Experimental study on the mechanical properties and damage evolution of red sandstone containing a single ice-filled flaw under triaxial compression

To better understand the mechanical properties and damage evolution of ice-filled preflawed rock, a series of triaxial compression tests on frozen red sandstone specimens containing a single preexisting flaw were carried out with a self-developed DRTS-500 subzero rock triaxial testing system. According to the experimental results, the influences of the confining pressure and flaw dip angle on the strength, deformation, damage evolution behavior, and failure mode of the specimens were analyzed in detail. The confining pressure increased the strength and enhanced the plastic characteristics of red sandstone with a single ice-filled flaw. The peak strength, elastic modulus, internal friction angle, and cohesion were distinctly related to the flaw dip angle, whereas the peak strain and Poisson's ratio were not obviously dependent on the flaw dip angle. The red sandstone specimens containing a preexisting ice-filled flaw exhibited shear failure under low confining pressure conditions. The failure mode of the specimens was greatly affected by the dip angle of the preexisting flaw under high confining pressure conditions. The acoustic emission (AE) events that occurred during the whole specimen damage process had different features in different loading stages. The damage evolution process of the specimens was analyzed by using a damage model based on AE counts, and the degree of damage of the specimen was the largest when the flaw dip angle was close to 45 similar to 60 degrees.