变边界下考虑起始水力坡降的软土固结数值解

Numerical solutions for the consolidation of soft clay with threshold hydraulic gradient and time-dependent boundaries

文章引入边界处孔隙水压力随时间指数变化的变排水边界及软黏土中存在的起始水力坡降,建立单层均质土体的一维固结模型;利用有限差分方法对所建立的固结模型进行数值求解,分别获得土层超静孔压、土层固结度的数值解;利用数值解深入分析随时间指数变化的变边界及起始水力坡降对固结性状的影响。分析结果表明:当起始水力坡降的无量纲参数R相同时,变边界无量纲参数B越大(排水边界越接近于完全透水边界),移动边界下移速度越快,土中超静孔压的消散速率越快,固结完成时间越短,反之亦然;当B值相同时,R值越大,移动边界至土层底部的时间越长,相同时刻下超静孔压残留值越大,土层平均固结度越小。

An one-dimensional consolidation model of single-layer homogeneous soil is developed by considering the time-dependent boundary where the excess pore water pressure exponentially changes with time and the threshold hydraulic gradient in soft clay.The finite difference method is adopted to solve the consolidation model,and the numerical solutions of excess pore water pressure and consolidation degree of soil layer are obtained respectively.Finally,the numerical solutions are adopted to analyze the influence of variable boundary and threshold hydraulic gradient on consolidation behavior.The results show that under the condition that the dimensionless parameter R of threshold hydraulic gradient is the same,the larger the dimensionless parameter B of variable boundary is(the closer the drainage boundary is to the completely permeable boundary),the faster the moving boundary moves down,the faster the dissipation rate of excess pore water pressure in soil is,and the shorter the consolidation completion time is;on the contrary,the smaller B is,the slower the moving boundary downward movement rate and the dissipation rate of excess pore pressure are,and the longer the consolidation completion time is.When the value of B is the same,the larger the value of R is,the longer it takes to move the boundary to the bottom of soil layer,the larger the residual value of excess pore water pressure at the same time is,and the smaller the average consolidation degree of soil layer is.