Answer Happy

Q3. The soil profile on which a foundation would be constructed is shown in Figure Q3. It was decided to install a 650 mm diameter cast in place concrete pile to penetrate 5.0 m into the loose sand layer. The base of the proposed pile cap would be placed at the ground surface, and the column would be situated at the center of the pile cap (no eccentricity would be allowed). Use an overall safety factor FS = 2.5 where necessary. Ground Surface (GS) 3 m 2m 5 m FIGURE Q3 Hint: Clay Qu=NC₂ Ab + + Σacu As Sand Qu = q'Na Ab + Ko', tan & A Soft Clay Y = 14 kN/m³ Ysat = 16 kN/m³ C₂=30 kN/m² α = 0.9 Stiff Clay Ysat = 18 kN/m³ Cu=80 kN/m² a=0.6 Loose Sand Ysat = 20 kN/m³ =20° N₂* = 70 K=1 8=0.80 Downloaded by Jebonr Perkasa ([email protected]) SKAA3712/SAB3712 9 a) Calculate the allowable compressive load of one pile if the pile settles sufficiently so that the shear strengths of soil are fully mobilized and the water table is located at 3.0 m below the ground surface. (12 marks) b) Determine the uplift capacity of a single pile with similar dimensions as in part (a) if the ground water table is 2.0 m above the ground surface and the overall reduction factor RF = 0.5. (6 marks) c) Determine the required length of a single pile with a similar diameter of 650 mm to support an allowable compressive vertical load of 250 kN. Assume the shear strength at the base of pile is not fully mobilized and the water table is at the ground surface. (8 marks) d) What is the minimum spacing (center-to-center) between piles in a pile group? State the reason(s) why such minimum distance must be complied. You may sketch an appropriate diagram to support your statement(s). (4 marks) 10