紧邻地铁半圆内支撑深基坑受力及变形特性数值研究

基于紧邻地铁车站及区间箱型隧道的昆明某超大型半圆内支撑深基坑工程,结合现场实测数据,对深基坑开挖过程进行仿真数值模拟;在此基础上研究紧邻地铁半圆内支撑深基坑受力及变形特性。研究结果表明:1超大型半圆内支撑体系有效地限制了地下连续墙的侧移,该设计方案成功、合理,可为昆明地区类似基坑设计提供借鉴;2半圆内支撑体系在圆弧端点处剪力、弯矩较大,需加强此处的支护结构;3半圆内支撑体系在圆弧拱顶处侧向位移较大,设置对称可有效地控制其变形;4侧方地铁结构对地下连续墙的侧向位移具有抑制效应,且抑制效应随距离的增大快速衰减,在基坑设计时可考虑此效应并结合地铁保护要求及基坑安全等级要求得到最佳方案。

Numerical Study on Pressure and Deformation Characteristics of Deep Foundation Pit with Semicircle Inner Support Adjacent to Metro

Based on a super large foundation pit in Kunming with semicircle inner support adjacent to the existing metro station and running tunnel and with reference to field data, Numerical simulation was applied to simulate the construction process. On this basis, pressure and deformation characteristics of foundation pit were studied. The results show that: (1) super large semicircle inner supporting system inhibit lateral displacement of diaphragm wall effectively. The design plan of foundation pit is successful and reasonable, and can provide reference for design plan of similar foundation pit in Kunming. (2) the shearing force and bending moment of arc extreme point of semicircle inner supporting system is bigger, and the supporting structure of arc extreme point is needed to strengthened. (3) lateral displacement of arc vault of semicircle inner supporting system is bigger, and setting up symmetric supporting system can effectively control the deformation. (4) Lateral subway structures have inhibitory effect on lateral displacement of diaphragm wall, and its inhibitory effect decays rapidly with the increase of distance. In the design of foundation pit , the effect should be considered, and protection requirements of metro and deformation requirements of foundation pit should also be considered in order to get an optimum scheme.