Fundamental Study of the Geological Disposal of High-Level Nuclear Waste

多屏障概念现在构成了大多数国家地质处置计划的支柱。多屏障系统的制造组件构成工程屏障系统（E.B.S）。EBS设计受到构建存储库的深层地质环境的约束。在这种环境下，地下水在减少，通量很小。该工程屏障系统由玻璃化废物、覆盖材料和缓冲材料组成。选择的缓冲材料具有非常低的渗透率，因此在EBS中有效地不发生平流。而施工、运行和封堵活动将在对围岩地质环境扰动最小的情况下进行。在施工过程中及施工后准确把握地质环境具有重要意义。作者提出的基于细观力学的连续介质理论可以反映节理密度、取向和连通性对节理性能的影响。本研究采用MBC分析方法对处置隧道的开挖进行分析，并通过分析，关注岩体中的节理，探讨隧道周围环境的变化。结果表明：(1)初始应力方向、节理密度及其组合对岩体的力学行为有较大影响。(2)处置隧道的形状或尺寸对节理变形有影响。(3)这些结果表明，隧道的开挖改变了透气性等地质环境。(4)高放废物处置机构建设前的数值计算结果，给出了高放废物处置机构开挖洞室和隧道后环境性质的近似变化。

The multi-barrier concept now forms the backbone of geological disposal programs in most countries. The manufactured components of the multi-barrier system constitute an engineered barrier system(E.B.S). The EBS design is constrained by the deep geological environment where the repository is constructed. In such an environment, groundwater is reducing and fluxes are small. The engineered barrier system consists of the vitriaed waste, overpack and buffer material. The buffer material is selected to have a very low permeability, so that effectively no advective flow occurs in the EBS.However, the construction, operation and closure activities will be carried out with a minimum disturbance to the geological environment in surrounding host rock. It is important to grasp the geological environment accurately during and after the construction. Micromechanics-based continuum(MBC)theory proposed by authors can reflect the effects of density, orientation and connectivity of joints as well as the property of the joints. In this study, the MBC analysis is employed to analyze the excavation of disposal tunnel and the change of the environment around the tunnel is discussed with paying attention to joints in a rock mass through the analyses.From the numerical results, it is concluded that(1)The mechanical behavior of the rock mass is strongly affected by the direction of initial stresses, the joint density, and their combinations.(2)The shape or size of the disposal tunnel has an impact on the joint deformation.(3)These results lead that the excavation of a tunnel changes the geological environment such as permeability.(4)The numerical results before the construction of disposal institution of high-level radioactive waste give us the approximate changes of environmental properties in the institution after the excavation of caverns and tunnels.