高放废物处置库围岩开挖损伤区研究的关键问题及进展

Key issues and research progress of excavation damage zone in surrounding rocks of high-level radioactive waste disposal repositories

高放废物(HLW)地质处置是将高水平放射性废物埋存于地下500～1 000 m地质体中,使放射性废物与生物圈长期隔离。地质处置库对核素的长期隔离能力是安全评价的关键课题。地下硐室的开挖将不可避免地对围岩造成损伤,形成开挖损伤区(EDZ),改变围岩的物理力学特性,对高放废物地质处置长期安全性存在潜在的影响。目前多个国家建成了高放废物处置地下实验室,并开展了大型原位开挖损伤区的研究,研究开挖损伤区的形成过程及其物理力学特性的变化。本文综述了国外结晶岩地下实验室开展的开挖损伤区研究,总结了EDZ关键研究问题;梳理了加拿大、瑞典、芬兰3个地下实验室多年来开展的系统的EDZ研究工作,对当前EDZ预测模型及模拟技术进行了总结;对我国地下实验室将开展的开挖损伤区研究工作进行了初步探讨,期望为我国的相关研究提供借鉴。同时,高放废物处置库是地下工程新实践,其EDZ的研究成果,形成的技术方法将对其他行业地下工程的建设,如引水隧洞、公路铁路隧道等也有重要的参考价值。

Geological disposal of high-level radioactive waste(HLW)is to dispose HLW in a zone of 500 to 1 000 m beneath ground surface and isolate HLW from biosphere for a long period.The key issue of safety assessment is the long term capability of a geological disposal repository for isolating nuclides.It is inevitable to induce Excavation Damage Zone(EDZ)for surrounding rocks during underground engineering construction process,and the induced damage in EDZ will change physical and mechanical properties of surrounding rocks and potentially affect long term safety of the repository.Underground Research Laboratories(URLs)have been built in many countries such as Sweden(ASPO),Canada(URL),Finland(ONKALO),etc.Systematic field tests have been conducted to study the EDZ.In this paper,researches about EDZ built in crystalline rock in URLs are summarized,some key issues in EDZ study are discussed,and the prospect of EDZ studies in our URL is proposed.Overall researches in URL regarding EDZ are comprehensive and may be of great reference value for other underground engineering construction projects such as diversion tunnels and highway tunnels.