暗挖隧道同时下穿铁路桥梁和隧道数值分析

Research on Protective Schemes of Tunneling Densely under Crossing Different Railway Structures

暗挖隧道下穿建(构)筑物时存在较大施工风险,以地铁暗挖区间隧道同时下穿京张高速铁路隧道和京包铁路桥为工程背景,在风险保护措施的基础上,采用三维有限元分析方法,分析了不加固和加固方案下京张隧道、京包铁路桥竖向位移和横向位移极值随施工步变化特征,总结了加固后京包铁路桥承台和桥桩差异沉降控制效果。结果表明,加固后京张隧道竖向位移极值减少约50%,京包铁路桥桥桩竖向位移极值减少60%,经过加固处理相关位移满足控制标准;先行施工的地铁暗挖区间隧道引起了较大位移,是铁路隧道保护关键阶段;竖向位移大于水平位移,是铁路结构位移控制关键;京张隧道竖向位移极值为中间偏左,京包铁路桥桥桩竖向位移极值为中间偏右。研究可为密集穿越工程提供借鉴与参考。

Great risk exists in undercrossing process of tunneling.Takeone excavation of metro tunnel crossing Jingzhang high-speed railway tunnel and Jingbao railway-bridge underground as an example,in which,with the FEM numerical method adopted and the protective measures used,the characteristics of the vertical and lateral displacement changes with the construction going on are analyzed for different reinforcement schemes.The differential settlement between bearing platform and bridge pile after reinforcement treatment is summarized.The result showsthat firstly the maximum vertical displacement of Jingzhang tunnel and Jingbao railway bridge are respectively reduced by about 50%and 60%after reinforcement which meets the control standard,secondly,the construction of the tunnel built in advance is the key stage of railway structure protection because the vertical displacement,the key index for displacement control,is larger than the horizontal displacement,and finally,the maximum vertical displacement of Jingzhang tunnel is located at the center-left place while that of Jingbao railway bridge at the center-right place.The experience will be used in similar projects.