塔木素黏土岩蠕变特性试验与理论研究

Experimental and theoretical study on the creep behavior of Tamusu mudstone

以我国高放废物处置库预选区——塔木素黏土岩为主要研究对象,以前期国内外高放废物地质处置库黏土岩场址评价方相关工作为基础,对复杂条件下塔木素黏土岩的时效响应特征开展系统的试验与理论研究工作。蠕变试验表明:相同围压作用下,偏压与塔木素黏土岩蠕变变形呈现正相关;蠕变过程中黏土岩弹性模量呈先增大后减小的趋势;黏土岩蠕变变形是强化作用与结构劣化共同作用的结果。根据塔木素黏土岩蠕变变形特点,引入蠕变硬化变量和蠕变损伤变量,结合Perzyna过应力理论构建蠕变屈服面和蠕变势函数,建立塔木素黏土岩蠕变本构模型;基于大型软件平台ABAQUS,编写UMAT子程序,对理论模型进行数值实现及验证。本文全面系统地揭示高放废物处置环境下塔木素黏土岩蠕变变形规律及变形机制,为我国黏土岩高放废物地质处置库的安全性、可行性及适宜性评价提供重要理论依据,研究工作对我国核工业的发展和长期安全具有重要的实用价值。

This study focuses on Tamusu mudstone,an argillaceous rock from the preselected area for high-level radioactive waste(HLW)underground disposal in China.Based on the previous work on the evaluation of argillaceous rock for the HLW geological disposal repositories,a systematic experimental and theoretical study is conducted on the creep characteristics of Tamusu mudstone under complex conditions.Creep tests show a positive correlation between deviatoric stress and creep deformation under the same confining pressure.The elastic modulus shows a trend of first increasing and then decreasing during the creep process.The creep deformation of Tamusu mudstone results from the combined effect of strengthening and structural degradation.Based on the creep behavior of Tamusu mudstone,creep hardening variables and creep damage variables were introduced,and further the creep yield surface and creep potential function were constructed based on Perzyna's overstress theory.A creep constitutive model for Tamusu mudstone was established,and it was numerically implemented and verified by the software ABAQUS and its UMAT subroutine.This study comprehensively and systematically interprets the creep deformation law and deformation mechanism of Tamusu mudstone in the HLW disposal environment,providing an important theoretical basis for the safety,feasibility,and suitability evaluation of China's argillaceous rock HLW geological disposal repository.The research work has important practical value for the development and long-term safety of China's nuclear industry.