| 摘要 |
A network of square-section troughs, embedded in the ground, consists of straight trough sections and curved and corner sections which are butted together at their ends. The vertical sidewalls (1) of the troughs have offset tongues (3) which can interlock. There are latches (7) on the floor (6) which interlock. There are outwards-extending flanges (2) at the top of the sides, with apertures (8) for vertical pins (4) which hold the tongues together and extend down into the ground to hold the trough sections in place.
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