地震条件下挡土墙主动土压力及其分布的新分析法

New analysis method of seismic active earth pressure and its distribution on a retaining wall

采用旋转挡土墙计算模型的变换法,将在地震和拟静力法条件下主动土压力的求解问题转化为在静力条件下主动土压力的求解问题。根据在静力条件下水平层分析法的主动土压力推导结果,直接获得在地震条件下主动土压力强度分布、土压力合力及其作用点位置的表达式,并运用图解法得到了临界破裂角的解析解。公式可考虑水平和垂直地震加速度、不同墙背倾角、墙背和坡面倾角与填料存在黏结力和外摩擦角、存在均布超载等诸多因素的影响,公式可以适用于在常用边界和地震条件下黏性土的主动土压力计算。旋转地震角法是将在地震和拟静力法条件下挡土墙计算模型旋转为在静力条件下挡土墙计算模型,但旋转挡土墙计算模型并不改变挡土墙和墙后填土的应力状态,按在静力条件下挡土墙主动土压力求解方法求解在地震和拟静力法条件下主动土压力,该方法大大简化了在地震和拟静力法条件下的主动土压力计算公式推导过程,统一了在拟静力法条件下的地震土压力求解,理论更加完善。

The seismic active earth pressure calculations problem with pseudo-static method is translated into non-seismic active earth pressure calculations problem in this paper using the transform method with rotating calculation model of retaining wall. Depend on the non-seismic active earth pressure formulations with differential layer method, the analytical formulas of resultant force of seismic earth pressure, application position of resultant force and distribution of seismic earth pressure with differential layer method are obtained directly, and the analytical solution of critical rupture angle by graphic method. The influencing factors including horizontal and vertical seismic accelerations, batter angle of wall back,cohesion and external friction angle between filler and back of retaining wall, equispaced overloading can be considered. The formulas can be used for seismic active earth pressure calculations of cohesive soil or non-cohesive soil with common border condition. The rotating seismic angle method in this paper is that the seismic active earth pressure calculation model with pseudo-static method is firstly rotated into static active earth pressure calculation model, and the stress states of retaining wall and soil behind retaining wall are not changed, and then the seismic active earth pressures with pseudo-static method are solved by the calculation methods of static active earth pressures. The deducing process of seismic active earth pressure formulations with pseudo-static method is simplified and unified greatly by using the new method. The seismic active earth pressure theory with pseudo-static method is perfected much more.