考虑剪应力作用的刚性挡土墙主动土压力分析

Calculation of active earth pressure against rigid retaining wall considering shear stress

以墙后为无黏性填土的竖直刚性挡土墙作为研究对象,假定墙后土体中形成圆弧形土拱,考虑水平土层间的剪应力,修正了水平层分析法,从而得到平动模式下主动土压力分布、合力大小及其作用点位置的表达式。通过与模型试验结果和现有理论成果的对比分析,证明了修正方法的合理性。参数分析表明,水平土层间的平均剪应力受墙土摩擦角、填土内摩擦角等因素的影响,与主动土压力一样沿墙高为非线性分布。同时,考虑水平土层间剪应力作用得到的侧向主动土压力系数、主动土压力合力与不考虑剪应力作用的理论解答相同,但合力作用点位置高于库仑解,且低于不考虑剪应力作用的理论解答。

A rigid retaining wall with a vertical back face backfilled with a cohesionless soil is analyzed. By assuming that the soil arch behind the retaining wall has a form of circle, the active earth pressure formulation of horizontally layered soil is modified with considering the shear stress between the soil layers; and a set of theoretical formulae are proposed for calculating the active earth pressure, the total earth pressure and its action point for the retaining wall under translation mode. In order to check their accuracy, the predictions by the proposed formulae are compared with the results of full-scale test and existing theories. The calculated results show that the mean shear stress between level soil layers is related to the wall-soil friction angle and the internal friction angle, and it is distributed nonlinearly along the wall height. The coefficient of lateral active earth pressure and the resultant of active earth pressure are both independent of the shear stress between level soil layers; while the position of action point of the resultant earth pressure by the proposed formulae considering the shear stress is higher than that of Coulomb＇s solution, and lower than that of existing theories in which the shear stress is neglected.