Question

The governing compressive stress in a concrete gravity dam which should not be allowed to exceed the permissible value of about 3000 KN/m^2 while analyzing full reservoir case is ____________________

(a) the vertical maximum stress at the toe

(b) the major principal stress at toe

(c) the shear stress at the toe

(d) the principal stress at the heel

I had been asked this question in an international level competition.

I need to ask this question from Gravity Dams in division Gravity Dam Design and Construction of Irrigation Engineering

Answer 1

Right answer is (b) the major principal stress at toe

For explanation I would say: In reservoir full case, the resultant is nearer to the toe and hence, maximum compressive stress is produced at the toe. The vertical direct stress distribution at the base is the sum of the direct stress and the bending stress and is given by the equation –

Pmax = V/B [1 + 6e/B] where V is the total vertical force, e is the eccentricity of the resultant force from the center of the base and B is the base width.