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建设中的北京地铁五号线崇文门站下穿既有地铁一号线区间隧道,为保证既有地下铁道正常运营和地下结构的安全,需严格控制新建车站施工引起的地层位移。结合新建车站暗挖施工及既有线地铁的实际情况,分析和计算穿越既有隧道施工地表允许沉降值。为了控制地表沉降,确保施工安全,拟采用小刚度管棚或大刚度顶管作超前预支护,用3D-S igm a三维有限元软件进行施工效应的计算模拟,掌握大管棚和顶管预支护洞室的力学效应,预测车站施工引起既有隧道的沉降量。最后分析比较两种预支护的支护效果,为选择合理的预支护方案提供参考。
Under construction, the Chongwenmen Station on the 5th line of Beijing Subway passes through the tunnel of the existing Metro Line 1 tunnel. In order to ensure the normal operation of the existing subway and the safety of the underground structure, the formation displacement caused by the construction of the new station must be strictly controlled. According to the actual situation of undercut construction and existing metro line in new station, the allowable settlement value of ground surface through the existing tunnels is analyzed and calculated. In order to control the settlement of the ground surface and ensure the construction safety, it is proposed to adopt the small rigidity pipe roof or the high rigidity pipe jacking for advance pre-support. The 3D-S igm a 3D finite element software is used to carry out the calculation and simulation of the construction effect, Mechanical effects of retaining tunnels, forecasting the settlement of existing tunnels caused by station construction. Finally, analysis and comparison of two kinds of pre-support the effect of support for the selection of a reasonable pre-support program to provide a reference.