Stress, displacement and bearing capacity analyzes by elasto-plastic finite element method based on finite deformation theory

本文首先提出了一种新的地基承载力评价方法，即基于微变形理论的弹塑性有限元固结变形分析方法。将该方法应用于条形荷载作用下正常固结地基的不排水和部分排水承载力分析。特别是，本文采用等参四边形单元，采用减缩积分法计算地基的极限承载力，所得结果与其他研究者的结果吻合较好。其次，基于修正的拉格朗日法，将有限变形分析转化为土/水耦合形式。在此基础上，开发了基于无限小变形和承载力分析的有限变形分析程序，并将其应用于均质、各向同性正常固结饱和地基在均布条形荷载作用下的固结变形和不排水承载力分析。将有限变形分析结果与微变形分析结果进行了比较。结果表明，有限变形分析得到的地基承载力大于无限小变形分析得到的地基承载力，且地基压缩性越大，两者的差异越大。

In this study, at first a new method, using the consolidation deformation analysis by the elasto-plastic finite element method based on the infinitesimal deformation theory, was proposed in order to evaluate the bearingcapacity of ground. This proposed method was applied to undrained and partially drained bearing capacity analyzes of isotropic or anisotropic normally consolidated grounds under the strip load. Especially, it was cleared that ultimate bearing capacity of ground obtained by this proposed analysis method, in which isoparametric quadrilateral elements using the reduced integration was used, was Well coincident with the results repoted by another investigators.Secondly, finite deformation analysis was formulated as soil/water coupling form based on the updated La-grangean method. And then, finite deformation analysis using the program, which was developed based on the one for infinitesimal deformation and bearing capacity analyzes, was applied to consolidation deformation and undrained bearing capacity analyzes for homogeneous, isotropic normally consolidated and saturated ground under the uniform strip load. the results obtained by finite deformation analyzes were compared with ones obtained by infinitesimal deformation analyzes. As the result, it was indicated that bearing capacity of ground obtained by finite deformation analysis was greater than that obtained by infinitesimal deformation analysis, and that the greater the compressibility of ground was, the greater the difference between both results was.