地铁盾构法施工下穿立交桥影响分析

Influence Analysis of Shielded Subway Tunnel Excavation Undercrossing an Existing Bridge

合肥市轨道交通4号线要下穿新客线当涂路立交桥,当涂路立交上列车客运量大,铁路运营对桥梁的变形、内力要求严格,为保证盾构下穿施工时铁路桥梁的运营安全,利用Midas gts计算程序对盾构施工下穿时桥梁的变形、内力影响进行了数值计算分析。分析得出:盾构下穿新客线当涂路立交时,新客线当涂路立交的桥墩横向、纵向位移小于控制值1 mm;单墩竖向沉降小于控制值1 mm;桥墩差异沉降小于控制值1 mm;桥梁的附加力改变量很小;变形、内力均符合相关要求。最后对盾构下穿桥梁需采取的保护措施提出了加强盾构管片配筋强度、左右线分开下穿、加强盾构施工工艺控制等建议。

The Hefei Metro Line No.4 crosses beneath the Dangtu Road bridge that carrying the new passenger high-speed railway.The passenger volume of Dangtu road rail bridge is large and the railway operation requires a strictive deformation and stress in the bridge.The influences of deformation and stress in the bridge structure are well analyzed by using the MIDAS GTS commercial finite element analysis software in this paper.The results show that the transverse and longitudinal lateral displacements at the bridge pier are less than 3 mm and the vertical settlement of the pier is less than 5 mm.The differential settlement at the pier is less than 5 mm and the change of the additional stress in the bridge structure is very small.Further,the deformation and stress in the structure meet the relevant requirements.To ensure the safety of the bridge during shielded tunnel excavation,the measures for the safe the construction undercrossing the bridge such as,strengthening the reinforcement strength of shielding segment,separating the undercrossing of left and right lines,strengthening the control of the shielded excavation,are also presented in the paper.