Research conclusions: Because of the limitation of route，terrain and geology condition in the portal section of tunnel with large span ， it is difficult to enter the tunnel and dispose the structure. In the bedding side-pressure section，the pre-consolidating piles can be set within the proper scope near the mountain side to eliminate the hazard of mountain sliding to the route and structure. There should be some space for the length and setting scope of pre-consolidating pile to increase some safety reserves. In the section with steep terrain and lining foundation where there is soft-weak surrounding rock，the rockbolt retaining wall shall be set near the mountain side for reduction of cutting height to reduce disturbance of excavation to mountain body and the construction method to back-press concrete and cooperate the advance pipe shed support shall be taken to solve the difficulty to enter the tunnel. At the same time，the structural form with different thickness on both sidewalk on two sides is adopted and the pile foundation spandrel beam is set in the soft-weak surrounding rock foundation and the external foundation of lining is set on the pile foundation spandrel beam to solve the design of the lining structure.