A square concrete pile (30cm side) 10 m long is driven into coarse sandhaving γ = 18.5 kN/m3 & N = 20. Determine the allowable load (F.S = 3.0)

(a) A 500 mm diameter bored pile is to be designed to support a safe vertical load of 25P kN. Where P = 8. The factor of safety is 2.5 and it is to be applied to the ultimate load. The succession of strata is 2 m of loose fill overlying firm, becoming stiff clay with depth. No side friction is to be allowed in the fill. For the clay the undrained cohesion cu (kPa) = 3z+40, where z is the depth in metres below ground level. %3D Calculate the minimum length of the pile required to support the load. Take a = 0.4, and Nc = 9. %3D (b) A pile weighing 8P kN has been proposed to be driven down into three layers of different materials as shown in Figure Q2, to support a structural load from a proposed building project. Where P = 8. Calculate the number of piles needed to support an ultimate structural load of Qu MN. Where Qu is the last two digits of your students' identification number (SID). For pile in cohesionless soil, assume o = 4'.

A 3 m deep excavation will be supported by a cantilever sheet pile. The foundation soil is dense sand, but it is assumed that the pile tip penetrates impermeable soil so hydrostatic pore pressure can be used. A surcharge of 10kPa is applied at the ground level. The water table is at the ground surface and dredge line as shown. Use Yw=10kN/m³ for your calculations. a) Using a factor of safety of 2.0 for Kp, check if D'=5m is safe or not (no need to iterate for other D'). b) Calculate the maximum bending moment. H=3.0m D.L. =+% D'=5m? 10 kPa G.L. Dense sand 3 Yt=20.0 kN/m³ c'=0 Ka=0.2 Kp=6.0 Impermeable soil

Determine the amount of axial shortening that the friction pile undergoes in service. Assume that the surface (or “skin”) friction f (force/lenth2) varies as shown and that E and A are constant.