盾构隧道施工对临近既有线沉降影响的数值分析

Numerical Analysis of Existing Railway Settlement Caused by Close Construction of the Shield Tunnel

确保临近既有线的运营安全是新建隧道施工的关键问题之一。针对某新建城际铁路双线盾构隧道存在多次临近既有京广线施工的复杂情况,基于合理假定条件,采用数值分析方法全面模拟计算了新建隧道临近并行既有线、下穿单线和下穿多线等关键施工过程中盾构掘进对临近既有线沉降的影响,对比分析了拟采用的施工措施对既有线沉降的控制效果,为保障临近既有线的运营安全奠定了理论基础。数值分析结果表明:临近并行和下穿单线施工时,可分别采用隔离桩保护和注浆加固地层的处理措施控制地表沉降且效果较好;下穿多线施工时,列车荷载对地表沉降的影响较大,考虑列车荷载后盾构施工诱发的地表沉降最大值由0.44 mm增大至1.32 mm,盾构穿越宜在无列车行驶时进行。

To ensure the safe operation of the adjacent existing line is one of the key issues in the construction control of the new railway tunnel.In view of the complicated situation of the construction of a new intercity railway double-lane shield tunnel near the existing Beijing-Guangzhou Line on several occasions,based on reasonable assumptions,numerical analysis method was used to comprehensively simulate and calculate the influence of shield tunneling on the settlement of the adjacent existing lines during the critical construction process,such as the adjacent parallel existing lines,undercrossing single-line and multi-line,and a comparative analysis of the proposed construction measures to control the settling effect of the existing line,which lay a theoretical foundation for ensuring the operation safety of the adjacent existing line.The results of numerical analysis show that:when the construction is near parallel and under the single line,the treatment measures of isolated pile protection and slurry reinforcement of the ground layer can be used to control the surface settlement and the effect is better;when the construction is under the multiple lines,the impact of the train load on the surface settlement is greater,the maximum value of the surface settlement induced by the shield construction after considering the train load increases from 0.44 mm to 1.32 mm,so the shield crossing should be carried out when no train is running.