基于非Darcy渗流的饱和黏土一维非线性固结分析

在考虑土体变形非线性的基础上,引入描述非Darcy渗流的Hansbo方程,修正饱和黏土一维固结方程,并采用有限差分法对该方程进行求解。通过与Davis和Raymond一维非线性固结理论解析解的对比,证明本文数值方法的有效性。在此基础上,探讨土体非Darcy渗流参数、压缩指数以及地面荷载值对固结过程的影响。计算结果表明,非Darcy渗流延缓饱和黏土中孔隙水压的消散速率和地基沉降速率,且随着压缩指数与渗透指数之比c或非Darcy渗流参数m和i1的增大,孔压消散速率和地基沉降速率都变慢,即不考虑渗流非Darcy特性的固结分析将会高估孔压消散速率和地基沉降速率,而地面荷载对固结进程的影响则与固结时间和压缩指数与渗透指数的比值有关。

ONE-DIMENSIONAL NONLINEAR CONSOLIDATION ANALYSIS OF SATURATED CLAY BASED ON NON-DARCY FLOW

Considering the nonlinear deformation of soil，the Hansbo¢s formula for the non-Darcy flow is introduced to modify Terzaghi¢s one-dimensional consolidation equation；and the numerical solution analysis is performed by using the finite difference method. In order to verify its validity，the calculating solution by the present method for the case that the flow of pore water obeys Darcy¢s law is compared with the analytical solution based on the nonlinear consolidation theory proposed by Davis and Raymond. Then the effects of the non-Darcy flow parameters，the compression index of soil and the external vertical load on the consolidation process are investigated respectively. The calculating results indicate that both the pore water pressure dissipation rate and the foundation settlement rate are delayed with the increase in the ratio c of the compression index to the permeability index or the non-Darcy flow parameters m and i1，thereby they will be overestimated if the non-Darcy's characteristic of flow is not taken into account. In addition，the effect of the external vertical load on the consolidation process is related to the consolidation time and the ratio of the compression index to the permeability index.