基于对数螺旋滑裂面的有限宽度土体被动土压力计算方法

基于半无限空间假定的经典朗肯和库仑土压力理论无法准确求解有限宽土体的被动土压力．为了求得不同宽度及墙土摩擦角影响下的被动土压力，首先，基于对数螺旋滑裂面假定，建立大主应力与滑裂面的耦合关系，结合应力莫尔圆导出了滑裂面与两侧墙体的夹角，提出了有限宽度土体的滑裂面控制方程；然后，通过对滑动土楔薄层单元应力分析，推导出被动土压力的大小和分布表达式；最后，采用离散元软件对不同宽度填土进行单侧挡墙平动模式下的被动土压力试验模拟，结果表明，所提出计算理论与数值模拟结果基本一致．该方法求解形式简单，具有很好的工程应用价值．

Calculation Method of Passive Earth Pressure of Confined Soil Based on Logarithmic Spiral Sliding Surface

The classical Rankine and Coulomb earth pressure theories are based on the assumption of semi-infinite space. It is no longer suitable for calculating the passive earth pressure of narrow backfill behind a retaining wall. This work aims at accurate calculation of the passive earth pressure of narrow backfills of different thicknesses with different soil-wall friction angles. Firstly, based on the assumption of logarithmic spiral sliding surface, the coupling relationship between the large principal stress and the sliding surface is established. Subsequently, the angles between the sliding surface and the walls on both sides were derived by the Mohr circle, and the governing equation of the sliding surface of limited soil was proposed. Then, the passive earth pressure and its distribution were obtained through the thin-layered element method. Finally, a series of numerical simulations were conducted by DEM(Discrete Element Method) to simulate the passive earth pressure of backfill with different widths under the translational mode of single retaining wall. It indicates that the results of proposed calculation theory are basically consistent with those of the numerical simulation. The proposed method has simple form and is of great value in engineering application.