Numerical Study on the Influence of Eccentric Contact Situation Between Back-fill Concrete on Top of Mid-wall and Surrounding Rock on the Stability of Multi-arch Tunnel

A finite element model was established based on the lining structure of multi-arch tunnel in expressway.In the light of left and right eccentric situation occurred between backfill concrete and surrounding rock,the deformation and stress of surrounding rock and lining structure under such situation were comprehensively analyzed by numerical simulation method.Results show that such eccentric situation won′t bring impact on the settlement of arch roof,but will cause the tensile stress on the arch roof surrounding rock and bending moment of lining greatly increased and remarkable eccentric compression occurred on the mid-wall.