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GATE 2016 CE (CE1) – Question 51

Geotechnical Engineering · Earth pressure theories: Rankine and Coulomb, sheet piles · 2 marks · Multiple choice

A homogeneous gravity retaining wall supporting a cohesionless backfill is shown in the figure. The lateral active earth pressure at the bottom of the wall is 40 kPa. The minimum weight of the wall (expressed in kN per m length) required to prevent it from overturning about its toe (Point P) is

Diagram for GATE 2016 CE (CE1) question 51
  1. 120
  2. 180
  3. 240
  4. 360

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Show answer and explanation

Correct answer: (A) 120

Explanation

The triangular active pressure has resultant(1/2)·40·6=120kN per metre of wall, acting2m above the base. Its overturning moment is240kN·m. The wall weight acts at the middle of the4m base, a2m stabilising lever arm. Limiting equilibrium gives W·2=240, so **120kN/m, A**.