15 questions. Tap an option to check it instantly, then read the solution.
Practice SSC JE and other civil engineering exam questions on lateral earth pressure and retaining walls: active, passive and at-rest pressure, Rankine's and Coulomb's theories, Ka, Kp and K0, pressure diagrams, the effect of cohesion, unsupported cuts in clay and related foundation questions. Tap an option to check it, then open the full explanation for each question.
Question 1Medium
Select the option that is appropriate regarding the following two statements. Assertion: Piping below the weir can be prevented by providing an impervious floor of sufficient length so that the path of percolation is increased and the exit gradient is decreased. Reason: If the exit gradient is less than a certain critical value, the soil starts boiling and is washed away by percolating water.
A longer impervious floor lengthens the seepage path and lowers the exit gradient, which prevents piping (Assertion true). Boiling starts when the exit gradient exceeds the critical value, not when it is less (Reason false).
Question 2Easy
The material supported by a retaining wall, kept above the horizontal plane at the elevation of the top of the retaining wall, is known as:
At the same depth (same σv), the active circle spans Kaσv to σv (small), while the passive circle spans σv to Kpσv (large). So the active radius is less.
Question 5Easy
Rankine's theory considers the stress in a soil mass when it reaches the state of ______.
Rankine analysed the soil when every point is on the verge of failure: the state of plastic equilibrium.
Question 6Easy
If a cantilever retaining wall is to retain soil to its full height H, for the analysis of bending moment at its base, the distance from the base where the total force due to backfill acts is:
An excavation is to be made in a saturated soft clay (φᵤ = 0) with vertical sides. What will be the maximum unsupported depth of the vertical cut? Given that the cohesion intercept = 30 kN/m² and the unit weight of clay = 15 kN/m³.
\(H_c = 4c/(\gamma\sqrt{K_a})\) with \(K_a = 1\) for φ = 0: \(H_c = 4 \times 30/15 = 8\) m.
Question 12Easy
A retaining wall with a vertical back retains a mass of cohesionless soil, the surface of which is level with the top of the wall. The active lateral earth pressure coefficient in terms of the angle of internal friction φ of the backfill is given by:
Answer: C. (1 − sin φ)/(1 + sin φ) or tan²(45° − φ/2)
Ka = (1 − sin φ)/(1 + sin φ) = tan²(45° − φ/2). Both forms in option (c) are the same thing.
Question 13Hard
If the bearing capacity of soil is 10 tonnes/m² and the projection of a plain concrete footing from the wall is a cm, the depth D of the footing is: i. D = 0.0775a, ii. D = 0.775a, iii. D = 0.775√a, iv. D = 0.775a²
Treating the projection as a cantilever: \(D = a\sqrt{3p/f_t}\). With p = 10 t/m² ≈ 0.1 N/mm² and allowable tension ft ≈ 0.5 N/mm², \(D = a\sqrt{0.6} \approx 0.775a\).
Question 14Medium
For bulkheads, which of the following earth pressure theories is applied directly?
Bulkheads are flexible sheet-pile walls whose deflection redistributes earth pressure, so neither theory can be applied directly without modification.
Question 15Medium
A friction pile of diameter 50 cm is embedded 15 m into a homogeneous consolidated clay deposit. If the adhesion factor is 0.7 and the cohesion (c) developed between the clay and pile shaft is 4 t/m², what is the safe load (t) for a factor of safety of 3.0?