Macro-meso properties and damage constitutive model of sandstone under chemical and freeze-thaw environments

Abstract

The coupled effect of chemical corrosion and freeze-thaw cycle degrades the physical and mechanical properties of rock, affecting the safety and durability of underground rock mass engineering. This study investigated the deterioration laws of sandstone under pH = 1 and 3 chemical and freeze-thaw cycle action for different time considering macro and meso scales. The stress-strain curve of sandstone under uniaxial compression can be divided into compaction, elastic deformation, yield, and post-peak stages. The compaction of sandstone after chemical and freeze-thaw cycle action became apparent, elastic stage was relatively shortened, elastic modulus and peak strength decreased, and peak strain increased. The density and homogeneity of sandstone declined as per the CT scan and image processing technologies. The deterioration was prominent with longer action time and smaller pH value of the solution. After 120 days of pH = 1 and 3 chemical and freeze-thaw cycle action, the peak stress of samples decreased by 22.10% and 15.16%, the elastic modulus declined by 89.57% and 85.09%, the peak strain increased by 96% and 62%, and the damage variables reached 3.27% and 1.83%. The damage constitutive model of sandstone was established using statistical damage theories. The theoretical stress-strain curves were consistent with experimental ones. The insights of this research have implications for the theoretical foundation of safety assessments and disaster prevention in practical engineering scenarios under chemical and freeze-thaw environments.