TUNNEL EXCAVATION DEVICE AND TUNNEL EXCAVATION METHOD

PROBLEM TO BE SOLVED: To provide a tunnel excavation device, which excavates the foundation into a toric shape that is adequate for a shield tunneling method.SOLUTION: A tunnel excavation device 1 has an excavation device body 2 and an excavation mechanism 4 that is installed on a tip of the excavation device body 2 and rotated with respect to the excavation device body 2. The tunnel excavation device excavates the foundation into a toric shape. The excavation mechanism 4 comprises: a cylindrical outer frame 24; a cylindrical inner frame 26, which is installed coaxially with the outer frame 24; a radial direction frame 28, which links the inner frame 26 and the outer frame 24 and extends in a radial direction; and an excavation bit 30, which is installed on apical surfaces of the outer frame 24, the inner frame 26 and the radial direction frame 28. An edge on an inner rear part in the radial direction of the radial direction frame 28 inclines backward and outward in the radial direction. A rear bit 32 is installed on the edge on the inner rear part in the radial direction.SELECTED DRAWING: Figure 1 【課題】シールド工法に適した円環状に地盤を掘削するトンネル掘削装置を提供する。【解決手段】掘削装置本体２と、掘削装置本体２の先端に設けられ、掘削装置本体２に対して回転駆動される掘削機構４と、を備えた地盤を円環状に掘削するトンネル掘削装置１であって、掘削機構４は、円筒状の外部フレーム２４と、外部フレーム２４と同軸に設けられた円筒状の内部フレーム２６と、内部フレーム２６と外部フレーム２４とを結んで径方向に延びる径方向フレーム２８と、外部フレーム２４と、内部フレーム２６と、径方向フレーム２８の先端面に設けられた掘削ビット３０とを有し、径方向フレーム２８の径方向内側の後部の縁は、後方に向かって径方向外方へ傾斜しており、径方向内側の後部の縁には後方ビット３２が設けられている。【選択図】図１