非极限状态挡土墙主动土压力研究

利用薄层单元法对挡土墙非极限状态主动土压力进行研究，认为挡土墙土压力是由墙后填土在平衡状态下出现的楔形土体产生，取挡土墙后楔形土体沿平行于填料坡面的薄层作为微分单元体，通过作用在微分单元体的力和力矩平衡条件，建立挡土墙非极限状态主动土压力微分方程，得到非极限状态土侧压力系数、土压力强度、土压力合力和作用点的理论公式。根据非极限状态摩擦角与墙体位移关系，分析填土内摩擦角、墙土摩擦角和挡土墙位移比对土侧压力系数、土压力分布、土压力系数和作用点的影响。分析表明采用极限平衡理论计算平动模式下刚性挡土墙非极限状态时的抗倾覆稳定性偏于危险。另外，公式计算结果与实测模型试验进行对比分析，主动土压力分布曲线吻合良好。

Active earth pressure on retaining wall under non-limit state

The thin layer element method is used to study the active earth pressure under non-limit state. It is considered that the earth pressure against the back of a retaining wall is due to the thrust exerted by a sliding wedge of the soil between the back of the wall and a plane which passes through the bottom edge of the wall. The basic equations are proposed by considering the equilibrium of the forces and moments on a thin-layer element of the wedge. By using the equilibrium equations, the coefficients of earth pressure, the unit earth pressure, the resultant force of earth pressure and the acting point of the resultant force are obtained. The effects of the internal frictional angle of backfill, the frictional angle between the wall and the backfill and the displacement ratio of the wall on the lateral coefficient of earth pressure, the earth pressure, the resultant force of earth pressure, the acting point of the resultant force are investigated. The discussions indicate that if they are designed according to the limit equilibrium theory, it will be dangerous for the overturning stability of retaining walls with the active translational movement mode under non-limit state. Moreover, the distributions of the active earth pressure computed by the deduced formula agree with the measured data of the engineering case well.