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Hadgu, T.*; Kalinina, E.*; Wang, Y.*; Ozaki, Yusuke; Iwatsuki, Teruki
Proceedings of 2nd International Discrete Fracture Network Engineering Conference (DFNE 2018) (Internet), 5 Pages, 2018/06
Experimental hydrology data from the Mizunami Underground Research Laboratory in Central Japan have been used to develop a site-scale fracture model and a flow model for the study area. The discrete fracture network model was upscaled to a continuum model to be used in flow simulations. A flow model was developed centered on the research tunnel, and using a highly refined regular mesh. In this study development and utilization of the model is presented. The modeling analysis used permeability and porosity fields from the discrete fracture network model as well as a homogenous model using fixed values of permeability and porosity. The simulations were designed to reproduce hydrology of the modeling area and to predict inflow of water into the research tunnel during excavation. Modeling results were compared with the project hydrology data. Successful matching of the experimental data was obtained for simulations based on the discrete fracture network model.
Kalinina, E. A.*; Hadgu, T.*; Wang, Y.*; Ozaki, Yusuke; Iwatsuki, Teruki
Proceedings of 2nd International Discrete Fracture Network Engineering Conference (DFNE 2018) (Internet), 7 Pages, 2018/06
The Mizunami Underground Research Laboratory is located in the Tono area (Central Japan). Its main purpose is providing a scientific basis for the research and development of technologies needed for deep geological disposal of radioactive waste in fractured crystalline rocks. The current work is focused on the experiments in the research tunnel (500 m depth). The collected tunnel and borehole data were shared with the participants of DEvelopment of COupled models and their VALidation against EXperiments (DECOVALEX) project. This study describes how these data were used to (1) develop the fracture model of the granite rocks around the research tunnel and (2) validate the model.
Elena, K.*; Teklu, H.*; Wang, Y.*; Iwatsuki, Teruki; Ozaki, Yusuke
no journal, ,
In this study, Discrete Fracture Network Model (DFN) is built based on the fracture data observed in the Mizunami Underground Research Laboratory. 297 fractures data with discharge is analyzed for the estimation of stochastic quantity under the assumption that those fractures are permeable and have an great impact on the hydraulic conductivity field. Both models of fracture and hydraulic conductivity around the Closure Test Drift at the depth of 500m are generated from derived stochastic models. The hydraulic model is input into the numerical simulation. The matching of calculated and observed inflow into research tunnel indicates the validity of generated model and modeling approach for fractured rock. These results are a part of results in Task C of Decovalex2019.
Teklu, H.*; Elena, K.*; Wang, Y.*; Iwatsuki, Teruki; Ozaki, Yusuke
no journal, ,
In this study, the time variation of hydraulic head and Cl concentration during excavation of Closure Test Drift at the depth of 500m in Mizunami Underground Research Laboratory is simulated. The equivalent continuous porous medium model converted from Discrete Network Model is used to consider the highly heterogeneous feature of fractured rock. The simulated change in hydraulic head shows the good accordance with the observed data. However, the estimated time variations of Cl concentration show the slight change and can not reproduce the observed data. The improvement of prediction of change in Cl concentration is one of future task. These results are parts of results of Decvalex2019 Task C.