地层结构对砂土液化影响的有效应力动力分析

Effects of soil layer construction on liquefaction of sandy soil by means of effective stress analysis method

根据上海市区典型土层的力学参数,构造不同地层组合的计算剖面,利用Biot固结理论和亚塑性边界面模型的排水有效应力动力分析法,研究地层结构对砂土液化的影响。分析发现:上履土层厚度增加时,砂土峰值孔压比随之减小;上履土层较软时,砂土峰值剪应力先增加、后减小;较硬时,峰值剪应力单调增加。下卧土层越厚,砂土层的峰值孔压比越小,峰值剪应力愈大,总体变化都不大,但下卧土层较软时,砂土层的峰值孔压比变化相对明显。

Based on the meachnical behaviors of representative soil layer in Shanghai, several computation profiles with different soil layer constructions are built. An effective-stress procedure, in which the bounding surface hypoplasticity model and Biot consolidation formulation are coupled, is used to analyze the effect of soil layer constructions on liquefaction of sandy soil. The results show： the thickness of covering soil layer increases, peak pore pressure ratio of sandy soil decreases; when it is softer, shear stress of sandy soil increases firstly, then decreases; but harder, it increases continuously. The deeper underlying soil layer is, the smaller peak pore pressure ratio and the more shear stress of sandy soil is; both are not obvious. But, if softer, the peak pore pressure ratio of sandy soil changes more sharply.