Question

A gravity dam is subjected to hydrodynamic pressure caused by __________

(a) the rising waves of the reservoir when a flood wave enters into it

(b) the rising waves in the reservoir due to high winds

(c) the increase in water pressure momentarily caused by the horizontal earthquake acting towards the reservoir

(d) the increase in water pressure momentarily caused by the horizontal earthquake acting towards the dam

The question was posed to me during an online exam.

My question comes from Gravity Dam Design in division Gravity Dam Design and Construction of Irrigation Engineering

Answer 1

Right answer is (c) the increase in water pressure momentarily caused by the horizontal earthquake acting towards the reservoir

To explain: Hydrodynamic pressure is the extra pressure exerted when the horizontal acceleration of an earthquake wave is acting towards the reservoir. As the foundation and dam accelerate towards the reservoir there is an increase in the water pressure which is nothing but hydrostatic pressure acting at a height of 3H/4π above the base. Mathematically, this value is given by Von-Karman equation.