Ultimate Load Carrying Capacity of an Under Reamed Piles 1

For Clayey Soils : Ultimate load carrying capacity capacity of an under reamed piles Qu = Ap.Nc.Cp + Aa . Nc. C'a C' a + C'a. As' + ἀ.Ca.As

1 Ul timate bearing capacity of Pil e 2 C/ C/s Area of pil e at Stem l evel 3 Bearing Capacity factor, Usual ly tajen 9 4 Co Cohesion of soil around toe

= = = =

Qu (KN) Ap (m2) Nc Cp(kNf/m2)

5 π /4(Du /4(Du22 - D2) D2) where where Du(mt Du(mt)) and and D(mt D(mt)) a = Aa  the under reamed and stem diameter, respectively. 6 Average Cohesion ion around under reamed = C'a (kNf/m2) 7 Reduction Reduction factor factor usally taken taken as 0.5 for clcl = ἀ 8 Avg cohesion of the soil along pi le stem = Ca (Kn/M2) 9 Surface Area of the stem = As(M2) 10 Surface ar are of of th the cy cylinder circumscribi ibin = A's (m (m2) under reamed reamed piles pile s

Input data 1 Di D i a of the pil e recommended = 2 l ength of the pi le = 3 Di Di a of the bulbs ( 2.5 D ) Du = 4 Spa Spacing ing Bet Betwe ween en Bulbs ulbs (1.2 (1.2 to 1.5 Du) = 5 Su Surface Area of Stem "As" = 6 Enter the cohesion at Toe "Cp" = 7 Enter the cohesion at bul b "C'a = 8 Average Cohesi on along the stem = 10 Be Bearing capacity factor Nc = 11 Reduction factor ἀ = 12 C/ C/s area of pile at tip " Ap" = 13 Suface Suface area circumsc circumscribing ribing the the bulb "A's" "A's" = Ultimate load carrying capacity capacity of the pile

Safe load carying capacity capacity of pil e

9

0.5

0.45 Mts 18 mts

1.125 Mts 0 Mts 25.4502 M2 24 KN/M2 34 KN/M2 29 KN/M2 9 0.5 0.159317 M2 0 M2

Mts mts Mts Mts M2 KN/M2 KN/M2 KN/M2

M2 M2

658.9763 KN

KN

65.89763 Tons

Tons

26.35905