The GATE Grind

GATE 2020 CE (CE1) – Question 20

Geotechnical Engineering · Three-phase system, phase relationships, index properties and soil classification · 1 mark · Multiple choice

Which statement is NOT correct?

  1. Clay with liquidity index greater than unity is in plastic consistency.
  2. Normally consolidated clay has zero cohesion in a consolidated undrained triaxial test.
  3. Ultimate bearing capacity of a surface strip footing on sand increases directly with footing width.
  4. For a point load, Boussinesq’s equation predicts higher vertical stress directly beneath the load than Westergaard’s equation.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) Clay with liquidity index greater than unity is in plastic consistency.

Explanation

Liquidity index is $LI=(w-PL)/(LL-PL)$. If LI > 1, w > LL and remoulded soil is in liquid consistency, not plastic consistency. Thus **A** is incorrect. Plastic consistency lies between PL and LL.