膨胀土条件下隧道下穿既有地铁车站CRD开挖工法优化  

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

作　　者：马乐乐 Ma Lele(China Railway 24th Construction Bureau Group Anhui Engineering Co.,Ltd.,Hefei 230011,China)

机构地区：[1]中铁二十四局集团安徽工程有限公司,安徽合肥230011

出　　处：《市政技术》2021年第1期66-73,共8页Journal of Municipal Technology

摘　　要：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PLAXIS 3D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:不同开挖工序对洞周位移有一定影响;1.5 m循环步距情况下的拱顶沉降和净空收敛是0.5 m的1.55~3倍。最后,选定以左上→右上→左下→右下的开挖工序、0.5 m的循环步距作为最优方案并进行现场施工。结合监测数据分析表明,隧道自身和既有地铁车站基本处于安全稳定状态,该优化方案合理可靠。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.

关 键 词：地铁 下穿隧道 膨胀土 有限元 开挖工序 循环步距 

分 类 号：U231.1[交通运输工程—道路与铁道工程]