河南某基坑最大开挖深度为5.8 m，场地以饱和淤泥质粉质黏土为主，与周边既有建筑最近距离为1.2 m，采用工字钢水泥土搅拌墙和预应力扩大头锚杆进行支护。运用PLAXIS有限元软件对该基坑支护结构进行数值模拟，得到了不同工况的土体位移、工字钢水泥土搅拌墙轴力和弯矩、预应力锚杆的锚固力和各开挖阶段的总乘子 ，结果表明，数值计算的土体水平位移与实际监测数据比较吻合，验证了工字钢水泥土搅拌墙建模的合理性；PLAXIS软件能较好地模拟基坑开挖过程中土层及结构的变形特点，验证了PLAXIS有限元软件在基坑工程的适用性；数值计算的土体水平位移、锚杆轴力、采用强度折减法计算的各开挖阶段的总乘子 均满足基坑设计要求，验证了工字钢水泥土搅拌墙在基坑支护的可行性，为类似基坑设计提供了理论依据。

The maximum excavation depth of one foundation pit in Henan Province is 5.8 m, the fields are mainly composed of saturated mucky silty clay, the minimum distance between the foundation pit and surrounding existing buildings is only 1.2 m, and I-steel cement soil mixing walls and prestressed bit expanded anchor are adopted to support the foundation pit. PLAXIS finite element software is used to numerical simulate the foundation pit supporting structure, and soil displacement, axial force and bending moment of I-steel cement soil mixing wall, anchoring force of prestressed bit expanded anchor and total multiplier are simulated and calculated. Some conclusions are drawn as follows: the simulated horizontal displacements of soils are near to the monitored data, which verified the rationality of FEM model of I-steel soil cement mixing wall; the deformation characteristics of structures and soils during the excavation of foundation pit are simulated reliably with the PLAXIS software, and PLAXIS is one appropriate method to simulate foundation pit engineering; the simulated and monitored horizontal displacements of soils, axial force of anchors, multiplier with strength reduction method during the excavation stages all meet with the requirement of foundation pit design; and so I-steel cement soil mixing wall is proved to be feasible for the foundation pit supporting engineering, so as to provide references for the similar engineering.