紧邻浅埋暗挖地铁隧道地下密集管线及土层变形

Deformation of Underground Dense Pipelines and Solum Adjacent to Shallow Buried Underground Subway Tunnels

针对地铁隧道施工影响下紧邻密集管线保护问题,依托南昌地铁实际工程,采用ABAQUS软件建立土体-密集地下管线-隧道暗挖三维有限元模型,结合现场实测数据与数值模拟结果,分析了隧道CRD(cross diaphragm)工法施工时的地层变形规律、地下管线应力特性与地下管线变形规律,并对管线周边土体有无注浆加固时的管线力学特性进行了对比。研究结果表明:①隧道开挖引起的管线变形以沉降为主,管土刚度差异对管线变形和应力影响显著。②管土刚度差异越小,管线变形趋势与土体变形趋势越接近;管土刚度差异越大,管线对地层变形的抵抗作用也越强会产生较大应力。③隧道左右导洞上方管段是危险区域,需重点保护。④密集地下管线主要表现为管线材质、管线几何特性、管线与隧道的空间位置关系不同,保护地下管线的核心在于控制地层沉降,地下管线保护关键阶段是隧道掌子面接近管线,此时应确保超前注浆效果和初期支护快速封闭,并加强对管线变形的监测。

In view of the protection of adjacent dense pipelines under the influence of subway tunnel construction,relying on the actual project of Nanchang subway,a three-dimensional finite element model of soil mass dense underground pipelines tunnel excavation was established by using ABAQUS software.Combined with the field measured data and numerical simulation results,the formation deformation law,underground pipeline stress characteristics and underground pipeline deformation law during tunnel CRD(cross diaphragm)construction were analyzed.The mechanical properties of the pipeline with or without grouting reinforcement were compared.The results show these as follows.The pipeline deformation caused by tunnel excavation is mainly settlement,and the pipe soil stiffness difference has a significant impact on the pipeline deformation and stress.The smaller the stiffness difference between pipe and soil,the closer the deformation trend of pipeline and soil is.The greater the stiffness difference between pipe and soil,the stronger the resistance of pipeline to formation deformation,which will produce greater stress.The pipe section above the left and right pilot tunnels of the tunnel is a dangerous area,which needs to be protected.Dense underground pipelines are mainly manifested in the different materials of pipelines,geometric characteristics of pipelines,and the spatial relationship between pipelines and tunnels.The core of protecting underground pipelines is to control the stratum settlement.The key stage of underground pipeline protection is that the tunnel face is close to the pipeline.At this time,it is necessary to ensure the effect of advance grouting and the rapid closure of initial support,and strengthen the monitoring of pipeline deformation.