Question

A 4m high, vertical retaining wall supports Silty SAND backfill with a horizontal surface. There is a hydrostatic horizontal water table at 1 m below the ground surface. The soil has bulk unit weight = 20 kN/m3, effective cohesion=5 kPa, and friction angle= 30o. What is the value of the water force on the wall? At what distance above the base of the wall does it act?

Answer 1

1 m water table 4 m W*H

Given data

height of wall of dam = 4 m

water table is 1 m below ground level

the pressure acting on the wall is

Yw* H

therefore total force acting on the wall will be area of the traingle i.e  

(H H 2. *

(*H)* H * (9.8* 3) *3 = 44.14 kN 2 force on the wall 2

And it will act at H/3 height of wall under water - table i.e 1 m