Tunnel support design for anisotropic stress state and comparison between in-situ convergence results and calculated results

Motoshima, Takayuki*; Yabuki, Yoshio*; Minamide, Masashi*; Nago, Makito*; Aoyagi, Kazuhei

Tonneru Kogaku Hokokushu (CD-ROM), 24, p.I_10_1 - I_10_5, 2014/12

http://ci.nii.ac.jp/naid/40020361441

Economic tunnel support design for Horonobe underground research laboratory was obtained according to the relationship in the direction of the initial stress and the direction of excavation. The authors compared between the in situ convergence results and calculated results in order to investigate the validity of initial stress measurements. As a result, a positive correlation was observed between the in situ convergence results and calculated results, and the difference between the two was able to be explained by the difference between the assumed deformation coefficient and the measured coefficient. From these results, the measurement results of the initial stress performed in the surface based investigation has been confirmed almost reasonable.

Study on construction technology for repository

Tanai, Kenji; Iwasa, Kengo; Hasegawa, Hiroshi; Miura, K.*; Okutsu, Kazuo*; Kobayashi, Masaaki*

JNC TN8400 99-046, 177 Pages, 1999/11

JNC-TN8400-99-046.pdf:6.03MB

For the construction of underground facilities comprising access tunnels, connecting tunnels, main tunnels and disposal tunnels, a large number of tunnels will be excavated in deep rock formations. These excavations will extend hundreds kilometers in total length. Therefore, special attention must be paid, to transporting large volume of debris, ventilation, emergency escape routes in case of accident, and other factors. In addition, special attention must also paid to potential accidents which might in underground excavations, including unstable facing phenomena (such as collapse and swelling of facing at weak layer sections), spring water flow resulting collapse of rock, gas eruption, and rock burst. While considering these factors to be emphasized during the construction of geological disposal facilities, the investigation reviewed the existing working methods on individual construction technologies of access tunnels, main tunnels, connecting tunnels, disposal tunnels, and disposal pit, based on the recognition that the present state deals with a wide range of geological environments, and conducted investigation about the construction methods for each tunnel on the basis current technologies, and described the outline of these methods. Furthermore, for the items to be particulaly emphasized on site characterization koko and siting data such as ground pressure and spring water, the investigation reviewed the current countermeasure works, and made survey on the phenomena appeared during actual tunnel construction works and their countermeasres, and carried out a study on effectiveness of these countermeasures. This constructing of disposal site in deep geological formations is basically possible by applying, or confirming, current excavation technologies for tunnels and underground facilities, A systematic construction system combines separate technologies relating to construction, (excavation technology, tunnel support work method, etc.). Such systems ...

Evaluation of long-term mechanical stability of near field

Takachi, Kazuhiko; Sugino, Hiroyuki

JNC TN8400 99-043, 52 Pages, 1999/11

JNC-TN8400-99-043.pdf:5.2MB

In the near field, as tunnels and pits are excavated, a redistribution of stresses in the surrounding rock will occur. For a long period of time after the emplacement of waste packages various events will take place, such as the swelling of the buffer, sinking of the overpack under its own weight, deformation arising from expansion of overpack corrosion products and the creep deformation of the rock mass. The evaluation of what effects these changes in the stress-state will have on the buffer and rock mass is a major issue from the viewpoint of safety assessment. Therefore, rock creep analysis, overpack corrosion expansion analysis and overpack sinking analysis have been made in order to examine the longterm mechanical stability of the near field and the interaction of various events that may affect the stability of the near field over a long period of time. As the results, rock creep behavior, the variations of the stress-state and the range of the influence zone differ from the rock strength, strength of buffer in the tunnel and side pressure coefficient etc. about the hard rock system and soft rock system established as basic cases. And the magnitude of the stress variations for buffer by the overpack sinking and rock creep deformation is negligible compared with it by the overpack corrosion expansion. Furthermore, though very limited zone of buffer around the overpack is close to the critical state by the overpack corrosion expansion, the engineered barrier system attains a comparatively stable state for a long period of time.

None

JNC TJ1400 99-038, 83 Pages, 1999/02

JNC-TJ1400-99-038.pdf:4.96MB

no abstracts in English

Measurement of secondary stress around excavation by the stress release method

Itamoto, Masaharu*; Tanaka, Masahiro*; Tanno, Takeo*

PNC TJ7592 98-001, 166 Pages, 1998/03

PNC-TJ7592-98-001.pdf:8.43MB

None

None

Toki, Shosuke*; Miura, Kinya*; *

PNC TJ1600 97-005, 37 Pages, 1997/03

PNC-TJ1600-97-005.pdf:2.18MB

None

Investigation of the excavation disturbed zone due to the excavation of galleries; Study in the Horonobe Underground Research Laboratory

Kubota, Kenji*; Morifuji, Yohei*; Aoyagi, Kazuhei; Sugita, Yutaka

no journal, , 

We performed in-situ experiments such as seismic and electrical resistivity tomography, geological survey and so on before, during, and 11 years after excavation of galleries at 140 and 250 m depth in an area of soft sedimentary rock in the Horonobe Underground Research Laboratory, Hokkaido, Japan. The results demonstrate that the extent of fractures and unsaturated zone induced by the gallery excavation were clarified. The extent of fractures related with EDZ was limited in about 0.45 m from the gallery wall in the 140 m gallery and to about 1 m from the gallery wall in the 250 m gallery. The extent of the unsaturated zone related with EdZ was about 1 m in the 140 m gallery, but it was not appeared in the 250 m gallery. Such changes induced by the gallery excavation occurred within one year after gallery excavation. On the other hand, the extension of the developed fractures and unsaturated zone was hardly clarified in about 11 years after gallery excavation.