基于损伤预测的粘土围岩深地质处置库硐距分析

Analysis on Cavern Spacing of Deep Geological Disposal of Clay Rock Based on Prediction of Excavation Damage Zone

粘土岩作为我国高放废物深地质处置库建设的预选围岩类型之一,其地下处置库硐距的优化对处置库的设计施工及核素迁移安全具有重大意义。本文基于塔木素粘土岩高放废物深地质处置预选地区天然地应力现场测量及室内岩石力学试验结果,采用弹性力学柯西问题理论分析与有限差分数值模拟相结合的方法,对处置库硐室开挖过程形成的损伤区范围进行预测。通过对比单硐与双硐开挖时不同硐室间距下开挖所形成的损伤区影响范围,来进行处置库硐距的优化,通过对比不同硐距下开挖损伤区的变化,分析当前应力水平下,硐室开挖后重分布应力随与中间岩柱中心点距离的变化趋势。结果表明,d=8~10 m是粘土围岩高放废物处置库的合理的硐距,此时开挖后的相邻硐室间损伤区没有产生明显交圈效应,当硐距大于10 m后,相邻硐室间的影响将逐渐减小,接近单硐开挖情况。该方案可为粘土岩预选区建造高放废物处置库提供参考依据。

Clay rock is one of the pre-selected surrounding rocks of China’s high-level radioactive waste repository,and the spacing optimization of the clay rock underground repository is of great significance to the design and construction of the repository and the safety of the nuclide migration.Based on the results of tectonic stress measurement in the pre-selected area of clay rock high-level radioactive waste disposal in Tamusu and indoor rock mechanics test,in this paper,the combination of Cauchy problem theoretical analysis in elasticity and finite difference numerical simulation was used to predict the damage zone formed during the excavation process of the repository.By comparing the influence range of the damage zone formed by excavation under single hole and double hole with different chamber spacings,the optimization of the cavern spacing was carried out.By comparing the changes of the excavation damage zone under different hole distances,the variation trend of the redistributed stress along with the distance from the center point of the middle rock pillar was analyzed after the excavation under the current stress level.The results show that when d is 8~10 m,it is a reasonable distance for the clay rock repository.Currently,there is no obvious circle-crossing effect in the damaged zone between the adjacent caverns after excavation.When the distance is more than 10 m,the influence will gradually decrease and approaching the single hole excavation.The program can provide a reference for the construction of high-level waste repository in the preselected area of clay rock.