Question

The water table is at the ground   level and backfill has saturated unit weight as 22KN/m^3. The height of wall is 6m and Ka=\(\frac{1}{3}.\) Find the pressure intensity.

(a) 45.22 KN/m^2

(b) 18.45 KN/m^2

(c) 83.24 KN/m^2

(d) 67.83 KN/m^2

I got this question in a job interview.

My query is from Earth Pressure Problems in chapter Failure Envelopes & Earth Pressure of Geotechnical Engineering II

Answer 1

The correct answer is (c) 83.24 KN/m^2

For explanation I would say: Given,

γsat=22 KN/m^3

γ’=γsat-γω=22-9.81= 12.19

Ka = \(\frac{1}{3}\)

H = 6m

We know that, Pa=Ka γ’ H+ γω H

Pa = \((\frac{1}{3})\)×12.19×6 + 9.81×6 = 83.24 kN/m^2.