基坑开挖对围护结构影响的数值分析

Numerical analysis of the influence of excavation of foundation pit on enclosure structure

项目本身的风险主要是地层对基坑支护的不利影响,必须加强基坑支护结构的支护作用,以控制基坑的变形并满足基坑稳定的要求。使用Plaxis有限元软件分析了基坑开挖过程中围护结构的变形和应力,研究结果表明,从基坑变形来看,二号线西侧基坑开挖后的水平位移较大,接近30 mm,三号线基坑的最大水平变形出现在1—1断面位置,位移值在28 mm左右。从周围土体的沉降来看,开挖引起的沉降变形小于围护结构的水平位移。三号线基坑1—1断面处的土体沉降较大,最大沉降量为21 mm左右。从支撑轴向力的角度来看,由于2号线基坑的开挖深度较大,因此每个支撑承受的轴向力较大,相比之下,三号线基坑支撑的轴力较小,因此要重视对二号线基坑的轴力监测。

The risk of the project itself is mainly the adverse impact of the stratum on the foundation pit support.The support function of the foundation pit support structure must be strengthened to control the deformation of the foundation pit and meet the requirements of foundation pit stability.The Plaxis finite element software is using to analyze the deformation and stress of the envelope structure during the excavation of the foundation pit.The research results show that:from the perspective of the deformation of the foundation pit,the horizontal displacement after excavation on the west side of line 2 is large,close to 30 mm,and the maximum horizontal deformation of the foundation pit on Line 3 occurs at the location of section 1—1 is about 28 mm.Judging from the settlement of surrounding soil,the settlement deformation caused by excavation is less than the horizontal displacement of the envelope.The soil settlement at section 1—1 of the foundation pit of line 3 is relatively large,with a maximum settlement of about 21 mm.From the perspective of the axial force of the support,because the excavation depth of the line 2 foundation pit is larger,the axial force supported by each support is greater.In contrast,the axial force supported by the line 3 foundation pit small,so we must pay attention to the axial force monitoring of the second pit foundation pit.