Determination of Passive Earth Pressure Coefficients for a Sloping Cohesive Backfill under Uniform Surcharge Loading

Abstract

Compared to the Rankine and Coulomb passive earth pressure theories, the logarithmic spiral theory considers curved failure surfaces, which is its greatest advantage. To improve the logarithmic spiral theory further, a new numerical method coupled with the Rankine and Coulomb theories was proposed and applied to determine the passive earth pressure coefficient of a sloping cohesive backfill under uniform surcharge loading. The method could yield either convex or concave failure surfaces, and the shape of the concave failure surface was assumed to be a logarithmic spiral. The Rankine and Coulomb theories were employed to determine the failure surface shape and distinguish convex and concave failure surfaces, respectively. Furthermore, approximate passive earth pressure coefficient equations for coefficients Kpγ, Kpq, and Kpc were proposed that consider the coupling effect of the soil weight, vertical surcharge loading, and cohesion. The predictions with the proposed method were compared to those reported by other authors.