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GATE 2025 CE (CE2) – Question 24

Geotechnical Engineering · Effective stress principle and quicksand condition · 1 mark · Multiple select

Which of the following statements is/are INCORRECT?

  1. As the depth of the ground water table from the ground surface increases, the effective stress in the soil decreases.
  2. Bulking of the moist sand is due to the capillary action in the sand.
  3. The effective stress in a liquified soil is almost zero.
  4. The earth pressure at any point in the soil, under all conditions, is always smaller than the vertical effective stress at that point.

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Show answer and explanation

Correct answer: (A) As the depth of the ground water table from the ground surface increases, the effective stress in the soil decreases.; (D) The earth pressure at any point in the soil, under all conditions, is always smaller than the vertical effective stress at that point.

Explanation

A is incorrect: a deeper water table means less buoyancy and less pore water pressure at a given depth, so the effective stress increases. B is correct, since the capillary film pushes the sand grains apart (bulking). C is correct, because liquefaction happens when the pore pressure equals the total stress. D is incorrect: the earth pressure is $K\sigma'_v$, and in the passive state $K_p > 1$, so it can be larger than the vertical effective stress.