Abstract The thermal effect significantly influences the behavior of surface and underground rock masses, especially rock fractures that act as heat exchangers with the environment. Understanding the impact of thermal treatment on granite joints under compression and shear is essential for various geotechnical and geological engineering projects. This paper examines how temperature ranging from room temperature to 500 °C impacts the mechanical properties of granite joints, including peak and residual shear strength, joint closure, normal and shear stiffness, and internal friction angle and cohesion, highlighting the importance of rock discontinuities for the stability of jointed rock masses. The results significantly enhance our understanding of the thermo-mechanical behavior of rock joints by introducing new governing equations for predicting granite joint behavior under different thermal treatment temperatures. It was found that the relevant parameters improved at varying rates with increasing temperature, reaching a threshold between 200 and 250 ℃ before gradually declining thereafter. The governing equations for granite joints as a function of temperature revealed that the relationship between normal stress and joint closure, both pre and post-thermal treatment, closely aligned with the partially modified Bandis's equation. Additionally, the peak shear strength before and after thermal treatment followed Patton's bilinear failure criterion rather than the linear Mohr–Coulomb criterion. Microscopic analysis revealed enhanced healing of intragranular fractures after thermal treatment at 250 ℃ compared to before treatment, resulting in improved joint behavior at this temperature. Conversely, thermal treatment at 500 ℃ led to a substantial widening of microcracks, significantly deteriorating joint behavior. Highlights <UnorderedList Mark="Bullet"> <ItemContent> The effect of thermal treatment on mechanical behaviour of granite joints was investigated. </ItemContent> <ItemContent> The behaviour of granite joints was studied under shear and compression. </ItemContent> <ItemContent> Granite joints behaves in two regimes as temperature increases from RT to 500 oC. </ItemContent> <ItemContent> The temperature threshold to initiate deterioration of joint behavior ranges between 200 and 250 oC. </ItemContent> <ItemContent> The residual shear strength is affected by temperature more than the peak shear strength. </ItemContent> </UnorderedList>

Thermal Effects on Granite Joint Behavior: Compression and Shear Experimental Investigation

期刊论文
发表日期：

2025年11月25日

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Mahmoud Alneasan,
Abdel Kareem Alzo’ubi,
Mohsen Aghababaei,
Hatem Abushammala,
Nader M. Okasha

摘要

Abstract

The thermal effect significantly influences the behavior of surface and underground rock masses, especially rock fractures that act as heat exchangers with the environment. Understanding the impact of thermal treatment on granite joints under compression and shear is essential for various geotechnical and geological engineering projects. This paper examines how temperature ranging from room temperature to 500 °C impacts the mechanical properties of granite joints, including peak and residual shear strength, joint closure, normal and shear stiffness, and internal friction angle and cohesion, highlighting the importance of rock discontinuities for the stability of jointed rock masses. The results significantly enhance our understanding of the thermo-mechanical behavior of rock joints by introducing new governing equations for predicting granite joint behavior under different thermal treatment temperatures. It was found that the relevant parameters improved at varying rates with increasing temperature, reaching a threshold between 200 and 250 ℃ before gradually declining thereafter. The governing equations for granite joints as a function of temperature revealed that the relationship between normal stress and joint closure, both pre and post-thermal treatment, closely aligned with the partially modified Bandis's equation. Additionally, the peak shear strength before and after thermal treatment followed Patton's bilinear failure criterion rather than the linear Mohr–Coulomb criterion. Microscopic analysis revealed enhanced healing of intragranular fractures after thermal treatment at 250 ℃ compared to before treatment, resulting in improved joint behavior at this temperature. Conversely, thermal treatment at 500 ℃ led to a substantial widening of microcracks, significantly deteriorating joint behavior.

Highlights

The effect of thermal treatment on mechanical behaviour of granite joints was investigated.

The behaviour of granite joints was studied under shear and compression.

Granite joints behaves in two regimes as temperature increases from RT to 500 oC.

The temperature threshold to initiate deterioration of joint behavior ranges between 200 and 250 oC.

The residual shear strength is affected by temperature more than the peak shear strength.