基于薄层单元法主动土压力计算的复合遗传算法

Complex genetic method of active earth pressure based on thin-layer element method

作用于挡土墙侧土压力的计算一直沿用经典的土压力理论,其土压力分布沿墙高呈直线分布,但实践证明它们与实际情况不符。在已有研究成果的基础上,为提高计算精度,假定挡土墙后土体潜在滑裂面为由对数螺线面和平面组合而成,根据挡土墙后土体薄层单元的极限平衡条件推导出土压力的计算公式。由于土压力计算值与滑裂面的位置有关,为寻找潜在最危险滑裂面,在简单遗传算法中引入复合形搜索法得到一种高效的复合形遗传算法,并将其用于墙后填土潜在最危险滑裂面搜索和相应主动土压力计算。最后,对室内模型挡墙和现场实际挡墙后填土土压力进行了分析计算,计算值与实测值吻合很好,这表明该方法不仅可行,而且可靠。

In general, the calculation of earth pressure existing in the back of retaining wall employs the classical earth pressure theory; and the earth pressure distribution along the wall back is linear. In practical engineering, however, the earth pressure distribution usually is nonlinear. In order to enhance the accuracy of earth pressure calculation, it was assumed that the potential slip surfaces of backfill soils were composed of log-spiral surface and plane. Based on the existing researching works, the formulae for calculating active earth pressure were obtained by utilizing thin-layer element method. Since the calculation value of earth pressure is relevant to the location of slip surface; in the search for the most dangerous potential slip surfaces, a new hybrid genetic algorithm, called complex genetic algorithm （CGA）, was developed by introducing complex method into simple genetic algorithm to enhance the calculation efficiency. CGA was used to determine the potential slip surfaces and calculate the corresponding active earth pressure Finally, the earth pressures of the laboratory model retaining wall and in situ retaining wall were analyzed and the results show that the calculation values given by the presented method are very consistent with the measured values. It is indicated that the presented method is feasible and reliable.