Conventional methods for calculation of passive earth pressure were mainly based on the assumptions of the linear Mohr-Coulomb yield condition and plane strain failure mechanism. However, both theoretical and experimental studies have shown that such assumptions are not satisfied in some geotechnical projects. Herein, a novel method incorporating a kinematically admissible 3-dimensional (3D) rotational failure mechanism and the nonlinear powerlaw yield criterion is proposed to compute the passive earth pressure acting on the inclined retaining walls. Instead of using the nonlinear yield criterion directly, a straight line tangential to the nonlinear yield curve is employed to represent the strength of soils, and therefore, the nonlinear problem is transformed into the traditional linear problem. The 3D failure mechanism is generated through rotating a circle defined by 2 log-spirals, and a plane strain block is inserted into the mechanism to consider the retaining walls with different widths. Earthquake effects are taken into account by using quasi-static representation, and the horizontal seismic coefficient concept is adopted for the estimation of passive earth pressure under seismic conditions. An analytical expression about the 3D passive earth pressure is educed by means of the upper bound theorem of limit analysis. Numerical results for different practical parameters are obtained from an optimization scheme where the minimum of passive earth pressure is sought. Compared with available 2-dimensional and 3D solutions, the proposed method is validated. A parametric study is conducted to investigate the effects of different parameters on the 3D static and seismic passive earth pressure.
KEYWORDS3D rotational mechanism, nonlinear yield criterion, passive earth pressure
| INTRODUCTIONThe calculation of passive earth pressure is a classical and long-standing research theme in geotechnical engineering. Many analytical and numerical approaches to the determination of passive earth pressure have been developed. In the previously published literature about the passive earth pressure estimation, the linear Mohr-Coulomb (MC) criterion was widely used to represent the shear strength of soils. However, many researches have shown that the linear MC criterion can't truly reflect the mechanical characteristics of geomaterials and the nonlinear strength envelope may be