复杂地质条件下矩形顶管下穿管线影响分析

Impact Analysis for Rectangular Pipe Jacking with Underpass Pipeline Under Complex Geological Conditions

为研究矩形顶管施工对邻近管线的影响,以某铁路出入口顶管工程为依托,建立三维数值模型对矩形顶管近接下穿管线过程中管线和地表变形规律进行研究,并结合现场实测数据进行分析。研究结果表明:(1)矩形顶管施工引起的地表变形以沉降为主,隧道上方土体产生了向隧道中心靠拢的趋势,地表沉降最大值16.3 mm,位于隧道中间位置,沉降影响范围为20 m;(2)受接收井的临空开挖面和施加在始发井的顶推力影响,开挖结束后接收井和始发井地表产生隆起,隆起最大值达到1.95 mm;(3)受土体挤压,管线水平位移最大值达到0.64 mm;在控制好管线沉降变形同时,也要注意对其施加水平约束,避免水平位移过大导致破坏;(4)管线变形和变形速率均在安全控制指标之内,数值模拟的管线变形规律与实测数据大致相同,数值模拟的地表和各管线变形规律是可信的。

In order to study the impact of rectangular pipe jacking on adjacent pipelines,a three-dimensional numerical model was established in this paper based on a case of pipe jacking at the portals of a railway,to study the deformation law of the pipeline and the ground surface during the process of rectangular pipe jacking approaching the underpass pipeline,and analyze it in combination with the measured data on-site.The results show that:(1)The surface deformation caused by rectangular pipe jacking is mainly settlement,and the soil above the tunnel tends to approach the center of the tunnel.The maximum surface settlement is 16.3 mm in the middle of the tunnel,and the settlement impact range is 20 m.(2)Affected by the free excavation face of the receiving shaft and the jacking force applied to the launching shaft,the surface of the receiving shaft and the launching shaft uplifts after excavation,with the maximum uplift reaching 1.95 mm.(3)The maximum horizontal displacement of the pipeline reaches 0.64 mm due to soil extrusion.While controlling the settlement and deformation of the pipeline,attention should also be paid to applying horizontal restraints to avoid damage caused by excessive horizontal displacement.(4)The deformation and deformation rate of the pipeline are within the safety control index,the deformation law of the pipeline simulated by the numerical method is roughly the same as the measured data,and the deformation law of the surface and each pipeline simulated by the numerical method is credible.