新九燕山隧道是双线铁路长大隧道,是包西铁路控制性重点工程.由于新建隧道下穿既有铁路隧道,并且下穿段最近的垂直距离7.8米,新建隧道该段围岩属于Ⅳ级,新建隧道下穿风险高.本文主要对隧道下穿施工方案进行了分析,并采用ANSYS数值分析方法进行了验证,同时加强施工过程的围岩监控和既有铁路隧道变形监控.实践证明,本施工方案对于降低隧道施工风险,确保施工安全具有重要的意义.%New Jiuyanshan tunnel is double track railway tunnel and the key project of Baoxi rail. For the new tunnels beneath existing railway tunnel, the nearest vertical distance of the beneath segment is 7.8 meters, and the new tunnels surrounding rock belongs to Class IV, so the risk of beneath new tunnel is high. The paper analyzes the program of beneath tunnel construction, and verifies it with the ANSYS numerical analysis method, and strengthens the surrounding rock monitoring of the construction process and the deformation monitoring of existing railway tunnel. Practice has proved that the construction program is of great significance for reducing the risk of tunnel construction and ensuring construction safety.
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