複雑な水文地質構造と周辺水利用に配慮したウォータータイトトンネルの構築: 旭川十勝道路　北の峰トンネル

摘要

The Kitanomine Tunnel(L = 2,928m) along the Asahikawa-Tokachi Road, construction of which began in 2009, was opened in November 2018. The area surrounding the tunnel features vast forests and abundant water resources, and atunnel construction with a watertight structure was carried out taking into consideration the impact on the surrounding hydrological environment. Particularly with the water sealing injection using ultrafine cement and so, examination of tunnel supports using soil-water coupled elasto-plasticity analysis, excavation management based on the three-dimensional seepage analysis results and secondary lining works devised with various methods such as a water barrier and repair system, a watertight tunnel was able to be constructed safely and assuredly under complex geological and groundwater conditions composed of alluvial fan sediment at volcanic foot and welded tuff accompanied by active faults.From the groundwater measurement results continuously carried out after the excavation, the expected recovery conditions were confirmed.%旭川十勝道路は，旭川市から占冠村を結ぶ延長約120kmの地域高規格道路として計画されており，北海道縦貫自動車道および北海道横断自動車道と接続することで，北海道における広域交流ネットワークを形成し，当該地域の交通円滑化，地域間連携や広域的な人流•物流の活性化に寄与する路線である.