Question

The total net pressure for a cohesive soil is given by ________

(a) Pa=\(\frac{1}{2}\) Ka γH^2 cot^2 α-2c cot⁡α

(b) Pa=γH^2-2c cot⁡α

(c) Pa=Ka γH^2-2c cot⁡α

(d) Pa=Ka H^2-2c cot⁡α

The question was asked in an internship interview.

This key question is from Active Earth Pressure of Cohesive Soils in portion Failure Envelopes & Earth Pressure of Geotechnical Engineering II

Answer 1

Correct answer is (a) Pa=\(\frac{1}{2}\) Ka γH^2 cot^2 α-2c cot⁡α

Best explanation: The total net pressure is given by,

\(P_a=\int_0^H p_a.dz = \int_0^H(γzcot^2 α-2c cot⁡α).dz\)

∴ Pa=\(\frac{1}{2}\) Ka γH^2 cot^2 α-2c cot⁡α.