| 摘要 |
<p>The process is for correcting the open space clearance in tunnels which have been in use for some time. Stone or layers of masonry are usually removed manually and cause prolonged closure of railway tunnels. Cuts are instead made in the stone surface, or masonry, running parallel. The ribs resulting from this cutting are then broken away. The cuts may be deeper than the vertical interval width between them. The cuts may be made by offset rotating circular saw blades on a wagon mounted on parallel driven shafts. Toothed chains may serve to break away the ribs.</p> |
