| 摘要 |
The underpass is a made using a hollow, concrete frame (8) which is rectangular or square with four walls (10, 11, 12, 13). The frame can be moved transversely on a frame (4) at the base and can be positioned in an open excavation (2) with sloping sides (6) running through an embankment (1) on which the road or railway runs. The frame has two extensions at each side, the upper extension (17) continues the line of the horizontal top (13) and the second extension (18) runs at an angle of between 34 and 45 deg , joining the end of the upper extension to the base of the vertical side of the frame, forming a hollow, triangular section. The angled extension has holes (22) in it and a layer of concrete is injected into the space between the underpass and the embankment.
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