Calculation Methods Of Passive Earth Pressure Against Rigid Retaining Wall Considering Displacement Effects

Classical earth pressure theories can reflect the mechanical concepts clearly and are simple, but the earth pressure calculated by these method usually supposes that the soil is in limit state, which may bring on the wasting or the insecure result if adopting that in project design. In most cases, the lateral displacement of the retaining wall is very small, earth pressure in practice mostly locates between static earth pressure and ultimate earth pressure. In order to design retaining walls more accurately, it is need to research the calculation of earth pressure with non-limit displacement.The process of soil behind retaining wall changing from resting state to limit state is gradual. The earth pressure is influenced by both the displacement size and displacement modes. The distribution of passive earth pressure against retaining wall is nonlinear, and the sliding surface in soil is usually a curve.In this paper, based on the soil tests and numerical calculation results that researchers ever did about earth pressure, the failure mechanism of different wall movement modes were analyzed and the relationship between the friction angles and the wall movement was obtained.Considering the possibility shape of slip surface of soil, the existing methods to calculate passive earth pressure were improved. Theoretical formulas of passive earth pressure intensity, resultant force and their applied points under different movement modes were derived.Model tests which fillings were dry sand of different density or saturated sand were calculated and analyzed. Calculated values are compared with the measured data and it is found that the two conclusions are consistent.The proposed methods to calculate the earth pressure consider modes and size of wall displacement, development of soil slip surface , features of friction angles and so on. They can calculate the earth pressure of each movement and are easy to master.They also can better reflect the characteristic of earth pressure and their applied points changed with the displacement.