鼓形变位模式下柔性挡土墙的主动土压力分布

针对鼓形变位模式的柔性挡土墙,采用库仑土压力理论的假设,挡土墙上的主动土压力假定由墙后填土在极限平衡状态下出现的滑动楔体产生,在该滑动楔体上沿填土深度方向取典型水平薄层单元进行分析,分段建立关于挡土墙上土压力强度的一阶微分方程,给出了鼓形变位模式下,柔性挡土墙上的土压力强度、土压力合力和合力作用点的理论公式,并与库仑土压力理论和有关实验结果进行了比较分析。结果表明,鼓形变位模式下,土压力合力与库仑土压力理论结果相等,土压力分布和合力作用点位置则明显不同;墙顶附近的土拱作用改变了土压力的分布,本文方法与前人实验得到的土压力均大致呈R形分布。最后,利用本文解,对土体内摩擦角、墙土摩擦角、土薄层单元间等效内摩擦角、墙体最大变位点深度等参数对挡土墙土压力强度、土压力合力和合力作用点的影响进行了分析。

Distribution of active earth pressure against flexible retaining walls with drum deformation

Based on the Coulomb’s concept that the earth pressure against the back of a flexible retaining wall with drum deformation was a thrust exerted by the sliding soil wedge formed by the back of the wall and a plane passing through the bottom edge of the wall with an angle of inclination θ.The differential equation of the first order was set up by the equilibrium of forces on the horizontal layer taken out from the wedge.The theoretical formulae of the unit earth pressures,the resultant earth pressures and the points of application of the resultant earth pressures on the flexible wall were obtained for the drum movement mode.The comparisons were made among the formula presented here,the Coulomb’s formula and some experimental observations.It was demonstrated that the magnitudes of the resultant earth pressures for the drum movement mode were equal to those determined by the Coulomb’s theory,but the distribution of the earth pressure and the points of application of the resultant earth pressures were significantly different.Soil arching altered the distributions of pressure on the flexible wall.Finally,some factors that have influences on the magnitude and distribution of earth pressures,such as soil properties,frictional characters between walls and soils,position of the maximum deformation of the walls were studied.