During the construction of metro station tunnels of subway Line 9 under existing subway tunnel Line 1 , usual operation of Line 1 roust be guaranteed. So after presupporting the ground, the tunnel was excavated by using the multi-step CRD method with initial support and lining with high stiffness and strength. A 3D numerical mode was used to verify the safety of chosen construction method. The results of simulation and field supervision have shown that settlement of existing structure and stress caused by the construction were all constrained within the allowed ranges, which had kept the exiting subway in usual state and the newly built tunnel safe.%北京地铁九号线军事博物馆站下穿一号线区间隧道,在下穿施工过程中,必须保证既有线路的正常运营.为此,先进行超前支扩,再采用多分部的CRD法施工,大刚度和强度初支进行支护,并采用三维数值方法分析了车站隧道下穿施工对既有线的影响,施工过程中的多项现场监测结果表明,既有结构的沉降和新建隧道结构受力都控制在安全范围之内,保证了既有隧道的正常和新建隧道安全.
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