Energy and damage analysis of fractured sandstone under true triaxial cyclic loading

Abstract

Exploring the energy evolution of fractured sandstone under true triaxial cyclic loading is helpful to clarify the law of rock damage and failure. The evolution characteristics of total absorbed energy, elastic energy, dissipated energy and plastic deformation energy during the test were systematically analyzed. A rock damage evaluation model was established, and the rock damage failure law was discussed in combination with the mesoscopic damage characteristics of the fracture surface. The results show as follows: with the increase of crack angle, the greater the peak strength of the sample during failure, the greater the total absorbed energy, they were 0.238, 0.276, 0.307 and 0.332 MJ/m3, respectively; the total absorbed energy, elastic energy and dissipated energy increase gradually during the whole test process, while the plastic deformation energy decreases first and then increases; based on hysteretic loop energy and total dissipated energy, an evaluation index was established to describe rock damage, and the results of the two evaluation methods are consistent, and it is found that the rock damage degree changes nonlinear with loading and unloading during the test; the number of cyclic loading and unloading during the failure of the sample has a significant influence on the internal damage of the sample. The more times of cyclic loading and unloading, the higher the degree of extrusion friction and the more complex the micromorphology of the fracture surface.

Keywords

• true triaxial
• cyclic loading and unloading
• fractured sandstone
• energy evolution
• fracture angle
• rock damage