地铁叠线隧道盾构掘进对地表沉降影响研究

Research on the Influence of Shield Tunneling on the Ground Settlement in Overlapping Metro Tunnels

研究目的:地铁叠线隧道由于掘进过程中上下线相互影响且大部分埋深较浅,其对地层的扰动相比常规隧道更为剧烈。本文以佛山地铁3号线某区间叠线隧道为工程背景,利用数值模拟软件建立有限元模型,研究叠线隧道掘进过程中横剖面上土体移动规律以及地表沉降规律,并探讨掘进面压力以及注浆压力对地表沉降的影响,从而为现场选择合理的地铁叠线隧道盾构掘进施工参数提供理论依据。研究结论:(1)叠线隧道掘进引起的地表沉降具有叠加效应;(2)上线隧道掘进时会引起下线隧道的上浮;(3)浆液处于软化阶段时,地表沉降会急剧增大,从注浆到浆液硬化,这一过程对地表沉降的贡献约40%;(4)增大盾构机掘进面压力以及注浆压力可以有效减小地表沉降,但当注浆压力大于200 k Pa时其作用不再明显;(5)本研究结论可为叠线隧道盾构施工时控制地表沉降提供理论指导。

Research purposes: Due to the interaction between the upper and lower lines in the process of tunneling and the shallow buried depth,the disturbance to the stratum of the overlapped metro tunnel is more severe than that of the conventional tunnel. Based on the construction background of an interval overlapped line tunnel of the Metro Line 3 in Foshan,a finite element model is established by using numerical simulation software to study the law of soil movement on the cross section and the law of ground settlement during the excavation of the overlapped line tunnel,and to explore the influence of the pressure of the excavation face and grouting pressure on the ground settlement,so as to provide the reasonable parameters for the shield excavation of the overlapped line tunnel in the field.Research conclusions:( 1) The surface settlement caused by the excavation of overlapping tunnels has the superposition effect.( 2) When the upper line tunnel is excavated,it will cause the lower line tunnel to float up.( 3) When the cement slurry is in the softening stage,the surface settlement will increase sharply,from grouting to hardening of the cement slurry,the contribution of this process to the surface settlement is about 40%.( 4) Increasing the face pressure and grouting pressure of shield machine can effectively reduce the ground settlement,but when the grouting pressure is greater than 200 kPa,its effect is no longer obvious.( 5) The research conclusions can provide theoretical guidance for the control of ground settlement during shield tunnel construction.