Assignment Task
Q1. Effective Shear Strength Parameters
(a) The following results were obtained from consolidated–undrained tests on specimens of saturated normally consolidated clay.
| Cell pressure σ3 (kN/m2 ) | 150 | 300 |
| Ultimate deviator stress Δq (kN/m2 ) | 190 | 320 |
| Ultimate pore pressure u (kN/m2 ) | 42 | 128 |
Determine the effective shear strength parameters (c’ and φ’)
(b) Develop an excel file that can be used to calculate effective shear strength parameters
(c’ and φ’) for any given values of σ3, Δq, and u.
Q2. Passive Earth Pressure
A rigid retaining wall is embedded into the ground with a vertical back. The embedment depth is 3.3 metres. Using Rankine’s method, determine the passive thrust per metre length of the wall when the wall retains:
- a level fill of dry sand (c = 0, φ = 36°, γ = 19 kN/m3). a
- a level fill of saturated sand with the water table located on the top of the wall.
(c’ = 0, φ’ = 35°, γsat = 20 kN/m3)
- Discuss the results calculated in (a) and (b). Write a brief conclusion.
- Develop an excel file that can be used to calculate the passive thrust per metre length of the wall [parts (a) and (b)] for any given values of (φ, φ’, γ, and γsat).
Q3. Ultimate Axial Pile Capacity
(a) For the soil profile shown in Figure 1, determine the ultimate axial pile capacity for a pile that is L=16 m long founded at the bottom of stiff clay. The ground water level (GWL) is located at 1 m below the surface and the pile is solid precast concrete (D=0.45 m in diameter).
Hint: both – method (shaft friction) and Nordlund methods (end bearing) are required for this question. Also, it is required to determine the depth of stiff clay (i.e., the total pile length minus 8 m).
(b) Develop an excel file that can be used to determine the ultimate axial pile capacity for any given values of ( L, φ’, and D) of this problem
L: total length of the pile
φ’: internal friction angle of the drained dense sand
D: diameter of the solid precast concrete Other
parameters remain the same.
