Question

Assertion (A): The possibility of quicksand condition occurring is more on the downstream of a weir on permeable foundation.
Reason (R): Seepage lines are directed upwards at the downstream of such a weir.

• A. both A and R are true and R is the correct explanation of A
• B. both A and R are true but R is not a correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is A both A and R are true and R is the correct explanation of A

(a)
On the upstream side the seepage lines (streamlines) are directed downwards and increase the effective stress. While on the downstream side seepage line are directed upwards and reduce the effective stress.