Construction Technology of Micro Bench Cut Method for Weak Rock Tunnel with High In-situ Stress

Taking Shanyang tunnel of Dali to Ruili (DaRui) railway as background, the construction technology of micro bench cut method for weak rock tunnel with high in-situ stress is established by combining the full-fgenius tunnelling method and bench cut method. For weak rock tunnel with large deformation, corresponding construction control points and technical characteristics are discussed. The following results are achieved. (1) The horizontal convergence deformation of Shanyang tunnel is larger than that of the subsidence displacement of the vault. Feet-lock bolt, reinforced grouting of arch foot surrounding rock, and expand support measures for arch foot are equipped to increase the stability and resistance of the supporting steel frame. (2) The narrow working surface of a single-line tunnel can be effectively utilized and the rapid construction of tunnel is also realized. (3) The construction technology can realize the rapid closure of the initial support into a ring, ensure the tunnel safety of the IV and V grade surrounding rock, reduce the construction cost, and improve the construction efficiency. The construction methods and techniques proposed in the article can provide reference for similar projects.