膨胀土条件下隧道下穿既有地铁车站CRD开挖工法优化

为保证膨胀土条件下新建隧道施工和既有结构的安全,以合肥地铁5号线下穿既有地铁车站工程为依托,考虑膨胀土胀缩性及裂隙性等不良特性,对其采用了袖阀管注浆加固方法.基于CRD工法的开挖工序和循环步距提出了不同优化方案,并通过PLAXIS3D岩土有限元软件,模拟了计算隧道及周边地层的受力和变形,选择出了最优方案.该研究表明:不...

Optimization of Tunnel Through the Existing Subway Station with Expansive Soil by CRD Method

In order to ensure the safety of the new tunnel construction and the existing structure under the condition of expansive soil,the tunnel project of Hefei Metro Line 5 through the existing subway station is taken as an example.The reinforcement method by sleeve valve pipe grouting is adopted.Because of the swell-shrink and crack character-istics of the expansive soil.Based on the excavation procedure and cycle step by CRD excavation method,different optimization schemes are proposed.Furthermore,the stress and deformation of tunnel and surrounding strata are simulated by PLAXIS 3D geotechnical finite element software,and the optimal scheme is selected.The results show that:different excavation procedures have a certain impact on the displacement around the tunnel;The vault settlement and clearance convergence under the condition of 1.5 m cyclic step is 1.55~3 times of that of 0.5 m.Finally,the optimal scheme,which the excavation procedure is upper left→upper right→lower left→lower right and cyclic distance is 0.5 m,is applied to the field construction.Combined with the analysis of monitoring data,the tunnel itself and the existing subway station are basically in a safe and stable state.The optimization scheme is rea-sonable and reliable.