Question

Tension cracks in the dam may sometimes lead to the failure of the structure by?

(a) Sliding of the dam at the cracked section

(b) Overturning about the toe

(c) Crushing of concrete starting from the toe

(d) Both overturning and crushing

The question was posed to me at a job interview.

This intriguing question originated from Gravity Dams topic in portion Gravity Dam Design and Construction of Irrigation Engineering

Answer 1

Correct answer is (c) Crushing of concrete starting from the toe

To explain I would say: When tension prevails, cracks develop near the heel and uplift pressure increases, reducing the net salinizing force. This crack by itself does not fail the structure but it leads to failure of the structure by producing excessive compressive stresses.