Analysis of energy dissipation characteristics in granite under high confining pressure cyclic load

Abstract

With cyclic high in-situ stress, the rock will damage and lead to serious engineering geological disasters. A property of rock failure is the rock damage evolution driven by energy. It is necessary to study the energy dissipation and damage evolution of rocks under cyclic loading with high in-situ stress. In this study, a rock mechanics experiment involving different numbers of loading and unloading cycles is carried out on granite samples with different confining pressures. Rock damage and deformation laws are determined. Results show that: in the process of cyclic, the hysteresis area of axial deformation decreases with increasing of cycles. Under the same confining pressure, the total input energy and dissipated energy negatively correlate with the number of cycles, and the elastic strain energy increases slowly with increasing cycle number during unloading. The dissipated energy increment between second cycle and first cycle is the smallest, after which it gradually stabilizes. The average energy consumption ratio positively linearly correlates with confining pressure, which is consistent with the change trend of average total energy and average elastic strain energy. The increment of porosity increases with the increase of confining pressure and the cumulative dissipated energy is positively correlated with the cumulative porosity.

Keywords

• High-pressure behaviour
• Triaxial cyclic load
• Porosity
• Energy dissipation