循环荷载作用下考虑非达西渗流的软黏土一维流变固结分析

One-dimensional rheological consolidation of soft clay under cyclic loadings considering non-Darcy flow

基于Hansob渗流理论和Merchant流变模型,将微分型流变方程耦合到一维固结理论中,建立了循环荷载作用下双变量表述的软黏土一维流变固结耦合方程组。采用Flex PDE软件对方程组进行了求解,通过与已有文献结果对比,验证了算法的可靠性,在该基础上研究了循环荷载作用下饱和软黏土的一维流变固结特性,分析了Hansob渗流参数、Merchant流变模型参数以及循环荷载类型对饱和软黏土固结特性的影响。研究结果表明,按超孔压定义的平均固结度U_p和按变形定义的平均固结度U_s均呈现循环变化特征,且U_p>U_s;当循环周次较大时,U_p进行稳定循环状态,由于流变效应,U_s峰值仍呈逐渐增大趋势;随着Hansob渗流参数m和1I的逐渐增大,地基固结速率逐渐降低,同一循环周次内U_p、U_s的峰值也随之降低;随着流变参数F的逐渐增大,同一循环周次内U_p的峰值逐渐降低,U_s的峰值显著提高;随着b的逐渐增大,同一循环周次内U_p、U_s的峰值逐渐降低。循环荷载作用下地基的平均固结度始终处于循环状态,无法达到固结完成状态,其最大平均固结度也远小于线性荷载的情况。

Considering Hansob's seepage flow law and the Merchant's rheological model, a one-dimensional rheological consolidation model of soft clay under cyclic loadings is established, which is described by using two variables, the excessive water pore pressure u and the vertical strainze. The rheological consolidation equations are solved by using Flex PDE software; and then the results are compared to those of existing literature to verify the reliability of the numerical solutions. Meanwhile, the behaviors of soil during rheological consolidation are investigated and the effects of the Hansob's flow parameters, the parameters of Merchant's rheological model on rheological consolidation are analyzed and discussed in detail. The results show that the average degree of consolidation in terms of the excessive water pore pressure U_p and that associated with settlement U_s vary predictably with the cyclic loading, and the maximum value of U_p is larger than that of U_s at the same time. Further, when the loading cycles are very big, U_p may reach the final cyclic steady-state while the peak value of U_s increases with the cycles due to the rheological effect. Moreover, the peak values of U_p and U_s both decreases with the increase of the parameters m and 1 I of Hansob's flow model. The peak value of U_p decreases with increasing the rheological model parameter F, while the peak value of U_s is on the contrary. Further, the peak values of U_p and U_s both decrease with the increase of the rheological model parameter b. The average degree of consolidation under cyclic loadings is in a circulation state all the time, which never reaches 100%, and it is smaller than that under ramp loading.