组合单元法在砂井地基有限元分析中的应用

针对砂井地基的平面应变有限元分析，本文首次将组合单元法引入到砂井地基的分析中，提出砂墙组合单元。该单元对常规等参元进行改进，在单元内部同时考虑砂井的涂抹作用和井阻作用，从而克服了常规有限元法在计算砂井地基时单元数和节点数过多的缺点。将砂墙组合单元加入USAP有限元计算软件，工程算例分析结果表明：与已有的各砂井地基的平面应变解答和荷兰的基础工程有限元分析软件PLAXIS相比，解答合理并有效地考虑砂井的涂抹作用和井阻作用；与常规有限元法相比，在保证计算精度的前提下，减少了可观的单元数和节点数，降低了计算的工作量。

Application of composite element method in sand drain ground finite element analysis

Based on the application of the domain-by-domain integration technique, a new element, sand-wall composite element, is provided for the plane strain finite element analysis of sand drain ground in this paper. The general element was improved in which both the effects of smearing and well resistance were taken into account inside the composite sand-wall element, therefore the drawback of the huge amount of element number and node number adopted in the general finite element analysis is overcame. The sand-wall composite element is incorporated in the finite element procedure USAP. Compared with other solutions of sand drain ground under plane strain condition and finite element analysis software PLAXIS, the calculated result of the improved element is reasonable and models both the effects of smearing and well resistance well. Compared with the general finite element analysis, it's proved that the composite element could reduce the calculation significantly whereas the accuracy of calculation is assured.