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<p>As underground salt cavern gas storage facilities progress to greater depths, the study of salt rock under high geothermal and high-pressure conditions is gaining increasing attention. It is essential to comprehensively understand the thermo-mechanical damage mechanisms of salt rock under these conditions and their impact on the stability of underground salt cavern gas storage facilities. The targeted formation depth for the Ningjin salt cavern gas storage facility in Xingtai, Hebei Province, China, is 2800 m, making it the deepest salt cavern gas storage facility in the world. With the further development of underground salt cavern gas storage, the research interest in salt rock under high ground temperature and high ground pressure is increasing. It is very important to fully understand the thermo-mechanical damage mechanisms of salt rock under high temperature and high pressure and its influence on the stability of underground salt cavern gas storage. To reveal the fracture development and damage evolution patterns of salt rock under the influence of temperature, a high-temperature triaxial servo testing machine and an acoustic emission (AE) testing system were utilized to study the deformation and failure characteristics and AE activity of salt rock at temperatures of 30&#xa0;°C, 70&#xa0;°C, 110&#xa0;°C, and 150&#xa0;°C. This study analyzed the changes in AE shoot, amplitude, ring count, AE energy, peak frequency, and <i>b</i> value during the damage evolution process of salt rock under varying temperatures and confining pressures. It was found that the AE amplitude exhibited minimal fluctuation and low-temperature sensitivity. In contrast, the peak frequency and <i>b</i> value parameters effectively characterized the internal crack development in the rock, with the peak frequency showing the highest temperature sensitivity, making it an optimal predictor for the fracture damage of salt rock. Analysis of AE rise time/amplitude (RA) and average frequency (AF) characteristics suggests that triaxial compression failure in salt rock generates mixed-mode cracks, with shear cracks being predominant. High temperatures inhibit the localization of AE events within the salt rock, and with increasing temperature, tensile failure becomes weaker while shear failure becomes more pronounced. These findings provide valuable insights into the thermo-mechanical damage mechanisms of salt rock and have significant implications for predicting thermal damage in engineering applications.</p>

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Experimental Research on the Thermo-mechanical Damage Mechanisms of Salt Rock

  • 期刊论文

  • 发表日期：

    2025年1月10日

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  • Ziheng Wang,
  • Feng Chen,
  • Haoran Li,
  • Xilin Shi,
  • Zhikai Dong,
  • Xin Meng,
  • Chunhe Yang

摘要

As underground salt cavern gas storage facilities progress to greater depths, the study of salt rock under high geothermal and high-pressure conditions is gaining increasing attention. It is essential to comprehensively understand the thermo-mechanical damage mechanisms of salt rock under these conditions and their impact on the stability of underground salt cavern gas storage facilities. The targeted formation depth for the Ningjin salt cavern gas storage facility in Xingtai, Hebei Province, China, is 2800 m, making it the deepest salt cavern gas storage facility in the world. With the further development of underground salt cavern gas storage, the research interest in salt rock under high ground temperature and high ground pressure is increasing. It is very important to fully understand the thermo-mechanical damage mechanisms of salt rock under high temperature and high pressure and its influence on the stability of underground salt cavern gas storage. To reveal the fracture development and damage evolution patterns of salt rock under the influence of temperature, a high-temperature triaxial servo testing machine and an acoustic emission (AE) testing system were utilized to study the deformation and failure characteristics and AE activity of salt rock at temperatures of 30 °C, 70 °C, 110 °C, and 150 °C. This study analyzed the changes in AE shoot, amplitude, ring count, AE energy, peak frequency, and b value during the damage evolution process of salt rock under varying temperatures and confining pressures. It was found that the AE amplitude exhibited minimal fluctuation and low-temperature sensitivity. In contrast, the peak frequency and b value parameters effectively characterized the internal crack development in the rock, with the peak frequency showing the highest temperature sensitivity, making it an optimal predictor for the fracture damage of salt rock. Analysis of AE rise time/amplitude (RA) and average frequency (AF) characteristics suggests that triaxial compression failure in salt rock generates mixed-mode cracks, with shear cracks being predominant. High temperatures inhibit the localization of AE events within the salt rock, and with increasing temperature, tensile failure becomes weaker while shear failure becomes more pronounced. These findings provide valuable insights into the thermo-mechanical damage mechanisms of salt rock and have significant implications for predicting thermal damage in engineering applications.