沪宁高速公路地基沉降有限元计算分析

采用比奥固结理论，考虑侧向变形、二维或三维渗流对沉降的影响，对沪宁高速公路路基作非线性有限元计算。将路堤和地基作为整体划分网格，取网格结点上的孔隙压力和竖向、水平向的位移为基本未知量，在路堤作用下，根据土体的劲度和渗透性建立方程组，从而解得孔压和位移。由有限元法与常规设计计算结果比较可知：用ｅ～ｌｇｐ′法考虑前期固结压力是必要的，但应用１０～１２的修正系数对总沉降作修正；有限元法算得的工后沉降小于分层总和法；路堤填筑速度对沉降过程有影响；增加预压时间可减少工后沉降。

Finite Element Analysis of Foundation Settlement of Shanghai Nanjing Expressway Embankment

The nonlinear finite element method with Biot′s consolidation theory is used to calculate the settlement of road bed of the Shanghai Nanjing Expressway.In calculation,the influence of lateral deformation and impact of 2 or 3 dimensional seepage on settlement is considered.The embankment and the foundation are taken as a whole to form the mesh.The pore pressure and the vertical and horizontal displacements are taken as fundamental unknowns.The equations are set up based on the stiffness and permeability of soil.For a given embankment loading condition,the pore pressure and displacements can be solved.A comparison between the results of the finite element method and traditional methods shows.The influence of pre consolidation on settlement(using e lg p method)must be considered and,at the same time,the total settlement modification coefficient of 1 0 to 1 2 should be adopted,the settlement after construction obtained through FEM is less than that from the layer wise summation method,the embankment construction speed has influence on the settlement procedure;increase of pre loading time can reduce post construction settlement.