Study on mechanical properties and energy change of rock materials in whole splitting process based on peridynamics.

Aiming to bypass the inability to directly observe the evolution process of rock internal deformation and fracture, this paper proposes that rock samples with different inclination angles can be analyzed from the standpoint of energy, using the bond-base peridynamic theory and the PMB model of brittle materials, combined with laboratory experiments. The whole process of shearing is analyzed, and the LAMMPS software is used to simulate the internal energy change of rock-like materials under shear conditions, while the damage evolution law of samples with different dip angles is studied from macro and micro perspectives. The result shows that prefabricated cracks and the inclination of cracks are important factors for specimen damage, a finding that has important theoretical value for rock mechanics research. The research results can reduce the occurrence of rock burst accidents, the difficulty of mine support, and the cost of mining engineering, as well as improve mine safety levels.

Damage law and mechanism of coal-rock joint structure induced by liquid nitrogen at low temperature.

The width and degree of connectivity of coal-rock joints directly affect the seepage capacity of flow energy such as gas. To study the damage law and mechanism of the coal-rock joint structure under the action of liquid nitrogen, two methods of liquid nitrogen unloaded and liquid nitrogen freeze-thaw were used to carry out damage modification experiments on coal-rock with different water saturation. Using OLS4000 laser confocal microscope and MH-25 universal testing machine to conduct electron microscope scanning and uniaxial compression test, measure the joint width expansions and Young's modulus of the coal-rock surface before and after the test, establish a physical and mechanical model of freeze-thaw damage to analyze the ice-wedge expansion stress influence on the damage of coal-rock joint structure and establish damage criterion. The research results show that the ice-wedge expansion stress, confining pressure, and temperature stress in the joint jointly affect the structural damage of coal-rock joints, and the ice-wedge expansion stress contributes the most. With the increase of water saturation, the damage to the coal-rock joint structure intensifies, and the ice-wedge expansion stress under the water saturation state has the most obvious influence on the damage to the coal-rock joint structure. The damage criterion constructed by the freeze-thaw damage physical-mechanical model can reveal the damage mechanism of the effect of ice-wedge expansion stress on the coal-rock joint structure. This paper has certain practical significance for the safety and stability evaluation of rock engineering in cold and arid regions and provides new ideas for effectively extracting clean energy such as coalbed methane and preventing rock bursts.