Understanding the mechanical behaviors of granite after high temperature exposure and under confining stress conditions is an important issue in deep rock engineering projects such as the mining of deep underground solid mineral resources, deep geothermal energy exploitation and deep nuclear waste repositories. In this research, conventional triaxial compression experiments were conducted on Nanan granite after thermal treatment from 200 °C to 600 °C. Based on the experimental results, the influences of pressure and temperature on the deformation and strength characteristics were analysed. The physico-mechanical change mechanisms of the heat-treated granite were revealed by optical microscopy. The test results show that under 600 °C, granite volume increases by 4.11%, whereas the mass and density decrease by 0.28% and 4.21%, respectively. Average values of triaxial compressive strength and elastic modulus, cohesion and internal friction angle all reduce with temperature, decreasing rapidly by 54.99%, 39.81%, 49.39% and 27.51% from 500 to 600 °C, respectively. Granite specimens are less brittle and have higher ductility and plasticity as the temperature increases. However, confining pressure improves the mechanical properties of granite. Optical microscope images show that microcracks in granite specimens are generated and extend gradually with temperature, causing the deterioration of the physico-mechanical behaviors of heat-treated granite.

在深部岩石工程项目（例如深部地下固体矿产资源开采，深部地热能开采和深部核废料处置库）中，了解花岗岩在高温暴露后和在有限应力条件下的力学行为是一个重要问题。在这项研究中，在200°C至600°C的热处理条件下，对Nanan花岗岩进行了常规的三轴压缩实验。根据实验结果，分析了压力和温度对变形和强度特性的影响。用光学显微镜揭示了热处理后花岗岩的物理力学变化机理。测试结果表明，在600°C下，花岗岩体积增加4.11％，而质量和密度分别减少0.28％和4.21％。三轴抗压强度和弹性模量，内聚力和内摩擦角的平均值均随温度降低，从500到600°C分别迅速降低54.99％，39.81％，49.39％和27.51％。花岗岩试样的脆性较小，并且随着温度的升高具有较高的延展性和可塑性。但是，围压可以改善花岗岩的机械性能。光学显微镜图像显示，花岗岩试样中会产生微裂纹，并随着温度的升高而逐渐扩展，从而导致热处理后的花岗岩的物理机械性能下降。花岗岩试样的脆性较小，并且随着温度的升高具有较高的延展性和可塑性。但是，围压可以改善花岗岩的机械性能。光学显微镜图像显示，花岗岩试样中会产生微裂纹，并随着温度的升高而逐渐扩展，从而导致热处理后的花岗岩的物理机械性能下降。花岗岩试样的脆性较小，并且随着温度的升高具有较高的延展性和可塑性。但是，围压可以改善花岗岩的机械性能。光学显微镜图像显示，花岗岩试样中会产生微裂纹，并随着温度的升高而逐渐扩展，从而导致热处理后的花岗岩的物理力学性能下降。