Thin-layer Micro-element Method for Cohesive Soil Passive Earth Pressure Determination on Retaining Walls

A thin-layer micro-element method that is based on the thought of horizontal slice method was developed to deduce the passive earth pressure of cohesive soil by considering the retaining wall height, wall back batter angle, filler elevation angle, equispaced overload, bulk density, internal friction angle, cohesion, and the external friction angle between the soil and the wall back. An explicit solution of the critical rupture angle was obtained using the graphic method. The effects of the aforementioned parameters on the critical rupture angle, the passive earth pressure distribution, and the resultant force of this pressure as well as its application position were analyzed. The results show that (1) the distribution of the passive earth pressure along the wall back is non-linear; (2) Coulomb and Rankine’s theories on passive earth pressure are special cases of the passive earth pressure formula under the corresponding simplified assumptions; and (3) the passive earth pressure and its distribution are greatly affected by factors such as the wall back batter angle, filler elevation angle, equispaced overload, soil cohesion, internal friction angle, and external friction angle of the soil. However, the bulk density has negligible effect on the application position of the resultant force of the passive earth pressure.