曲线滑裂面下有限宽度填土主动土压力计算

Calculation of active earth pressure for limited soils with curved sliding surface

开展了刚性挡墙平动变位模式情况下墙后有限宽度土体破坏试验。试验结果表明,在墙后填土宽度较小情况下,土体破坏面为通过墙踵及某一固定点的曲面,由此基于变分极限平衡法,导得滑裂面曲线的具体方程式为对数螺旋曲线。在此基础上,结合薄层单元法,得到了墙后有限宽度土体的主动土压力合力及土压力强度的分布。与室内观测结果及库仑土压力值的对比表明,该方法相比经典土压力方法更接近于实测值。分析了不同填土宽高比n下的主动土压力分布规律,结果表明,主动土压力随n增加而逐渐增加,但n达到0.55时趋于稳定,因此,该值可作为墙后土体有限宽度的界限值。

An experiment is conducted to determine the active earth pressure for soil with limited width behind a retaining wall in translational motion. The test results show that a continuous failure surface of limited-width soil behind a retaining wall passes through the wall toe and a fixed point. Based on the variational limit equilibrium method, a specific equation for the curve of the slip surface is deduced with logarithmic helical curve. The distribution of active soil pressure and soil pressure intensity with a limited width behind wall are derived using thin-layer element method. Comparing with the results of laboratory observations and Coulomb earth pressure, the result by the proposed method is closer to the measured value than the classical earth pressure method. The distribution of the active earth pressure is analyzed under different ratios n of the width to height of the backfill. The results show that the active earth pressure increases with the increasing of n, but approaching to a constant value as n reaches a threshold of limited width of 0.55.