Question

If the backfill carries a uniform surcharge q, then the lateral pressure at the depth of wall H is ____________

(a) pa=Ka γz+Ka q

(b) pa=Ka γz-Ka q

(c) pa=Ka γz*Ka q

(d) pa=Ka γz/Ka q

This question was posed to me during an interview.

The above asked question is from Active Earth Pressure: Rankine’s Theory topic in section Failure Envelopes & Earth Pressure of Geotechnical Engineering II

Answer 1

Correct option is (a) pa=Ka γz+Ka q

Easy explanation: When the backfill is horizontal and carries a surcharge q, then the vertical pressure increment will be by q. Due to this, the lateral pressure will increase by Ka q. Hence, lateral pressure at the depth of wall H is pa=Ka γz+Ka q.