Taking the interval tunnel construction between Yingbin road station and Sangong station undercrossing bridge group in Urumqi Metro Line No.1 as the engineering background,a three-dimensional computational model of tunnel-stratum-bridge group was established by using FLAC 3D and the influence of undercrossing construction on the bridge group was analyzed.The results show that the horizontal displacement of the tunnel side wall is slightly larger than vertical displacement of vault,the maximum displacement of tunnel initial support is 14.8 mm,the maximum vertical displacement of highway bridge and railway bridge is 2.73 mm and 2.1 mm separately,the initial support of the tunnel is in a safe state,and the tunnel construction has little influence on the bridge group.Based on this analysis results,four main control measures of undercrossing construction including the trial excavation before undercrossing the bridge group,control of strata deformation,emergency measures formulation and advanced geological forecast were put forward and the monitoring results of undercrossing section don't exceed the deformation control standard given by the test and evaluation unit.%以乌鲁木齐地铁1号线迎宾路站-三工站区间隧道下穿桥群施工为工程背景,采用FLAC 3D建立隧道-地层-桥群三维计算模型,分析下穿施工对桥群的影响.结果表明:隧道边墙水平位移较拱顶竖向位移稍大;隧道初支最大位移14.8 mm,公路桥和铁路桥最大竖向位移分别为2.73,2.10 mm,隧道初支处于安全状态,隧道施工对桥群影响较小.针对该分析结果,提出下穿桥群前试挖、控制地层变形、制订应急措施、超前地质预报4项下穿施工控制措施.下穿段各项监测结果均未超过检测评估单位给定的变形控制标准.
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