| 摘要 |
<p>The spacing system is of advantage where multiple circular section cable ducts have to be laid in a trench in the earth. To maintain the distance between the tubular channels (11, 12, 13) and also allow the ducts to be laid in one operation, the gaps (16, 18) between adjacent channels are filled with distance pieces (19). The distance pieces are typically of lattice construction and interlock with each other to form a structure holding the tubular channels together. They also extend over most of the length of the duct section to give support during laying. With this form of spacer the trench size can be kept small. The lattice design allows the back fill to get between the channels, which can assist cooling.</p> |
