Investigation of the soil-lining interaction at a tunnel entrance during freeze-thaw cycling: Model testing and semi-empirical modeling

Abstract

Periodic freeze-thaw cycling can significantly reduce the bearing capacity of mountain tunnel linings. In this study, a model test is carried out to research the lining stress characteristics and the freezing depth of tunnel entrances in cold regions. Then, specific consideration is given to the freezing and thawing depths, the frost heaving pressure, and the internal forces around the lining. Generally, the results show that the occurrence times of the freezing and thawing depths at different positions are similar, but the various trends are different. Moreover, the frost heaving pressure at point 4 (sidewall) has the earliest occurrence time, the fastest rate of increase, and the most prolonged increase duration. Under the influence of the frost heaving pressure, the maximum axial force position shifts from the knee to the spandrel, and the sidewall is in tension. Furthermore, the periodic change in the frost heaving pressure may induce a permanent deformation at the tunnel entrance lining, especially at the position between the knee and the sidewall. Finally, based on the conformal transformation and complex variable method, a semi-empirical model is developed to predict the distribution of internal forces around the non-circular shallow tunnel subjected to frost heaving. Overall, this study helps to estimate the soil-lining interaction at a tunnel entrance during freeze-thaw cycling.