Numerical Study on Passive Earth Pressures Using Kotter's Equation

A numerical protocol was developed to compute the passive earth pressure coefficients, K-p, for the case of an inclined rigid wall retaining an inclined cohesionless backfill. A complete log-spiral failure surface is assumed in this study. Kotter's equation is used in the analysis to obtain the resultant soil reaction on the failure surface. In addition, a limit-equilibrium approach is used to identify the unique failure surface, which fulfils all three equilibrium conditions, viz., Sigma H = 0, Sigma V = 0, and Sigma M = 0, with the passive thrust located at the lower one-third height of the retaining wall. The analysis is further extended to evaluate the bearing capacity factor, N, for the case of a centrally loaded rigid rough strip footing resting on a cohesionless soil medium. For this purpose, particular failure mechanisms are considered. The computed N values are found to be in good agreement with most of the available theoretical solutions. (C) 2016 American Society of Civil Engineers