考虑Hansbo渗流的砂井地基大变形固结问题

LARGE-STRAIN CONSOLIDATION OF FOUNDATION WITH SAND DRAINS BASED ON HANSBO’S FLOW

基于Gibson大变形固结理论,通过引入Hansbo渗流模型和软黏土非线性变形特性,同时考虑土层的沉积效应,分别建立了以孔隙比e和超孔压u表示的砂井地基大变形固结方程。通过与已有研究成果的对比,验证了本文方法的可靠性和砂井地基大变形固结方程两种描述方式的等效性。通过FlexPDE得到方程的数值解,在此基础上,研究了砂井地基大、小应变固结理论与Barron固结解的差异性,探讨了Hansbo渗流参数m和I1对砂井地基固结的影响,最后对比分析了砂井地基轴对称固结、径向固结和竖向一维固结的关系。研究结果表明:考虑Hansbo渗流的砂井地基非线性大变形固结模型的固结速率最慢,且在固结后期,Hansbo渗流时大、小应变固结与Barron固结的平均固结度基本趋近;随着Hansbo渗流参数m和I1的逐渐增大,砂井地基的固结速率逐渐降低;随着砂井影响半径的增大,砂井地基轴对称固结与径向固结的差异性也越来越大,且在固结早期会出现一维竖向固结速率高于轴对称固结和径向固结的现象。

Based on Gibson’s theory for the large-strain consolidation,the governing equations for the void ratio and the excessive pore pressure for the large-strain consolidation of foundation with sand drains are derived by introducing the Hansbo’s flow model with consideration of the sedimentary effect of the soil layer.By comparing with the existing research results,the reliability of the proposed method and the equivalence of the two description methods of the large deformation consolidation equation of the sand well foundation are verified.The numerical solutions of the equations are obtained by using the FlexPDE software,then the differences of the consolidation behaviors among the large-strain,the small-strain and the Barron’s consolidation are investigated.And the effect of the parameters(m and I1)of the Hansbo’sflow model on the consolidation behaviors is analyzed in detail.Finally,the consolidation behaviors of the axisymmetric consolidation,the radial consolidation and the 1 D vertical consolidation are compared.The results show that the large-strain consolidation rate with the Hansbo’s flow is smaller than that of any other consolidation models,and the average degree of the consolidation of the consolidation models with the Hansbo’s flow tends to be the same with a comparatively long time.And the consolidation rate decreases with the increase of the parameters m and I1 and of the Hansbo’s flow.Moreover,the difference of the average degree of the consolidation between the axisymmetric consolidation and the radial consolidation increases with the increase of the influence radius of the sand drains,and during the early stage of the consolidation,the consolidation rate of the 1 D vertical consolidation is larger than those of the axisymmetric consolidation and the radial consolidation.