Study on Optimization of Excavation Scheme of the Entrance Section of Hongjiaban Tunnel

The choice of excavation method is particularly important for small clear distance tunnel with short distance between two holes.The finite element software is used to simulate the excavation of Hongjiaban tunnel,which obtained a series of laws, such as the stress change of surrounding rock, the stress of supporting structure and the displacement of surrounding rock during the excavation of the tunnel with a small distance, which is helpful to better guide the construction.There are different excavation methods for tunnel excavation under different surrounding rocks. The rock mass of the entrance section of Hongjiaban tunnel is the Class V surrounding rock, and a variety of excavation methods can be used, such as full section method, reserved core soil method and CRD method. Through the numerical analysis of the above three methods, the advantages and disadvantages of each method are discussed, and the most suitable excavation method for Hongjiaban tunnel is optimized.