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*; *; Morooka, Koichi*
JNC TJ8400 2000-043, 170 Pages, 2000/03
JNC-TJ8400-2000-043.pdf:7.63MB
This study is an object to collect and arrange data about the mass transfer path during a natural barrier system by grasping actual rock feature, in order to be useful for a performance assessment of a natural barrier system at geological disposal of HLW. An existence of permeability high large-scale faults extends a large influence over a performance assessment of geological disposal. With "The Second Progress Report on Research and Development for the Geological Disposal of HLW in Japan" which Nuclear Cycle Development Institute (JNC) issued, it is as" A repository would be located at least 100 meters away from major faults and major fracture zones which could adversely affect the stability and performance of the repository" as a Reference Case concept model of a natural barrier system, Then, they are as "in the Reference Case, the transport path consists of the host rock and the downstream fault". It will not be easy to know the distribution of faults in the subsurface deep division without data acquired from many boreholes and underground laboratory. With this study, specific data on the large-scale faults and fracture zones has been collected and arranged by investigating in underground galleries and on the literatures of a post-operated mine site. Based on this result, a consideration on the principal transfer pass at a natural barrier system has been conducted. The contents conducted in this report is the follows. (1)investigation of literature about data of fracture, shear zone, and geology, (2)field investigation of fracture and shear zone in the rock, (3)arrangement of these results, (4)modeling of the major water conductive feature, and (5)evaluation of an assumption which has been introduced in the Second Progress Report issued by JNC.
Yoshioka, Naoya*; Tsuchihara, H.*; Horita, M.*; Kinoshita, Naoto*
PNC TJ1449 96-007, 349 Pages, 1996/03
None
Sugihara, Kozo*; Ninomiya, Yasuo*
PNC TN7410 90-009, 45 Pages, 1990/02
Among many R&D categories for the performance assessment of geological disposal, it is very important to develop the techniques to measure and to evaluate the disturbed zone due to excavation. This study aimes to investigate the disturbed zone around the drift excavated in the sedimentary rock formation and to evaluate the accuracy, reliability and effectiveness of existing techniques for excavation, measurement and analysis for the use of the repository construction. For this purpose, a drift (2.5
2.5m, L=30m) was excavated by NATM. Rock mass displacement, rock bolt stress, permeability and pore water pressure were measured in and around the drift. Using this drift as measuring drift, a test drift (3.03.0m, L=20m) was excavated parallel to the measuring drift. As the supporting system of this drift only rock bolting was employed. In-situ measurement of rock displacement, elastic wave velocity, permeability and initial stress have been carried out. These results were compared with the predicted results to investigate the effectiveness of the existing evaluation techniques. Laboratory test results and geological mapping data were also used to understand the rock mass behavior and the disturbed zone around drift. These investigations revealed that low velocity zone of elastic wave was generated around the drift, and in the zone, permeability decreased and displacement increased. Rock mass movement was predicted roughly by numerical analysis based on the laboratory test results. And detailed numerical analysis considering the initial stress data and disturbed zone around the drift, provided good simulation of rock mass movement. But measurement technigues of mechanical and hydrological properties of narrow zone adjacent to the drift wall and understanding of relationship between mechanical property change and hydrological one and phenomenon of disturbed zone generation remained as future study subjects.