基坑开挖对下卧既有隧道变形的影响

Influence of foundation pit excavation on the deformation of existing tunnel

为研究基坑开挖对下卧既有隧道变形的影响,依托某基坑上跨既有隧道工程,采用数值计算,建立三维有限元模型,分析基坑开挖对下卧隧道变形影响,并将数值计算结果与现场监测数据进行对比分析。结果表明:对于初步预测基坑开挖引起下卧隧道的隆起变形,数值计算方法可靠、实用;采用微压力扰动搅拌阶梯式注浆加固、考虑“时空效应”的分层、分块开挖及基底抽条开挖、架设型钢支撑对控制隧道变形效果显著。

In order to study the influence of foundation pit excavation on the deformation of the underlying existing tunnel,relying on the existing tunnel project on the upper span of a foundation pit,a three-dimensional finite element model is established by numerical calculation,the influence of foundation pit excavation on the deformation of the underlying tunnel is analyzed,and the numerical calculation results are compared with the field monitoring data.The results show that the numerical calculation method is reliable and practical for the preliminary prediction of the uplift deformation of the underlying tunnel caused by foundation pit excavation.Using micro pressure disturbance mixing stepped grouting reinforcement,layered and block excavation considering"space-time effect",base strip extraction excavation,and erection of section steel support have significant effects on the control of tunnel deformation.