Quick sand is
- Aa type of sand
- Ba condition in which a cohesion less soil loses its strength because of upward flow of waterCorrect
- Ca condition in which a cohesive soil loses its strength
- Dnone of the above
Solution
Concept
Definition and condition of quicksand
Formula
NONE
Step-by-step solution
1. Quick sand is not a specific type of soil, but a hydraulic condition in cohesionless soils. 2. When water flows upward through soil under a hydraulic gradient equal to or greater than the critical gradient, effective stress becomes zero. 3. As effective stress reaches zero, the soil completely loses its shear strength and behaves like a liquid. Answer: B
Explanation
Quick sand is not a type of soil, but a specific hydraulic condition in cohesionless soils like sand. When water flows upward with sufficient velocity, the upward seepage pressure balances the buoyant weight of the soil particles. Consequently, the effective stress becomes zero and the soil loses all shear strength.
Why the other options are wrong
A) Quicksand is a dynamic hydraulic condition of soil rather than a specific physical type of sand. C) Quicksand condition occurs specifically in cohesionless soils, not cohesive soils. D) Option B is correct.
Shortcut
Quick sand is a hydraulic condition from upward flow, not a type of sand.
Common mistake
Mistaking quicksand as a specific physical type of soil rather than a hydraulic condition caused by seepage pressure.
Correct answer: B) a condition in which a cohesion less soil loses its strength because of upward flow of water