关于挡土墙主动土压力计算问题

For Active Earth Pressure on Retaining Wall

采用库仑土压力理论 ,挡土墙的主动土压力是由墙后填土在极限平衡状态下出现的滑动楔体产生的假设 ,建立关于挡土墙上土压力强度的一阶微分方程 ,并求得精确解 ,分别给出了墙体水平变位、墙体绕地基转动、墙体绕墙顶转动三种变位模式下 ,土压力强度、土压力合力和土压力合力作用点的理论公式 ,并与库仑土压力公式和有关实验结果进行了比较分析。结果表明 ,三种墙体变位模式下的土压力合力等于库仑土压力公式计算结果 ,但土压力合力作用点有显著差别。结合工程设计 ,对挡土墙主动土压力的大小和分布 ,以及作用点的取值等问题进行了讨论 。

Based on the Coulomb's concept that the earth pressure against the back of a retaining wall is due to the thrust exerted by the sliding wedge of soil from the back of the wall to a plane which passes through the bottom edge of the wall and has an inclination equal to the angle of θ,the differential equation of first order is set up by the equilibrium of forces on the flake element taken out from the wedge.The theoretical answers to the unit earth pressures,the resultant earth pressures and the points of application of the resultant earth pressures on retaining wall are obtained for the three wall movement modes of translation,rotation about base and rotation about top.The comparisons are made among the formula presented here,Coulomb's formula and some experimental observations.It is demonstrated that the magnitudes of the resultant earth pressures for the three wall movement modes are identical and equal to that determined by Coulomb's theory,but the points of application of the resultant earth pressures have significantly difference.The discussions are made on the distribution of earth pressure,the magnitudes and the points of application of the resultant earth pressures for practical design.