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Journal Articles

Evaluation of fractures in a rock as flow paths around tunnel using ground penetrating radar

Masumoto, Kazuhiko*; Takeuchi, Ryuji

Oyo Chishitsu, 57(4), p.154 - 161, 2016/10

https://doi.org/10.5110/jjseg.57.154

Fractures developing around the tunnel during the excavation result in issues related not only to the mechanical stability of the rock cavern, but also to the groundwater flow paths. In order to estimate the possibility of application of the GPR (Ground Penetration Radar) to estimate the fractures as low paths, the authors conducted the GPR survey along the side wall of 500 m access tunnel of the Mizunami Underground Research Laboratory of JAEA. The results of the profile measurements indicated that water-conductiong fractures were detected as a reflected waves using GPR survay. Furthermore, as the results of fixed-point measurements during the injection of the saline water, it could be indicated to estimate the flow paths of saline water in the fractures, in a non-destructive way, based on spectral analysis in the reflected waveforms of GPR.

JAEA Reports

None

Sato, Toshinori

JNC TN7400 99-012, 99 Pages, 1999/12

JNC-TN7400-99-012.pdf:6.13MB

JAEA Reports

Nuclide migration analysis in fractured rock

Sawada, Atsushi; Ijiri, Yuji; ; Watari, Shingo

JNC TN8400 99-093, 58 Pages, 1999/11

JNC-TN8400-99-093.pdf:11.24MB

This paper decribes the results of PA studies considering heterogeneous fracture characteristics, for the purpose of contributing for the performance assessment of the natural barrier system PA in H12 report (The second progress report on research and development for the Geological Disposal of HLW in Japan). In this study, 3-D discrete fracture network mode1 (DFN) and 1-D multiple pathways model is applied for 100m scale of rock block. Although nuclide release rate calculated by DFN are widely distributed among the realizations, it is shown that several tens realizations are enough number to understand the stochastic characteristics of the nuclide release. From the data uncertainty analysis, there are no significant effects for the nuclide retardation in fracture geometry parameters such as fracture radius, density and etc. 1-D multiple pathways model is developed with focusing on the heterogeneity of the transmissivity, which has a large effect to the nuclide retardation effects. The nuclide release rate calculated by using 1-D multiple pathways model approximates to the results of DFN. This result also shows that the relatively large fractures/faults that connects disposal tunnel and downstream faults have an important role for performance assessment in natural barrier system.

JAEA Reports

Radionuclide migration analysis in porous rock

Ijiri, Yuji; ; ; Watari, Shingo; K.E.Web*; ;

JNC TN8400 99-092, 91 Pages, 1999/11

JNC-TN8400-99-092.pdf:6.62MB

JNC has been developed the performance assessment approaches for both fractured rock and porous rock. An equivalent continuum model is incorporated for solving the radionuclide migration in porous rock, while a discrete fracture network model is incorporated for solving the radionuclide migration in fractured rock (see more detail in Sawada et al. [1999]). This report describes the methodology, the data and the results of the performance assessment of porous rock. From the results of radionuclide migration analyses that were based on the hydrogeological properties obtained from the Neogene sedimentaly rock at the Tono mine, it was found that the release rate of selenium-79 and cesium-135 are dominant in porous rock. The sensitivity analyses using one-dimensional porous model revealed that hydraulic conductivity has more influences on the results than porosity does. In addition, it was found that smaller distribution coefficients of sandstone yield higher release rate than mudstone and tuff, and smaller distribution coefficients of saline water conditions yield higher release rate than fresh water conditions. The radionuclide migration in Neogene sedimentaly rock, where flow in rock matrix as well as in fractures are significant, was evaluated by superposing the results of porous model and fracture model. Since fracture model tends to yield more conservative results than porous model, it is obvious that the performance of Neogene sedimentary rock can be conservatively assessed by fracture model alone. The nuclide migration analyses performed in this report were based on the hydrogeological properties obtained at the depth between 20 meters and 200 meters frrom the ground surface. Therefore, it should be noted that the release rate at the depth of a future repository in Neogene sedimentary rock, 500 m, will be smaller than that shown in this report due to peemeability decrease from 200 m to 500 m.

JAEA Reports

Physical model simulation for resistivity tomography; An Experimental tank and detection limit for a pole-pole array

Kumata, Masahiro;

Onoe, Hironori; Takayasu, Kentaro; Hayashida, Kazuki; Takeuchi, Ryuji; Iwatsuki, Teruki

no journal, ,

no abstracts in English

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Evaluation of fractures in a rock as flow paths around tunnel using ground penetrating radar

None

Nuclide migration analysis in fractured rock

Radionuclide migration analysis in porous rock

Physical model simulation for resistivity tomography; An Experimental tank and detection limit for a pole-pole array

Study on groundwater recovery experiment in Mizunami Underground Research Laboratory, 3; Conceptual modeling of fracture distribution around the underground gallery

Development of predictive simulation technology for geological environment after underground facility closure; Evaluation of fracture characteristics of rock mass around tunnel based on observation data

Joint research of Kajima corporation and Japan Atomic Energy Agency; Study on hydrogeological characterization of crystalline rock around the underground gallery using ground-penetrating radar

Study for fractured rocks on the Mizunami Underground Research Laboratory, 1; Discrete fracture network modeling

Development of methodologies for validation of groundwater flow and mass transport model, 1; A Case study using investigation data obtained at the Aspo Hard Rock Laboratory

Development of methodologies for validation of groundwater flow and mass transport model, 2; A Case study using investigation data obtained at the Mizunami Underground Research Laboratory

Case study on the development of methodologies for validation of groundwater flow and mass transport model, 1; Outline of the study

Case study on the development of methodologies for validation of groundwater flow and mass transport model, 2; Effects of the modeling methods of low permeability fractures on groundwater flow characterization

Case study on the development of methodologies for validation of groundwater flow and mass transport model, 3; Effects of the conditioning methods of fractures on groundwater flow characterization

Case study on the development of methodologies for validation of groundwater flow and mass transport model, 4; Construction of the ECPM model based on the DFN model

Case study on the development of methodologies for validation of groundwater flow and mass transport model, 5; Effects of the modeling concept of fractures on groundwater flow and mass transport characterization

Mizunami Underground Research Laboratory Project; Study on groundwater recovery experiment; Modeling of fracture distribution in the crystalline rock around the research gallery