盾构隧道下穿城铁地面线施工风险分析及对策研究

Construction Risk Analysis and Countermeasure Research for Shield Tunnel Passing beneath Surface Route of Urban Metro

在城市地铁工程建设中,常有区间隧道下穿地面既有构筑物的情况发生。依托于实际工程,通过现场监测数据分析等手段,对盾构隧道下穿既有城铁地面线的施工方案进行研究和探讨。城铁既有线对路基、轨道的沉降变形控制要求较为严格,本工程由于条件限制,在无法注浆加固既有线路路基和无法施加扣轨措施的条件下,采取了设置防脱护轨、调整盾构掘进参数、利用天窗时间增减道砟来调整轨道变形等主要措施,成功控制了既有线路轨道变形,保证了既有线路的运营安全。并在研究中发现,盾构土压不稳是造成地表沉降的重要原因,

In the process of urban metro construction, it is quite frequent that a metro tunnel needs to pass beneath the existing surface structures. This paper, based on actual project and through field monitoring data analysis and other means, carried out research and discuss on the construction scheme of shield tunnel passing beneath the existing surface route of urban metro. The existing urban metro routes are often accompanied more stringent requirement on settlement deformation control of subgrade and track. Because of various restrictions, both the grouting method and the rail-buckling method could not be used in subsoil strengthening of this existing route. For this reason, other reasonable measures were adopted, such as arranging guardrail against derailment, adjusting the parameters of shield tunneling, and regulating the track deformations by increasing or decreasing the ballast during maintenance time and so on, and eventually the track deformations of the existing route were controlled successfully so that the operation safety of the existing route could be ensured. In the research, it was also found that the instability of shield earth pressure was one of the most important reasons which caused the surface subsidence.