Numerical Simulation of Sandstone Degradation Under Freeze-Thaw Cycles with Grain-Based Model

ABSTRACT In this study, the grain-based model (GBM) is used to evaluate the influence of freeze-thaw cycles (FTCs) action on the mechanical properties of sandstone. Five mineral components of sandstone are built in the numerical model based on GBM. To explore the influence of FTCs, water particles are distributed on the boundaries of different mineral components. Inter-particle heat conduction module captures the heat transfer process, resulting in temperature redistributions and the development of thermal strains. A modified elastoplastic model is used to capture the accumulation of residual strain that occurred during the ice-water phase change. The micro-cracks in sandstone samples after FTCs reflect the damage caused by FTCs. The uniaxial compressive test is carried out to evaluate the deterioration of FTCs on uniaxial compressive strength (UCS) and Young's modulus of sandstone specimens. Furthermore, it is found that the brittleness of sandstone is decreased with the increasing freeze-thaw cycles. These numerical results prove that the GBM developed in this study can be used to capture the deteriorative effects of FTCs on sandstone. This study provides a better understanding of the influence of FTCs on the mechanical properties of sandstone, which might be helpful for the design and assessment of climate-resilient infrastructure. INTRODUCTION Global warming has exposed more and more areas undergoing freeze-thaw cycles. The freeze-thaw cycles deteriorate the mechanical properties of rock which raises the risk of geotechnical infrastructures failure in these regions. At temperatures below 0 °C, the water contained within pores solidifies into ice, resulting in a volume increase of approximately 9 % (Hou et al. 2021). This volume expansion caused by the phase change of water increases the frost-heaving pressure on the surrounding rock, which produces microcracks or enlarges the pre-existing joints of rock masses (Wang and Zhou 2018). The increasing discontinuities in rock mass allow more water to fill into rock and cause damage to the physical and mechanical properties of rock under freeze-thaw cycles. Therefore, it is significant to understand the damage mechanism of rock under freeze-thaw cycles for the safe design of civil infrastructures in cold regions.