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Journal Articles

Discrete fracture network modeling based on in-situ data at underground gallery, 2

Nakajima, Makoto*; Seno, Shoji*; Onoe, Hironori; Ishibashi, Masayuki; Saegusa, Hiromitsu; Sawada, Atsushi

Dai-42-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.107 - 112, 2014/01

Japan Atomic Energy Agency is proceeding with the Mizunami Underground Research Laboratory Project in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock for geological disposal of high level radioactive wastes. We have carried out discrete fracture network modeling, groundwater flow and particle tracking simulation in order to understand the important factors for the solute transport characterizations. In this paper, a method for estimating hydraulic parameter of discrete fracture network model based on in-situ data at underground gallery are described.

JAEA Reports

Applicability study of numerical analysis for coupled mechanical and hydrological processes by drift excavation (Contract research)

Yamamoto, Nobuyuki; Iwano, Keita*; Namikawa, Tadashi*; Morikawa, Seiji*; Seno, Shoji*; Tabei, Kazuto*; Toida, Masaru*; Yokota, Hideharu

JAEA-Research 2013-003, 252 Pages, 2013/06

JAEA-Research-2013-003.pdf:77.85MB

This study reconsiders rock's mechanical and hydrological parameters based on additional ${it in-situ}$ data given in this year, and conducts the mechanical-hydrological analysis using the Micromechanics-Based Continuum (MBC) model which can consider the behavior of fracture. The acquired analysis results are compared with actual test data such as drift convergence and hydraulic pressure around the drift. Then, following knowledge is obtained.

JAEA Reports

Developing the soil moisture sensor using optical fiber technique (Joint research)

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Hirata, Yoichi*; Takenobu, Kazuyoshi*; Tagishi, Hirotaka*; Kunimaru, Takanori; Maekawa, Keisuke; Yamamoto, Yoichi; Toida, Masaru*; et al.

JAEA-Research 2012-001, 77 Pages, 2012/09

JAEA-Research-2012-001.pdf:4.85MB

This research focused on methods of estimating the amounts of groundwater recharge, which are normally required as upper boundary conditions in groundwater flow analyses, based on measurements of infiltrating water in the ground, to systematize the methods and establish systems which are stable and measurable on site over a long time. Regarding developing measurement systems, fiber-optic strain measurement methods that enable multiple-point and long-distance measurement were used for measuring three quantities: suction pressure, soil moisture and volumetric water content rate obtained by applying water absorption swelling material, and each measurement was discussed. The results showed that the fiber-optic soil aquameter has two types of practical application: one for measuring suction pressure (Type I), and the other for measuring volumetric water content rate obtained by applying water absorption swelling material (Type III). Furthermore, by using measurement instruments in actual fields, the validity of the two methods for estimating the rainfall infiltration capacities of shallow-layer soils, that is, estimating the capacities either directly by measurements of soil water or from unsaturated hydraulic conductivities, was confirmed.

Journal Articles

Estimation of infiltration amount from in-situ moisture measuring method in shallow ground

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Toida, Masaru*; Tagishi, Hirotaka*; Takenobu, Kazuyoshi*; Yamamoto, Yoichi

Chikasui Jiban Kankyo Ni Kansuru Shimpojium 2011 Happyo Rombunshu (CD-ROM), p.17 - 26, 2011/11

no abstracts in English

JAEA Reports

Study on reciprocal relation of pore water pressure with genetic algorithm and neural network model(Contract research)

Seno, Shoji*; Kunimaru, Takanori; Nakajima, Makoto*; Toida, Masaru*; Watanabe, Kunio*; Sohail, A. R.*

JAEA-Research 2008-126, 120 Pages, 2009/12

JAEA-Research-2008-126.pdf:29.29MB

At first, to exclude the influences of working of nature such as tide and atmospheric pressure from the source data, an analysis with Bayesian model was progressed. As the result of the estimation of these influences calculated by BAYTAP-G (Bayesian Tidal Analysis Program Grouping Model), it was found that the influence of the atmospheric pressure was comparatively large and that of tide was comparatively small.

Journal Articles

Hydrogeological investigations of surface-based investigation phase of Horonobe URL project

Kurikami, Hiroshi; Takeuchi, Ryuji; Yabuuchi, Satoshi; Seno, Shoji*; Tomura, Goji; Shibano, Kazunori; Hara, Minoru; Kunimaru, Takanori

Doboku Gakkai Rombunshu, C, 64(3), p.680 - 695, 2008/09

Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. This paper shows the results of hydrogeological investigations in the surface-based investigation phase of the project. Hydrological and meteorological investigations show that the infiltration rates of the drainage basins varies and that the infiltration rate depends on the flora and the topography. The hydraulic tests using the deep boreholes reveals that hydraulic conductivity of the scale of a few decameters to a hundred meter varies widely and decreases with depth in the same formation, while the laboratory hydraulic tests suggest that hydraulic conductivity of the intact rock is influenced by the stress history. The hydraulic tests and the long-term monitorings of hydraulic pressure clarify relatively high pressure in the deep underground. Furthermore, groundwater flow analysis shows that the groundwater in and around the URL area flows regionally from the east to the west and depends locally on the geography and geology.

JAEA Reports

Assessment of uncertainties associated with characterization of geological environment in the Tono area; Japanese fiscal year, 2006 (Contract research)

Toida, Masaru*; Suyama, Yasuhiro*; Seno, Shoji*; Atsumi, Hiroyuki*; Ogata, Nobuhisa

JAEA-Research 2008-035, 89 Pages, 2008/03

JAEA-Research-2008-035.pdf:5.66MB

"Geoscientific research" performed at the Tono Geoscience Center is developing site investigation, characterization and assessment techniques for understanding of geological environment. Their important themes are to establish a methodology for analyzing uncertainties in heterogeneous geological environment, and to develop investigation techniques for reducing the uncertainties efficiently. This study proposes a new approach where all the possible options in the models and data-sets that cannot be excluded in the light of the evidence available, are identified. This approach enables uncertainties associated with the understanding at a given stage of the site characterization to be made explicitly using an uncertainty analysis technique based on Fuzzy geostatistics. This, in turn, supports the design of the following investigation stage to reduce the uncertainties efficiently. In the study, current knowledge had been compiled, and the technique had been advanced through geological modeling and groundwater analyses in the Tono area. This report systematized the uncertainty analysis methodology associated with the characterization of the geological environment, and organized the procedure of the methodology with the application examples in the study. This report also dealt with investigation techniques for reducing the uncertainties efficiently, and underground facility design options for handling geological uncertainties based on the characterization of the geological environment.

JAEA Reports

Measurement of groundwater table in shallow boreholes

Seno, Shoji; Kurikami, Hiroshi; Yabuuchi, Satoshi; Hara, Minoru

JAEA-Research 2006-079, 22 Pages, 2007/03

JAEA-Research-2006-079.pdf:5.57MB

Horonobe Underground Research Laboratory of Japan Atomic Energy Agency has been investigating surface hydrogeological features in and around the Horonobe Underground Research Laboratory (URL) area as a part of Horonobe URL project. The objective of measurement of groundwater tables in shallow boreholes is to understand the distribution of the groundwater table and its seasonal fluctuation that will be boundary conditions of a groundwater flow analysis. This report shows the results of the measurement since December 2003 to October 2005 every few month and discussion on the surface hydrogeological features. The results are as follows: (1) The real watershed between the Shimizu river basin and the Penke-ebekorobetsu river basin exists a little to the south of the geographical watershed among the monitoring line. (2) Snow fall/melting is the largest impact on the annual fluctuation of the groundwater table, while influence of precipitation is temporal. (3) The amplitude of the fluctuation of groundwater table depends on the location. (4) Peak level of groundwater table after precipitation is gentler than that of the river water table and appears two or three days later.

Journal Articles

On the applicability of the hermetic permeability tests by means of a pair of flow pumps to low-permeability rocks

Seno, Shoji*; Toida, Masaru*; Kobayashi, Ichizo*; Tanaka, Mayumi*; Matsui, Hiroya; Kunimaru, Takanori; Kurikami, Hiroshi

Nippon Chikasui Gakkai 2006-Nen Shuki Koenkai Koen Yoshi, p.310 - 315, 2006/10

no abstracts in English

JAEA Reports

Long-term groundwater pressure monitoring in deep boreholes in the Horonobe Underground Research Laboratory Project

Yabuuchi, Satoshi; Kurikami, Hiroshi; Seno, Shoji*; Hara, Minoru; Kunimaru, Takanori; Takeuchi, Ryuji

JAEA-Research 2006-056, 32 Pages, 2006/09

JAEA-Research-2006-056.pdf:1.87MB

Long-term groundwater pressure monitoring has been performed in HDB-1,2,3,6,7 and HDB-8 boreholes in the Horonobe Underground Research Laboratory Project. Groundwater pressure in many levels in the boreholes shows an almost steady state at present, however it is still recovering since the beginning of the observation in some levels. Relatively high groundwater pressure is observed in HDB-2 borehole, about 7km away from the URL area. According to the groundwater pressure monitoring in deep boreholes so far, it is inferred that hydraulic head becomes higher with the increase of the depth and hydraulic head in the east is higher than in the west around the URL area. Through the groundwater monitoring, performance of the long-term groundwater monitoring systems could be examined and some problems of the parts could also be found.

Journal Articles

Hydrogeological model in Horonobe Underground Research Laboratory project

Kurikami, Hiroshi; Kunimaru, Takanori; Yabuuchi, Satoshi; Seno, Shoji; Shimo, Michito*; Kumamoto, So*

Proceedings of 2nd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2006), p.584 - 589, 2006/05

no abstracts in English

JAEA Reports

Estimation of underground water recharge rate in Horonobe nderground Research Laboratory project by water balance method- From August, 2003 to July, 2004 -

Seno, Shoji; Takeuchi, Ryuji; Kurikami, Hiroshi; Hara, Minoru

JNC-TN5400 2005-005, 0 Pages, 2005/08

JNC-TN5400-2005-005.pdf:16.46MB

Horonobe Underground Research Center of Japan Nuclear Cycle Development Institute has been investigating surface hydrogeological features in and around the Horonobe nderground Research Laboratory (URL) area as a part of Horonobe URL project. In order to calculate the recharge rate into the deep underground by the water balance method, monitoring systems of the river flux and meteorological stations have been phased in since 2002.In this report, the annual recharge rates of the P-1, P-2 and P-3 basins that are located in and around the URL area are calculated by using the data from August 2003, when the installation of the monitoring systems had been completed, to July 2004.The result shows that the recharge rates of the P-1, P-2 and P-3 basins are 230 mm/y, -20 mm/y and 340 mm/y, respectively. It means that the P-1 and P-2 basins are recharge areas and the P-3 basin is a discharge area. The average infiltration rate within the three basins is estimated to be 100 mm/y.

JAEA Reports

Groundwater Flow Analysis of Horonobe Underground Research Laboratory Project

Kurikami, Hiroshi; Takeuchi, Ryuji; Seno, Shoji

JNC-TN5400 2005-003, 97 Pages, 2005/07

JNC-TN5400-2005-003.pdf:22.19MB

This report shows the process and the result of the research on the hydrogeological modeling and groundwater flow (GW) analyses of Horonobe Underground Research Laboratory(URL) Project until fiscal year 2004. In the report, Surface-based Investigation (Phase I) of the project was divided into two phases; the investigation phase based on literature review and the borehole investigation phase. In the investigation phase based on literature review, the sensitivity analyses were carried out with the hydrogeological model built based on the considerable information from the literature review. The results showed that the sensitivities of recharge rate and hydraulic conductivity of the surface layer on hydraulic head and those of hydraulic conductivities of both Wakkanai formation and Koetoi formation on GW migration time were high. The results also showed that the GW flow system in and around the URL area was governed by the Shimzu river and Penke-ebekorobetsu river in the shallower zone (local GW flow system) and the Teshio river in the deeper zone (regional GW flow system). "Regional scale" analytical domain was defined based on the results. In the borehole investigation phase, the results of both the in-situ hydraulic tests and the laboratory hydraulic tests were summarized as follows: *The deeper it was, the lower the hydraulic conductivity was in the same layer, especially in Wakkanai formation. *The hydraulic conductivity of the upper layer was lower than that of the lower layer in the same depth. *The distribution of hydraulic conductivity was strongly related to that of fracture zone. The GW flow analyses based on newly developed geological model and the results of the hydraulic tests described above were performed. The GW flow analyses were verified by comparing with the measured hydraulic pressures in the boreholes. Besides, the behavior of saline GW was examined. Furthermore, the excavation of the URL shafts and tunnels was simulated. From the results, ...

Oral presentation

Estimation of the amount of soil erosion using suspended sediment load; An Example in the Horonobe area, northern Hokkaido

Seno, Shoji; Niizato, Tadafumi; Kurikami, Hiroshi; Yasue, Kenichi; Yabuuchi, Satoshi; Hara, Minoru; Kunimaru, Takanori; Nakayama, Masashi; Funaki, Hironori; Yamaguchi, Takehiro

no journal, , 

We should estimate ten-thousand-year stability of geological environment to meet the geological disposal of high level radioactive waste. Especially groundwater flow plays an important role because it might cause migration of nuclides. Since long term transitions of geology and topography may influence hydrogeological conditions such as hydraulic gradient and hydraulic conductivities, estimations of vertical displacement rate and erosion rate are also important. This report discusses the method to estimate an amount of erosion in the future based on suspended sediment concentration in rivers as an example in Horonobe area, northern part of Hokkaido.

Oral presentation

Analysis of long-term pore water pressure data for the sedimentary rock, 1; Seismic response investigation and trend analysis

Nakajima, Makoto*; Seno, Shoji*; Toida, Masaru*; Kunimaru, Takanori

no journal, , 

Horonobe Underground Research Center of Japan Atomic Energy Agency has been conducting long-term observation of the pore water pressure fluctuation as part of the research activities in the Horonobe Underground Research Project. This article reports results of analyses on seismic response and on long-term trend of the observed pore water pressure. Firstly, in the analysis on the seismic response, it was supposed that the response will arise at the time of large magnitude earthquake. Then, in the trend analysis, the trend line obtained after removals of the influences of the fluctuation factors was smoother than the plot line of the source data and clearly remained peculiar changes during events. Further, as the result of comparison of the fluctuation factors, it was supposed that the influence of the earth tide was comparatively little in this site.

Oral presentation

Analysis of long-term pore water pressure data for the sedimentary rock, 2; Analysis using the genetic algorithm method and the neural network method

Seno, Shoji*; Toida, Masaru*; Watanabe, Kunio*; Sohail, A. R.*; Kunimaru, Takanori

no journal, , 

Horonobe Underground Research Center of Japan Atomic Energy Agency has been conducting long-term observation of the pore water pressure fluctuation as part of the research activities in the Horonobe Underground Research Project. The pore water pressures are now monitored at 70 points from 100 to 1,000m in depth of 9 boreholes. In this article, some generic algorithm (GA) method and neural network (BPANN, GAANN) methods were applied to the observed pore water pressure data. The cross-correlations for a single borehole data and for different two boreholes data, or for a pore water pressure data with any other observed data (e.g. earth tide, atmospheric pressure, groundwater level, river water level and flow rates) were investigated and used for the prediction analysis.

Oral presentation

Development of methodlogy for the groundwater monitoring in natural barrier

Tanaka, Mayumi*; Toida, Masaru*; Atsumi, Hiroyuki*; Seno, Shoji*; Nakajima, Makoto*

no journal, , 

Ground penetrating radar with modulating frequency combined with static pressure measurement using hydrotesting tool for damaged zone, which were developed by Kajima coporation, has been applied to the drift of Tono mine for the evaluation of hydraulic characteristics of the damaged zone around the drift.

Oral presentation

Excavation disturbed zone around 140 m horizontal drift in Horonobe URL; Tunnel excavation analysis used MBC model

Sanada, Hiroyuki; Sugita, Yutaka; Kunimaru, Takanori; Iwano, Keita*; Morikawa, Seiji*; Seno, Shoji*; Namikawa, Tadashi*

no journal, , 

no abstracts in English

Oral presentation

Study on measurement of soil moisture content by using the optical fiber pressure sensor

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Hirata, Yoichi*; Kunimaru, Takanori

no journal, , 

no abstracts in English

Oral presentation

Estimating of in-situ hydraulic conductivity related with evaluating of rainfall infiltration behavior in shallow ground

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Tagishi, Hirotaka*; Takenobu, Kazuyoshi*; Kishi, Atsuyasu

no journal, , 

Infiltration rate at the ground surface is one of the essential boundary conditions for a quantitative evaluation of groundwater flow. Conventional method for quantifying infiltration rate based on the water budget, however, includes significant uncertainties resulting from different types of quantities to be measured. In this study, focusing on a method where the infiltration rate is estimated directly from temporal changes in soil water contents in the region of interest, the measurement data was confirmed based on the ${it in-situ}$ unsaturated hydraulic tests. Then, the reliability of the measurement was verified by comparing the ${it in-situ}$ data to the laboratory test results and uncertainties associated with the ${it in-situ}$ measurements were quantified.

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