Characteristics and Association Mechanism of Energy Dissipation and Crack Development in Siltstone Under Triaxial Cyclic Loading and Unloading

The separation and investigation of plastic dissipation energy and damage dissipation energy, and the exploration of the association between energy dissipation and crack development, contribute to revealing the essence of rock failure. In this study, triaxial cyclic loading and unloading tests were performed on porous siltstone widely distributed in mining areas in western China. According to the characteristic stresses and energy evolution characteristics, the failure process of siltstone was divided into five stages. The cumulative energy dissipation ratio shows a spoon-shaped evolution characterized by a significant decline, slight decline, slow increase, significant increase, and stable trend. Importantly, a method for separating plastic dissipation energy and damage dissipation energy was proposed and applied to investigate the evolution characteristics of plastic dissipation energy and damage dissipation energy. Corresponding to the energy characteristics, the acoustic emission activity exhibits significant phased characteristics in five stages. Furthermore, the analysis of crack evolution based on acoustic emission parameters reveals that the proportion of tensile cracks increased significantly near peak failure, and the development of tensile cracks substantially contributed to the damage of load-bearing structures. In particular, the evolution of shear cracks exhibited a strong correlation with the cumulative plastic dissipation energy, while the evolution of tensile cracks showed a strong correlation with the cumulative damage dissipation energy. Finally, the energy dissipation mechanisms of tensile cracks and shear cracks were revealed.Highlight A characteristic stress determination method based on evolution characteristics of multiphase volumetric strainSpoon-shaped evolution characteristics of the cumulative energy dissipation ratioA determination method of plastic energy dissipation and damage energy dissipationAssociation mechanism between the development of shear and tensile cracks and the evolution of plastic and damage dissipation energy