Abstract: The freeze-thaw damage of surrounding rock will cause the deformation pressure of lining to increase,which will adversely affect the stability of lining,which is a key problem in the research of tunnel engineering in seasonal cold area. In this paper,the stress-strain curves of sandstone under different freeze-thaw cycles and compression tests are obtained,and then the deformation parameters and strength parameters of surrounding rock are obtained from the stress-strain curves. Finally, the change rule of rock mechanics parameters is embedded into ABAQUS software to numerically analyze the long-term stability of the tunnel under freeze-thaw cycle,and the stress field and displacement field of surrounding rock and lining under 0,6,12, 18 and 24 cycles of freeze-thaw cycle are obtained respectively. The results show that:① With the increase of the number of freeze-thaw cycles,the maximum and minimum principal stresses on the surrounding rock decrease linearly;② The maximum principal stress,the minimum principal stress and the displacement of the lining increase exponentially;③ Compared with the condition without freeze-thaw,the maximum and minimum principal stresses of surrounding rock after 24 freeze-thaw cycles decreased by 43. 69% and 20. 66%,respectively;④ The maximum principal stress,minimum principal stress of lining and maximum settlement of vault increased by 13. 64%,15. 75% and 49. 36% respectively. In the design of tunnel support in cold area, it is necessary to consider the problem that the self-stability of surrounding rock attenuates under freezing and thawing action, which leads to the increase of the force of supporting structure.

Key words: tunnel in cold region,tunnel stability,freeze-thaw cycle,surrounding rock,stress field,displacement field