柔性挡墙的主动土压力计算及分布研究

Calculation and distribution of active earth pressure against flexible retaining walls

已有研究表明,柔性挡墙在不同位移量和位移模式下,主动土压力的大小和分布均发生变化,其分布也与刚性挡墙有明显区别。在前人室内试验和数值模拟结果的基础上,建立了考虑位移变化效应的柔性挡墙土压力计算模型,采用中间状态系数来统一反映挡墙位移模式和位移量的影响,提出了任意位移柔性挡墙主动土压力合力系数的计算公式;在求得合力基础上,将土体简化为非线性弹簧和刚塑性体的组合体,提出了任意位移下的土压力分布和合力作用点高度的计算方法。以前人模型试验为算例,将本文方法与试验结果、已有理论方法的对比表明,本文方法得到的土压力分布与试验值更接近。研究还发现,随着柔性挡墙位移量的增大,土压力合力逐渐减小,土压力分布的非线性程度逐渐增大;合力作用点位置随挡墙位移形态的变化而改变;在典型鼓胀形变位模式下,土压力呈R形分布。

The previous studies have shown that the resultant and distribution of active earth pressures against flexible retaining walls vary with the modes and magnitudes of wall movement, and the distribution of earth pressures is significantly different from that of rigid walls. Based on the previous experimental and numerical results, a model to calculate the earth pressures on the flexible retaining walls is proposed, which can consider the effect of wall movement. A middle-state coefficient is introduced to reflect the influence of the modes and magnitudes of wall movement. The formulae of the coefficients of the resultant earth pressures on the flexible wall under any lateral deformation are presented. Then the soil behind the wall is simplified as the combination of nonlinear springs and a rigid plasticity object and the unit earth pressures and the heights of points of application of resultant forces are obtained. The comparisons among the proposed formula, previous methods and the experimental observations show that the results of the proposed method are more satisfactory than these of the previous methods. With the increase of the wall movement, the resultant active pressures decrease and the nonlinearity of the distribution of earth pressures augments gradually. The heights of points of application of resultant forces change with the mode of wall movement. The distribution of earth pressures exhibits a“R” shape under the drum deformation of the wall.