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<p>Thermal degradation can profoundly affect the mechanical behaviour of rocks in various geomechanical applications. In this study, we investigated the influence of thermal treatment on the structural, elastic, and deformational properties of Westerly granite (WG) subjected to preheating in the range of 100&#xa0;°C to 800&#xa0;°C. A comprehensive suite of experimental methods was employed, including thin-section microscopy with crack density analysis, mercury intrusion porosimetry (MIP), volumetric analysis, and ultrasonic measurements under hydrostatic pressures up to 120&#xa0;MPa using P and two orthogonally polarised S waves. Additional parameters, such as weight loss, dimensional changes, and pressure-induced strain, were also assessed. The results demonstrate a pronounced effect of thermal treatment on all investigated mechanical and elastic parameters of WG. Microscopic analysis of samples heated to 800&#xa0;°C revealed regions of clogged porosity, filled with either detached grain fragments or fine-grained powder. MIP, volumetric data, and image analysis documented an exponential increase in total pore volume with rising preheating temperature. A bilinear trend in microcrack porosity was observed—characterised by a moderate increase up to 500&#xa0;°C, followed by a steeper rise beyond this threshold—likely associated with crystallographic transformations, particularly the α–β transition in quartz. In contrast, hydrostatic loading revealed a reduction in compaction capacity and elastic anisotropy of preheated specimens. Ultrasonic velocity measurements and elastic moduli exhibited an exponential increase with hydrostatic pressure across all temperature treatments. The integrated results provide a robust framework for quantifying the temperature sensitivity of granite’s mechanical behaviour. These findings enhance our understanding of thermal degradation in crystalline rocks and offer valuable data for developing predictive models of rock performance in high-temperature engineering environments.</p>

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Influence of Thermal Loading on Microcrack Evolution and Elastic Anisotropy in Westerly Granite

  • 期刊论文

  • 发表日期：

    2025年9月26日

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  • Tomáš Lokajíček,
  • Richard Přikryl,
  • Martin Racek,
  • Daniela Řimnáčová,
  • Vendula Natherová,
  • Matěj Petružálek,
  • Tomáš Svitek,
  • Ali Aminzadeh

摘要

Thermal degradation can profoundly affect the mechanical behaviour of rocks in various geomechanical applications. In this study, we investigated the influence of thermal treatment on the structural, elastic, and deformational properties of Westerly granite (WG) subjected to preheating in the range of 100 °C to 800 °C. A comprehensive suite of experimental methods was employed, including thin-section microscopy with crack density analysis, mercury intrusion porosimetry (MIP), volumetric analysis, and ultrasonic measurements under hydrostatic pressures up to 120 MPa using P and two orthogonally polarised S waves. Additional parameters, such as weight loss, dimensional changes, and pressure-induced strain, were also assessed. The results demonstrate a pronounced effect of thermal treatment on all investigated mechanical and elastic parameters of WG. Microscopic analysis of samples heated to 800 °C revealed regions of clogged porosity, filled with either detached grain fragments or fine-grained powder. MIP, volumetric data, and image analysis documented an exponential increase in total pore volume with rising preheating temperature. A bilinear trend in microcrack porosity was observed—characterised by a moderate increase up to 500 °C, followed by a steeper rise beyond this threshold—likely associated with crystallographic transformations, particularly the α–β transition in quartz. In contrast, hydrostatic loading revealed a reduction in compaction capacity and elastic anisotropy of preheated specimens. Ultrasonic velocity measurements and elastic moduli exhibited an exponential increase with hydrostatic pressure across all temperature treatments. The integrated results provide a robust framework for quantifying the temperature sensitivity of granite’s mechanical behaviour. These findings enhance our understanding of thermal degradation in crystalline rocks and offer valuable data for developing predictive models of rock performance in high-temperature engineering environments.