L型挡土墙滑裂面确定方法与地震稳定性分析

提出了L型挡土墙两种破坏模式，即长踵板式和短踵板式，且破坏模式受几何参数和物理力学参数影响。研究了两种破坏模式下L型挡土墙滑裂面确定方法和地震稳定性问题，界定了两种破坏模式的临界条件。考虑第二、第三滑裂面产生条件，应用极限分析运动学原理，建立地震荷载作用下L型挡土墙临界状态方程，推导出地震加速度系数表达式。根据极值原理，给出最优解，从而计算得到临界屈服加速度系数及其对应的滑裂面倾角。通过算例分析可知：临界屈服加速度系数小于M-O公式法，长踵板式L型挡土墙滑裂面倾角与坦墙判别公式结果相同，且滑裂面之间的夹角等于90o-φ，即与滑移线场的结论相同。短踵板式L型挡土墙滑裂面夹角近似等于90o-φ。

Seismic stability of L-shape retaining walls and determination method of sliding surface

In this study, two seismic failure mechanisms of L-shape retaining walls (i.e., long heel failure and short heel failure) were presented, and the failure mechanisms were influenced by geometric parameters and physico-mechanical parameters. The seismic stability of L-shape retaining walls and the determination method of sliding surface were investigated in this paper, and the critical condition of two failure mechanisms was defined. Based on the kinematical approach of upper bound theorem, the critical state equation of L-shape retaining wall was established, taking account of the occurrence of the second and third sliding surfaces condition. Then the multivariate function to calculate seismic acceleration coefficient was derived and optimized by extremum principle, so as to obtain the critical yield acceleration factor and the inclination of sliding surface. A case study and comparative analysis showed that the critical yield acceleration factor was smaller than that derived from the M-O method. When the heel of L-shape retaining wall was long enough, the angle between two sliding surfaces equaled to 90°-φ. It means that the result of using this method is the same as the result of slip-line field theory. When the heel of L-shape retaining wall was short, the angle between sliding surfaces was approximately 90°-φ.