Abstract Knowledge of mechanical properties of rocks under real-time high temperature and three-dimensional stress is critically important for stability analysis in Hot Dry Rock. In this context, the effects of temperature and horizontal stress on the mechanical behaviors of granite were investigated. A series of triaxial compression tests were performed on granite samples under real-time high temperature (up to 400 °C) by a self-developed real-time high temperature true triaxial test system. The test results showed that the mechanical properties of studied granite first increase before some temperature threshold, and then decrease with increasing temperature. The brittle characteristics of studied granite observed under low horizontal stress and room temperature are attenuated with increasing stress and temperature. Furthermore, observation of the fracture morphology of the samples indicates that the biotite particles undergo toughness enhancement at elevated temperature, which is the main reason for the reduction of rock brittleness and reinforcement in mechanical properties with increasing temperature. Finally, the effects of real-time high temperature on cohesion and internal friction angle were analyzed and compared with the previous test results of cohesion and internal friction angle of the samples subjected to pre-treatment of high temperature. A sound difference in cohesion and little difference in the internal friction angle were observed between the two cases. The test results could improve our understanding of the impact of temperature and stress on the mechanical properties of granite.

中文翻译：

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实时高温三维应力作用下花岗岩的力学性能

摘要 了解岩石在实时高温和三维应力下的力学特性对于干热岩石的稳定性分析至关重要。在此背景下，研究了温度和水平应力对花岗岩力学行为的影响。采用自主研发的实时高温真三轴试验系统，在实时高温（最高400℃）条件下对花岗岩试样进行了一系列三轴压缩试验。试验结果表明，所研究花岗岩的力学性能在达到某个温度阈值之前先升高，然后随温度升高而降低。在低水平应力和室温下观察到的研究花岗岩的脆性特征随着应力和温度的增加而减弱。此外，对样品断口形貌的观察表明，黑云母颗粒在升高的温度下韧性增强，这是随着温度升高岩石脆性降低和力学性能增强的主要原因。最后，分析了实时高温对内聚力和内摩擦角的影响，并与前期高温预处理样品的内聚力和内摩擦角的测试结果进行了比较。在两种情况下观察到内聚力的明显差异和内摩擦角的微小差异。测试结果可以提高我们对温度和应力对花岗岩力学性能影响的理解。