Abstract
In order to solve the energy crisis, geothermal energy development has been increasingly valued in recent years. In many geothermal engineering projects, hydraulic fracturing can cause many cracks to appear inside the rock mass during the extraction process of dry hot rock. At present, there have been many studies on mode I cracks and mixed mode I/II cracks. In order to ensure the smooth progress of the project, it is necessary to supplement the research on mode II crack rocks in high-temperature geothermal environments. A series of experiments were conducted using the Split Hopkinson Pressure Bar (SHPB) device and cracked granite specimens treated at different temperatures, the failure modes could be tracked by using a high-speed camera. The dynamic experiment was simulated using software coupling. The Grain Boundary Model (GBM) can well describe the force-thermal coupling damage behavior among various crystal particles. Some analyses were conducted on dynamic fracture toughness, failure mode, strain distribution, thermal damage, and changes in the number of cracks. The research results illustrated that high temperatures lead to a decrease in the mode II fracture toughness of granite, an increase in fracture time, and greater susceptibility to damage. High temperature will increase the maximum strain at the moment of failure. It was also found that the proportion of intra-grain cracks increased with the temperature. After 500 °C, the number of cracks generated during the fracture process is inversely proportional to the temperature.
Published Version
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