An elastoplastic model of frost deformation for the porous rock under freeze-thaw

Freeze-thaw action has caused many engineering geology disasters in cold regions, such as frost cracking of tunnel and pavement, rockfall of rock slope, falling off of building materials. The freeze-thaw damage of porous rock is mainly induced by the frost heaving pressure due to pore water freezing. Although some elastic crystallization theories have been proposed to model the freezing process of pore water, the long-term frost heave characteristics under cyclic freeze-thaw are rarely studied. The ice crystallization and frost heave theory under freeze-thaw have been developed in the elastoplastic regime in this study. A novel elastoplastic model has been proposed to estimate the long-term frost heave and frost damage under freeze-thaw. This model has considered the influence of the pore size, yield stress of matrix and degree of water saturation on the development of the frost heaving pressure in pores. During freezing, a plastic region will produce inside the matrix around the pore. This plastic region gradually expands outwards with the increase of this pressure. During thawing, the elastic deformation will be recovered but a considerable residual plastic strain is accumulated. However, the growth rate of the residual plastic strain will decrease under freeze-thaw due to the production of new empty voids. Therefore, the freezing of pore water in porous rock is an elastoplastic problem. Besides, the water saturation and mechanical properties of the porous rock are very important to quantify the frost heave. This study provides a better understanding of the frost damage of the porous rock and a reference for the stability of rock engineering under freeze-thaw in cold regions.