Abstract:  To comprehensively investigate the stress distribution patterns of tunnels in cold zone under the joint action of freezethaw cycle and nonhydrostatic pressure, an overall frost heave model of freezethaw cycle of tunnels in cold zone under nonhydrostatic pressure is established based on compound function considering the inhomogeneous frostheave characteristics of the frozen surrounding rocks of the tunnels in cold zone and the influence of freezethaw cycle on the mechanical properties of the surrounding rocks. Then the elastic solution of the stress of the tunnels in cold zone under the action of nonhydrostatic pressure is deduced, and a comparative validation and parametric analysis are conducted on the obtained solution. Finally, the influence of the number of freezethaw cycles, inhomogeneous frostheave coefficient, lateral pressure coefficient, freezing and expansion rate on the stress of tunnels in the cold zone is discussed. The results reveal the following: （1） The frostheave force increases by 89% and 26.7% with increasing number of freezethaw cycles and inhomogeneous frostheave coefficient, respectively. （2） The lateral pressure coefficient 〖WT〗λ 〖WT５《TNR》〗has a considerable impact on the frostheave force,the frostheave force increases and decreases with increasing azimuthal angle when 〖WT〗λ〖WT５《TNR》〗≥1 and 〖WT〗λ〖WT５《TNR》〗＜1, respectively. （3） The hydrothermal migration coefficient considerably affects the frostheave force rather than other three volumetric freezing and expansion rate parameters, which can increase the frostheave force by 36.4%.

Key words: tunnels in cold zone, freezethaw cycle, uneven frost heave, lateral pressure coefficient, compound function