Question

Which of the following is not provided in order to control the possibility of sand boiling?

(a) Relief wells

(b) Drain trenches

(c) Vertical cut-offs

(d) Berms

This question was addressed to me in an online interview.

I'm obligated to ask this question of Rock Fill Dams topic in division Earthen and Rock Fill Dams of Irrigation Engineering

Answer 1

Right answer is (c) Vertical cut-offs

Explanation: There is a possibility that the water may boil up near the toe of the dam when large scale seepage takes place through the pervious foundation overlain by a thin less pervious layer. Relief wells or drain trenches and d/s berms beyond the toe of the dam are all provided to control sand boiling.