The GATE Grind

GATE 2020 CE (CE1) – Question 45

Geotechnical Engineering · Effective stress principle and quicksand condition · 2 marks · Multiple choice

The shown 10 m soil profile receives instantaneous uniform surcharge 70 kPa. Groundwater is 3 m below ground. Layer unit weights are shown; take water unit weight 9.81 kN/m³. Immediately after preloading, find effective stresses at P and Q respectively (kPa).

Diagram for GATE 2020 CE (CE1) question 45
  1. 124 and 204
  2. 36 and 90
  3. 36 and 126
  4. 54 and 95

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (D) 54 and 95

Explanation

Immediately after instantaneous loading, the fine-grained layers carry the surcharge as excess pore pressure, leaving effective stresses unchanged. At P, $\sigma^{\prime}=3(18)=54$ kPa. At Q, $\sigma^{\prime}=54+4(20-9.81)=94.76\approx95$ kPa. **D**.