考虑界面应力分布不均匀影响的挡土墙主动土压力分析方法

目前关于挡土墙土压力的计算多采用水平分层研究方法，该法在计算分析中常假设分层单元界面上的竖向正应力和水平剪切应力均匀分布，未考虑界面应力分布不均匀对土压力计算结果的影响。为此，本文基于现有的墙后填土应力分布及主应力偏转规律，将界面上不均匀分布的剪应力和正应力等效为作用在楔体单元边界的集中力，通过楔体单元受力分析及其静力平衡条件，建立了可以考虑单元界面剪应力和正应力分布不均匀影响的挡土墙主动土压力分析新方法，并探讨了不均匀界面应力对土压力计算结果的影响。研究结果表明：分层单元不均匀界面应力作为滑动楔体内部土体的内力不会对土压力合力的大小产生影响，但会对土压力分布和土压力合力作用点位置产生影响，且相对于水平剪切应力，竖向正应力对土压力计算结果的影响更大。通过对比论证，发现在考虑界面应力分布不均匀情况下，计算结果可以更准确地描述土压力的分布规律，土压力分布曲线的拐点随着墙土接触摩擦角$delta $的增大和填土内摩擦角$varphi $的减小而上升，土压力合力作用点位置随着$delta /varphi $的增大而上升。

An active earth pressure analysis method of retaining wall considering the influence of uneven interfacial stress distribution

At present, calculation of the earth pressure of retaining walls mostly adopts the horizontal layered research method. In the calculation and analysis with this method, it is often assumed that the vertical normal stress and horizontal shear stress on the interface of the layered element are uniformly distributed, and influence of the uneven distribution of the interface stress on the earth pressure calculation results is not considered. Based on the existing backfill stress distribution and principal stress deflection law, the shear stress and normal stress that are unevenly distributed on the interface are equivalent to the concentrated force acting on the boundary of the wedge element. Based on the analysis of its static equilibrium conditions, a new method for the active earth pressure analysis of retaining walls that can consider the influence of uneven distribution of shear stress and normal stress at the element interface is established, and the influence of uneven interface stress on the calculation results of earth pressure is discussed. The research results show that the non-uniform interfacial stress of the layered element, as the internal force of the soil inside the sliding wedge, will not affect the magnitude of the resultant earth pressure, but will affect the distribution of the earth pressure and the position of the resultant action point, and it is relative to the resultant earth pressure. Horizontal shear stress and vertical normal stress have greater influence on the calculation results of earth pressure. By comparison and demonstration, it is found that the calculation results can describe the distribution law of earth pressure with reasonable accuracy when considering the uneven distribution of interface stress. The inflection point of the earth pressure distribution curve increases with the decreasing $delta $ and increasing $varphi $, and the position of the action point of the resultant earth pressure increases with the increasing $delta /varphi $.