The lining responses for shallow mountain tunnels subjected to frost heaving

Mountain tunnels in cold regions are vulnerable to adverse effects of freezing action. Thus, it is necessary to identify the lining responses of shallow mountain tunnels subjected to freezing action. To quantify the influence of freezing action and key design parameters (such as cross-sectional shape; lining thickness; and waterproof measures) on the lining response, a thermal-hydro-mechanical coupled finite element (FE) model is established and verified. Then, specific consideration is given to the lining internal force and resulting axial stresses. And the influences of the cross-sectional shape, concrete parameters, and waterproof measures on the lining responses are investigated. Generally, the rectangular tunnel has the worst security; the circular tunnel is the safest. On the other hand, when the thermal conductivity is less than 2.2 [W/(m·K)], a greater thermal conductivity will cause a greater risk of damage to the lining. Moreover, the drainage plate can reduce the value of minimum axial stresses, whether frozen or not, even eliminating the tension-damaged area. Overall, this study helps to estimate the lining responses and prevent frost damages for shallow mountain tunnels during freezing period.