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Journal Articles

Mechanical characteristics of rock segment for reducing amount of cement use and stability of drift tunnel

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Fujita, Tomoo; Sugita, Yutaka; Nakama, Shigeo; Sanada, Masanori*

Doboku Gakkai Rombunshu, F2 (Chika Kukan Kenkyu) (Internet), 73(1), p.11 - 28, 2017/03

This study examined the mechanical characteristics of rock segments and backfill materials and analyzed the stability of the drift that is supported by the rock segments and gravel backfill. The results confirmed the technical aspects of the formation of the rock segments and the effectiveness of the planned efforts to further reduce the amount of cement used.

JAEA Reports

Three-dimensional stress analysis of reflooding tunnel during submerging process using crack tensor model at Mizunami Underground Research Laboratory

Ozaki, Yusuke; Matsui, Hiroya; Kuwabara, Kazumichi; Tada, Hiroyuki*; Sakurai, Hideyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; Kobayashi, Shinji*

JAEA-Research 2016-007, 125 Pages, 2016/06

JAEA-Research-2016-007.pdf:34.66MB

In Mizunami Underground Research Laboratory (MIU), the stress analysis of fractured rock have been performed with crack tensor model. In MIU, a reflooding test is performed at 500m stage. In this study, stress analysis of rock during submerging process of the tunnel is performed by using crack tensor model. The deformation of the rock under different water levels in the tunnel is simulated. The stress condition by high pressure due to inflow of groundwater into tunnel is also estimated. These simulation are performed under assumption that groundwater does not permeate into rock for the estimation of maximum pressure acting on the rock. The stress analysis with consideration of permeation of groundwater into rock is also conducted for the estimation of stress condition after the diffusion of water pressure in tunnel. The results of these analyses lead the conclusion that the pressure of the rock reaches the groundwater pressure near the face of tunnel when the tunnel is submerged.

JAEA Reports

Three-dimensional excavation analysis based on crack tensor model at the Mizunami Underground Research Laboratory

Takayama, Yusuke; Sato, Toshinori; Sanada, Hiroyuki; Tada, Hiroyuki*; Kumasaka, Hiroo*; Fukuda, Tsuyoshi*; Kobayashi, Shinji*

JAEA-Research 2015-003, 102 Pages, 2015/07

JAEA-Research-2015-003.pdf:20.21MB

In the rock mechanical study in the Mizunami Underground Research Laboratory Project, the development of the evaluation method for the excavation damaged zone due to excavation of shafts and research galleries is one of the important issues. In this study, three-dimensional excavation analysis is conducted. Crack tensor used in these analysis were measured using the data collected in wall surface observation in study tunnels such as the horizontal tunnels to a depth of 500 m. The results of analysis were compared with existing measurements at a depth of 500 m obtained using in-situ strain meters. The excavation analysis using crack tensor and initial stress obtained from the Phase I and Phase II were carried out to examine the influence of crack tensor and initial stress on the results of analysis.

JAEA Reports

A Study on the method of an equivalent continuous body modelling using crack tensor theory in the Mizunami Underground Research Laboratory Project

Sanada, Hiroyuki; Sato, Toshinori; Tanno, Takeo*; Hikima, Ryoichi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Ishii, Takashi*; Sakurai, Hideyuki*

JAEA-Research 2014-006, 124 Pages, 2014/06

JAEA-Research-2014-006.pdf:11.26MB

Japan Atomic Energy Agency has been implementing the Mizunami Underground Research Laboratory (MIU) Project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques to construct a deep underground laboratory in crystalline rock. In the rock mechanical study in the MIU Project, the development of the evaluation method for the excavation damaged zone due to excavation of shafts and research galleries is one of the important issues. In this report, crack tensor was calculated using the tunnel wall mapping and rock mechanical test results in the shaft and research galleries in the MIU. Two dimension excavation analysis was conducted at the Ventilation Shaft and GL -500 m Sub Stage using the calculated crack tensor at GL -500 m. Based on calculated crack tensor at GL 500 m, validation of the crack tensor at GL -500 m estimated during Phase I was verified. Relative error of crack tensor was calculated in order to examine variation of relative error to the scale of observation areas.

Journal Articles

Excavation analysis using crack tensor theory at the Mizunami Underground Research Laboratory, Japan

Sanada, Hiroyuki; Hikima, Ryoichi; Tanno, Takeo; Sato, Toshinori; Goke, Mitsuo*; Tada, Hiroyuki*; Kumasaka, Hiroo*

Proceedings of ITA-AITES World Tunnel Congress 2013 (WTC 2013)/39th General Assembly, p.855 - 860, 2013/05

Japan Atomic Energy Agency (JAEA) has been implementing the Mizunami Underground Research Laboratory (MIU) Project for the R&D of geological disposal of High-level Radioactive Waste (HLW) in granite. The MIU Project has been divided into three overlapping phases: Surface-based Investigation Phase (Phase I), Construction Phase (Phase II), and Operation Phase (Phase III). In this paper, FEM analysis using crack tensor theory at the MIU was carried out in order to estimate deformation around the horizontal tunnel for investigations and construction during Phase III, and to confirm the validity of FEM analysis results including parameter settings using fracture information from the vertical borehole drilled during Phase I. The relationship between statistical observations on tunnel walls and pilot boreholes was used to estimate the crack tensor for the investigated area. FEM analysis in this work described the increase of stress in concrete liners due to decrease of Young's Modulus compared to Phase I. Since investigations during Phase II could effectively detected high angle fractures, which couldn't be satisfactorily detected during Phase I, the crack tensor was improved using the Phase II results. Predictions and applicability of the analysis method are to be confirmed with in situ experiments during Phase III.

Journal Articles

Development of rock segment for reduction of amount of cement use

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Sanada, Masanori; Noguchi, Akira*; Kishi, Hirokazu*; Nakama, Shigeo; Fujita, Tomoo

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.133 - 138, 2013/01

The authors have been developing methods for constructing tunnels using the minimum quantities of cement-type support materials in high-level radioactive waste disposal facilities and advancing research and development about the technical formation of rock segment using low alkaline mortar. In this study, the mechanical characteristic values concerning the rock segment and backfill materials were examined. The stability analysis of tunnel supported by the rock segment and backfilling with gravel were performed. Technical formation and effectiveness of the alternative supports planned for further reduction in cement influence was confirmed from a study result above-mentioned.

Journal Articles

Fundamental study on REV based on crack tensor at the Mizunami Underground Research Laboratory

Tanno, Takeo; Sato, Toshinori; Sanada, Hiroyuki; Hikima, Ryoichi; Kumasaka, Hiroo*; Tada, Hiroyuki*

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.109 - 113, 2013/01

The crack tensor model which is a kind of equivalent continuum model has been studied in rock mechanical investigation in the MIU. The fractured rock mass is modeled as the elastic continuum model with this crack tensor. In this study, this crack tensor based on the geological observation in the MIU project was calculated, and REV (Representative Elementary Volume) in the ventilation shaft and -300m access/research gallery was studied based on the relative error of this crack tensor. As a result, the convergence of the relative error was faster in the -300m access/research gallery than in the ventilation shaft.

JAEA Reports

Study on equivalent continuum modeling with crack tensor on crystalline rock

Tanno, Takeo; Sato, Toshinori; Sanada, Hiroyuki; Hikima, Ryoichi; Matsui, Hiroya; Tada, Hiroyuki*; Goke, Mitsuo*; Kumasaka, Hiroo*; Ishii, Takashi*

JAEA-Research 2012-002, 86 Pages, 2012/03

JAEA-Research-2012-002.pdf:8.48MB

The Crack tensor model which is a kind of equivalent continuum model has been studied in rock mechanical investigation in the MIU. The fractured rock mass is modeled as the elastic continuum model with the crack tensor. In this study, crack tensor based on the geological observation in the MIU project was calculated, and REV (Representative Elementary Volume) in the shafts and research galleries was studied based on the relative error of the crack tensor. The correlation between the crack density, the trace length of crack and the trace of crack tensor and the rock mass classification was also studied.

Journal Articles

Study on an equivalent continuum model at the Mizunami Underground Research Laboratory

Tanno, Takeo; Sato, Toshinori; Matsui, Hiroya; Sanada, Hiroyuki; Kumasaka, Hiroo*; Tada, Hiroyuki*

Dai-41-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.185 - 190, 2012/01

The Japan Atomic Energy Agency (JAEA) is conducting the MIzunami Underground research laboratory (MIU) project in order to develop comprehensive geological investigation and engineering techniques for deep underground applications (e.g. geological disposal of HLW). This modelling study has a two-fold objective, to contribute to the evaluation of the mechanical stability of shaft and research drifts, and to plan the future studies. A crack tensor model, a method of an equivalent continuum model, has been studied at the MIU. In this study, the relationship between the estimated crack tensor parameters and the rock mass classification was revealed.

JAEA Reports

A Study on the technology for reducing cement-type materials used for tunnel supports at high-level radioactive waste disposal sites (Joint research)

Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Kabayashi, Yasushi*; Nakama, Shigeo; Fujita, Tomoo; Naito, Morimasa; Tada, Hiroyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; et al.

JAEA-Research 2010-057, 101 Pages, 2011/03

JAEA-Research-2010-057.pdf:7.47MB

Cement-type materials that are used for supports or grouting at high-level radioactive waste disposal facilities leach into the groundwater and create a highly alkaline environment. Of concern in highly alkaline environments are the alteration of bentonite used as buffers or backfill materials, and of surrounding rock mass, and the increased uncertainty regarding the provision of performance of the disposal system over a long period of time. In this study, to reduce the quantity of cement-type materials that cause highly alkaline environments, technical feasibility of the support structure including the materials which considered the long-term performance of the HLW disposal system are discussed by using knowledge and technology accumulated in JAEA and Shimizu Construction. Moreover, based on the results, the problems remained in the application to the future HLW disposal institution are summarized.

JAEA Reports

Estimation of crack tensor for evaluating excavation disturbance of research gallery at the Mizunami Underground Research Laboratory

Matsui, Hiroya; Tanno, Takeo; Hirano, Toru*; Goke, Mitsuo*; Kumasaka, Hiroo*; Tada, Hiroyuki*; Ishii, Takashi*

JAEA-Research 2010-043, 87 Pages, 2010/12

JAEA-Research-2010-043.pdf:3.99MB

The results are as follows (1) For the ventilation shaft at GL-350m, the crack tensor deformation analysis based on FY2004 work's results showed the calculated displacement was smaller than the measured displacement. A geometrical parameters of fractures in FY2004 work's result was different from one based on geological observation in the shaft. Therefore, the crack tensor of FY2004 work's results seems to be underestimated. (2) Large discontinuities with NE strike and high dipping observed in a shaft were major reason for the difference of crack tensors determined by borehole investigation from surface and geological observations in a shaft. Therefore, the crack tensor for pilot borehole investigation in a shaft was calculated as well and compared with each results. It was found that the fabric tensor is similar with it of geological observation and the vale was medium. (3) The crack tensor around GL-500m was estimated by relation of statistical quantities for fractures between GL-300m and GL-500m. Consequently, the deformation analysis based on the estimated crack tensor showed an increase in convergence and stress in the support system compared to FY2004 work's results.

JAEA Reports

Excavation disturbance analysis based on Crack Tensor Model and Virtual Fracture Model for predicting the rock mass behavior during excavation of shafts and research galleries at the Mizunami Underground Research Laboratory

Seno, Yasuhiro; Nakama, Shigeo; Sato, Toshinori*; Goke, Mitsuo*; Tada, Hiroyuki*; Sakurai, Hideyuki*

JAEA-Research 2007-081, 120 Pages, 2008/01

JAEA-Research-2007-081.pdf:13.48MB

A 3D Crack Tensor Model analysis was carried out to predict the rock mass behavior of the complex (articulated) section at -500 m. Properties were chosen based on the Rock Mechanics Model constructed in the Surface-based Investigation Phase (Phase I). The Virtual Fracture Model was applied to analyze the change the hydraulic conductivity.

Journal Articles

Excavation disturbance analysis in consideration of excavation damaged zone for research drift of Mizunami Underground Research Laboratory

Goke, Mitsuo*; Tada, Hiroyuki*; Seno, Yasuhiro; Nakama, Shigeo; Sato, Toshinori

Tonneru Kogaku Rombunshu, 16, p.35 - 45, 2006/11

no abstracts in English

Journal Articles

Japanese underground research laboratory project and prediction of rock mass behavior around deep shafts and galleries using continuous and discontinuous models

Sato, Toshinori; Mikake, Shinichiro; Nakama, Shigeo; Seno, Yasuhiro; Mori, Takayuki*; Iwano, Keita*; Goke, Mitsuo*; Tada, Hiroyuki*

Proceedings of 7th International Conference on Analysis of Discontinuous Deformations (ICADD-7) (CD-ROM), p.245 - 256, 2005/12

Two one-thousand meter deep shafts and research galleries at several levels will be excavated in granite for the Mizunami Underground Research Laboratory (MIU) project. Research on the deep geological environment in this project will provide the basis for Research and Development on geological disposal of high-level radioactive waste. The site of MIU project is located in Mizunami, Gifu, in the central part of the main island of Japan. By July 2003, entrances to the shafts were constructed, and excavation of lower part of shaft entrance was started in March 2004. Current status (September 2005) of construction is excavation of the shafts to a depth of 150 m has been done. Mechanical investigations including hydraulic fracturing test and laboratory tests on core samples were performed, and numerical analysis using continuous model and discontinuous model; MBC (Micro-mechanics based continuum model), Crack tensor model and FRACOD (fracture propagation code), were also performed to predict mechanical stability of openings and support systems, and rock mass behavior around openings. In this analysis EDZ (Excavation Damaged Zone) due to blasting and excavation step were considered in same cases. This paper describes the current status of Mizunami Underground Research Laboratory for crystalline rock and the results of prediction for rock mass behavior around the deep underground openings using some analytical methods. Measurements during shaft sinking and future plan of investigations in the URL are also describes in this paper.

JAEA Reports

Drift excavation analysis based on crack tensor model and virtual fracture model in consideration of excavation damaged zone

Goke, Mitsuo*; Horita, Masakuni*; Tada, Hiroyuki*

JNC TJ7400 2004-007, 102 Pages, 2004/02

JNC-TJ7400-2004-007.pdf:4.85MB

Tono Geoscience Center (TGC), Japan Nuclear Cycle Development Institute (JNC) conducts the Mizunami Underground Research Laboratory (MIU) project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques in the deep underground application. The purposes of this work were to contribute to the rock mechanical modeling for MIU project. We proposed an analytical method of modeling of excavation damaged zone. The crack tensor analytical model was applied to analyze the rock stress in consideration of the existence of excavation damaged zone as a research drift and a shaft were excavated. The virtual fracture model was applied to the hydraulic conductivity change analysis.The results are as follows:1) As compared with analytical result without excavation damaged zone, the crack tensor stress analysis in consideration of excavation damaged zone showed that the convergence of a shaft and a drift increased and the maximum value of principal stress decreased, while the safety factor distribution was almost changeless.2) As compared with analytical result without excavation damaged zone, the hydraulic conductivity change analysis in consideration of excavation damaged zone showed the maximum increase rate of hydraulic conductivity increased remarkably.3) As the stiffness decreased in excavation damaged zone, the convergence of a shaft and a drift increased, the maximum value of principal stress decreased, and the maximum increase rate of hydraulic conductivity increased. Especially, in analytical case supposed that new cracks parallel to perimeter of a drift broke out in excavation damaged zone, the maximum increase rate of hydraulic conductivity was up to 5000 times.4) As the stiffness of rock mass decreased by taking into the existence of excavation damaged zone, the convergence reduction effect increased, and the stress in support parts increased.

JAEA Reports

Hydraulic Conductivity Change Analysis of Surrounding Rock Mass in Excavating Research Drift

Goke, Mitsuo*; Tada, Hiroyuki*; Horita, Masakuni*; Wakabayashi, Naruki*

JNC TJ7400 2003-003, 93 Pages, 2003/02

JNC-TJ7400-2003-003.pdf:5.87MB

Tono Geoscience Center (TGC), Japan Nuclear Cycle Development Institute (JNC) conducts the Mizunami Undergroud Research Laboratory (MIU) project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques in the deep underground application. The purposes of this study were to contribute to the construction of rock mechanical modeling for MIU project. The virtual fracture model based on mechanical property on the Toki granite was applied to the 2-D hydraulic conductivity change analysis in excavating a research drift and a shaft. The crack tensor analysis model was introduced to the stress analysis before the hydraulic conductivity change analysis. The results are as follows: (1) The crack tensor stress analysis showed very small displacement on the perimeter of a shaft and a drift in intact rock mass, while large displacement appeared in fault zone. (2) More than 10 times large hydraulic conductivity from the initial one appeared in the extent of 1m from the perimeter of a drift and a shaft, in the hydraulic conductivity change analysis with the virtual fracture model for the intact rock mass. The maximum increase of hydraulic conductivity was up to 100 times from initial one. The fault zone showed more than 10 times larger hydraulic conductivity in the extent of 4m from the perimeter. (3) The extent of hydraulic conductivity change was affected by the direction of a drift due to the direction of fractures and the initial stress condition. For example, the rate of hydraulic conductivity increased from initial one changed 110 times to 670 times with the direction of a drift, at the side wall of a drift at the depth of 945m. (4) There was no clear effect to reduce the displacement by supports in the drift in intact rock mass.

Oral presentation

Development of construction method for a drift minimizing use of cementious material, 7; Experimental study on the rock mortar composite material based on low alkaline cement

Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Kobayashi, Yasushi

no journal, , 

no abstracts in English

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 8; The Bending test of the rock segment using low alkaline mortar

Saito, Akira*; Goke, Mitsuo*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are supposing a low cement use tunner support made for granite rock block connecting low alkaline cement applying to HLW repositories. Because of the bending moment of the segment by dead load and the variance of the earth pressure, We made a model segment bending experiment to get a mechanical properties. The maximum load of the positive bending moment is around 210kN, which is around twice of the dead load of 117kN. The other hand, the maximum load in the negative bending moment is around 44kN, as same as the dead load. As the result of observating the cracks of the model segment, We found three or four cracks along the surface of the boundary of the rock block and mortar in the positive bending experiment. The other hand, we found only one crack at the center avoiding rock block in the negative bending experiment. Next, we will improve the construction method, prevention of the crack in the segment and the exfoliation of mortar and the steel panel.

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 9; Test of a deformation of macadam and stability of drift tunnel

Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are proposing to use the rock segment reducing the amount of the cementutious materials. In this report, we are getting young's modulus and poisson's ratio from the deformation experiment of the macadam mass, and performed a stability analysis of the gallery filled with macadam between the hostrock and the rock segment. We performed a alternating bearing test with high confirming pressure, and we estimated the Young's modulus and the poisson's ratio of the mass macadam from the result of the bearing test. After that, we performed the stability analysis of the galleries in the condition of the JAEA second report with the rock segment and the macadam. We found that the strain at the surface of the host rock is smaller than that of conventional one, and the stability of the host rock is remained, and the compressive stress in the rock segment is the half of the compressive strength of it. We considered that the rock segment support system is stable enough for the supporting system.

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 10; Study on bending properties of the rock segment using low alkaline mortar

Tada, Hiroyuki*; Saito, Akira*; Nakaya, Atsushi*; Kumasaka, Hiroo*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

Bending test of the segmental rings consist of staggered pieces of rocks bonded by low-pH mortar is conducted in order to identify the mechanical properties of rock segmental rings comparing with parallel arrangement. As a result, it was found that the maximum load was reached at 130 to 210 kN in the positive bending tests for staggered rock blocks, lower than 210 to 270 kN for rock blocks arranged in parallel. In the negative bending tests, on the other hand, the maximum load was reached at 30 to 40 kN, lower than a maximum load of 40 kN for the rock blocks arranged in parallel. The results thus varied. Cracks occurred along the interface between the rock block and mortar in the specimen for the blocks arranged in parallel. For the staggered rock blocks, cracks penetrated through the mortar and the rock block near the point of loading in the specimen. Thus, it was confirmed that cracking occurred in different manners.

26 (Records 1-20 displayed on this page)