正交下穿截污管盾构开挖面被动失稳颗粒流模拟研究

Study on Passive Instability Particle Flow Simulation of Tunnel Face in the Shield Tunnel Perpendicular Undercrossing the Sewage Interception Pipe

目的 对砂土地层土压平衡式盾构下穿截污管施工工况进行研究,以解决由于支护压力过大导致的开挖面被动失稳问题。方法 以沈阳地铁三号线下穿截污管区段为背景,利用颗粒流程序建立数值模型,研究截污管存在下的开挖面被动失稳模式、支护压力变化以及地层应力分布。同时分析了管隧垂直净距与细观摩擦系数对极限支护压力的影响。结果 开挖面失稳模式和极限支护压力均受盾构开挖位置的影响,当开挖面位于管道前方1.0 D时,管道对失稳模式的影响最大;盾构穿越管道前,管道下部土层出现应力增大现象;极限支护压力随着管隧垂直净距、颗粒摩擦系数的增大而增大。结论 在盾构接近且未穿越截污管时,管道对开挖面被动失稳机理产生了显著影响。

The construction conditions of earth pressure balanced shield perpendicular undercrossing the existing sewage interception pipe in sandy soil stratum are studied,so as to solve the problem of passive instability of tunnel face caused by excessive support pressure.Taking the section of Shenyang Metro Line 3 undercrossing the existing sewage interception pipe section as the background,a numerical model is established using the particle flow code to study the passive failure modes of the tunnel face,the change of the support pressure and the distribution of the ground stress under the presence of the existing sewage interception pipe.Additionally,the study examines the impact of the vertical clearance between the pipe and the tunnel,as well as the friction coefficient,on the limit support pressure.The failure mode and limit support pressure of the tunnel face are affected by the shield excavation location,and the pipe has the greatest influence on the failure mode when the tunnel face is located 1.0 D in front of the pipe.Before the shield crosses the pipeline,there is an increase in stress in the soil layer below the pipeline.The limit support pressure increases with the increase of the vertical clearance between the pipe and the tunnel and the friction coefficient of the particles.When the shield is close to,but does not cross the sewage interception pipe,the pipeline has a significant effect on the passive instability mechanism of the tunnel face.