Question

For a dry backfill with no surcharge, the active earth pressure intensity is _________

(a) pa=Ka γH

(b) pa=γH

(c) pa=Ka H

(d) pa=Ka γ

I got this question during an online exam.

My question comes from Active Earth Pressure: Rankine’s Theory in section Failure Envelopes & Earth Pressure of Geotechnical Engineering II

Answer 1

Correct option is (a) pa=Ka γH

The best explanation: The active earth pressure intensity is given by,

pa=Ka γH,

where, \(\frac{σ_1}{σ_3} = \frac{σ_v}{σ_h} = K_a=\frac{1}{tan^2(45°+\frac{φ}{2})},\)

γ=unit weight of the back fill

H= height of the retaining wall.