高放废物处置库黏土围岩温度-渗流-应力耦合数值分析

Numerical Analysis of Thermo-Hydro-Mechanical Coupling of Clay Surrounding Rock for High-level Radioactive Waste Disposal Repository

深地质高放射性废物处置库运营过程中,围岩通常处在复杂的温度-渗流-应力多场共同影响的地质环境中,在温度-渗流-应力耦合作用下,合理地确定高放废物处置库硐室间距范围对处置库设计和长期安全稳定性评价尤为重要。基于国内外研究资料,针对塔木素预选区高放废物处置库黏土围岩,使用FLAC3D有限差分软件模拟计算了4种不同的硐室间距,并通过对围岩温度场、渗流场、应力场和变形场进行对比分析,对高放废物处置库硐室间距进行了优化。结果表明:在温度-渗流-应力三场耦合作用下,高放废物处置库黏土围岩相邻硐室间距最优设计值为10~12 m;当硐室间距小于10 m时,废物罐中心温度峰值超过了最高温度设计值100℃,当硐室间距大于12 m时,相邻硐室间的影响逐渐减弱,温度峰值逐渐趋近于单硐室。研究结果可为我国高放废物处置库黏土围岩硐室间距优化设计提供参考依据。

In the operation of the deep geological high-level radioactive waste disposal repository, the surrounding rock is usually in a complex geological environment under the common influence of multiple fields including temperature, seepage and stress.Under the coupling action of temperature, seepage and stress, it is particularly important to determine the reasonable chamber distance range of the high-level radioactive waste disposal repository for the design of the disposal repository and long-term safety and stability evaluation. Based on the research data at home and abroad, aiming at the clay surrounding rock of the high-level radioactive waste repository in Tamusu pre-selection area, this paper adopts FLAC3Dfinite difference software to carry out numerical simulation calculation of four different repository spacings. Through comparative analysis of temperature field, seepage field, mechanical field and deformation field of clay surrounding rock, the spacings of repository are optimized. The results show that under the thermo-hydro-mechanical coupling, the optimal design value of the distance between adjacent repositorys of the high-level radioactive waste disposal repository in clay surrounding rock is 10-12 m. When the repository spacing is less than 10 m, the maximum temperature of waste tank center exceeds the maximum design temperature of 100℃. When the repository spacing is greater than 12 m, the influence of adjacent repositorys gradually decreases, and the peak temperature gradually approaches to a single repository. The research results can provide some reference for the optimized design of the clay surrounding rock of the high-level radioactive waste disposal repository in China.