more clusters. For structures (like beams, walls, floors, etc.) the system is similar, but different types of structures have different parameters and therefore different types of data sets. PLAXIS 3D FOUNDATION distinguishes between material data sets for Soils & Interfaces, Beams, Floors, Walls, Embedded Piles, Ground Anchors and Springs. The input of material data sets is generally done after the input of all geometry objects. Before the mesh can be generated material data sets have to be assigned to all clusters and structures. The input of material data sets can be selected by means of the Materials button on the General toolbar, from the options available in the Materials menu or from the Materials button in the Borehole window.

3-6



Soil Properties To create a material set for the clay layer, using the last of the three possible methods, follow these steps:

•

The Borehole window should still be open. If it is not open, choose the Select tool from the toolbar and double-click on the borehole at (0.0, -75.0). This opens the Borehole window and shows the layers in the selected borehole. In this case only a single layer is present, with a bottom at –40.0 m and a top at 0.0 m. Open the Material Sets window by clicking on the Materials button.

•

Click the New button on the lower side of the Material Sets window. A new dialog box will appear with three tab sheets: General, Parameters and Interfaces (see Figure 3.6 and Figure 3.7).

•

In the Material Set box of the General tab sheet, write ‘Lacustrine Clay’ in the Identification box.

•

Select Mohr-Coulomb as the material model from the Material model combo box and Drained from the Material type combo box (default parameters).

•

Enter the unit weights in the General properties box according to the material data set as listed in Table 3.1. As no consolidation will be considered in this exercise, the permeability of the soil will not influence the results. Therefore, the default values can be kept in the Permeability box.

Table 3.1 Material properties of the soil layers Parameter

Name

Lacustrine Clay

Building

Unit

Material model

Model

MohrCoulomb

Linear elastic

-

Type of material behaviour

Type

Drained

Non-porous -

Unit weight of soil above phreatic level

γunsat

17.0

50.0

kN/m3

Unit weight of soil below phreatic level

γsat

18.0

-

kN/m3

Young’s modulus (constant)

Eref

1·104

3·107

kN/m2

Poisson’s ratio

ν

0.3

0.15

-

Cohesion (constant)

cref

10.0

-

kN/m2

Friction angle

φ

30.0

-

º

Dilatancy angle

ψ

0.0

-

º

3-7

TUTORIAL MANUAL

Figure 3.6 General tab sheet of the soil and interfaces data set window

•

Click the Next button or click the Parameters tab to proceed with the input of model parameters. The parameters appearing on the Parameters tab sheet depend on the selected material model (in this case the Mohr-Coulomb model). The Mohr-Coulomb model involves only five basic parameters ( E, ν, c, φ, ψ). See the Material Models Manual for a detailed description of the different soil models and their corresponding parameters.

Figure 3.7 Parameters tab sheet of the soil and interfaces data set window

3-8



•

Enter the model parameters Eref, ν, cref, φ and ψ of ‘Lacustrine Clay’ of Table 3.1. in the corresponding edit boxes of the Parameters tab sheet. The value of the Young’s modulus has to be entered as ‘1E4’.

•

Since the geometry model does not include interfaces, the third tab can be skipped. Click the OK button to confirm the input of the current material data set. Now the created data set will appear in the tree view of the Material Sets window.

•

Drag the set ‘Lacustrine Clay’ from the Material Sets window (select it and hold down the left mouse button while moving) to the graph of the soil column on the left hand side of the Borehole window and drop it there (release the left mouse button). Notice that the cursor changes shape to indicate whether or not it is possible to drop the data set. Correct assignment of the data set to the soil layer is indicated by a change in the colour of the layer. Hint: PLAXIS distinguishes between a project database and a global database of material sets. Data sets may be exchanged from one project to another using the global database. The data sets of all lessons in this Tutorial Manual are stored in the global database during the installation of the program. To copy an existing data set, click the Global button of the Material Sets window. Drag the appropriate data set (in this case ‘3DF Lesson 1 Lacustrine Clay’) from the tree view of the global database to the project database and drop it there. Now the global data set is available for the current project. Similarly,

data sets created in the project database may be dragged and dropped in the global database. Hint: Existing data sets may be changed by opening the Material Sets window from the General toolbar. > The program performs a consistency check on the material parameters and will give a warning message in the case of a detected inconsistency in the data. The building is modelled by a linear elastic non-porous material. Although this material will not be used until the calculation stages are defined, the material data set needs to be created beforehand. To define this data set, follow these steps:

•

Click the New button in the Material Sets window.

•

In the Material Set box of the General tab sheet, write ‘Building’ in the Identification box.

•

Select Linear elastic as the material model from the Material model combo box and Non-porous from the Material type combo box.

•

Enter the unit weight in the General properties box according to the ‘Building’ material data set as listed in Table 3.1. This unit weight corresponds to the total permanent and variable load of the building.

3-9

TUTORIAL MANUAL

•

Click the Next button or click the Parameters tab to proceed with the input of the model parameters. The linear elastic model involves only two basic parameters (E, ν).

•

Enter the model parameters of Table 3.1.in the corresponding edit boxes of the Parameters tab sheet.

•

Click the OK button to confirm the input of the current material data set. Now the created data set will appear in the tree view of the Material Sets window.

•

As the set ‘Building’ will be used later when defining the calculation stages, the Material Sets window can now be closed by clicking the OK button.

•

The Soil tab sheet of the Borehole window may be skipped in this exercise.

•

Click the OK button in the Borehole window to return to the draw area.

Work planes Work planes are horizontal layers with different y-coordinates, at which the structural objects, loads and construction stages can be defined. Work planes are needed at each level where a discontinuity in the geometry or the loading occurs in the initial situation or in the construction process. They are defined in the Work Planes window. This window can be opened with the Work Planes button, found on the toolbar just left of the Active work plane combo box, or from the Work Planes option in the Geometry menu. One work plane has already been automatically created at y = 0.0 m. For this first project, we need to define one additional work plane. To do this, follow these steps: Open the Work Planes window by clicking the Work Planes button on the toolbar. A new window will appear, in which the automatically generated work plane at y = 0.0 m is shown (see Figure 3.8). A vertical cross section is shown, indicating in red the currently selected work plane.

Figure 3.8 Work Planes window

• 3-10

Click the Add button. A new work plane is inserted at y = -3.0 m, below the current work plane. PLAXIS 3D FOUNDATION


•

Select the new work plane (y = -3.0 m) by clicking on the entry in the table on the left and enter a value y = -2.0 m. Press on the keyboard to accept the new value. After accepting this value, the overview of work planes is updated, as shown in Figure 3.8.

•

Click the OK button to close the Work Planes window and return to the draw area.

Building Geometry To create objects, you can either use buttons from the toolbar or the options from the Geometry menu. For a new project the Geometry line button is already active. Otherwise this option can be selected from the Models toolbar or from the Geometry menu. For this project, the contours of the building have to be drawn by a geometry line to create another cluster.

•

From the Active work plane combo box, click on the arrow to open the combo box and click on the entry 0.0 (see Figure 3.9) to select the work plane at y = 0.0 m.

Figure 3.9 Active work plane combo box In order to create this cluster, follow these steps: Select the Geometry line option in the Model toolbar (the second button on this toolbar) or from the Geometry menu.

•

Position the cursor at the coordinate (0.0, -18.0). Check that the units in the status bar read 0.0 x -18.0 m and click the left mouse button once. The first geometry point in addition to the default geometry boundary points (number 4) has now been created.

•

Move to the right to position (18.0, -18.0). Click the left mouse button to generate the second point (number 5). At the same time the first geometry line is created from point 4 to point 5. This is indicated by a black line.

•

Finally, move downwards to position (18.0, 0.0) and click again.

Click the right mouse button to stop drawing. The program has now detected two separate clusters. The small square cluster will be used later to construct the building.

•

3-11

TUTORIAL MANUAL

Hint: When adding a geometry line to a work plane, this geometry line will be repeated in all other work planes. When structural objects such as floors and beams are added, these will be added to the currently active work plane only. Walls and vertical beams will be added below the currently active work plane. In addition, a corresponding geometry line or point will be added to all other work planes. > Incorrectly positioned points and lines can be modified or deleted by first choosing the Selection button from the toolbar. To move a point or line, select

>

>

the point or line and drag it to the desired position. To delete a point or line, select the point or line and press the key on the keyboard. Unwanted drawing operations can be removed by pressing the Undo button from the toolbar or by selecting the Undo option from the Edit menu or by pressing from the keyboard. Lines can be drawn perfectly horizontal or vertical by holding down the key on the keyboard while moving the mouse.

2D Mesh Generation When the geometry model is complete and all borehole information has been entered, it is recommended to generate a 2D finite element mesh before generating a full 3D mesh. PLAXIS 3D FOUNDATION allows for a fully automatic mesh generation procedure, in which the geometry is divided into volume elements and compatible structure elements, if applicable. The mesh generation takes full account of the position of lines and points in the geometry model, so that the exact position of layers, loads and structures is accounted for in the finite element mesh. The 2D mesh generation process is based on a robust triangulation principle that searches for optimised triangles and which results in an unstructured mesh. Although unstructured meshes do not form regular patterns of elements, the numerical performance of these meshes is usually better than structured meshes with regular arrays of elements. In addition to the mesh generation itself, a transformation of the input data (properties, boundary conditions, material sets, etc.) from the geometry model (points, lines and clusters) to the finite element mesh (elements and nodes) is made. To generate the mesh, follow these steps: Click the Generate 2D mesh button in the toolbar or select the Generate 2D Mesh option from the Mesh menu.

•

After the generation of the mesh a new window is opened ( Output window) in which the generated mesh is presented (see Figure 3.10).

•

This window can be used to inspect the generated mesh and to decide if mesh refinement is required. Large displacement gradients are expected around and under the building. Hence, it is appropriate to have a finer mesh around and under the building.

•

Click the Close button to return to the Input window.

3-12



Figure 3.10 2D finite element mesh of the geometry

•

Select the small cluster that represents the building. This cluster is now indicated in red as shown in Figure 3.11. From the Mesh menu, select the option Refine Cluster. As a result, a local refinement of the indicated cluster is visible in the presented mesh. Click the Close button to return.

Figure 3.11 The selected cluster

3-13

TUTORIAL MANUAL

•

If necessary, the mesh can be further optimised by performing global or local refinements. Here it is suggested that the current mesh is accepted. Hint: By default, the global coarseness of the mesh in horizontal as well as vertical direction is set to Coarse, which is adequate as a first approach in many cases. The Global Coarseness setting can be changed in the Mesh menu. In addition, options are available to refine the mesh globally or locally. > At this stage of input, it is still possible to modify parts of the geometry or to

>

add geometry objects. If modifications are made at this stage, the finite element mesh has to be regenerated. The automatically generated mesh may not be perfectly suitable for the intended calculation. Therefore it is recommended that the user inspect the mesh and makes refinements if necessary.

3D Mesh Generation After generation of the 2D mesh, the model must be extended to a full 3D mesh. This can be done by clicking on the Generate 3D mesh button or selecting the corresponding option from the Mesh menu. The information in vertical direction on layer boundaries, construction levels and changes in the geometry has already been entered, using work planes and boreholes. No extra information is needed in order to generate the 3D mesh. The 3D mesh is created by connecting the corners of the 2D triangular elements to the corresponding points of the corresponding elements in the next work plane. In this way a 3D mesh, composed of 15-noded wedge elements is formed. Where needed extra element levels are automatically introduced. If multiple boreholes are used and not all layers are present in all boreholes, so-called degenerated elements will be introduced, to deal with the transition between the various layers. See Section 3.3.1 of the Reference Manual for more details. To generate the 3D mesh, follow these steps: Click the Generate 3D mesh button on the toolbar or select Generate 3D Mesh from the Mesh menu. The 3D mesh generation procedure is started and the 3D mesh is displayed in the Output window. Additional element levels are automatically introduced between the work planes at –2 m and –40 m to reduce the element size in y-direction. The arrow keys of the keyboard or holding down the left mouse button while moving the mouse allow the user to rotate the model so that it can be viewed from any direction (see Figure 3.12).

•

3-14

Click the Close button to return to the Input program.



Figure 3.12 Generated 3D mesh in the Output window

3.2.2

PERFORMING CALCULATIONS

Once the mesh has been generated, the finite element model is complete. Before the actual calculation is started, the calculation stages have to be defined. The first of these will be the definition of initial conditions. The second stage will be the construction of the building.

Figure 3.13 The Calculations toolbar

•

Click the Calculation button to switch to Calculation mode (see Figure 3.13).

•

The program proposes to save the model. Press Yes to do so and save the model under its predefined name (Lesson 1).

The definition of calculation stages, such as switching on and off parts of the geometry, assigning different material data sets to clusters or structural elements or changing the magnitude of loads, is done in the Calculation mode of the Input program. Clicking the Calculation button will hide the Model toolbar and show the Calculation toolbar. This toolbar, see Figure 3.13, contains a Phase list combo box and a number of buttons to define calculation phases, perform the calculation and activate the Output program, in order to view the results. The Calculation mode of the Input program is a separate mode where calculation phases are defined and calculations can be started.

3-15

TUTORIAL MANUAL Clicking the Phases button will open the Phases window (see Figure 3.14). In the Phases window you can add and delete calculation phases, and set the parameters for the calculation procedure. All defined calculation phases appear in the list at the lower part of the window.

Figure 3.14 The Phases window with the General tab sheet As in all PLAXIS programs the 3D FOUNDATION program has convenient procedures for automatic load stepping and for the activation and deactivation of loads and parts of the geometry (staged construction). These procedures can be used for many practical applications. Staged construction is a very useful type of loading input. In this special PLAXIS feature it is possible to change the geometry and load configuration by deactivating or reactivating loads, volume elements or structural objects as created in the geometry input. Staged construction provides an accurate and realistic simulation of the various loading, construction and excavation processes. This option can also be used to reassign material data sets to clusters or structural elements.

Initial Conditions Before starting the actual calculations the initial conditions must be generated. In general, the initial conditions comprise the initial geometry configuration and the initial stress state. The initial water conditions for the clay layer have been entered already in 3-16


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) the Borehole window. These conditions are also taken into account to calculate the initial effective stress state. When a new project has been defined, a first calculation phase, named ‘Initial phase’, is automatically created and selected in the Phase list combo box and the Phases window. All structural elements and loads that are present in the geometry are initially automatically switched off; only the soil clusters are initially active. In PLAXIS 3D FOUNDATION two methods are available to generate the initial stresses, Gravity loading or the K0 procedure. By default Gravity loading is used, which requires no additional except for running the calculation. In this example, however, the K0 procedure actions will be used. Hint: The K0 procedure may only be used for horizontally layered geometries with a horizontal ground surface and, if applicable, a horizontal phreatic level. See the Reference Manual for more information on the K0 procedure. > The default value of K0 is based on Jaky's formula: K0 = 1-sinϕ. If the value was changed, the default value can be regained by entering a negative value for K0.

In order to generate the initial stresses according to the K0 procedure, follow these steps: Click on the Phases button to open the Phases window.

•

In the General tab sheet, the Calculation type is set to the default of Gravity loading. In order to generate initial stresses according to the K0 procedure, select K0 procedure from the Calculation type combo box.

•

Select the Parameters tab.

•

If the K0 procedure calculation type is selected, the Parameters tab sheet contains the K0 input values. In this tab sheet, accept the default values of K0 as suggested by PLAXIS.

Defining Construction Stage After the definition of the initial conditions, the construction of the building can be modelled. This will be done in a separate calculation phase, which needs to be added. To do this, follow these steps: In the Phases window click the Next button. This will add a new phase named and displays the General tab sheet.

•

In the in General tab sheet, write an appropriate name the from new phase the Number/ID box (for (optionally) example ‘Building’) and select thefor phase which the current phase should start (in this case the calculation phase can only start from phase 0 – Initial phase, which contains the initial stress state).

•

Leave the Calculation type to Plastic and click the Parameters tab to open the Parameters tab sheet.

3-17

TUTORIAL MANUAL

•

The Parameters tab sheet (see Figure 3.15) contains the calculation control parameters. Keep the default settings in the Iterative procedure box and keep the number of Additional steps to 250.

•

The calculation parameters for phase ‘Building’ have now been set. Click OK to close the Phases window.

Figure 3.15 The Parameters tab sheet of the Phases window Back in the main window of the Input program, the Phase list combo box will show ‘Building’. The draw area can now be used to define the construction stage for the current project. To do this, follow these steps:

•

Select the work plane at y = 0.0 m from the Active work plane combo box.

•

Click on the cluster representing the building. The Select Items window will appear.

•

Click on the text Soil below to select the cluster between the current work plane and the one below representing the building. Click the Change button to change the material set for the building. From the Material Sets window, select the ‘Building’ material and click OK.

•

Click OK to close the Select Items window.

3-18



•

The cluster representing the building is now drawn in the material set ‘Building’ colour instead of being drawn in grey diagonals (when no change of material has been applied) to indicate a change of material. Hint: Instead of clicking on the Soil above or Soil below items and then clicking on the Change button, it is also possible to double-click the text Soil above or Soil below. This will immediately open the Material Sets window. > Instead of changing a material set by first selecting the soil or structural

element, it is also possible to open the Material Sets window and then drag and drop the material set directly to the soil cluster or structural element. Click the Preview button to check the definition of the calculation stage. The preview option enables a direct visual check of the situation to be calculated before the calculation is started. The preview should show a different material set for the cluster representing the building (see Figure 3.16). If materials are not shown in the preview, select the Materials option from the Geometry menu.

Figure 3.16 Preview of the geometry in phase ‘Building’

•

After the preview click the Close button to return to the main window. If the situation was unsatisfactory, correct the situation in the main window. The calculation definition is now fully complete. The calculation can now be started. Click the Calculate button. This will start the calculation process.

All calculation phases that are marked for calculation, as indicated by a blue arrow (two phases in this case) will, in principle, be executed in the order controlled by the Start from phase parameter. 3-19

TUTORIAL MANUAL During the execution of a calculation a window appears which gives information about the progress of the actual calculation phase (see Figure 3.17). The information, which is continuously updated, shows amongst others the calculation progress, the current step number, the global error in the current iteration and the number of plastic points in the current calculation step. It will take several minutes to perform the calculation. When a calculation ends, the window is closed and focus is returned to the main window. Also, the Phase list is updated, showing a green tick mark to indicate that the calculation was finished successfully.

Figure 3.17 The calculation information window Hint: Calculation phases may be added, inserted or deleted using the Next, Insert and Delete buttons in the Phases window. > Check the list of calculation phases carefully after each execution of a (series of) calculation(s). A successful calculation is indicated in the list with a green tick mark (√) whereas an unsuccessful calculation is indicated with a red cross (×). Calculation phases that are selected for execution are indicated by a blue arrow (→).

3.2.3

VIEWING OUTPUT RESULTS

Once the calculation has been completed, the results can be evaluated in the Output program. In the Output program the displacement and stresses in the full 3D model as well as in the individual work planes or structural elements can be viewed. The

3-20


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) computational results are also available in tabular form. To view the results for the current analysis, follow these steps:

•

Select the last calculation phase (Building) in the Phase list combo box. Note that the Calculate button has changed into an Output button. Click the Output button to open the Output program. The Output program will by default show the 3D deformed mesh at the end of the selected calculation phase. The deformations are scaled to ensure that they are clearly visible.

•

Select Displacements > |u| from the Deformations The shows colour Total shadings of the total displacements (see Figuremenu. 3.18). A plot legend is presented with the displacement values at the colour boundaries. When the legend is not present, select the Legend option from the View menu.

Figure 3.18 Shadings of total displacements at the end of the last phase

•

The Presentation options combo box in the toolbar currently reads Shadings. Select Contour Lines from this combo box. The plot shows contour lines of the total displacements. A legend is presented with the displacement values corresponding to the labels shown at the work planes.

Apart from the entire 3D geometry, output can also be obtained at the work planes. The work planes can be selected using the tabs at the top of the output window. Each tab corresponding to a work plane is labelled by the y-coordinate of the work plane. The right-most tab, labelled 3D, will show the full 3D model.

•

Select the work plane at y = -2.0 m by clicking the first tab. The plot now shows contours of total displacements in the work plane with labels corresponding to the legend.

3-21

TUTORIAL MANUAL

•

Select Arrows from the Presentation options combo box. If the materials of the soil are visible, deselect this option from the Geometry menu to get a better view of the arrows. The plot shows the total displacements of all nodes as arrows, with an indication of their relative magnitude. To change the scale of the arrows, click the Scale factor button, or select the Scale option from the Edit menu or the right mouse button menu. In the Scale Factor window select Manual scale and change the Scale factor to 100. Click the OK button to close the Scale Factor window. Hint: The arrow keys or holding the left mouse button while moving the mouse may be used to change the orientation of a 3D model on the screen. The < ←> and <→> keys may be used to rotate the model around the y-axis whereas the <↑> and <↓> keys may be used to rotate the model in its current orientation around the horizontal screen axis. Hint: In addition to the Total displacements, the Deformations menu allows for the presentation of Incremental displacements and Phase displacements. The incremental displacements are the displacements that occurred in one calculation step (in this case the final step). Incremental displacements may be helpful in visualising failure mechanisms. Phase displacements are the displacements that occurred in one calculation phase (in this case the last phase). Phase displacements can be used to inspect the impact of a single construction phase, without the need to reset displacements to zero before starting the phase. > The plots of deformations and stresses may be combined with geometrical features, as available in the Geometry menu.

3-22


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) 3.3

CASE B: RAFT FOUNDATION

The model is now modified so that the basement consists of structural elements. This allows for the calculation of structural forces in the foundation. The raft foundation consists of a 50 cm thick concrete floor stiffened by concrete beams. The walls of the basement consist of 30 cm thick concrete. The loads of the upper floors are transferred to the floor slab by a column and by the basement walls. The column bears a load of 11650 kN and the walls carry a line load of 385 kN/m, as sketched in Figure 3.19. In 2

addition, the floor slab is loaded by a distributed load of 5.3 kN/m . The properties of the clay layer will be modified such that stiffness of the clay will increase with depth.

385 kN/m

385 kN/m

11650 kN

5.3 kN/m

12.0 m

12.0 m

6.0 m

6.0 m

Figure 3.19 Geometry of the basement Objectives: Saving project under different name • • Adding walls • Adding floors Adding vertical beams • Adding horizontal beams • • Adding point loads Adding line loads • Adding distributed loads on a horizontal plane • • Modifying existing data sets • Soil stiffness increases with depth

3-23

TUTORIAL MANUAL

• • • • • • • •

Defining wall material set Defining floor material set Defining beam material set Zooming in Output Multi-select of clusters for mesh refinement Deleting phases Switching clusters on and off Switching structural elements on

•• • •

Switching loads on Defining loads Drawing cross sections Viewing structural output

3.3.1

GEOMETRY INPUT

The geometry used in this exercise is the same as the previous one, except that additional elements are used to model the foundation. It is not necessary to create a new model; you can start from the previous model, store it under a different name and modify it. To perform this, follow these steps: Click the Go to Input program button at the left-hand side of the toolbar in the Output window to return to the Input program. Click the Save button on the File toolbar or select the Save option from the File menu to save the existing project. Click the Model button to switch to the Model mode.

•

Select the Save as option from the File menu. Enter a non-existing name for the current project file in the file requester (e.g. ‘Lesson 1b’) and click the Save button.

Building Geometry To have a more advanced modelling approach, structural elements will be used to model the foundation. In order to construct the outside walls of the basement, follow these steps:

•

From the Active work plane combo box, select the work plane at y = 0.0 m. Select the Wall option (the sixth button on the Model toolbar).

•

Position the cursor at point 4 with position (0.0, -18.0). Check that the units in the status bar read 0.0 x -18.0 m and click the left mouse button once. As this point already exists, no new point is created.

•

Move to the right to point 5 with position (18.0, -18.0). Click the left mouse button. At the same time the first wall is created from point 4 to point 5 between the current work plane and the one below. This is indicated by a thick blue line.

3-24


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) Interfaces are automatically added to both sides of the wall. These are indicated by black dashed lines. Interfaces are used to model the soil-structure interaction.

•

Finally, move to point 6, position (18.0, 0.0) and click the left mouse button again.

•

Click the right mouse button to stop drawing.

To construct the column in the basement, follow these steps: Select the Vertical beam option (the fourth button on the Model toolbar).

•

Move the cursor to (6.0, -6.0) and click to add the vertical beam between the current work plane (y = 0.0 m) and the one below ( y = -2.0 m). The beam is indicated by a symbol in the shape of a capital I.

To construct the basement floor, follow these steps:

•

Select the work plane at y = -2.0 m from the Active work plane combo box. Select the Floor option from the Model toolbar.

•

Click anywhere within the building cluster. This cluster should now be coloured olive (green), indicating that a floor has been added. Select the Horizontal beam option from the toolbar to add a horizontal beam. These beams will be used to stiffen the basement floor.

•

Position the cursor at the coordinate (6.0, -18.0) and click the left mouse button once.

•

Move to position (6.0, 0.0) and click the left mouse button again.

•

Click the right mouse button to stop drawing. A beam is now created between these two points. The beam is indicated by a thick light purple line.

•

To add the second beam, move to position (0.0, -6.0) and click the left mouse button once.

•

Move to position (18.0, -6.0) and click the left mouse button again. Click the right mouse button to stop drawing.

Loads After the basement geometry has been fully defined, the load resulting from the building itself anditself the is load on the basement floor haveonto to the be modelled. The load the building transferred from the top floors basement floor by thefrom column and the walls. This load can be modelled using a point load and line loads. The load on the basement floor can be modelled using a distributed load on a horizontal plane. To add the distributed load on the basement floor, follow these steps:

3-25

TUTORIAL MANUAL

•

Make sure that y = -2.0 m is still selected as the current work plane in the Active work plane combo box. Select the Distr. load horizontal plane option from the Model toolbar.

•

Click at each of the four clusters representing the concrete floor to add a distributed load. The distributed load will be indicated by a blue cross-hatched area. By default the distributed load has a value of 1 kN/m2 and is acting in the negative y-direction. Leave these at their default value for now. Later on, in the definition of calculation stages, the value of all loads will be changed to the desired values.

To add loads to the top of the walls and column, follow these steps:

•

Select the work plane y = 0.0 m in the Active work plane combo box. Select the Line load option. Add a line load at the location of the two walls by clicking on the coordinates (0.0, -18.0), (18.0, -18.0) and (18.0, 0.0). Click the right mouse button to stop drawing. By default the line load has a value of 1 kN/m and is acting in the negative y-direction. Select the Point load tool from the Model toolbar.

•

Move the cursor to (6.0, -6.0) and click to add the point load. The point load has a default value of 1 kN, acting in the negative y-direction. Such a load is represented by a blue circle with a letter A next to it.

Soil Properties The material set for the clay layer has already been defined. To modify this material set to take into account the stiffness of the soil increasing with depth, follow these steps: Open the Material Sets window by clicking on the corresponding button on the toolbar.

•

Select the ‘Lacustrine Clay’ material set and click the Edit button.

•

In the Parameters tab sheet, change the stiffness of the soil Eref to 5000 kN/m2.

•

Click the Advanced button to enter some additional parameters for advanced modelling features.

•

In the Advanced Parameters Mohr-Coulomb window enter a value of 500 in the Eincrement box. Keep the default value of 0.0 m for yref. Now, the stiffness of the 2

2

soil is depth. defined as 5000 kN/m at y = 0.0 m and increases with 500 kN/m per meter

•

Close the Advanced Parameters Mohr-Coulomb window by clicking the OK button.

•

Click the OK button to close the material set window of ‘Lacustrine Clay’.

3-26



Wall Properties In addition to the soil, all structural elements also need a material data set. Without closing the Material Sets window, follow these steps to create the data set for a wall:

•

Set the Set type in the Material Sets window to Walls. If the Material Sets window has already been closed, select the option Walls from the Materials menu.

•

Click the New button. Enter ‘Basement Walls’ in the Material set identification

•

box (see Figure 3.20). Select Linear for the properties. As the material is considered homogeneous, select the Isotropic option.

Figure 3.20 Input for the Walls material data set

•

Enter the properties as given in Table 3.2. The weight of the wall takes into account the overlap of the wall with the soil at only one side of the wall. The value for the shear modulus G12 is automatically updated after entering the values E1 and ν12.

3-27

TUTORIAL MANUAL Table 3.2 Material properties of the Basement Wall (wall) Parameter

Name

Basement Wall

Unit

Type of behaviour

Type

Linear, isotropic

-

Thickness

d

0.3

m

Weight

γ

15.5

kN/m3

Young’s modulus

E

3·107

kN/m2 7

Shear modulus Poisson’s ratio

G ν

1.304·10 0.15

2

kN/m -

•

Click the OK button to close the data set.

•

If the Material Sets window partially obscures the walls of the building, the window can be dragged aside. Drag and drop the ‘Basement Wall’ data set to the four parts of the wall in the draw area. The cursor will change to indicate if the material set can be dropped. The walls will briefly flash red and change colour from light blue to dark blue, indicating that a material data set has been assigned successfully. Hint: As walls are considered to be plate elements, there will be an overlap of the soil with the plate. As a consequence, the weight of the wall as well as the

weight of the soil will be taken into account. To compensate for this extra weight, the weight of the wall can be reduced by the weight of the soil. In case of an excavation at one side of the wall, the weight of the wall can be reduced by only half of the weight of the soil.

Hint: To check whether the correct material set has been assigned to a structural element, double click the object, and select it from the Select window that appears. A window will appear, see Figure 3.21, indicating the type of object and the material data set assigned to it. The Change button can be used to assign a different material data set to the object.

Figure 3.21 Inspecting the material data set for a structural element

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Beam Properties The material properties for the beams are entered in a similar manner. Without first closing the Material Sets window, do the following:

•

Set the Set type to Beams.

•

Click the New button and enter ‘Basement Column’ as the Material set identification (see Figure 3.22).

•

Enter the properties as given in Table 3.3.

Figure 3.22 Input for the Beams material data set Table 3.3 Material properties of the beams Parameter

Name

Basement Column

Basement Beam

Type of behaviour Cross section area Volumetric weight Young’s modulus Moment of Inertia

Type A

Linear 0.49 24.0 3·107 0.020 0.020 0

Linear 0.7 6.0 3·107 0.058 0.029 0

γ

E I3 I2 I23

Unit

m2 kN/m3 kN/m2 m4 m4 m4

3-29

TUTORIAL MANUAL

•

Click the OK button to close the data set.

•

If the Material Sets window partially obscures the vertical beam, the window can be dragged aside. Drag and drop the ‘Basement Column’ data set to the vertical beam in the draw area. The cursor will change to indicate if the material set can be dropped. The beam will briefly flash red and change colour from light purple to dark purple, indicating that a material data set has been assigned successfully.

•

In the Material Sets window click the New button to create the ‘Basement Beam’ data set.

•

In the Beam Properties window, enter the properties as given in Table 3.3.

•

Click the OK button to close the window.

•

Without closing the Material Sets window, select the work plane y = -2.0 m with the horizontal beams from the Active work plane combo box.

•

Drag and drop the ‘Basement Beam’ data set to all horizontal beams in the draw area.

Floor Properties The material properties for the floor are entered in a similar manner. Without closing the Material Sets window, do the following:

•

Set the Set type in the Material Sets window to Floors. Click the New button and enter ‘Basement Floor’ as the Material set identification.

•

Select Linear for the properties and select the Isotropic option.

•

Enter the properties given in Table 3.4 and click the OK button to close the data set.

Table 3.4 Material properties of the Basement Floor (floor) Parameter

Name

Basement Floor

Unit

Type of behaviour Thickness Weight Young’s modulus Shear modulus

Type d E G

Linear, isotropic 0.5 15 3·107 1.304·107

m kN/m3 kN/m2 kN/m2

Poisson’s ratio

ν

0.15

-

γ

•

Drag and drop the ‘Basement Floor’ data set to the floor clusters in the draw area. The floor will briefly flash red and change colour from light green to dark green.

•

Close the Material Sets window by clicking OK.

3-30



Mesh Generation Click the Generate 2D mesh button in the toolbar or select the Generate 2D Mesh option from the Mesh menu.

•

A warning will pop up saying that the geometry has been changed and the staged construction phases must be redefined. This is due to the fact that the project is copied from Lesson 1. Click OK.

•

The 2D mesh is displayed in the Output window (see Figure 3.23). As the element distribution the beams, walls and button floor istotooreturn coarse, mesh refinement is around necessary. Click the Close to additional the Input window.

•

Click in the middle of a floor cluster (single click) at y = -2.0 m. The selected cluster is now indicated in red. Hold down the key while selecting all floor clusters.

Figure 3.23 2D finite element mesh of the geometry

•

Select the Refine Cluster option from the Mesh menu. The Output program will show the generated 2D mesh with a mesh refinement in the floor clusters. The walls and horizontal beams will also be automatically refined as they border on these refined clusters. Click the Close button.

•

In order to refine all floor clusters once more, select all floor clusters while holding down the key and select the Refine Cluster option from the Mesh menu. Click the Close button in the Output program to return to the Input window. Click the Generate 3D mesh button on the toolbar or select Generate 3D mesh from the Mesh menu. The 3D mesh is displayed in the Output window. The 3D mesh and the various structural elements are shown in two different windows.

3-31

TUTORIAL MANUAL Select the Zoom in button from the toolbar and zoom to the structural elements in the top window. When the loads are shown, deselect this option in the Geometry menu to see the structural elements better (see Figure 3.24). Click the Close button to return to the Input window.

Figure 3.24 Generated 3D mesh in the Output window 3.3.2


As the mesh has been regenerated, all calculation phases have to be redefined. Click the Calculation button to switch to calculation mode.

•

The program proposes to save the model. Press Yes to do so.

Initial Conditions As in the previous example, the K0 procedure will still be used to generate the initial conditions. To check if this method is still selected, follow these steps: Click on the Phases button to open the Phases window. Select the initial phase in the lower part of the Phases window. Check if K0 procedure is still selected as Calculation type in the General tab sheet. If Gravity loading is selected, choose K0 procedure.

3-32



Defining Construction Stages Instead of constructing the building during one calculation stage, separate calculation phases will be used. First, the construction of the walls and the excavation is modelled. In the next phase, the construction of the floor and beams is modelled. The activation of the loads will be modelled in the last phase. To define these construction stages, follow these steps:

•

Without closing the Phases window, select the phase ‘Building’. Click the Delete button in the window or the key from the keyboard to delete this phase.

•

A window will pop up to ask if this phase should be deleted. Click Yes. Click the Next button to insert a new phase. Leave the Calculation type to Plastic and keep the default settings for the Iterative procedure in the Parameters tab sheet. Click the OK button to close the Phases window.

•

Select the work plane at y = 0.0 m.

•

Click on the geometry line corresponding to the basement wall. The Select Items window will pop up. Switch on the Wall option and click the OK button. This should activate the basement wall. An active wall is coloured blue; an inactive wall is coloured grey.

•

Activate all walls.

•

Click on a soil cluster enclosed by the walls. In the Select Items window, switch off the Soil below. It is not necessary to switch off the water, since the water starts at the level y = –2.0 m, which is just below the excavation. Click OK to close the Select Items window. The cluster will now be coloured white, to indicate it is switched off.

•

Switch off all clusters enclosed by the walls.

This completes the definition of the phase in which the construction of the walls and the excavation is modelled. To define the phase in which the construction of the floor and beams is modelled, follow these steps: Click the Next phase button. Keep all default phase information and click OK.

•

At y = 0.0 m, click at the vertical beam and switch on this option in the Select Items window to activate it. Close this window. The vertical beam will now colour dark purple to indicate it is active.

•

At y = -2.0 m activate all horizontal beams by clicking them once. The beams will now colour dark purple.

•

Activate all floor clusters by clicking them and switching them on in the Select Items window. The other options in this window should remain unaffected. The floor clusters will colour dark green.

3-33

TUTORIAL MANUAL Click the Next phase button. Keep all default phase information and click OK.

•

At y = -2.0 m click at one of the clusters loaded by a distributed load. In the Select Items window switch the Distributed load (horizontal plane) on and click the Change button.

•

In the Distributed Load (horizontal plane) window, set the y-value to -5.3 and all x- and z- values to 0. This indicates a load of 5.3 kN/m 2, acting in the negative y-direction.

• •

Repeat this action for all distributed loads.

•

Click the line load on one of the wall elements. Activate the Line load in the Select Items window and click the Change button.

•

In the Line Load (horizontal) window, set both y-values to -385, indicating a load of 385 kN/m acting in the negative y-direction. Repeat this operation for each individual line load.

At y = 0.0 m click the point load at (6.0, -6.0). Switch the Point load on in the Select Items window and click the Change button. In the Point Load window set the y-value to -11650, indicating a load of 11650 kN acting in negative ydirection. Close both windows by clicking OK.

Click the Preview button to check the definition of the calculation stages. For example, Figure 3.25 shows the preview of the last calculation phase.

Figure 3.25 Preview of last calculation phase

3-34


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) Click the Calculate button. This will start the calculation process. 3.3.3


•

Select in the Phase list combo box. Click the Output button to open the Output program. The deformed mesh at the end of this phase is shown. Make sure that all structural elements are visible by selecting this option in the Geometry menu.

•

Select the last phase in the Displayed step combo box to switch to the results at the end of the last phase. In order to evaluate stresses and deformations inside the geometry, select the Cross section tool. A top view of the geometry is presented and the Cross Section Points window appears. As the largest displacements appear under the column a cross section through this column is most interesting.

•

Enter (0.0, -6.0) and (75.0, -6.0) as the coordinates of the first point (A) and the second point (A’) in the Cross Section Points window. Click OK. A vertical cross section is presented. This cross section can be rotated in the same way as a regular 3D view of the geometry.

•

Select Total Displacements > uy from the Deformations menu (see Figure 3.26). The maximum and minimum values of the vertical displacements are shown in the title. When the title is not visible, select this option from the View menu.

Figure 3.26 Cross section of total vertical displacements

3-35

TUTORIAL MANUAL

•

Return to the 3D view of the geometry by selecting this window from the Window menu.

•

Generate a second cross section between the column and the wall through the points (0.0, -12.0) and (75.0, -12.0). Select Total Displacements > uy from the Deformations menu. The maximum vertical displacement will be less than in the cross section through the column.

•

Return to the 3D view of the geometry by selecting this window from the Window menu.

•

Double-click the floor. A separate window will appear showing the displacements of the floor.

•

To look at the bending moments in the floor, select M11 from the Forces menu. Select Shadings from the Presentation combo box (see Figure 3.27). To view the bending moments in tabulated form, click the Table button. A new window is opened in which a table is presented, showing the values of bending moments in each node of the floor.

Figure 3.27 Bending moments in the floor plate

3-36


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) 3.4

CASE C: PILE-RAFT FOUNDATION

As the displacements of the raft foundation are rather high, embedded piles will be used to decrease these displacements. These embedded piles are bored piles with a length of 20 m and a diameter of 1.5 m. Objectives: Adding embedded piles • • Defining embedded pile material set

•• •

Using ‘Reset Staged Construction’ Open already calculated project in Output Tile vertically in Output

3.4.1

GEOMETRY INPUT

The previous example is used to start from. Go back to the Input window, save the previous example, click the Model button to switch to the Model mode and select the Save as option from the File menu to save the project under another name (e.g. ‘Lesson 1c’).

Embedded Piles Geometry To construct the embedded piles, follow these steps:

•

Select y = -2.0 m from the Active work plane combo box. Select the Embedded pile button from the Model toolbar.

•

Position the cursor at (6.0, -18.0) and click once.

•

In the Embedded Pile window, set the Length to 20 m and press to accept this value. The position of the end point will be automatically updated (see Figure 3.28). Keep the Connection as Rigid to connect both rotations and displacements of the embedded pile top with the floor.

•

Click OK to close this window. The embedded pile is indicated by a circle with an internal + sign.

•

In the same manner, add embedded piles with a length of 20 m to (18.0, -18.0), (6.0, -6.0) and (18.0, -6.0). Hint: Instead of adding a material data set to an embedded pile afterwards, a material set can also be added when defining the embedded pile by clicking the Change button in the Embedded Pile window. This will open the Material Sets window with Embedded Pile as Set type. A new material data set can be created or an already existing data set can be selected. Clicking the OK button will automatically add this data set to the embedded pile. The name of this material data set will be shown in the Material set box of the Embedded Pile window.

3-37

TUTORIAL MANUAL

Figure 3.28 The Embedded Pile window

Embedded Pile Properties To create the material data set for the embedded pile, follow these steps: Open the Material Sets window by clicking on the corresponding button on the toolbar.

•

Set the Set type to Embedded Piles and click the New button. Enter ‘Pile Foundation’ as the Material set identification.

•

The pile behaviour is described by the stiffness properties of the pile itself as well as the bearing capacity of the pile with the surrounding soil at the skin and foot of the pile. Enter the properties as given in Table 3.5.

•

The value for the cross section area A and the moments of inertia I2, I3 and I23 are automatically calculated from the diameter of the massive circular pile (see Figure 3.29). Confirm the input by clicking OK.

•

Drag and drop the ‘Pile Foundation’ data set to the four embedded piles in the draw area. The embedded pile will change colour to indicate that the material set has been assigned successfully.

•

Close the Material Sets window by clicking the OK button.

3-38


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) Table 3.5 Material properties of the Pile Foundation (embedded pile) Parameter

Name

Pile Foundation 7

Unit

Young’s modulus

E

3·10

kN/m2

Weight

γ

6.0

kN/m3

Properties type

Type

-

Diameter

Diameter

Massive circular pile 1.5

Cross section area

Α

1.767

m2

Moment of inertia against bending around the third axis Moment of inertia against bending around the third axis Moment of inertia against oblique bending

I3

0.249

m4

I2

0.249

m4

I23

0

m4

Skin friction distribution

Type

Linear

-

Maximum traction allowed at the top of the embedded pile Maximum traction allowed at the bottom of the embedded pile Base resistance

Ttop,max

200

kN/m

Tbot,max 500 Fmax

m

kN/m 104

kN

Figure 3.29 The Pile Properties window.

3-39

TUTORIAL MANUAL

Mesh Generation As the geometry model is complete now, the mesh can be generated. Create the 3D mesh by clicking the Generate 3D mesh button. After viewing the mesh, click the Close button. No additional refinements are needed. 3.4.2


After generation of the mesh, all construction stages must be redefined. Even though in practice the piles will be constructed in another construction stage than constructing the walls, for simplicity both actions will be done in the same construction stage in this lesson. To redefine all construction stages, follow these steps:

•

Click the Calculation button to switch to the Calculation mode.

•

Open the Phases window and check if the K0 procedure is still selected as Calculation type for the initial phase.

•

Select the in the lower part of the Phases window and click the OK button.

•

At y = 0.0 m, activate all walls and switch off all soil clusters enclosed by the walls.

•

At y = -2.0 m, activate all embedded piles by clicking them once. The embedded piles will colour dark purple.

•

Open the Phases window and select in the lower part of this window. Click once with the right mouse button and select Reset Staged Construction. Click the OK button to close the Phases window. All settings of the phase ‘’ starts from (in this case ‘’) will now be copied to ‘’.

•

At y = -2.0 m, activate all floor clusters and all horizontal beams. At y = 0.0 m, activate the vertical column.

•

Open the Phases window and select the last phase. Click once with the right mouse button and select Reset Staged Construction to copy the settings of the previous phase. Click the OK button to close the Phases window.

•

At y = 0.0 m, activate the point load and set the load to 11650 kN in the negative y-direction. Activate all line loads and set the load to 385 kN/m acting in negative y-direction.

•

At y = -2.0 m, activate all distributed loads and set the load to 5.3 kN/m 2 acting in negative y-direction.

•

3-40

After inspecting the preview, click the Calculate button to start the calculation process.


FOUNDATION IN OVERCONSOLIDATED CLAY (LESSON 1) 3.4.3


To inspect the influence of the embedded piles on the settlement of the foundation, both output windows will be tiled next to each other. In order to do so, follow these steps:

•

Select the last phase in the Phase list combo box and click the Output button to go to the Output program. When more than one window is open in Output, minimize all other windows.

•

Click the Open project button from the toolbar or select this option from the

File menuselect to open the results of theand previous In thepart Open window, the previous project select project the last (Lesson phase in 1b). the lower of the window. Click the Open button.

•

In the Window menu, select the option Tile Vertically to present both results next to each other. When using embedded piles, the maximum displacement will be reduced with about 20 %.

•

For both projects, draw a cross section between the points (0.0, -12.0) and (75.0, -12.0) to see the influence of the embedded piles on the displacements at 6 m from the column.

•

Minimize all windows except both cross sections and tile these vertically by using this option from the Window menu. In this cross section, the maximum displacements will be reduced with about 50%.

Hint: Multiple windowsappear may be time menu. in the POutput program. (sub-) All windows in opened the list atof the thesame Windows LAXIS follows the Windows standard for the presentation of sub-windows (Cascade, Tile, Minimize, Maximize, etc). See your Windows manual for a description of these standard possibilities.

It is more convenient to compare both cross sections when both legends are equal. In order to do so, follow these steps:

•

Make sure that the legend is visible in both cross sections. If it is not visible, select this option from the View menu.

•

Click at the legend of the cross section of Lesson 1b. In the Legend window, select Manual scaling and enter Minimum value = -0.020, Maximum value = 0.120 and Number of intervals = 28. Click the OK button to confirm the input.

•

In the same manner, change the scaling of the legend of the cross section of Lesson 1c.

As both cross sections now have the same legend, it is easy to compare both results to see the influence of the embedded piles on the total displacements (see Figure 3.30).

3-41

TUTORIAL MANUAL

Figure 3.30 Cross sections at z = -12.0 m of the total displacements in the last phase.

3-42


EXCAVATION PIT (LESSON 2) 4

EXCAVATION PIT (LESSON 2)

This lesson describes the construction of an excavation pit in soft clay and sand layers. The pit is a relatively small excavation of 12 by 20 m, excavated to a depth of 6.5 m below the surface. Struts, walings and ground anchors are used to prevent the pit to collapse. After the full excavation, an additional surface load is added on one side of the pit.

(34, 12)

(41, 12)

(34, 19) (30, 20)

(41, 19)

50.0 m

Ground anchors

4.0 m 4.0 m (30, 32)

(50, 20)

Strut

4.0 m

(50, 32) 5.0 m 5.0 m 5.0 m 5.0 m

80.0 m

Figure 4.1 Top view of the excavation pit The proposed geometry for this exercise is 80 m wide and 50 m long, as shown in Figure 4.1. The excavation pit is placed in the centre of the geometry. An additional cluster for the surface load next to the pit is needed. Figure 4.2 shows a cross section of the excavation pit with the soil layers. The clay layer is considered to be impermeable. Objectives: Using the Hardening Soil model • • Adding ground anchors • Using interface properties

• • • • • •

Defining ratioset (OCR) Defining over-consolidation ground anchor material Defining vertical mesh coarseness Pre-stressing a ground anchor Changing water conditions Selection of stress points to generate stress/strain curves Viewing plastic points 4-1

TUTORIAL MANUAL y=0 y = -1

Fill

(30, 0)

(50, 0) Sheet pile walls

y = -4 Sand y = -6.5 (18, -9) y = -9.5 y = -11

(62, -9) Soft clay

Sand

y = -20

Figure 4.2 Cross section of the excavation pit with the soil layers

4.1

GEOMETRY INPUT

To create the geometry model, follow these steps:

General Settings

•

Start the Input program and select New project from the Create/Open Project dialog box.

•

In the Project tab sheet of the General Settings window, enter an appropriate title for the project and keep the other settings to their default.

•

In the Dimensions tab sheet, keep the standard units ( Length = m, Force = kN, Time = day) and enter for the dimensions Xmin = 0, Xmax = 80, Zmin = 0 and Zmax = 50. Keep the default values for the grid spacing ( Spacing = 1 m and Number of intervals = 1).

•

Click the OK button and the draw area appears.

Borehole In order to define the soil layers, a borehole needs to be added and material properties must be assigned. As all soil layers are horizontal, only a single borehole is needed. Click the Borehole tool button and add a borehole to (0.0, 0.0).

•

4-2

To change the level of the bottom boundary layer click in the table on the ycoordinate of this layer boundary and enter a value of -20.0 m.



•

The soil consists of four separate layers. It is therefore necessary to add 3 extra layer boundaries. Select the bottom layer boundary (y = -20.0 m) and click Insert three times to add three extra layer boundaries.

•

Click in the table on the y-coordinate of the second layer boundary. Enter a value of -1.0 m for this layer boundary.

•

In the same manner, change the other layer boundaries to -9.5 m and -11.0 m. The borehole information is shown in Figure 4.3.

•

Enter a value of y = -4.0 m for the Water level.


Soil and Interface Properties Click the Materials button and create a new material set. Write ‘Fill’ in the Identification box. From the Material model combo box, select Hardening soil model. In contrast with the Mohr-Coulomb model, the Hardening Soil model takes into account the difference in stiffness between virgin-loading and unloading-reloading. For a detailed description of the Hardening Soil model, see the Material Models Manual.

•

Add the remaining properties of the ‘Fill’ material in the General tab as listed in Table 4.1. As no consolidation will be considered in this exercise, the permeability of the soil will not influence the results. Therefore, the default values can be kept in the Permeability box.

4-3

TUTORIAL MANUAL Table 4.1 Material properties for the soil layers Parameter

Name

Fill

Sand

Soft Clay

Unit

Material model

Model

Hardening soil model



-

Material behaviour

Type

Drained

Drained

Drained

-

Unsaturated soil weight γunsat

16.0

17.0

16.0

kN/m3

Saturated soil weight

20.0

20.0

17.0

kN/m3

Secant stiffness for CD E ref 50 triaxial test

22000

43000

2000

kN/m2

Tangent stiffness

oedometer E ref oed

22000

43000

2000

kN/m2

reloading E ref ur

66000

129000

10000

kN/m2

0.5

0.5

1.0

-

Unloading/ stiffness

γsat

Power for stress-level m dependency of stiffness Cohesion

cref

1

1

5

kN/m2

Friction angle

φ

30

34

25

°

Dilatancy angle

ψ

0

4

0

°

Poisson’s constant

νur

0.2

0.2

0.2

-

0.65

0.7

0.5

-

1.0

1.0

1.5

-

0.5

0.441

0.741

-

Interface factor

reduction Rinter

Over-consolidation ratio

OCR

Lateral earth pressure K0 coeff.

ref

•

ref

ref

In the Parameters tab sheet, enter values for E 50 , E oed , E ur , m, cref, φ and ψ according to Table 4.1. To check Poisson’s ratio, click the Advanced button. Hint: The Tension cut-off option is activated by default at a value of 0 kPa. This option is found in the Advanced options on the Parameters tab sheet of the Soil material data set window. Here the Tension cut-off value can be changed or the option can be deactivated entirely.

4-4



•

In the Interfaces tab sheet, select Manual in the Strength box and enter a value of 0.65 for the parameter Rinter. This parameter relates the strength of the soil to the strength of the interfaces, according to the equations:

ci = Rinter csoil

and

tanϕi = Rinter tanϕsoil ≤ tanϕsoil

Hence, using the entered Rinter-value gives a reduced interface friction and interface cohesion (adhesion) compared to the friction angle and the cohesion in the adjacent soil. The default value Rinter = 1.0 (rigid) will give ci = csoil and ϕi = ϕsoil. A more detailed description is given in the Reference Manual.

•

Click OK to close the window.

•

In the same way, define the material properties of the ‘Sand’ and ‘Soft Clay’ material as given by Table 4.1.

•

Assign the ‘Fill’ material to upper soil layer. Assign the ‘Soft Clay’ material to the soil layer between y = -9.5 m and y = -11.0 m. Assign the ‘Sand’ material to the remaining two soil layers.

•

Click the OK button to close the Material Sets window.

•

In the Soil tab of the Borehole window, enter the corresponding OCR values and K0 values as given by Table 4.1. Close the Borehole window.

Sheet Pile Wall Geometry As a wall is only created between two adjacent work planes, it is more convenient to create the wall and add its material data set first before inserting additional work planes. To create the sheet pile wall, follow these steps: Select the Wall option from the toolbar. Draw a wall by clicking at the coordinates (30.0, 20.0), (30.0, 32.0), (50.0, 32.0) and (50.0, 20.0). Return to position (30.0, 20.0) and click once to close the wall. Click the right mouse button to stop drawing.

Wall Properties To define the material data set of the sheet pile wall, follow these steps:

•

Select the Walls option from the Materials menu or open the Material Sets window and select Walls as Set type. Create a new material set for the sheet pile wall. The properties are given in Table 4.2. In creating the material data set for the sheet pile wall, the geometrical orthotropy of the sheet piles is converted into orthotropic Young’s and shear moduli for the wall material data set. Using E1 = 12 Esteel I1 / d 3 the moment of inertia of the sheet pile wall as supplied by the manufacturer can be converted to a representative Young’s modulus. Similar relations hold for the other directions. See Chapter 6 of the Material Models Manual for more details and an example for a sheet pile wall.

4-5

TUTORIAL MANUAL Table 4.2 Material properties for the sheet pile walls Parameter

Name

Sheet Pile Wall

Unit

Type of behaviour

Type

Linear, non-isotropic

-

Thickness

d

0.379

m

Volumetric weight

γ

2.55

kN/m3 7

kN/m2

Young’s modulus

E1

1.46·10 5

2

Shear modulus

E2 G12

7.3·105 7.3·10

kN/m2 kN/m

G13

1.27·106

G23

5

3.82·10

kN/m

ν

0.0

-

Poisson’s ration

kN/m2 2

A wall drawn in one action is considered as a group as long as no additional points are created on the wall. Groups can also be defined by the user and can be used to modify the properties of all components of this group at once. More information about grouping is given in Section 3.2 of the Reference Manual. To add a material data set to a group, following these steps:

•

If the Material Sets window partially obscures the wall, drag the window aside such that the full wall is visible. Select the tool fromclick the toolbar. While holding downwhole the or keySelection on the keyboard, somewhere at the wall. The wall will colour red to indicate that all wall elements are selected.

•

Assign the material data set for the walls to the wall.

•

Close the Material Sets window by clicking the OK button.

Work Planes Open the Work Planes window and select the work plane at y = -3.0 m. This work plane has automatically been created when drawing the wall. Change the y-coordinate to y = -11.0 m.

•

•

•

4-6

Three extra work planes are necessary between y = 0.0 m and y = -11.0 m. Select the work plane at y = -11.0 m and click the Insert button three times to insert work planes between the currently selected work plane and the one above. Change the y-value of the work plane at y = -5.5 m to -9.5 m, the y-value of the work plane at y = -2.75 m to -6.5 m and the y-value of the work plane at y = 1.375 m to -1.0 m. Click OK to close the Work Planes window.



Remaining Geometry Make sure the work plane at y = -1.0 m is selected. Select the Horizontal beam tool. To define the waling click once at the coordinates (30.0, 20.0), (30.0, 32.0), (50.0, 32.0) and (50.0, 20.0). Return to position (30.0, 20.0) and click once to close the waling. Click the right mouse button to stop drawing.

•

In order to define the first strut, click once at position (35.0, 20.0) and at position (35.0, 32.0). Click the right button to stop drawing.

•

In the asame a strutand between (40.0, 20.0) and (40.0, 32.0) and define strut manner, between define (45.0, 20.0) (45.0, 32.0). Select the Ground anchor option from the Model toolbar. Click at the coordinate (30.0, 24.0) and the Ground Anchor window will appear (see Figure 4.4). In the End box, change the value of X to 18.0 and the value of Y to -9.0. The values in the Direction box as well as the value of the total length L in the Length box will be automatically updated. In the Length box, change the value of Lgrout to 5.0 m and click the OK button to close the window. The ground anchor is indicated by a circle with an internal black cross.

•

In the same manner, add ground anchors to (30.0, 28.0), (50.0, 24.0) and (50.0, 28.0). At x = 30.0 m enter X = 18.0 and Y = -9.0 in the End box. Leave the value of Z unaffected. At x = 50.0 m enter X = 62.0 and Y = -9.0 in the End box. The length of the grout body should be 5.0 m for all ground anchors.

Figure 4.4 The Ground Anchor window

Beam Properties Like the soil layers, material data sets have to be defined for the structural elements. To define the material data sets of the beams, follow these steps: 4-7

TUTORIAL MANUAL

•

Select the Beams option from the Materials menu or open the Material Sets window and select Beams as Set type.

•

Create the material data sets for the struts as well as the waling as given in Table 4.3.

•

Assign the material set ‘Strut’ to the struts and the material set ‘Waling’ to the walings in the work plane at y = -1.0 m.

Table 4.3 Material properties for the beams Parameter

Name

Strut

Waling

Type of behaviour

Type

Linear

Linear

Cross section area

A

0.007367

0.008682

m2

Volumetric weight

γ

78.5

78.5

kN/m3

8

Unit

8

kN/m2

Young’s modulus

E

2.1·10

Moment of Inertia

I3

5.073·10-5

1.045·10-4

m4

I2

-5

5.073·10

3.668·10

-4

m4

I23

0.0

0.0

2.1·10

m4

Ground Anchor Properties

•

In the Material Sets window select Ground Anchors as the Set type and click the New button to create a new material set.

•

In the Ground Anchor Properties window, enter the ground anchor properties as given in Table 4.4 (see Figure 4.5).

•

In creating the material data set for the grout body part of the ground anchors, the material properties of the anchor running through the grout body and the grout body itself must be converted to a representative Young’s modulus and diameter of the grout body. See the Material Models Manual for a more detailed description about this.

Table 4.4 Material properties for the ground anchors Parameter

Name

Ground Anchor Unit

Material type

Type

Elastic

-

Axial stiffness Young’s modulus

EA E

6.5·105

m2 kN/m2

Diameter of the grout body

Diameter 0.14

Skin resistance at top of grout body

Ttop,max

Skin resistance at bottom of grout body Tbot,max

4-8

7

4.3·10

m

200.0

kN/m

0.0

kN/m



•

Assign the material set to all ground anchors. The ground anchors will change colour from light orange to dark orange to indicate that the material set has been assigned successfully.

•

Click OK to close the Material Sets window.

Figure 4.5 The Ground Anchor Properties window

Load To define the distributed load next to the excavation pit, follow these steps:

•

Change the Active work plane to y = 0.0 m. Select the Geometry line option from the Model toolbar. Draw a geometry line through the coordinates (34.0, 19.0), (41.0, 19.0), (41.0, 12.0) and (34.0, 12.0). End at (34.0, 19.0). A new cluster has been generated. Select the Distr. load horizontal plane option from the toolbar and click once in the generated cluster to add the load.

Mesh Generation The mesh for this example will be of medium coarseness, with a further refinement of the excavated clusters. To generate this mesh, follow these steps:

•

From the Mesh menu, select Global Coarseness. In the Mesh Generation Setup window, set the horizontal as well as the vertical element distribution to 4-9

TUTORIAL MANUAL

Medium. This will give a finer mesh in horizontal as well as in vertical direction. Click the Generate button to generate the 3D mesh.

•

The generated 3D mesh is still too coarse in the excavation pit and under the distributed load. To refine the mesh, click the Close button to return to the Input window.

•

While holding down the key or key for multi-selection, select all clusters in the excavation and under the distributed load. In the Mesh menu, select the Refine Cluster option. The 2D mesh will now show a finer mesh in these clusters.

•

Close the 2D mesh and click the Generate 3D mesh button to generate the 3D mesh (see Figure 4.6).

•

Click the Calculation button to proceed to the Calculation mode. Save the project under an appropriate name.

Figure 4.6 Preview of the generated 3D mesh 4.2


The calculation consists of 6 phases. The initial phase will consist of the generation of initial stresses using the K0 procedure. The next phase will consist of the installation of the sheet piles and a first excavation. Then, the walings and struts will be installed. In phase 3 the ground anchors will be activated and pre-stressed. Further excavation will be performed in the phase after that. The last phase will be the application of the additional load next to the pit.

4-10



•

Open the Phases window and change the Calculation type of the first phase to K0 procedure. In the Parameters tab, check the K0 values and OCR values as given in Table 4.1.

Defining Construction Stages To define the other calculation stages, follow these steps: Click the Next button to add a new phase. Leave the Calculation type to Plastic and keep the default settings for the Iterative procedure in the Parameters tab sheet. Click the OK button to close the Phases window.

•

Check that in the Phase list combo box is selected.

•

At y = 0.0 m click at a cluster in the excavation pit and turn off the Soil below option in the Select Items window to switch off the soil. It is not necessary to switch off the water as the water starts at a lower level. In the same manner, deactivate all clusters in the excavation pit between y = 0.0 m and y = -1.0 m. The clusters will colour white to indicate that they have been deactivated.

•

Activate all walls between y = 0.0 m and y = -11.0 m by just clicking them once. If necessary, switch on the Wall option in the Select Items window. Click the Next phase button. In the Phases window keep all default phase information and click the OK button.

•

At y = -1.0 m activate all walings and struts. Click the Next phase button. Keep all default phase information and close the window.

•

At y = -1.0 m double click a ground anchor. A Ground Anchor window appears with the pre-stress option. Select the Adjust prestress box and enter a Prestress force of 200 kN. Click OK to close the window. In the same manner activate and adjust the pre-stress force of all ground anchors. Hint: A pre-stress force is exactly matched at the end of a finished staged construction calculation and turned into an anchor force. In successive calculation phases the force is considered to be just an anchor force and can therefore further increase or decrease, depending on the development of the surrounding stresses and forces.

Click the Next phase button. Keep all default phase information and close the window.

•

At y = -1.0 m, switch off the soil clusters as well as the water in the excavation pit. This simulates the dry excavation of the pit.

•

At y = -6.5 m click at one of the clusters in the excavation pit. In the Select Items window select Water below and click the Change button.

4-11

TUTORIAL MANUAL

•

In the Cluster Pore Pressure Distribution window select User defined pore pressure distribution and select the option Cluster phreatic level. Change the value of yref to -6.5 m to simulate a cluster phreatic level at y = -6.5 m (see Figure 4.7). Close both windows by clicking OK.

•

Repeat this for the other three clusters inside the excavation.

Figure 4.7 The Cluster Pore Pressure Distribution window

•

Select the work plane at y = -9.5 m. As the clay layer is almost impermeable the pore pressures distribution can be interpolated between the cluster above the clay layer and the cluster below the clay layer. To simulate this behaviour select one of the clusters in the excavation pit, select the Water below option in the Select Items window and click the Change button. In the Cluster Pore Pressure Distribution window select the Interpolate from adjacent clusters or lines option. Close both windows and repeat this for the other clusters inside the excavation. To check the pore pressures definition, click the Preview button. From the Stresses menu choose Pore pressures > psteady. Select the Cross section tool. Click somewhere around position (0, 0, 25). The position is indicated by the status bar at the bottom of the window. While holding down the key, move the cursor to the other side of the geometry.

• •

Select Contour Lines in the Presentation options combo box. Make sure that the option Legend is checked in the View menu. If necessary, an appropriate scan line can be defined by selecting this option in the Edit menu. Select the Zoom in button and zoom to the soil below the excavation to get a better view (see Figure 4.8). Return to the Input window by clicking the Close button.

4-12


EXCAVATION PIT (LESSON 2) Click the Next phase button. Keep all default phase information and close the window.

•

At y = 0.0 m, activate the distributed load and click the Change button. Change the Y-value of the force to -20 kN/m2 and close both windows. Hint: To check whether the calculation stage has been defined correctly, click the Preview button. This will present a 3D view of the geometry. This can be used to check which clusters are active and what material properties have been assigned to clusters.

Figure 4.8 Preview of the steady state pore pressures in in a cross section. Before starting the calculation process, some stress points next to the excavation pit and loading have to be selected in order to be able to plot a stress strain curve later on. Click the Select points for curves button to open the Output program. Nodes and stress points can be selected by just clicking them, but they can also be selected by their coordinates. To use the latter option, choose the Mesh Point Selection option from the Edit menu. In the Point-of-interest coordinates box, enter X = 37.5 m, Y = -1.5 m and Z = 19 m and click the Search closest node and stress point button. Click the Select stress point button to select this stress point. The selected stress point will be shown in the Selected Stress Points list box in the Output window.

•

Select also stress points near the coordinates (37.5, -5, 19), (37.5, -6, 19) and (37.5, -7, 19) and close the Mesh Point Selection window. Close the Output window by clicking the Update button. 4-13

TUTORIAL MANUAL

•

Click the Calculate button to start the calculation process. Hint: Instead of selecting nodes or stress points for curves before starting the calculation, points can also be selected after the calculation when viewing the output results. However, the curves will be less accurate unless the Delete intermediate steps has been deselected for each phase in the Phases window. To plot curves of structural forces, nodes can only be selected after the calculation.

>

>

4.3

Nodes or stress points can be selected by just clicking them. When moving the mouse the exact coordinates of the position are given in the status bar at the bottom of the window. When moving the mouse over a node or stress point, the number of this point will also appear in the status bar. When it is desired to select a node or stress point at a certain position, select the Mesh Point Selection option from the Edit menu and enter the coordinates of this point. The closest node and stress point will be given when the appropriate button has been clicked.


After the calculations, the results of the excavation can be viewed by selecting a calculation phase from the Phase list combo box and pressing the Output button.

•

Select the final calculation phase and click the Output button. The Output program will open and shows the deformed mesh at the end of the last phase. The stresses and deformations in the work planes and 3D geometry can be viewed by clicking on the corresponding tabs and selecting the desired output from the menu. For example, choose Plastic Points from the Stresses menu to investigate the plastic points in the model (see Figure 4.9). In the Plastic Points window, select all options except the option Stress points.

•

Click at a part of the wall to select this part. Press - simultaneously on the keyboard to select all wall elements. The selected wall elements will colour white. While holding the key or key on the keyboard double click at one of the wall elements to see the deformations plane of the total displacements |u| in all wall elements. To generate a curve, select the Curves Manager tool from the toolbar or the Curves option from the File menu. In the Curve points tab of the Curves

Manager window all pre-selected stress points are shown. In the Charts tab click the New button to create a new chart.

•

4-14

In the Curves Generation window select Strain in the X-axis box. Keep point K as the selected point and change Type to ε1. Select Stress in the Y-axis box, keep point K as the selected point and change Type to σ’1. Click OK to confirm the input.



Figure 4.9 Plastic points at the end of the final phase The graph will now show the major principal strain against the major principal stress. Both values are zero at the beginning of the initial conditions. After generation of the initial conditions, the principal strain is still zero whereas the principal stress is not zero anymore. To plot the curves of all selected stress points in one graph, follow these steps: • Select Add Curve from Current Project from the Edit menu.

•

In the Curve Generation window, select point L in the X-axis box. This point will be automatically selected in the Point combo box in the Y-axis box.

•

Click OK to generate the curve.

•

Generate curves for point M and N in the same way.

•

To flip the chart horizontal as well as vertical, choose Chart Settings from the Format menu or choose this option from the right mouse button menu. In the Chart Settings window select both Flip horizontal as well as Flip vertical and click OK.

The graph will now show the stress strain curves of all four stress points (see Figure 4.10). To see information about the markers, make sure the Value Indication option is selected the Viewinmenu and hold the mouse on apoint marker for graph, a while. about thefrom coordinates the graph, the number of the in the theInformation number of the phase and the number of the step is given. Especially the lower stress points show a considerable increase in the stress when the load is applied in the last phase.

4-15

TUTORIAL MANUAL

Hint: To re-enter the Curve Generation window (in the case of a mistake, a desired regeneration or a modification) the Curve Settings option from the Format menu can be selected. As a result the Curves Settings window appears, on which the Regenerate button should be clicked. > The Chart Settings option in the Format menu may be used to modify the settings of the chart.

y ≈ -7.0 m

y ≈ -5.0 m y ≈ -6.0 m

y ≈ -1.5 m

Figure 4.10 Stress – strain curve

4-16


LOAD CAPACITY OF A SUCTION PILE (LESSON 3) 5

LOAD CAPACITY OF A SUCTION PILE (LESSON 3)

In this lesson a suction pile in an off-shore foundation will be considered. A suction pile is a hollow steel pile with a large diameter and a closed top, which is installed in the seabed by pumping water from the inside. The resulting pressure difference between the outside and the inside is the driving force behind this installation. In this exercise the length of the suction pile is 10 m and the diameter is 4.5 m. An anchor line is attached on the side of the pile, 7 m from the top. To avoid local failure of the pile the thickness of the tube where the anchor line acts on the pile is increased. The soil consists of silty sand. To model undrained soil behaviour, an undrained effective stress analysis with undrained strength parameters will be performed (see Section 2.6 of the Material Models Manual). This exercise will investigate the displacement of the suction pile under working load. Four different angles of the working load will be considered. The installation process itself will not be modelled. The geometry for the problem is sketched in Figure 5.1. Objectives: • Adding piles Undrained effective stress analysis with undrained strength parameters • Soil cohesion increases with depth • Copying material data sets • • Changing settings in Output Selecting a node after calculation to generate a curve with structural forces • y

x

y = -6.5 m

α

y = -7.5 m

y = -7.0 m

y = -10 m

4.5 m

Figure 5.1 Geometry of the suction pile

5-1

TUTORIAL MANUAL 5.1

GEOMETRY

An area of 60 m wide and 60 m long surrounding the suction pile will be modelled. With these dimensions the model is sufficiently large to avoid any influence from the model boundaries.

General Settings To enter the geometry for this exercise, follow these steps:

•

Start the Input program and select New project from the Create/Open Project dialog box.

•

Enter an appropriate title for the exercise.

•

Keep the standard units and set the model dimensions to Xmin = -30 m, Xmax = 30 m, Zmin = -30 m and Zmax = 30 m. Keep the default settings for the spacing and enter 4 in the Number of intervals box.

•

Click OK and the draw area appears.

Borehole In the current example only one soil layer is present and only a single borehole is needed. Add a borehole to the geometry and change the y-value of the bottom layer boundary to -30 m.

•

Change the water level to 50.0 m. Open the Material Sets window and create the data set given in Table 5.1. As no consolidation will be considered in this exercise, the permeability of the soil will not influence the results. Instead of using effective strength properties, the cohesion parameter will be used in this example to model undrained shear strength (see Section 2.6 of the Material Models Manual). Advanced parameters can be entered after clicking the Advanced button in the Parameters tab.

•

Assign the material data set to the soil layer and close the Material Sets window.

•

Enter the K0 value according to Table 5.1 in the Soil tab sheet and close the Borehole window.

5-2


LOAD CAPACITY OF A SUCTION PILE (LESSON 3) Table 5.1 Material properties of the sand layer and its interface. Parameter

Name

Sand

Unit

Material model

Model

Mohr-Coulomb

-


Type

UnDrained

-

Soil weight

γunsat 20 , γsat

Young’s modulus

Eref

1000

kN/m2

Poisson’s ratio

ν

0.35

-

Cohesion (constant)

cref

0.1

kN/m2

Friction angle

φ

0.0

°

Dilatancy angle

ψ

0.0

°

Increase of stiffness

Eincrement

1000

kN/m2/m

Reference level

yref

0.0

m

Increase of cohesion

cincrement

4.0

kN/m2/m

Interface strength reduction

Rinter

0.7

-

Lateral earth pressure coeff.

K0

0.5

-

3

kN/m

Pile Geometry As the pile will cross several work planes, it is more convenient to draw the pile before adding work planes. Click the Pile button on the toolbar to open the Piles dialog (see Figure 5.2).

Figure 5.2 The Piles window 5-3

TUTORIAL MANUAL

•

Keep the pile type on the default option of a Circular tube in order to create a hollow steel pile.

•

Leave the thickness of the pile to 0.0 m, as the steel pile will be modelled as a shell element only. Enter a value of 4.5 m in the Diameter box.

•

Make sure the options Shell, Outside interface and Inside interface are all checked.

It is possible to add a material data set to the shell at once. In this example, the shell of the pile consists material data sets: one with thickness 0.15 m data and one withbe a thickness of 0.05ofm.two Both material data sets will be acreated, butof only one set will added to the pile immediately. The other data set will be added after the definition of additional work planes.

•

Click the Materials button and create a new material data set. Enter the properties of the ‘Thin Wall’ given in Table 5.2 and click the OK button to confirm the input.

•

Select the created wall data set in the Material Sets window and click the Copy button to copy this data set. This will open a new dialog box with the same properties as already defined for the ‘Thin Wall’ material data set.

•

Enter ‘Thick Wall’ in the Material set identification box and change the value of the thickness d to 0.15 m. Click OK to confirm the input.

Table 5.2 Material properties for the suction pile Parameter

Name

Thin Wall

Thick Wall

Top

Unit

Type of behaviour

Type

Linear, isotropic

Linear, isotropic

Linear, isotropic

-

Thickness

d

0.05

0.15

0.05

m

Weight

γ

58.5

58.5

68.5

Young’s modulus

E

8

8

kN/m3 8

kN/m2

2.1·10

2.1·10

2.1·10

Shear modulus G

9.545·107

9.545·107

9.545·107

kN/m2

Poisson’s ratio ν

0.1

0.1

0.1

-

•

In the Material Sets window, select the ‘Thin Wall’ data set and drag and drop this to the wall in the Piles window. The wall will change colour to indicate that the material data set has been assigned successfully. The ‘Thick Wall’ material set will be used later.

•

Close the Material Sets window.

A pile is composed of different Sections. Using the left and right arrows at the bottom right of the Section box, one can switch between the different sections. Alternatively, clicking on a section in the preview of the pile will select the clicked section.

5-4



•

Change the Angle of Section 1 to 45°. Proceed to Section 2 and also change the angle to 45°. Proceed to Section 3. Note that the Angle has automatically increased from the default angle of 60° to 90° as a result of the changes in sections 1 and 2. Change the angle for section 3 also to 45°. A new section is automatically added to complete the circle.

•

Now all 4 (8) sections should have a 45° angle, and should all have a shell (in the figure indicated by a thick blue line), an inside interface and an outside interface (in the figure indicated by dashed lines) present.

• •

Click OK to close the pile designer. Move the cursor to (0.0, 0.0) and click once to place the pile in the geometry model. This will automatically insert a work plane at y = -3.0 m. As the length of the pile is 10 m, the level of this work plane has to be modified. Hint: The point where the pile is inserted in the work plane is called the pile reference point. An existing pile may be edited by double clicking the pile reference point. As a result, the pile designer appears in which the existing pile is presented.

Open the Work Planes window and change the level of the bottom work plane to y = -10.0 m.

•

Select the work plane at y = -10.0 m and insert a work plane at y = -7.5 m and y

•

= -6.5 m. The work plane at y = -7.0 m will be added later on. Close the window.

The whole pile has now a thickness of 0.05 m, whereas the pile between y = -6.5 m and y = -7.5 m should have a thickness of 0.15 m. In order to change these material properties, follow these steps:

•

Select the work plane at y = -6.5 m. Select the Zoom in tool from the toolbar and zoom in around the pile. Select the Selection tool from the toolbar. While holding the or button double click the wall and select the appropriate option from the Select window. In the Wall window click the Change button and select the ‘Thick Wall’ data set. Click the OK button to close the Material Sets window. ‘Thick Wall’ will be shown in the Material set box of the Wall window. Click OK to close the window.

Floor To close the top of the suction pile, a floor element is used. To add this element, follow these steps:

5-5

TUTORIAL MANUAL

•

Select the work plane at y = 0.0 m. Select Floor in the toolbar and add a floor to the inside of the suction pile.

•

Open the Material Sets window by clicking the appropriate button from the toolbar and select Floors as the Set type.

•

Create a new material data set and enter the properties of the ‘Top’ as given in Table 5.2.

•

Drag and drop this material set to the floor cluster. Close the Material Sets window.

Anchor Load To introduce the anchor load 7.0 m below the top of the suction pile, another work plane is needed. To add the load, follow these steps:

•

Open the Work Planes dialog and select the work plane at y = -7.5 m.

•

Click Insert to add a new work plane. A new work plane will appear at

y = -7.0 m.

•

Close the Work Planes dialog. Hint: The work plane at y = -7.0 m was not added earlier, as this would complicate

modifying the pile properties. When the work plane had been added before, the material data set of the pile should have been changed in two work planes instead of one. Select the work plane at y = -7.0 m. Select Point load on the toolbar and add a point load at (2.25, 0.0), the rightmost point of the pile.

Mesh Generation In order to limit the mesh refinement during mesh generation to the area immediately surrounding the suction pile, an additional soil cluster will be created. In order to do so, follow these steps:

•

Select the Reset View option from the View menu to restore the full draw area.

•

Select Geometry line from the toolbar and draw a cluster with corner points (10.0, -10.0), (-10.0, 10.0), (10.0, 10.0) and (10.0, -10.0). Hold the key to draw a perfectly horizontal or vertical line. Close the cluster by clicking on the first corner and stop drawing.

This completes the geometry definition and material parameters input. In order to generate the mesh:

5-6



•

Select the Selection tool from the toolbar and select the cluster surrounding the pile. Select Refine Cluster from the Mesh menu and click Close to return to the main window.

•

Refine the cluster surrounding the pile once more (see Figure 5.3).

•

Select Global Coarseness in the Mesh menu and change the Vertical element distribution to Medium. Click Generate to generate the 3D mesh.

•

Close the Output window and go to the Calculation mode by clicking the

Calculation button.

Figure 5.3 Refining the cluster surrounding the suction pile 5.2

CALCULATIONS

The calculation for this exercise will consist of six phases. These are the determination of initial conditions, the installation of the suction pile and four different load conditions.

Initial conditions and suction pile installation

As the soil layers are completely horizontal, the K0 procedure option will be used to determine initial stresses. Open the Phases window and set the Calculation type to K0 procedure. In the Parameters tab sheet, check the K0 values as given in Table 5.1.

5-7

TUTORIAL MANUAL To model the installation of the suction pile, follow these steps:

•

Press Next to add a new calculation phase. Switch to the Parameters tab sheet and check the Ignore undrained behaviour option. Leave all other settings at their default values and click OK to return to the main window.

•

Zoom in around the suction pile by using the Zoom in tool from the toolbar.

•

Select the work plane at y = 0.0 m. Activate the floor cluster by clicking it once and selecting the appropriate option from the Select Items dialog. The floor

should be coloured green. As the suction pile in one work plane can be considered as a group, the whole group can be activated at once.

•

While holding the key or key, click on the wall of the suction pile to activate it. It should be coloured blue, indicating the wall is active.

•

Select the work plane y = -6.5 m and in the same manner activate the suction pile wall in this work plane. Leave the soil inside the suction pile active.

•

In the same manner, activate the suction pile wall in the work planes y = -7.0 m and y = -7.5 m. Now add another calculation phase. On the Parameters tab sheet, check the option Reset displacements to zero.

•

In the work plane y = -7.0 m, double click the point load at (2.25, 0.0). It is represented by a grey circle. Select Point load from the Select window that appears.

•

In the Point Load window, set the X-value and the Y-value according to in Table 5.3. The applied loading conditions are defined such that the total load is 4500 kN in each calculation phase. The only difference is the direction of this load.

•

Click OK to close the window. The load should now be represented by a blue arrow. If it is not active (i.e. coloured grey), click once at the point (2.25, 0.0) to activate the load.

•

Add another calculation phase. On the General tab sheet, set Start from phase to 1 - . On the Parameters tab sheet, select Reset displacements to zero.

•

Activate the point load and change its properties according to in Table 5.3.

•

Define the last two phases in the same manner. Let both phases start from phase 1 and select the option Reset displacements to zero in the Parameters tab sheet. Activate the point load and change its properties according to the corresponding phase in Table 5.3.

5-8


LOAD CAPACITY OF A SUCTION PILE (LESSON 3) Table 5.3 X-value and Y-value of point load Load Phase

Direction of load

X-value

Y-value

30°

3897 kN

2250 kN

40°

3447 kN

2893 kN

50°

2893 kN

3447 kN

60°

2250 kN

3897 kN

This concludes the input of the calculation phases. To start the calculation: Click the Calculate button to start the calculation.

5.3


To view the results:

•

Select the last phase and click the Output button. The deformed mesh of the whole geometry will be shown.

In particular, the displacements of the suction pile itself are of interest. To select the pile, follow these steps:

•

If necessary, deselect Materials and Interfaces from the Geometry menu to make the suction pile visible. Hint: Clusters or material sets of the soil can be partly or totally made invisible by choosing the option Partial Geometry from the Geometry menu in the Output program.

•

Click somewhere at the pile wall. This will only select a part of the wall. Press + to select all wall elements of the suction pile.

•

From the right mouse button menu, select Structures to open the results of the wall of the suction pile in a new window.

•

Select Shadings from the Presentation options combo box and rotate the model such that the x-axis is perpendicular to the screen (see Figure 5.4). If the axes are not visible, select this option from the View menu. It is quite clear to see that the point force acting the pile doesthick not disturb indicating that the pileon is sufficiently here. the displacement field locally

•

In the same manner, the total displacements of the suction pile under a different direction of the load can be inspected by selecting the appropriate phase from the Displayed step combo box. In particular, is of interest, as in this phase the horizontal part of the load will have the largest value.

5-9

TUTORIAL MANUAL

Figure 5.4 Total displacements of the suction pile at the end of . To view the curve of the total displacements of the pile, a node has to be selected. To select a node, follow these steps: Zoom in to the model by using the Zoom in option from the toolbar. •

•

Activate the nodes by selecting Nodes from the Geometry window. If the nodes overlap each other, their size can be reduced by selecting Settings from the View menu and moving the arrow of the Symbol Size in the Settings window to the left. Click OK to confirm the input.

•

Move the mouse to the node at the coordinate (2.25, -7.0, 0.0). This is the place where the point load acts. If necessary, the Hint Box in the View menu can be selected. Moving the mouse over a point will now give the coordinates of this point in a hint box.

•

From the right mouse button menu select the first node from the Select for Curves sub-menu. In case of displacements, the same curve will be plotted independent of the wall element the node is selected in. In case of forces, the curve does depend on the wall element the node is selected in. This is due to extrapolation of the forces in the stress points of an element to the nodes. Select the Curves Manager option from the toolbar or the Curves option from the File menu. In the Curves Manager window click the New button in the Charts tab to create a new chart.

5-10



•

In the Curve Generation window, keep Displacement in the X-axis box and change the Type to ux. Select Displacement in the Y-axis box and keep the total displacement |u| as the type of displacement along the y-axis. Click the OK button to generate the curve.

The curve shows the horizontal displacements in x-direction against the total displacements (see Figure 5.5). As the direction of the point load increases with each calculation phase, resulting in a decreasing force in x-direction and an increasing force in y-direction, it is to be expected that the displacement in x-direction will decrease. The curve also shows that the total displacement slightly decreases when the direction of the load increases.

Figure 5.5 Horizontal displacements – total displacements curve In addition to the displacement curve, a curve of structural forces will be generated. To do so, follow these steps:

•

Start a new chart in the Curves Manager window. Select Structural Force in the X-axis box as well as the Y-axis box. Select Axial N 2 as Type in the x-direction and select Axial N1 in the y-direction. The structural force N1 is the normal force in the longitudinal direction of the pile wall, whereas the structural force N 2 is the normal force in the circumferential direction of the pile wall.

•

Click the OK button to generate the curve (see Figure 5.6).

5-11

TUTORIAL MANUAL When the direction of the load increases, resulting in a larger force in y-direction, the axial force in the longitudinal direction as well as the axial force in the circumferential direction of the pile wall will decrease.

Figure 5.6 Normal force in circumferential direction – normal force in longitudinal direction curve

5-12


SAFETY ANALYSIS OF AN EMBANKMENT (LESSON 4) 6

SAFETY ANALYSIS OF AN EMBANKMENT (LESSON 4)

After the construction of an embankment on soft soil with a high ground water level, an additional load will be applied very fast. As a result of the ‘undrained behaviour’ of the soil the effective stresses remain low resulting in a low shear strength. A consolidation period is necessary to let the excess pore pressures dissipate so that shear strength of the soil can increase. The undrained behaviour of the soil will be modelled by an undrained effective stress analysis with effective parameters instead of undrained strength parameters, as used in Lesson 3. An undrained effective stress analysis with effective parameters will give a realistic prediction of pore pressures and can be followed by a consolidation analysis. This lesson concerns the safety analysis of the embankment. A safety factor by means of phi/c-reduction will be calculated for three situations, i.e., when no load has been applied yet, immediately after applying the load and when a consolidation period has been considered. The proposed geometry is 90 m long and 30 m wide. The embankment is 4.0 m high. The slope at the left has an inclination of 1:4 and the slope at the right has an inclination of 1:3. Figure 6.1 shows the geometry of the embankment. Objectives: Undrained effective stress analysis with effective parameters • Non-horizontal ground surface • Non-hydrostatic water conditions •

• • • • • • •

Triangulate (mesh option) Mesh refinement of lines Gravity loading Consolidation Phi/c reduction Viewing excess pore pressures Viewing incremental displacements

25 kN/m2 Embankment

4m

24 m 6m

10 m

Clay

16 m

16 m

m1 44 mm2

38 m

Figure 6.1 Geometry and dimensions of the embankment

6-1

TUTORIAL MANUAL 6.1

GEOMETRY INPUT

The proposed geometry for this exercise is 90 m long and 30 m wide. As the ground surface is non-horizontal, first some geometry lines have to be added to be able to define this ground surface.

•

After entering the general settings for this exercise, add a geometry line between (16.0, 0.0) and (16.0, 30.0), one between (32.0, 0.0) and (32.0, 30.0), one between (40.0, 0.0) and (40.0, 30.0) and one between (52.0, 0.0) and (52.0, 30.0). Add a borehole at (32.0, 0.0) and change the y-value of the first layer boundary to y = 4.0 m and the y-value of the second layer boundary to y = 0.0 m. Add two layer boundaries at y = -0.5 m and y = -10.0 m.

•

Create both material data sets given in Table 6.1 and assign them to the appropriate soil layers. It is not necessary to enter K0 values as the initial stresses will be generated by means of gravity loading.

Table 6.1 Material properties for the soil layers Parameter

Name

Embankment Clay

Unit

Layers Material model

Model

0.0 – 4.0 MohrCoulomb

-10.0 – 0.0 MohrCoulomb

m -


Type

Drained

UnDrained

-

Soil weight above phreatic level γunsat

17

15

kN/m3

Soil weight below phreatic level γsat

20

18

Permeability

kx, ky, kz

1.0

kN/m3

1·10

-4

4

m/day 2

Young’s modulus

Eref

1.9·10 2000

Poisson’s ratio

ν

0.3

0.35

-

Cohesion

cref

1.0

2.0

kN/m2

Friction angle

φ

30.0

24.0

°

Dilatancy angle

ψ

0.0

0.0

°

Interface reduction factor

Rinter

Rigid

Rigid

-

kN/m

•

Uncheck the Hydrostatic box. Select the third layer boundary and change the water pressure to Wpress+ = 0.0 kN/m2 and Wpress- = 0.0 kN/m2 (see Figure 6.2).

•

Add a second borehole at position (16.0, 0.0). The borehole will be an exact copy of the previous one. Change the y-value of the first layer boundary to 0.0 m to reduce the thickness of the embankment layer to zero. The water conditions must remain unchanged.

6-2




•

Add boreholes to other points and change the values of the first layer boundary as given in Table 6.2. The water conditions must remain unchanged.

Table 6.2 Y-coordinates for the layer boundaries of the boreholes Layer boundary Borehole location

1

2

3

4

(16.0, 0.0)

0.0

0.0

-0.5

-10.0

(32.0, 0.0)

4.0

0.0

-0.5

-10.0

(40.0, 0.0)

4.0

0.0

-0.5

-10.0

(52.0, 0.0)

0.0

0.0

-0.5

-10.0

(16.0, 30.0)

0.0

0.0

-0.5

-10.0

(32.0, 30.0)

4.0

0.0

-0.5

-10.0

(40.0, 30.0)

4.0

0.0

-0.5

-10.0

(52.0, 30.0)

0.0

0.0

-0.5

-10.0

Load

Open the Work Planes window and change the work plane level to y = 4.0 m. Draw a geometry line from position (36.0, 30.0) to position (36.0, 24.0) and end at position (40.0, 24.0) to define for the cluster the distributed load. Add a distributed load on a horizontal plane to this cluster.

6-3

TUTORIAL MANUAL

Mesh generation The mesh for this example will be of medium coarseness, with a further refinement of some clusters and the toe of the embankment. To generate this mesh, follow these steps:

•

From the Mesh menu, choose the Triangulate option. PLAXIS 3D FOUNDATION will now perform a very coarse triangulation of the geometry in the draw area before the mesh is generated. The purpose of this triangulation is to define planes between geometry points and the model boundaries, where the ground surface level and the soil layer boundaries of the generated 3D mesh are linearly interpolated. Select Global Coarseness from the Mesh menu and set the horizontal as well as the vertical element distribution to Medium. Select the cluster with the distributed load as well as the cluster representing the steep slope at the right hand side. Hold down the key to select multiple clusters. Choose Refine Cluster from the Mesh menu and the Output program will show the generated 2D mesh.

•

•

Return to the main draw area, select the geometry line at x = 52.0 m and choose Refine Line from the Mesh menu. Hint: In particular, for safety analysis a fine mesh is required. A mesh that is too coarse leads to an over-estimation of the safety factor. In this example the current mesh is accepted to avoid excessive calculation times.

•

Return to the main draw area and generate the 3D mesh (see Figure 6.3). Click Close to return to the main draw area.

Figure 6.3 Preview of the generated 3D mesh

6-4


SAFETY ANALYSIS OF AN EMBANKMENT (LESSON 4) 6.2

CALCULATIONS

The calculation consists of 6 phases. The construction of the embankment itself is not considered in this exercise; the embankment will already be present during generation of the initial stresses. As the ground surface is not horizontal the initial stresses will be generated using Gravity loading. Open the Phases window and check that the calculation type is set to Gravity loading. Select the Parameters tab sheet and make sure the Ignore undrained

behaviour option is checked. Hint: Since the initial stresses are not affected by undrained behaviour, it is important that undrained behaviour is disabled during Gravity loading. This can be done by selecting Ignore undrained behaviour in the Parameters tab sheet of the Phases window. > In contrast to the K0 procedure, the calculation of initial stresses by means of gravity loading results in displacements. These displacements are not realistic, because the embankment is modelled as it appears in reality and the calculation of the initial stresses should not influence the displacements computed later in the analysis. These unrealistic displacements can be reset to zero at the start of the next calculation phase by selecting Reset displacements to zero in the next phase.

•

Add a new calculation phase. In this phase, additional load will be applied on the embankment. Leave the Calculation type to Plastic. In the Parameters tab sheet, make sure the Reset displacements to zero option is checked.

•

Close the Phases window by clicking the OK button and activate the distributed load at y = 4.0 m. Change the load to -25.0 kN/m2 in y-direction.

•

Add a new phase and change the Calculation type to Consolidation to simulate the consolidation process. Keep Ultimate time as the Loading input in the Parameters tab sheet and change the Time interval to 200 days. Hint: By default, all model boundaries are considered to be permeable. These boundary conditions can be modified by clicking the Advanced button in the General tab sheet. In this exercise the default boundary conditions are adopted.

•

Add a new0calculation phase.inChange thefrom Calculation type tobox Phi/c reduction and select – Initial phase the Start phase combo to perform a safety analysis when no load has been applied yet. In the Parameters tab sheet change the Additional steps to 40 and make sure the Reset displacements to zero as well as Delete intermediate steps options are checked.

•

Add a new phase and change the Calculation type to Phi/c-reduction and select 1 - in the Start from phase combo box to perform a safety analysis 6-5

TUTORIAL MANUAL immediately after application of the load. In the Parameters tab sheet change the Additional steps to 40 and make sure the Delete intermediate steps option is checked.

•

Add a new phase and change the Calculation type to Phi/c-reduction. Select 2 in the Start from phase combo box to perform a safety analysis after consolidation. Change the Additional steps to 40 and make sure the Delete intermediate steps option is checked. Hint: The default value of Additional steps in a Phi/c-reduction calculation is 100. In contrast to a Plastic or Consolidation calculation, the number of additional steps is always fully executed. In most Phi/c-reduction calculations, 100 steps are sufficient to arrive at a state of failure. If not, the number of additional steps can be increased to a maximum of 1000. If necessary, the number of additional steps can be decreased to 1.

•

Close the Phases window. Click the Select points for curves button to open the Output program. Select the tab sheet at y = 4.0 m. Select the node on the crest of the embankment at (40.0, 4.0, 30.0) by just clicking once (see Figure 6.4 ). It may be necessary to zoom into the area around the crest to select the correct point.

Figure 6.4 Location of selected corner point for curves

•

6-6

Close the Output program by clicking the Update button and start the calculation. After the calculation save the project.


SAFETY ANALYSIS OF AN EMBANKMENT (LESSON 4) 6.3


The generated excess pore pressures after loading of the embankment can be investigated as follows:

•

Select in the Phase list combo box and click Output to open this phase in the Output program.

•

From the Stresses menu select Pore pressures > pexcess and select Principal Directions from the Presentation options combo box. The principal excess pore pressures after application of the load are now shown. Zooming in and rotation of the model will give a better view. As expected, the largest excess pore pressures occur below the loading in the clay layer.

•

Select of the Displayed step combo box to look to the excess pore pressures after 200 days of consolidation. The minimum value of the pore pressures will be considerably lower.

To see the failure mechanism of the embankment without any additional load, follow these steps:

•

Select of the Displayed step combo box. Select the Reset View button from the toolbar or choose this option from the View menu to restore the full draw area.

•

Select the Viewpoint option from the View menu or click at the Viewpoint in the status bar at the bottom of the window. In the Viewpoint window, click the Default view to restore the default viewpoint and close the window.

•

From the Deformations menu, choose Incremental Displacements > | Δu| to see the incremental total displacements (see Figure 6.5).

Figure 6.5 Failure mechanism of the embankment without additional loading. 6-7

TUTORIAL MANUAL The plot clearly shows the failure along a circular slip surface. The failure mechanism of the embankment after loading and the failure mechanism after loading and a consolidation period can be viewed by selecting the appropriate phase in the Displayed steps combo box. The circular slip surface will only apply to a smaller part of the embankment. To view the safety factors of the embankment, follow these steps: Start the Curves Manager and create a new chart. This chart should show the total displacement |u| of the node at position (40.0, 4.0, 30.0) at the X-axis and the multiplier ΣMsf at the Y-axis. To make a distinction between the safety factor of the embankment without any load, the safety factor immediately after the load has been applied and the safety factor after a consolidation period of 200 days, it is more convenient to add two curves. To do so, follow these steps:

•

Select Add Curve from Current Project from the Edit menu and click OK in the Curve Generation window as all default settings are accepted. This will create a copy of the first curve. Add a third curve in the same way.

•

To deselect some phases from the first curve, select Curve Settings from the Format menu and click the Phases button in the Curve 1 tab sheet. In the Select Phases window deselect all phases except . In the same manner, deselect all phases except for Curve 2 and deselect all phases except for Curve 3. Click the OK button to close the Curves Settings window and return to the chart (see Figure 6.6). The first curve (blue) now shows the safety factor of the embankment without additional loading. Applying a load will of course decrease the safety factor as shown in Curve 2 (red), whereas considering a consolidation period will increase the safety factor (Curve 3, yellow).

6-8



No additional loading Additional loading with consolidation Additional loading

Figure 6.6 Displacement – safety factor curve of different calculation phases.

6-9

TUTORIAL MANUAL

6-10


APPENDIX A - MENU TREE APPENDIX A - MENU TREE A.1 INPUT MENU es ne ci L

. w w tea /w / dp :pt t U h

nl. isx al p

re m ia lc si D

la bo l G

en fie R

lp e H

lsa un a M

h se M

la bo l G

esn es ra o C

atel gu na ir T

en fie R

ls a rie ta M

dn a lsi o S

se acf re tn I

s am e B

rso lo F

s d a o L

da o L .r ts i D

en la P .z ro H

da o L .r ts i D

k se orW lanP

le oh e orB

y tre m eo G

e na l P .t re V

t uo b A ine L en fie R

oint P en fie R

lsl a W

edd de b es m il E P

dn uo r G

da o L en i L

e in L .t d re a o V L

ad o L tn io P

yr te m eoG neiL

la tn la oz i m ict m orH eaB reV eaB

re ts ul C

w ei V

nI m oo Z

tu O m oo Z

w ie V te se R

leb a T

rse lu R

ti d E

od n U

yp o C

p uo r G

pu or gn U

ll A ra el C

lei F

tu tpu oO t o G

r loF

se x A

ll A te se R sr hoc n A

w e N

ne p O

ev a S

easv a S

hs e M

3 D tea re ne G

hs e M

sg ni rp S

l alW

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leiP

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d nu roG

di r G

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rse b m u N tn io P

sr be m u N ni ah C

cte jo r P kc a P

)s tc ej or P t enc e R (

itx E

ro h ncA

g n priS

tyi xi F neiL

la ict erV

tyi xi F neiL

sp uo r G

ryo cte ir rg am ro P

2 D tea re ne G

t inr P

kr D o W

sg int te S l era ne G

A-1

TUTORIAL MANUAL

A.2 OUTPUT MENU

p le H

w o d n i W

ess se rt S s n o it a m r fo e D

y etr m o e G

w ie V

it d E

el i F

A-2

lsa un a M

. w w /w /: pt th

ln .s ix lap

re m ia lc si D

tu ob A

ed ac sa C

yl taln oz i lei or T H

yl la ticr e V lei T

ev tic A (

)s w od ni W

la pi cn ir P

ev it ce ff E

la to T la pi c ni r P

rse et ess m esr eta ar t t a S S P

es ah P

st en m ec al spi D

la tn e m er cn I

st en m ec al spi D

na is et ra C

de m ro fe D

ev it ce ff E

hs e M

la to T n ess ais e esr rta t S C

ess esr t S

la to T

st en m ec al spi D

ent em l E

no i at m orf e D

na is et ar C la to T

sn ia rt S

esr sus er P er o P

st ino P ict sa l P

ani est ra C es ah P

la tn e m er cn I

acesf re tn I

tu O m oo Z

w ie V te se R

tn io p w ei V

eld o M

oni tc e S ss ro C

pyo C

el ca S

alv ert nI

nei L na c S

ll A tc el e S

ll A tc lee se D

tc ej o

ow dn i

r nP ep O

eW osl C

ev tic eA so l C

ll eA so l C

st ino ctP lee S

In m oo Z

urso tn o C

na is et ra C

ci rt e m ul o V

/l ap ic ni r P es ah P

le ve

s uret cu rt S

ent em l E

sn ia rt S

l/a ipc ni r P la to T

ectj or P

la it ra P

ectsj or P

etry m oe G

se urv C ro f

als rie at M

sev ru C

ticL ae rh P

leb a T

ectj or P

ci rt e m ul o V

la tn e m er cn I

/l ap ic ni r P

se do N

st ni o P sse rt S

se x A

r uo tn o C le do M

yt i sd ao L

el it T

ryo tc e r ri agen kD r a o M W

esi ti xi F

ectivn no ot l C P

nde eg L

xo B tn i H

tn ir P

entc e R (

) ctse ojr P

rse b m u N ed o N

sg int te S

nti o P sse rt S

ersb m u N

cen tas i D

tn e m er us ae M

ent em l E

ersb m u N

te S ialr ersb et m a u MN

tea re C

no tia m in A

tc ej or P la re ne G

su clb u ert ersb r/S e su m stu l u l C N C

oni oni ta ta m ro d m r fn oa ofn I L I

sr e b m u N ert

oni t ali a re m ta rfo M In

itx E


no it al uc al C

oni ta m ro fn I

APPENDIX A - MENU TREE

ess se rt S :s n o it ec S ss o r C

no it ce S ss or C

s n o it a rm o fe D

la to T

st en m acel spi D

na is et ra C

ev tic ef f E

sea h P

st en m acel spi D

na is et ra C

la t en m er cn I

se ss er t S la to T

la ipc inr P

st en m acel spi D

na is et r a C la to T

la ipc inr P

ev tic ef f E

se ss er t S la to T

et ta S

rse et m ar a P

se ru s reo esr P P

s ina rt S

sn ia la rtS t en sian m er ter ncI aC

m ul o V / ipalc ni r P

sea h P

gn id ne B

M tsn e m o M

na sie rt aC sea h P

s ina rt S

2

:s lei P e m u lo V d n a s m ea B

se cr o F s n io t a m r o f e D

21

Q ra eh S

N la ix A

la t o T

31

tn e m ec lap s i D

es a h P

gn id en B

Q ra eh S tn e m ec lap s i D

M st ne m o M

la to T

:s ll a W d n a sr o o l F

esc r o F s n o it a m ro fe D

N la i x A

M st ne m o M

el ab T

tn e m ec lap s Inc D i

la to T

st ne m ec al ps i D

sea h P

23

Q ra eh S

N la i x A st ne m ec al ps i D

m ul la o t V / en ipal m er cn cn ir I P

alt ne m er

12

2

m ul o V / ipalc ni r P

3

gn id en B

11

1

st ni o P ci ts la P

la tn e m er cn I

Q ra eh S

13

Q ra eh S

gn id ne B

M tsn e m o M

22

12

no sir o T

M tsn e m o M

leb a T

st ne m ec al ps i D

A-3

TUTORIAL MANUAL

ec a fr et n I

:s ec rfa te n I

:s r o h c n A d n u o r G d n a se li P d e d e b m E

A-4

s n io ta m re fo D

se sse rt S

la ot T

’N σ ev it ce ff E

tsn e em c talo plasi T D

tsn e em c aseh plasi P D

N

σ

la ict re V la tn e crem nI

y

τ

ra e h S tsn e em c plasi D

la tn oz ir o H

zx

τ

ra e h S

tsn e em c latie plasi R D la t o T ev

ev tia le R

13

se cr o F

N ali x A

Q are h S

s n o it a rm o fe D

st en m ec al spi lD tao T

tsn e m ec la ps i

la nt

eD ash P

e em rc nI

g ind ne B

Q are h S

M st ne m o M

p

tsn e em c latie plasi R D

ev latie R

es ah P ev

3

g ind ne B

l1e

st ne m e lac ps i D

lacp is D

M st ne m o M

tivea le R

lacp is D

p

crem nI

l3e

uR st ne m e tivea le R

p

el ab T

la tn e

se rc o F ink kinS S T

uR st ne m e

ss ec xe

yd ae ts

e ivt ca

l2e

uR st ne m e tivea le R

τ

ra e h S

2

12

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le r

lacp is D

2

alr tea L

T se cr o F

ev it al e R f eol ba T

st ne m e lac ps i D

alr tea L

3

T se cr o F

le ba T


APPENDIX A - MENU TREE

A.3 CURVES MENU

p el H

sl ua na M

. w w w //: tpt h

w o d n i W

ed ac sa C

yl la tn oz el iro i T H

ta m ro F

sg int te S e vr u C

sg ni tt e S rta h C

ew i

w ei V te se

V

R

ti d E

lei F

yp o C

tc ej ro P enp O

leb a T m or f ev ru C dd A

w od ni W es ol C

ln .s i axl p

tc ej or P tn er r u C

re im lac si D

tu bo A

yl la ci el rte i T V

ev it c (A

dn eg e

no tia ci dn I eu la

L m or f ev ru C dd A

tc jeo r P e vi tc A es lo C

tc jeo r P re ht on A

V m or f ev ru C dd A

st ecj or P ll A es ol C

s) ow dn i W

rda ob ipl C

se rvu C ro f st ni o P tc el e S

se vr u C

re ga na M tc jeo r P

yr toc rei D kr o W

tn ir P

)s tc ej or P tn ec e R (

ti x E

A-5

TUTORIAL MANUAL

A-6


Plaxis 3D Tutorial

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