基坑开挖影响下下卧盾构隧道变形及控制措施研究

近年来地铁建设不断加快,在地铁隧道上方施工已成常态。为研究基坑开挖影响下下卧盾构隧道的隆起变形,评价不同变形控制措施的实际控制效果,以武汉市轨道交通6号线琴台变电站地下电缆通道工程为例,采用两阶段法计算了基坑开挖影响下下卧盾构隧道的隆起变形,同时采用数值模拟方法对无加固、压力注浆加固、水泥土搅拌桩加固和压力注浆+水泥土搅拌桩综合加固控制措施4种工况下下卧隧道的隆起变形值进行了数值模拟计算,并将数值模拟结果与实际工程监测数据进行了对比分析。结果表明:对于初步预测基坑开挖引起下卧盾构隧道的隆起变形,该理论计算方法可靠、实用;压力注浆+水泥土搅拌桩综合加固控制措施使下卧盾构隧道的隆起变形和横断面收敛变形值分别减小至2.3 mm和0.35 mm,控制效果良好,具有一定的实际推广意义,可为类似工程提供参考。

Deformation and Control Measures of the Underlying Shield Tunnel under the Influence of Foundation Pit Excavation

In recent years,the subway construction is speeding up,and the construction above the subway tunnel has become normal.In order to study the uplift deformation of the underlying shield tunnel under the influence of foundation pit excavation and evaluate the actual effect of different deformation control measures,taking Qintai substation underground cable channel project of Wuhan subway line 6 as an example,this paper uses thetwo-stage method to calculate the uplift deformation of the underlying shield tunnel,and uses the numerical simulation method to calculate the shield tunnel uplift deformation displacement under four working conditions,namely,non-reinforcement,pressure grouting,cement soil mixing pile and pressure grouting plus cement soil mixing,and compares with the actual engineering monitoring data.The research results show that the theoretical calculation method is reliable and practical for the preliminary prediction of the uplift deformation of the underlying shield tunnel caused by the excavation of foundation pit;the comprehensive control measures,i.e.,pressure grouting plus cement soil mixing,reduces the uplift deformation and section convergence deformation of the underlying shield tunnel to 2.3 mm and 0.35 mm respectively,with good control effect,which has a certain practical significance and can provide reference for similar projects.