The operation of enhanced geothermal system and geological disposal of radioactive waste typically involve considerable variations in the host rock temperature, and the resulting thermal damage induced by mismatched inter-mineralic expansion could hence modify fundamentally the mechanical rock behaviour. Despite tremendous efforts dedicated to the examination of quasi-static performance after temperature changes, the influence of thermal exposure on the rock response in the long term, however, has stilled remained largely unaddressed. In this study, a series of triaxial creep experiments are thus carried out over variably confined Beishan granite that has been thermally-stressed across a wide range of temperatures. The evolution of failure strain, creep rate, and long-term strength parameters with respect to thermal damage and confinement condition is then critically analyzed. Our experimental investigation suggests that the competition between thermal cracking and hydrostatic compaction could reshape radically the crystalline fabric and hence exert a decisive structural control over the resulting creep deformation. In particular, we have shown that a suitably configured residual crack network could contribute to apparent blunting of subcritical cracking and therefore enhance considerably the rock resistance to stress corrosion. Pervasive grain disintegration, however, stemmed from aggressive thermal treatment would otherwise eradicate effectively the favourable particle interlocking and hence weaken substantially the long-term rock stability. The authors believe the novel findings presented could refine the understanding of time-dependent rock deformation after experiencing intense thermal loading, and thus have significant implications for the reliable decarbonized electricity production towards delivering sustainable energy transition.

增强型地热系统的运行和放射性废物的地质处置通常涉及主岩温度的显着变化，因此由不匹配的矿物间膨胀引起的热损伤可能因此从根本上改变岩石的力学行为。尽管为检查温度变化后的准静态性能付出了巨大努力，但从长远来看，热暴露对岩石响应的影响在很大程度上仍未得到解决。在这项研究中，一系列三轴蠕变实验因此在变约束的北山花岗岩上进行，该花岗岩在很宽的温度范围内受到热应力。失效应变、蠕变率的演变，然后严格分析与热损伤和约束条件有关的长期强度参数。我们的实验研究表明，热裂化和静水压实之间的竞争可以从根本上重塑结晶织物，从而对由此产生的蠕变变形施加决定性的结构控制。特别是，我们已经表明，适当配置的残余裂纹网络可能有助于明显钝化亚临界裂纹，从而显着增强岩石的抗应力腐蚀能力。然而，由侵蚀性热处理引起的普遍晶粒崩解否则会有效地消除有利的粒子互锁，从而大大削弱岩石的长期稳定性。