Abstract:During the tunnel construction in permafrost regions,construction heat and heat exchange of air inside and outside the tunnel caused by excavation,primary lining insulation,and secondary lining will affect original ground temperature field of the surrounding rock. This influence will destroy thermodynamics balance of the permafrost stratum and change mechanical characteristics (thawing and sinking,dilatability,stability of tunnel,etc.) of permafrost. So,it is one of the important controlling factors during tunnel construction in permafrost regions to protect permafrost and to reduce the influence of original ground temperature field caused by construction. According to the establishment of thermal model of frozen surrounding rock,primary lining structure,insulation material and circumstance air inside the tunnel and on basis of construction method,surrounding temperature,and ground temperature,the surrounding rock temperature fields of different working procedures are simulated with finite element program ANSYS. The rules of surrounding rock temperature fields and the depths of thawing caused by uncovered time of gross tunnel and primary lining are analyzed. According to different constructions,the effects of stability of tunnel surrounding rock caused by the depth of thawing are studied,which can provide theoretic basis and reference to the design and construction of similar projects.