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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1.2m,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∑Msf,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∑Msf。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 a foundation pit in Henan Province is 5.8 m. The site is dominated by saturated silty silty clay with a nearest distance of 1.2m from the existing building nearby, using I-shaped cement-soil mixing walls and pre-stressed expansion head bolts Support. The supporting structure of the foundation pit is numerically simulated by PLAXIS finite element software. The displacement of soil under different working conditions, the axial force and bending moment of I-shaped cement-soil mixing wall, the anchoring force of prestressed anchors, The results show that the numerical calculation of soil horizontal displacement is in good agreement with the actual monitoring data, which verifies the rationality of modeling the I-shaped cement-soil mixing wall. PLAXIS software can simulate well the foundation pit The deformation characteristics of soil and structure in excavation process are verified, and the applicability of PLAXIS finite element software in foundation pit engineering is verified. The numerical calculation of soil horizontal displacement, bolt axial force, Multipliers ΣMsf. All of them meet the design requirements of foundation pit and verified the feasibility of I-beam cement-soil mixing wall in foundation pit support, which provides a theoretical basis for similar foundation pit design.