Construction Optimization for Subway Interval Tunnels Crossing a High‑Speed Rail Shield Tunnel at a Short Distance

It is a high-risk project in most cases for urban subway tunnels to pass through structures at close distances. In order to effectively control the stratum deformation and reduce the construction disturbance, it is extremely critical to select a practical tunnel construction method. Based on the Jing-Zhang high-speed rail shield tunnel under an extremely small interval of the subway section of Beijing Line 12 in China, a numerical simulation was conducted regarding the bench-cut method, the temporary inverted arch (TIA) method, the center diaphragm method, and the center cross diaphragm method. The key issues are discussed in detail, such as the laws of the stratum deformation, the surface subsidence pattern, the deformation of the shield segment, and the force characteristics of the supporting structure. The research results show that the maximum deformation of the shield segment caused by subway construction is within the range of ±15 m from the central section of the double interval. The TIA method not only reduces the stress caused by the bending moment of the initial support, but also takes full advantage of the locking effect of the anchor pipe, and the stratum deformation is well controlled.