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Koide, Kaoru; Yanagizawa, Koichi
PNC TN7410 93-016, 42 Pages, 1993/10
The purpose of this study is to develop estimation methods of hydrological characteristics of subsurface using regional data such as remote sensing data and topographical data in order to evaluate regional groundwater flow in Japan. This study consists of following three steps. The first step is to develop methods to extract the ground surface information. The second step is to quantify the relationship between the ground surface conditions and hydrological characteristics. And the final step is to develop estimation methods of hydrological characteristics of subsurface by using ground surface information. This paper describes the development of extraction methods on the ground surface information as the first step in our study. In this paper, topography and vegetation parameters were selected as the ground surface information which is considered relating to water balance which is one of hydrological characteristics. The study site was selected in the area (5km 
5km) around the Tono uranium Mine, Central Japan. In order to extract topographic information, we developed a computer program to calculate direction and inclination of hill slopes using digital elevation map (DEM). The program was validated by comparing calculated results with measured slope data which were read from topographic map in the study site. We also examined grid intervals of DEM so that terrain in the study site can be represented appropriately. As a result, it was known that the grid interval of DEM should be less than 30m in the study site. We tried to classify forest types into three classes, a broad-leaved forest, conifer forest and mixed forest, using seasonal change of the normalized vegetation index (NVI) that was calculated from SPOT HRV data. Multi-temporal data (summer, autumn and winter) of SPOT were used to determine seasonal change of NVI of each forest type. As a result, it was definitely shown that each forest type has a different seasonal change of NVI. We ...
Yusa, Yasuhisa
PNC TN7410 92-052, 239 Pages, 1992/12
This report describes a summary of the workshop on SEE project (Shaft Excavation Effects Project). The workshop was held in Toki-city on, 30 November 1992. The purpose of this workshop is to summarize the results of SEE project, and to exchange information and to promote mutual understanding between research workers of universities, private corporations and staff of PNC. These proceedings reproduce the papers presented at the workshop, together with a summary of the discussions and copies of all papers that are concerned with SEE project and are currently published.
; ; Sato, Toshinori; Yoshioka, Naoya
PNC TN7410 92-046, 56 Pages, 1992/12
As a result of underground excavation to construct an underground facility, an excavation disturbed zone (EDZ) is often generated in rock mass around a shaft and a drift. In order to design and construct an underground facility, and to evaluate its long-term stability, it is necessary to understand the phenomena related to excavation disturbance. PNC (Power Reacter and Nuclear Fuel Development Corporation) excavated a shaft of 6m diameter and 152.3m depth in Neogene sedimentary rocks, and studied the influence induced by the shaft excavation on rock mass and groundwater flow around the shaft. This project was named SEE (Shaft Excavation Effects) project, and was carried out from 1978 to 1991. This report described a part of the SEE Project, focusing on mechanical and hydrological variation of rock mass around the shaft. The current conclusions were su㎜arized as follows: (1)Mechanical and hydrological variation of rock mass around the shaft was induced by stress redistribution and fracturing around the shaft. (2)The zone where mechanical and hydrological characteristics were varied was extended about 1m from shaft wall. (3)It is considered that unrecoverable deformation is generated in rock mass around a shaft because of fracturing and plastic deformation. We introduced a concept of permanent deformation modulus to take account of the unrecoverable deformation, and estimated the results of borehole jack tests. Consequently, we found the permanent deformation modulus was useful to identify the EDZ.
Ogata, Nobuhisa; Osawa, Hideaki; Semba, Tsuyoshi; Yanagizawa, Koichi
PNC TN7410 92-001, 48 Pages, 1992/01
In order to groundwater flow in rock formation, it is essential to make a topographic and hydrogeological models and to set up the initial and boundary conditions. Hydraulic properties are considered to be dominated by various factors of fracture (i.e. width, density, network) in the crystalline rock. Investigated was relationship between the hydraulic conductivity. which is one of important factors for evaluation of groundwater flow, and the fracture properties, using the method of multivariate analysis such as multiple regression analysis and cluster analysis. A total of 56 data on hydraulic conductivity and physical parameter were used that had been obtained from 2 boreholes drilled in the granitic rock of Tono area, Gifu, in the central Japan. The results are as follows: (1)The results of these two multivariate analysis are almost consistent. The hydraulic conductivity in the granitic rock is dominated by fracture system, such as number and width of the fracture, fissure-filling minerals. (2)The classificatory structure which obtained from the cluster analysis corresponds to that from hydraulic conductivity. Different hydraulic conductivities were distributed in each cluster that is dominated by width of open fracture, filling minerals, number of intersect and predominant direction of fractures. (3)The cluster analysis also implies that fracture properties of test sections with the similar hydraulic conductivities occasionally differ among them. Hence, the classifications is must be made based on the data of fracture properties as well as hydraulic conductivities. Future studies using sufficient number of data is necessary.
Imai, Hisashi; Yanagizawa, Koichi
PNC TN7410 90-026, 29 Pages, 1990/12
In order to develop the methodology and equipment for hydrogeological investigation, a study on regional groundwater flow has been carried out by PNC (Power Reactor and Nuclear Fuel Development Corporation) around the Tono area located in the southeast of Gifu prefecture, central Japan. Within this study, three kinds of analytical study concerning the three dimentional groundwater flow are being carried out; (1)Regional groundwater flow analysis in the area of 10 kilometers square with 1000 meter depth. (2)Local groundwater flow analysis around the experimental shaft to examine the effect of shaft excavation in the area of 300 meters square with 300 meter depth. (3)Also effect analysis on the groundwater flow considering the relaxation of rock mass due to the shaft excavation in the restricted small area of 20 meters with 50 meters depth. According to the above study of groundwater flow analysis, the properties of developing analytical code of TAGSAC (Three Dimentional Analysis of Groundwater Flow, Saitama University Code) using FEM method under saturated or unsaturated condition are presented by following fivefold; (1)The utility background of TAGSAC (2)The analysis examples by TAGSAC (3)The governing equation used in TAGSAC and the handling of the equation in unsaturated condition (4)The problems and improving plan for TAGSAC (5)The programme source of TAGSAC
Ogata, Nobuhisa*
PNC TN7410 90-005, 35 Pages, 1990/01
In order to establish a hydrogeological model for a rock mass, data is reguired on its hydrogeological properties. A development for geophysical logging technique which is considered to be available for obtaining data on physical properties of rock mass is being carried out aiming at examination of its applicability to a hydrogeological evaluation of the rock mass with a assumption of correspondances between the hydrogeological and the physical properties of the rock mass. In the development of the technique, a borehole was drilled in a granitie rock, followed by measurements of physical parameters by geophysical loggings and laboratory tests on the drill cores and loggings. A consideration is being made on the relationship between the physical properties and the features of fractures and alterations which were obtained by the above methods. The results are as follows : (1)While electric and sonic loggings are found to be available for identification of fracture and alteration zones, micro-resistivity logging is for single fractures. (2)Density-neutron loggings may be useful for detection of fractures with water potentially. (3)The high porosity (
) zones resulted from density-neutron loggings tend} to correspond to fracture zones with alteration. (4)The high porosity (
) zones resulted from sonic logging are likely to correspond to those with high fracture densities regardless of alteration. (5)Division into three rock segments with depth based on the core logging was proved to be compatible with the results of the geophysical logging. Specifically, the features of fracture and alteration correlate with rock classfication and proposity difference (| - |) in each segment.
*
PNC TN7410 90-004, 41 Pages, 1989/12
The Second Phase of the Stripa Project included the continued development of methods and techniques for repository site investigations. The crosshole investigations demonstrated that it is possible to characterize fractures in crystaline rock with a reliability and realism not obtained before. At the investigated site at Stripa, it was shown that groundwater flow is concentrated within a few major fractures that were identified by geophysical methods. The main features were considered to be broadly planar, containing patches of high and low hydraulic conductivity. Detailed investigations of the fracture hydrology at Stripa and of the migration of tracers in the groundwater, together with additional information of the groundwater composition, resulted in an improved knowledge of groundwater flow in fractured crystalline rock. The work at Stripa has shown that it is possible to collect and analyze data that enable one to determine the type of distribution its parameters for each of the essential geometrical and hydraulic properties of the fracture system, and hence compare one site with another as part of experience building in safety assessment studies. The migration experiment demonstrated that the groundwater flow could be very unevenly distributed in the rock. Together with the tritium measurements it also gave strong support to the notion that a non-negligible portion of the flow takes place in channels which have little contact with other main channels. A further research effort has to be devoted to development of appropriate numerical models for the description of flow in fractured crystalline rock. The hydrogeochemical investigations at Stripa also indicated that a new type of solute source must be considered - fluid inclusions in the host rock. The age of the solutes may be entirely different from the age of the groundwater. At Stripa, the age of the solutes is likely to be hundreds of millions of years older than the groundwaters. Furthermore, this ...
