土かぶり1．7mの国道交差点直下をハーモニカエ法でアンダーパス:国道1号　原宿交差点立体工事

摘要

The Harajuku Intersection is the point where Route No.l crosses with the Yokohama City Ring Road No. 4located in Totsuka-ku, Yokohama City, Kanagawa Prefecture. The intersection had a many traffic of approximately 100,000 vehicles a day. It was the worst traffic jam hotspot in the refecture and congestion cost on the intersection was estimated at approximately 10 billion yen a year. This grade separation works were planned for eliminating traffic congestion (Route No.l to become underpass). This report gives information on the construction under the difficult condition that the works was executed using Harmonica Method under small cover, in urban area and near existing structures.%神奈川県横浜市戸塚区に位置する国道1号原宿交差点は，横浜市道環状4号と交差し，1日あたり約10万台の交通が利用する慢性的な渋滞交差点であり，県内渋滞ワースト1，その渋滞損失額は年間約100億円を計上する．原宿交差点立体工事は渋滞交差点を立体化（国道1号を地下へ）し，交通混雑を解消し，円滑な交通を確保することを目的に計画された．本稿では非開削工法として新技術であるハーモニカ工法を採用し，小土かぶり，都市内施工，近接施工といったきわめて難しい条件下における施工事例を報告する．