Support design and construction results for general parts and intersections of deep shafts

立坑一般部および水平坑道との連接部の支保設計と施工結果

長田 翔平*; 市田 雄行*; 藤枝 大吾; 青柳 和平  

Nagata, Shohei*; Ichida, Toshiyuki*; Fujieda, Daigo; Aoyagi, Kazuhei

幌延深地層研究センターの深度500mまでの立坑掘削に先立ち、支保パターン選定のために、覆工コンクリートの強度や厚さ、打設長をさまざまに設定した三次元逐次掘削解析を行い、コンクリートに作用する応力状態を評価した。この結果に基づき、支保パターンを選定し、立坑の掘削を開始した。掘削中のコンクリートに作用する応力の実際の計測結果も参照しながら、東立坑の深度500mまでの掘削を完了させることができた。また、事前の解析や実際のコンクリートに作用する応力の計測結果を踏まえて、適切な支保パターンを選定できることを実証できた。この成果は、立坑掘削を対象とした情報化施工手法の信頼性向上に資するものとなる。

We performed three-dimensional excavation analysis of three shafts and intersection of horizontal tunnel excavated to 500 m depth at Horonobe URL, and evaluated stress acting on concrete lining under various conditions such as differences in diameter of shafts, lining shape, lining thickness, concrete strength, and installation interval of the lining. The design of the support was determined based on the analysis results, and then the construction of the shafts and horizontal galleries were started. Considering the measured stress acting on the concrete lining of the shaft and sprayed mortar installed at the intersection of shaft and horizontal gallery, we could successfully excavate the shaft to 500 m depth and intersection of horizontal gallery at 420 m depth. We also concluded that appropriate support pattern can be selected based on the measured stress acting on the concrete lining and numerical analysis performed prior to the excavation. This can contribute to enhance the reliability of the appropriate observational construction technology targeting excavation of shaft.