| 摘要 |
A tunnel drive shield has an arcuate support frame constituted by a pair of foot segments, a pair of wall segments supported by the foot segments and a ridge segment connecting the tops of the wall segments. The foot segments engage the tunnel floor, and the wall segments are braceable outwardly towards the tunnel walls. Each foot segment is provided with a pair of longitudinal floor skids displaceably mounted on the base thereof. Each foot segment is also provided with a pair of longitudinally-spaced, vertically-movable support feet, which are movable into contact with the tunnel floor to relieve, at least partially, the load on the floor skids. The support feet are used to support the shield while the floor skids are removed. The rest of the shield can then be dismantled within the confines of the tunnel.
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