情報化施工による大深度立坑掘削の中間評価; 幌延深地層研究計画地下研究施設整備(第II期)事業

Evaluation of deep shaft excavation with computerized construction; Horonobe Underground Research Laboratory, Underground Research Facilities Project (2nd Period)

藤田 朝雄 ; 青柳 和平  ; 名合 牧人*

Fujita, Tomoo; Aoyagi, Kazuhei; Nago, Makito*

日本原子力研究開発機構は、幌延深地層研究計画を実施しており、北海道天塩郡幌延町において、立坑と研究坑道の建設を行っている。本報告では、幌延深地層研究センターの立坑掘削時の情報化施工手法の検討について取りまとめた。特に、換気立坑掘削時の壁面周辺岩盤の崩落の進展により覆工コンクリートにクラックが発生した事象をうけて、立坑掘削時の岩盤の崩落現象とその対策や、崩落の進展に応じた支保選定のフローを構築し、後続の立坑掘削へ反映させた。また、立坑掘削時に問題となる湧水への対策工として実施した断層部へのプレグラウト工の施工について述べ、その効果について論じた。

The Japan Atomic Energy Agency (a National Research and Development Agency) is constructing shafts and research tunnels in Horonobe-cho, Teshio-gun, Hokkaido as part of the Horonobe Underground Research Project. This report summarizes investigations into computerized construction while excavating the shaft for the Horonobe Underground Research Centre. Cracking in the lining concrete occurred due to the development of rock spalling near the wall surface while excavating the ventilation shaft. To that end, we created a flowchart to select kinds of shaft supports for use in subsequent works that took steps appropriate for the bedrock collapse phenomenon during excavating, countermeasures for this and extent of spalling. In addition, this report contains information on pre-grouting works on the fault zone and its results which were conducted as a measure against groundwater inflow which can be a problem during excavating works and also the results of these works.