砂卵石地层盾构施工对高铁桥梁的影响及控制

Research on Influence and Control of Shield Tunneling Construction in Sandy Pebble Stratum on High-speed Railway Bridge

在北京地铁8号线天桥—永定门外区间隧道的施工过程中,盾构需要从既有京津城际铁路和京山铁路的上跨桥梁下方穿过,穿越段地层以砂卵石为主。盾构在砂卵石地层中施工极易导致地表沉降和塌陷,而高速铁路运营线又对轨道平顺性有着严格的要求;因此隧道施工的风险极高。借助数值分析软件对盾构隧道下穿铁路桥梁的动态施工过程进行模拟,研究盾构施工引起的砂卵石地层扰动变形、孔隙水压力变化及桥梁结构变形等规律,并据此提出确保桥梁运行安全的工程保障措施与监控量测体系。上述研究成果不仅用于指导隧道工程的设计与施工,而且也可为今后类似工程问题提供借鉴和参考。

The shield passes through a bridge, on which Beijing-Tianjin intercity railway and Jingshan railway are laid, during tunneling in the section from Tianqiao to Yongdingmenwai of Beijing Metro Line 8 with mainly sandy pebble stratum. It＇s a high-risk project for it＇s easy to cause surface subsidence and collapse during shield tunneling in sandy pebble stratum, in addition to the strict requirements of track smoothness for high-speed railway. Based on numerical analysis software, the paper simulated dynamic construction process of shield tunnel overpassing railway bridge, researched the deformation of sandy pebble stratum, distribution of pore pressure and deformation of bridge structure caused by tunnel excavation. It finally put forward engineering countermeasures and monitoring schemes to ensure the safety of bridge. Research results can not only guide the design and construction of tunnel engineering, but also provide reference for similar project issues.