Comparison and analysis of different excavation methods in soft rock-extremely soft rock tunnel

In order to further study the law of surrounding rock deformation of soft rock-extremely soft rock double arch tunnel, resolve problem of tunnel excavation in complex geology conditions, based on project example, the central heading full section, central heading step and division method (three heading method) as research object, measured and simulated results were compared and analyzed, and used ANDIA software to do dynamic simulation. The results show that the characters of surrounding rock deformation are different with different excavation methods; Simulated and measured results are almost the same,and the maximum difference has only 6%, reflecting simulated value has a certain reliability; The more the step numbers are excavated in soft rock-extremely soft rock tunnel, the smaller the area excavated is, the smaller the rock is disturbance, the smaller the surface subsidence and two state convergence value is, more be able to meet construction requirements; Compared with the other two methods, division method is more to reduce the deformation in the surrounding rock with class of V.