Semi-Analytical Approach to Evaluate Seismic Passive Earth Pressures Considering the Effects of Soil Cohesion and a Curvilinear Failure Surface

Abstract

The widely acknowledged Mononobe-Okabe (MO) model is not recommended for seismic passive earth pressures analysis because it yields nonconservative results when the ratio of the wall’s to the soil’s frictional angle is equal to or greater than 0.5. A more advanced analytical approach, termed the log-spiral-Rankine (LSR) method, was recently introduced and is capable of producing more conservative solutions for the aforementioned scenario by considering soil cohesion, a curvilinear failure surface, and so on. Implementation of the LSR method, however, is quite complicated, as it requires several iterations to obtain the final converged solution. This study proposes an alternate way to approximate the more accurate LSR solutions from the simple MO equation for evaluation of seismic passive earth pressures in cohesive backfills. The approach uses two modification factors to account for the effects of soil cohesion and curvilinear failure surface, respectively. The overall error of the proposed equation is approximately 2%. More importantly, the new equation is easy to implement and thus suitable for routine design practice.