地铁车站洞桩法施工引起的地表沉降和邻近柔性接头管道变形研究

在城市复杂建设环境下,地铁车站施工对地层和邻近管道的影响问题备受关注。依托北京地铁10号线黄庄站工程,基于地表和管道沉降的实测数据,建立"车站结构-地层-管道"三维耦合有限元模型,研究车站洞桩法施工对地层和管道的影响。采用主从接触面有限滑移方法模拟管道与土体相互作用,并利用两节点连接单元约束模型模拟柔性接头管道的接头变形,获得车站洞桩法施工对地表沉降和邻近柔性接头管道沉降、变形、应变、接头转角和脱开的影响规律。结果表明,"导洞开挖支护"和"中跨扣拱及拱部土体开挖支护"两个施工阶段是车站洞桩法施工中引起地表沉降的重要工序;管道变形与其相对于隧道的位置关系密切,管道正下方土体开挖过程对管道的影响最为显著;柔性接头管道的变形主要由管道接头承担,可采用接头转角和脱开作为管道变形的控制指标;管道接头转角的变化经历初始变化、凸曲率、凹曲率和稳定等四个阶段,而管道接头脱开经历初始变化、快速增长和稳定等三个阶段。

Study of surface settlement and flexible joint pipeline deformation induced by metro station construction with PBA method

Using the Huangzhuang metro station project of Beijing metro line 10 as the background,a 3-D finite element model including the station structure,soil and pipeline was established using the field monitoring data.The master-slave contact surface method was adopted to simulate the pipe-soil interaction,and two-node connector element constrain model to simulate the pipe joint deformation.The influence of metro station construction using PBA method on ground movement was examined,and the response of adjacent pipelines was studied concerning the following aspects: settlement,deformation,strain,joint rotation and pullout.The results showed that the ground settlement induced by the construction of the headings and the center arch contributed the most of the total settlement.Pipeline deformation was closely related to the relationship between the station and pipe,and moreover,the response of adjacent pipelines was mainly induced by the excavation of the soil below the pipelines.The pipeline joint born most of the deformation of the flexible joint pipeline,and the pipeline joint rotation and pullout can be used as a deformation criterion.The stages of pipeline joint rotation variation included the initial stage,convex curvature stage,concave curvature stage and stable stage.The joint pullout includes 3 stages: initial variation stage,rapid increase stage and stable stage.