Abstract
The deformation and failure of sandstone samples are closely related to energy changes in the material. To explore the energy evolution during the process of sandstone sample damage, loading and unloading tests with different test paths were conducted. The results show that more energy is stored and consumed before the stress reaches its peak, while after the peak stress, more energy is released and consumed. Energy dissipation increases internal cracking, leads to sample damage and lithologic deterioration, and reduces the bearing capacity of the sample. During triaxial unloading of the confining pressure, the higher the initial unloading confining pressure, the more the elastic energy stored, and the more the energy released when the sandstone sample fails, resulting in more severe damage. Therefore, during the excavation of high‐stress rock masses, large amounts of elastic energy stored in sandstone can be rapidly released, leading to rock burst disasters. Additionally, during triaxial unloading confining pressure tests, the damage in sandstone when the sample is close to failure increases more rapidly than that during conventional triaxial compression tests because of the unloading effect of the confining pressure. This phenomenon also illustrates that the failure of sandstone induced by unloading is more sudden than that induced by loading.
Highlights
Mining, tunnel excavation, and other projects in deep mines involve high-stress rock unloading, which often leads to serious accidents that threaten the security of mining [1]
During the triaxial unloading confining pressure, the hydrostatic energy accumulates at the hydrostatic loading stage of the sandstone. erefore, all the curves originate at the hydrostatic pressure point, and the analysis focuses on the energy evolution after the hydrostatic loading stage
We conducted conventional triaxial compressional loading tests and triaxial unloading confining pressure tests under different loading paths for sandstone specimens. e results show that more energy is stored and consumed before the stress reaches its peak, while after the peak stress, more energy is released and consumed. e energy dissipation causes the internal cracks in the sandstone to expand, resulting in damage and deterioration, and the released energy causes the failure of the sandstone
Summary
Tunnel excavation, and other projects in deep mines involve high-stress rock unloading, which often leads to serious accidents that threaten the security of mining [1]. Based on uniaxial compression and triaxial compression tests, Ma et al [13] studied the influence of the loading rate and confining pressure on the energy dissipation characteristics of coal samples. Ese results provide important references for the study of rock energy evolution and the relationship between rock energy evolution and rock deformation and failure These studies mainly examined marble and granite under uniaxial compression, conventional triaxial compression, and triaxial unloading and confining pressure. To explore the essential characteristics of sandstone deformation and failure, we performed triaxial compression and triaxial unloading tests of sandstone under different confining pressures and studied the energy changes during the damage process under triaxial compression and triaxial unloading confining pressure. To explore the essential characteristics of sandstone deformation and failure, we performed triaxial compression and triaxial unloading tests of sandstone under different confining pressures and studied the energy changes during the damage process under triaxial compression and triaxial unloading confining pressure. e results may be used as guidance for the prevention and control of mine disasters caused by excavation and stress unloading in deep mines
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