Experimental Investigation on Fracture Behavior and Mechanical Properties of Red Sandstone Subjected to Freeze–Thaw Cycles

Abstract

The freeze–thaw process plays a dominant role as far as the exploration and development of natural resources in cold regions are concerned. Freeze–thaw cycles can cause frost heaving pressure in the rock matrix and result in micro cracking, which influences its physical and mechanical properties. A series of physical and mechanical tests are performed on red sandstone to investigate the fracture behavior and mechanical properties induced by freeze–thaw cycles. The testing results show that after being treated by freeze–thaw cycles, the mass, density, and P-wave velocity of rocks decrease, while the volume of rocks increases. The peak stress and elastic modulus decrease with the increase in freeze–thaw cycles, while peak strain and Poisson’s rate increase. When 30 MPa confining pressure is applied, the peak stress and elastic modulus of untreated samples reach the maximum values of 92.49 MPa and 12.84 GPa, respectively. However, after being treated by 30 freeze–thaw cycles, the peak strain and Poisson’s rate reach the maximum values of 0.631 % and 0.18, respectively. The development of micro-cracks and the growth of pores induced by frost heaving stress are the main reasons for the deterioration of the mechanical properties of rocks. Confining pressure and freeze–thaw cycles can transfer the rock’s failure mode from tensile to shear and make red sandstone show more ductility features.