Strength behavior of thermally-damaged rock is quite different from that of undamaged or intact rock. In this study, a concept of degradation of geological strength index (GSI) is used and a GSI-softening model in the framework of generalized Hoek-Brown (HB) failure criterion is proposed to characterize the strength behavior of thermally-damaged rock. The proposed GSI-softening model is then verified using several sets of test data collected from previous publications. It is found that the fast increase of strength with increasing confining pressure for thermally-damaged rock can be well captured using the proposed GSI-softening model. The results also show that the GSI value degrades from 100 of undamaged rock to a value ranging from 72 to 88 for the thermally-damaged rocks examined in this study. The material parameter for the thermally-damaged rock is about 1.5 to 3 times higher than the original value of undamaged rock, which indicates that the frictional strength of thermally-damaged rock is much more prominent than that of undamaged rock. The degraded GSI value generally decreases linearly as the temperature in the treatment increases for the examined rocks in this study, while the material parameter linearly increases with the increase in the treatment temperature.

热损伤岩石的强度行为与未损伤或完整岩石的强度行为有很大不同。在这项研究中，使用了地质强度指数（GSI）退化的概念和广义 Hoek-Brown（HB) 提出破坏准则来表征热损伤岩石的强度行为。然后使用从以前的出版物中收集的几组测试数据来验证提议的 GSI 软化模型。发现使用所提出的 GSI 软化模型可以很好地捕捉热损伤岩石强度随着围压增加而快速增加的情况。结果还表明，对于本研究中检查的热损坏岩石，GSI 值从 100 的未损坏岩石降低到 72 到 88 的值。热损伤岩石的材料参数比未损伤岩石的原始值高约1.5～3倍，说明热损伤岩石的摩擦强度比未损伤岩石的摩擦强度要突出得多。