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<p>Accurately evaluating the long-term evolution of host rock integrity is critical for the safety assessment of deep geological repositories for high-level radioactive waste (HLW). While current models effectively simulate coupled thermo-hydro-mechanical (THM) processes, a significant gap exists in translating these complex physical field simulations into a direct, quantitative assessment of the rock's barrier function. This study develops and demonstrates a new multi-dimensional Rock Integrity Coefficient (RIC) system to bridge this gap. A thermo-mechanically coupled elastoplastic damage constitutive model, incorporating the Mohr–Coulomb criterion, was implemented within a finite element framework. The model was applied to investigate the granite host rock at the Beishan potential repository site in China. A series of numerical simulations were conducted based on an L9 orthogonal array, considering variations in disposal tunnel spacing and depth. The core of our methodology is the RIC system, which integrates four integrity dimensions—thermal (peak temperature &lt; 100&#xa0;°C), mechanical (stress concentration factor &lt; 1.5), structural (damage variable &lt; 0.3), and interfacial (thermal barrier ΔT &lt; 60&#xa0;°C)—to provide a holistic barrier performance metric. Our results, tracked over a 100-year period, reveal a progressive degradation of integrity parameters under decaying thermal load, with identifiable inflection points at 10 and 40&#xa0;years. The analysis demonstrates that even temperatures below 200&#xa0;°C can induce significant cumulative damage, potentially compromising the rock's long-term low permeability. The primary innovation of this work is the RIC framework itself, which advances beyond conventional THM analysis by providing an integrated, time-dependent tool for barrier assessment. The established integrity indicator system offers a more scientifically grounded approach for environmental risk assessment and provides critical insights for the optimized design of HLW repository sealing systems, ultimately supporting the long-term goal of safe radionuclide containment.</p>

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Impact of Granite Thermo-Mechanical Coupling on the Long-Term Integrity of Engineered Barriers System (EBS) in HLW Repositories

  • 期刊论文

  • 发表日期：

    2026年2月26日

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  • Minsi Zhang,
  • Fang Liao,
  • Yong Yang,
  • Zhongsi Dou,
  • Shengjun Xie,
  • Wenhua Zha

摘要

Accurately evaluating the long-term evolution of host rock integrity is critical for the safety assessment of deep geological repositories for high-level radioactive waste (HLW). While current models effectively simulate coupled thermo-hydro-mechanical (THM) processes, a significant gap exists in translating these complex physical field simulations into a direct, quantitative assessment of the rock's barrier function. This study develops and demonstrates a new multi-dimensional Rock Integrity Coefficient (RIC) system to bridge this gap. A thermo-mechanically coupled elastoplastic damage constitutive model, incorporating the Mohr–Coulomb criterion, was implemented within a finite element framework. The model was applied to investigate the granite host rock at the Beishan potential repository site in China. A series of numerical simulations were conducted based on an L9 orthogonal array, considering variations in disposal tunnel spacing and depth. The core of our methodology is the RIC system, which integrates four integrity dimensions—thermal (peak temperature < 100 °C), mechanical (stress concentration factor < 1.5), structural (damage variable < 0.3), and interfacial (thermal barrier ΔT < 60 °C)—to provide a holistic barrier performance metric. Our results, tracked over a 100-year period, reveal a progressive degradation of integrity parameters under decaying thermal load, with identifiable inflection points at 10 and 40 years. The analysis demonstrates that even temperatures below 200 °C can induce significant cumulative damage, potentially compromising the rock's long-term low permeability. The primary innovation of this work is the RIC framework itself, which advances beyond conventional THM analysis by providing an integrated, time-dependent tool for barrier assessment. The established integrity indicator system offers a more scientifically grounded approach for environmental risk assessment and provides critical insights for the optimized design of HLW repository sealing systems, ultimately supporting the long-term goal of safe radionuclide containment.