基于PSO搜索潜在滑裂面非极限状态土压力计算

作用于刚性挡土墙侧土压力的计算一直沿用经典的朗肯或库仑土压力理论,这两种理论只能求得极限状态的土压力,而在许多实际情况下,挡土墙的土压力处于非极限状态.本文将潜在滑裂面视为一任意曲线,改进水平层分析法,同时基于摩擦角随位移的变化关系,对平动模式下墙后填土进行分析,推导出非极限状态下主动方向土压力分布、合力大小及作用点的理论公式.以各薄层微元的滑裂面倾角为变量,利用PSO(粒子群算法)对潜在滑裂面进行搜索从而获得土压力最优解.分析了内摩擦角、刚性挡土墙位移量对非极限状态主动方向土压力分布、土压力合力大小、土压力合力作用点高度以及潜在滑裂面的影响.本文提出的计算方法得出的结果与试验数据的大小及变化趋势基本吻合,具有推广应用价值.

Computation of Earth Pressure under Non-limit State Based on PSO Search of Potential Slip Surface

The computation of earth pressure against rigid retaining wall usually adopts classical Rankine or Coulomb''s theory, which can only get limit state of earth pressure, but in many practical cases, the earth pressure against retaining wall is in the non-limit state. So, this paper presented an analysis of the backfill under the mode of translation based on the improved thin-layer element method and the relationship between friction angle and displacement variation. The distribution of earth pressure, resultant force and its action point of a retaining wall under non- limit state were obtained. The optimal solution of earth pressure was obtained by using PSO (particle swarm optimization) to search the potential slip surface, on which the inclination angle of the segment for the thin layer element was extracted as a valuable. Then, the effects of the internal frictional angle, wall displacement on the distribution of earth pressure, resultant force, action point and potential slip surface were discussed. Finally, the results of the proposed method were compared with laboratory test data, which shows that the calculated results have a good agreement with the experimental observations.