浅埋暗挖地铁区间下穿高铁特大桥风险分析

Risk Analysis of Shallow-buried Subway Tunnels Passing Through High-speed Railway Grand Bridge

为研究浅埋暗挖隧道近距离下穿对邻近高铁特大桥的影响,以北京某地铁暗挖区间线路,与桥桩夹角为40°,净距仅2.1 m为工程背景,建立三维数值模型,模拟地铁左、右线暗挖区间侧穿高铁桥桩的施工过程,揭示既有高铁桥墩的变形特性。研究表明,未施加防护措施下,暗挖施工使高铁特大桥墩顶产生的最大竖向位移为5.03 mm,最大横向位移为3.23 mm,最大纵向位移为3.96 mm,不满足控制标准;在采取隔离桩及注浆加固措施的工况下,桥墩顶最大竖向位移为2.91 mm、最大横向位移为1.71 mm;最大纵向位移为1.13 mm,满足控制标准。结果表明,暗挖隧道小角度近距离下穿高铁特大桥方案可行,施作隔离桩及地表注浆加固措施可有效降低隧道施工对桥梁的影响。

In order to study the impact of shallow-buried tunnels passing through a high-speed railway grand bridge within a close range,based on a construction site of subway tunnels in Beijing which passing through a high-speed railway bridge with the angle of 40°and distance of 2.1 m,a three-dimensional numerical model was established to simulate the process for the left and right line tunnels passing through piles respectively.the study reveals that,without protective measures,the maximum vertical displacement of the pier-top of the high-speed railway bridge caused by the excavation is 5.03 mm,the maximum transverse displacement is 3.23 mm,and the maximum longitudinal displacement is 3.96 mm.All of which cannot meet the standards.Under the condition of adopting isolation pile and surface grouting reinforcement,the maximum vertical displacement of the pier-top is 2.91 mm,the maximum transverse displacement is 1.71 mm,and the maximum longitudinal displacement is 1.13 mm,all of which meet the standards.The research shows that:the scheme of tunnels passing through a high-speed railway bridge in small-angle and close range is feasible,and the construction of isolation piles and ground surface grouting reinforcement can effectively reduce the impact of tunnels construction on bridges.