Understanding the temperature-dependent shear behaviors of rock discontinuity would be critical for evaluating the stability of deep underground engineering structure. However, there are few documents available in the literature. In this study, a number of direct shear tests were performed on granite discontinuities with equal/similar joint roughness coefficient (JRC) after high temperatures from room temperature to 800 °C under five levels of normal stress, respectively. A linear increase in peak shear strength can be observed as the temperature increased from room temperature to 400 °C, then followed by a non-linear decline trend as the temperature continuously increased until to 800 °C. Cohesion and internal friction angle exhibited similar trends (reverse S-shape) with the increase in temperature, while the extent of thermal treatments on the two parameters was different. Peak shear displacement and secant peak shear stiffness were also greatly influenced by the thermal treatments, and two temperature-dependent empirical equations with the inclusion of temperature were developed. From room temperature to 400 °C, thermal treatments caused little influence on the surface degradation, while such an effect gradually became prominent with the increase in temperature from 400 to 800 °C. The temperature-dependent shear mechanisms for the failure of the granite discontinuities can be divided into three types (i.e., physical, chemical and geometrical), while the thermally induced over-closure, stated by Barton, would not be suitable for the increase in discontinuities’ peak shear strength due to the different heating procedures.

中文翻译：

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花岗岩间断面随温度变化的剪切行为的试验研究

了解岩石不连续性的温度相关剪切行为对于评估深部地下工程结构的稳定性至关重要。但是，文献中可用的文件很少。在这项研究中，在从室温到 800 °C 的高温后，分别在五个正应力水平下对具有相等/相似接头粗糙度系数 (JRC) 的花岗岩不连续性进行了多次直接剪切试验。当温度从室温升高到 400 °C 时，可以观察到峰值剪切强度的线性增加，然后随着温度持续升高到 800 °C，出现非线性下降趋势。随着温度的升高，内聚力和内摩擦角表现出相似的趋势（倒S形），而两个参数的热处理程度不同。峰值剪切位移和割线峰值剪切刚度也受热处理的影响很大，并且开发了两个包含温度的与温度相关的经验方程。从室温到400°C，热处理对表面降解的影响很小，而随着温度从400°C升高到800°C，这种影响逐渐显着。花岗岩不连续性破坏的温度相关剪切机制可分为三种类型（即物理、化学和几何），而巴顿所说的热致过度闭合不适用于不连续性的增加' 由于不同的加热程序而产生的峰值剪切强度。