| 摘要 |
The component (1), designed to be laid in a trench or for lining an underground tunnel, has a basic trapezoid cross-section with a flat base (11), inclined side walls (12) and a top (13) made from four vaulted sections (131, 132, 133, 134). The inner surface of the base is flat in the middle (15) and slopes down at the sides (16), and the lower corners (17) are thicker than the side walls. The top is made with blind holes (18) for couplings, and variants can have side branches or a manhole through the top. |
