Development of modeling methodology for hydrogeological heterogeneity of the deep fractured granite in Japan
Development of modeling methodology for hydrogeological heterogeneity of the deep fractured granite in Japan
复制标题
日本深层裂隙花岗岩水文地质非均质性建模方法的发展
DOI：
10.1016/j.ijrmms.2021.104737
复制
发表时间：
2021
影响因子：
7.2
通讯作者：
T. Iwatsuki
中科院分区：
文献类型：
--
作者：
H. Onoe;M. Ishibashi;Yusuke Ozaki;T. Iwatsuki
建设和运营一个大型地下设施，用于地质处置高放废物数十年，将导致地下设施周围的地质环境发生变化。由于日本裂隙花岗岩的渗透性和非均质性高于欧洲，隧道开挖对地下水环境的干扰预计将是巨大和复杂的。因此，裂缝特征的模拟对于准确预测地下设施施工和关闭后地质环境的变化具有重要意义。然而，针对深度超过几百米的破碎花岗岩的建模方法在日本尚未完全建立。因此，在这项研究中，我们以日本水上地下实验室为例，研究了500米深的巷道周围破碎花岗岩的建模方法。因此，我们发展了裂缝建模方法，不仅可以估计裂缝的地质参数，而且可以根据裂缝迹长分布的重现性来估计水力参数。通过应用这种建模方法，可以构建能够准确再现裂缝统计特征的离散裂缝网络(DFN)模型。此外，应用条件化方法校正裂缝的位置和透过率，以使观测数据与特定地点相匹配，从而能够评估局部裂缝特征。阐明了现场勘察与裂隙花岗岩水文地质非均质性模拟所需数据之间的关系，提出了在地下设施建设阶段利用DFN模型进行裂隙花岗岩现场勘察、建模和处置面板设计的策略，为日本地质处置工程提供了有益的借鉴。
Constructing and operating a large underground facility for the geological disposal of high-level radioactive waste for decades will cause changes in the geological environment around the underground facility. Since the permeability and heterogeneity of fractured granite in Japan are higher than those in Europe, the disturbance to the groundwater environment due to tunnel excavation is expected to be large and complex. Therefore, modeling of fracture characteristics is important to accurately predict changes in the geological environment due to the construction and after the closure of the underground facility. However, the modeling approach focused on the fractured granite deeper than several hundred meters has not been completely established in Japan. Therefore, in this study, we investigated the methodology of modeling for fractured granite around the drift at a depth of 500 m in the Mizunami Underground Laboratory, Japan as a case study. As a result, we developed the fracture modeling method to estimate not only geological parameters of fractures but also hydraulic parameters based on the reproducibility of trace length distribution of fractures. By applying this modeling method, it was possible to construct a Discrete Fracture Network (DFN) model that can accurately reproduce the statistical characteristics of fractures. Besides, the application of the conditioning method to correct the fracture location and transmissivity to match the observation data to a specific site was demonstrated to enable the evaluation of local fracture characteristics. Furthermore, the relationship between the in-situ investigation and the data required for the modeling of hydrogeological heterogeneity of the fractured granite was clearly described, and the strategy of in-situ investigation, modeling, and disposal panel design for fractured granite using the DFN modeling during the underground facility construction phase as a useful knowledge of the geological disposal project in Japan was proposed.