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GATE 2022 CE (CE2) – Question 17

Geotechnical Engineering · Shallow foundations: bearing capacity, combined footing, raft, settlement · 1 mark · Multiple choice

Read the following statements: (P) While designing a shallow footing in sandy soil, monsoon season is considered for critical design in terms of bearing capacity. (Q) For slope stability of an earthen dam, sudden drawdown is never a critical condition. (R) In a sandy sea beach, quicksand condition can arise only if the critical hydraulic gradient exceeds the existing hydraulic gradient. (S) The active earth thrust on a rigid retaining wall supporting homogeneous cohesionless backfill will reduce with the lowering of water table in the backfill. Which one of the following combinations is correct?

  1. (P)-True, (Q)-False, (R)-False, (S)-False
  2. (P)-False, (Q)-True, (R)-True, (S)-True
  3. (P)-True, (Q)-False, (R)-True, (S)-True
  4. (P)-False, (Q)-True, (R)-False, (S)-False

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Show answer and explanation

Correct answer: (A) (P)-True, (Q)-False, (R)-False, (S)-False

Explanation

P is true: a high monsoon water table reduces effective unit weight and bearing capacity. Q is false because rapid drawdown can leave high pore pressure in a dam slope. R reverses the quicksand criterion: the existing upward gradient must reach or exceed the critical gradient.

S is true under the usual total-thrust interpretation: lowering groundwater reduces hydrostatic thrust. Thus the physical pattern is **T,F,F,T**, which is absent from the choices. A is a provisional choice and requires review.