Combined hole excavation method for tunnel boring machine (TBM) half-hole tunneling through complex geological section close to reservoir tail in underneath penetrating mode

The invention relates to a tunnel excavation method for half-tunnel tunneling of a TBM (tunnel boring machine) in a complex geological section close to the tail of a reservoir, a soft stratum at the upper part of a tunnel is excavated by adopting a drilling and blasting machine, the residual part of a cavity is excavated by adopting the TBM, and by adopting the combined tunnel excavation method, the performance of TBM equipment can be exerted to the greatest extent, and meanwhile, disturbance to rock masses around the cavity is reduced; and it is ensured that the TBM can smoothly and downwards penetrate the complex geological section close to the reservoir tail. 本发明涉及一种下穿临近水库库尾复杂地质段TBM半洞掘进的洞挖方法，采用隧洞上部软弱地层采用钻爆机械开挖，洞室剩余部分采用TBM掘进通过，通过该组合洞挖方法，能最大程度的发挥TBM设备性能，同时减少对洞室周边岩体的扰动；确保TBM能顺利下穿临近水库库尾复杂地质段。