Review on the study of fracture closure behavior in host rock for high-level radioactive waste disposal
The fractures in the surrounding rock of high-level radioactive waste(HLW)disposal repositories can be served as potential pathways for groundwater and radionuclide migration and brings a threat to the long-term safety of the repository.Over extended periods after repository closure,these fractures may undergo deformation or even"sealing"due to mechanisms such as stress redistribution and mineral dissolution-precipitation,thereby altering the performance of the multi-barrier system of the repository.This paper made a systematically review on the literature of fracture closure behavior,analyzed the mechanisms and key influencing factors contributing to fracture sealing in the surrounding rock of disposal repository,and summarized the current status and limitations of experimental and numerical studies on fracture closure,which will provide a reference for future experimental research and safety evaluations.The literature review indicated that previous studies have demonstrated the possibility of fracture sealing under multi-field coupled conditions in repository environments,with mineral free-face dissolution-precipitation and pressure dissolution identified as key mechanisms for sealing.These processes are influenced by factors such as temperature,stress,mineral composition and grain size,and pore water chemistry.Future research should integrate laboratory experiments and field trials in underground laboratories to establish and refine comprehensive multi-field coupled numerical models,thereby improving the predictive capability of fracture long-term evolution so as to provide robust theoretical and data support for the safety assessment of geological repository.
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