Abstract: Four excavation methods (middlepilot and fullface, middlepilot and halfsection, threepilot and fullface and threepilot and halfsection) of the construction of a largespan doublearch tunnel with grade Ⅲ surrounding rock are numerical simulated by means of ANSYS software, on basis of lasticplastic constitutive relationship and DP yield criterion and stratastructure mode. Variation rules of displacement of surrounding rock, stress of surrounding rock and force of supporting structure under 4 construction methods are analyzed and evaluated. The conclusions obtained can provide reference for the design and construction of largespan doublearch tunnel.

Key words: largespan doublearch tunnel, construction method, stratastructure model, nonlinear analyses