土石流危険渓流交差部を明かり巻きトンネルで施工: 九州新幹線　筑紫トンネル（梶原工区）

摘要

九州新幹線鹿児島ルートは，福岡市から鹿児島 市を結ぶ延長257kmの新幹線鉄道路線である． このうち，新八代・鹿児島中央問（延長128km） は平成16年3月に開業した．一方，博多・新八代 間（工事延長121km）は平成22年度末の完成に向 け鋭意施工中である（図-1）．筑紫トンネルは，福 岡県と佐賀県の県境である福岡県那珂川町内～佐 賀県鳥栖市内に位置する九州の陸上トンネルでは 最長となる延長11,935mのトンネルである（図-2）．%The Kyushu Shinkansen Chikushi Tunnel is located on the prefectural border between Nakagawa Machi, Fukuoka Prefecture and Tosu City, Saga Prefecture and is the longest land tunnel in Kyushu at 11,935m. 150 -180 m from the starting point is a point that crosses the Shinkansen tracks and the Kajihara River, river bed height is at almost the same height as tracks height. In the earlier planning, the embankment structure for the main track and a box culvert in the bank for the river in order for flow to be directed to the bottom part of the rails is planned. However, after this, according to research, it was established that the upper stream of site was a dangerous stream of debris flow and, in order to ensure the safety of the Shinkansen, an erosion control dam was constructed on the downstream side of the site as a debris flow control countermeasure, Shinkansen passes under the sediment storage area of the dam, that is stream water and debris flow pass over the tunnel. This report gives information on the selection of river down-flow methods for Shinkansen construction and design and construction of the tunnel.