初期掘進区間の重要構造物直下1D以下を大断面シールドで施工: 阪神高速大和川線大和川シールド

摘要

The Shield TBM for Yamatogawa line started on 30th March, 2012 and the beginning propulsion of 154 m was completed successfully after three months. During the beginning propulsion, we had to cross directly under two important structures consecutively, the Nankai Koya Line and the Ryohoku sluice-gate, with small cover of from O.6D to 1.0D (7 -12 m). Before driving into the zone of influence on the important structures, preliminary measurements were implemented on two section and we repeated to establish and verify shield excavation management. Despite driving under small cover and through Uemachi Fault, Excavation and measurement management led to deformation caused by shield driving satisfied criteria of each structure and excavation safe. This report gives information on excavation and measurement management in beginning propulsion.%本工事は，平成24年3月30日に掘進を開始し，3か月を経て，約154mの初期掘進を無事完了した.初期掘進では， 発進直後，南海高野線および陵北樋門と連続した2つの重要構造物の直下を0.6~1.05( 7 ~12m)の小土かぶりで横断 する.そこで，重要構造物の影響範囲に入る手前に，2断面のトライアル計測を実施し，シールド掘進管理の確立·検 証を重ねた.計測管理の結果，発進直後の小土かぶり施工および上町断層区間にもかかわらず，シールド掘進による地 盤変伏は各構造物の管理値を十分に満足し，安全な掘進管理を行うことができた. 本稿では，初期掘進ェの掘進管理および計測管理について報告するものである.