A STUDY ON ROCK MASS BEHAVIOUR INDUCED BY SHAFT SINKING IN THE HORONOBE UNDERGROUND RESEARCH LABORATORY

幌延深地層研究所におけるショートステップ工法による立坑掘削に伴う岩盤の力学挙動に関する研究

Japan Atomic Energy Agency has been excavating three deep shafts through soft sedimentary rock in the Horonobe Underground Research Laboratory. In this paper, the authors discussed rock mass behavior induced by a 6.5 m diameter shaft sinking. They conducted geological mapping in an excavation face and boreholes dug around the shaft wall, field measurements such as convergence measurements and monitoring of rock displacements using multi-interval borehole extensometers around a shaft at around 160 m and 220 m in depths, and three-dimensional numerical analysis which models the shaft excavation procedure such as timing of installation of support elements and setting and removal of a concrete form. As a result, it was clarified that remarkably large compressive strains occurred within about 1 m into the shaft wall in a radial direction since the rock mass behavior was controlled by the concrete lining and that the behavior would predominantly be induced by the fractures closing which opened significantly and propagated during excavation steps before the installation of a concrete lining and the directions where the strains occurred heavily depended on the fracture orientation around the shaft.　幌延深地層研究所にて新第三紀堆積岩に施工中の立坑（内径6.5m）の深度約160mと220mにて，立坑底盤の岩盤観察，内空変位と地中変位の計測と，立坑の施工手順を再現した三次元解析を実施し，ショートステップ工法による立坑周辺岩盤の力学挙動を分析した．その結果，同工法の施工手順は，ほぼ無普請で3m掘削した後に，厚さ400mmの覆工コンクリートを構築するため，掘削に伴う岩盤の内空側への変形は覆工コンクリートにより顕著に抑制され，壁面から半径方向に概ね1mの岩盤に圧縮ひずみが生じること，また，その最大圧縮ひずみの方向と岩盤の割れ目の方向性の関係から，そのひずみは覆工コンクリートを構築するまでの掘削により，一度開口・伸展した割れ目が覆工コンクリートの構築により再び閉口するために生じることを論述した．

• Record URL:
  https://doi.org/10.2208/jscejte.68.40
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=A+STUDY+ON+ROCK+MASS+BEHAVIOUR+INDUCED+BY+SHAFT+SINKING+IN+THE+HORONOBE+UNDERGROUND+RESEARCH+LABORATORY&author=K.+TSUSAKA&author=T.+TOKIWA&author=D.+INAGAKI&author=Y.+HATSUYAMA&author=M.+KOIKE&author=Y.+IJIRI&publication_year=2012
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/21856575
• Authors:
  • TSUSAKA, Kimikazu
  • TOKIWA, Tetsuya
  • INAGAKI, Daisuke
  • HATSUYAMA, Yoshihiro
  • KOIKE, Masashi
  • IJIRI, Yuji
• Publication Date: 2012

Language

• English
• Japanese

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 40-54
• Serial:
  • Journal of Japan Society of Civil Engineers, Ser. F1 (Tunnel Engineering)
  • Volume: 68
  • Issue Number: 2
  • Publisher: Japan Society of Civil Engineers
  • ISSN: 2185-6575
  • Serial URL: https://www.jstage.jst.go.jp/browse/jscejte/-char/en

Subject/Index Terms

• TRT Terms: Boreholes; Excavation and tunneling; Extensometers; Fracture mechanics; Rock mechanics; Shaft sinking; Underground structures
• Subject Areas: Bridges and other structures; Construction; Geotechnology; Highways; I43: Rock Mechanics; I54: Construction of Tunnels;

Filing Info

• Accession Number: 01504797
• Record Type: Publication
• Source Agency: Japan Science and Technology Agency (JST)
• Files: TRIS, JSTAGE
• Created Date: Jan 27 2014 9:40AM