The awareness of the impact of high temperatures on rock properties is essential to the design of deep geotechnical applications. The purpose of this research is to assess the influence of heating and cooling treatments on the physical and mechanical properties of Egyptian granodiorite as a degrading factor. The samples were heated to various temperatures (200, 400, 600, and 800 °C) and then cooled at different rates, either slowly cooled in the oven and air or quickly cooled in water. The porosity, water absorption, P-wave velocity, tensile strength, failure mode, and associated microstructural alterations due to thermal effect have been studied. The study revealed that the granodiorite has a slight drop in tensile strength, up to 400 °C, for slow cooling routes and that most of the physical attributes are comparable to natural rock. Despite this, granodiorite thermal deterioration is substantially higher for quick cooling than for slow cooling. Between 400:600 °C is ‘the transitional stage’, where the physical and mechanical characteristics degraded exponentially for all cooling pathways. Independent of the cooling method, the granodiorite showed a ductile failure mode associated with reduced peak tensile strengths. Additionally, the microstructure altered from predominantly intergranular cracking to more trans-granular cracking at 600 °C. The integrity of the granodiorite structure was compromised at 800 °C, the physical parameters deteriorated, and the rock tensile strength was negligible. In this research, the temperatures of 400, 600, and 800 °C were remarked to be typical of three divergent phases of granodiorite mechanical and physical properties evolution. Furthermore, 400 °C could be considered as the threshold limit for Egyptian granodiorite physical and mechanical properties for typical thermal underground applications.

中文翻译：

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花岗闪长岩加热和冷却处理后的损伤演变

意识到高温对岩石特性的影响对于深层岩土工程应用的设计至关重要。本研究的目的是评估加热和冷却处理对埃及花岗闪长岩作为降解因素的物理和机械性能的影响。将样品加热到各种温度（200、400、600 和 800 °C），然后以不同的速度冷却，在烘箱和空气中缓慢冷却或在水中快速冷却。已经研究了孔隙率、吸水率、P 波速度、抗拉强度、破坏模式以及由于热效应引起的相关微观结构变化。研究表明，花岗闪长岩的抗拉强度略有下降，最高可达 400 °C，适用于缓慢冷却路线，并且大部分物理属性与天然岩石相当。尽管如此，快速冷却的花岗闪长岩热劣化明显高于缓慢冷却。在 400:600 °C 之间是“过渡阶段”，所有冷却路径的物理和机械特性都呈指数级下降。独立于冷却方法，花岗闪长岩显示出与峰值拉伸强度降低相关的延展性破坏模式。此外，在 600 °C 时，微观结构从主要的晶间开裂转变为更多的穿晶开裂。花岗闪长岩结构的完整性在 800 °C 时受到损害，物理参数恶化，岩石抗拉强度可以忽略不计。在这项研究中，400、600 和 800 °C 的温度被认为是花岗闪长岩力学和物理性质演化的三个不同阶段的典型特征。此外，