Experimental research on energy evolution of red sandstone samples under uniaxial compression

Energy dissipation and energy release appear evidently during the deformation and failure process of rock. In order to obtain the evolution and distribution laws of energy with stress in rock, tests on red sandstone samples under cyclic loading-unloading uniaxial compression with 4 different loading rates were carried out. The results show that: (1) The total absorbed energy, accumulated elastic energy and dissipated energy in rock samples all increase as the axial stress increases before failure, and the total absorbed energy grows fastest, followed by the elastic energy, and the dissipated energy grows slowest. (2) The elastic energy grows nonlinearly with the axial stress, and the increasing rate is small before 24% of ultimate strength, and then becomes larger gradually, but growth slows down when approaching destruction; and the dissipated energy grows slowly at first and increases substantially in the coming failure phase, with an increase of about 85%. (3) The proportion of elastic energy grows from 60% to 82% approximately in the whole loading process with the increasing rate slowing down gradually, and decreases slightly when approaching destruction; and the proportion of dissipated energy varies conversely. (4) In the quasi-static loading range, the smaller the loading rate, the greater the dissipated energy generally; and loading rate has no influence on the evolution of elastic energy basically. (5) The elastic energy density-stress curves of rock samples have no discreteness, and can reflect the inherent nature of the material itself.