Effects of temperature and confining pressure on the permeability of Beishan granite from high-level radioactive waste disposal repository

Abstract

Understanding the variation of rock permeability with temperature and confining pressure is the foundation for projects such as high-level radioactive waste disposal, deep geothermal exploitation, and carbon dioxide storage. This paper presents an experimental study of the permeability evolution of thermally damaged Beishan granite under effective stress. The results show that temperature has a significant impact on the permeability of granite, and there is an obvious threshold temperature (400–500 °C), initial permeability and permeability change rate increased gradually with temperature. The permeability of Beishan granite shows non-linear decreasing trend with the increase of effective stress, ultimately tending towards stability. The microstructure of granite after thermal damage can be observed by scanning electron microscopy and used to assist in explaining the microscopic mechanism of permeability changes. A new granite permeability prediction model is proposed, which integrates permeability with temperature and effective stress, providing an important reference for the safety of high-level radioactive waste disposal.

Keywords

• Beishan granite
• Permeability
• Thermal damage
• Effective stress
• Prediction model