| 摘要 |
<p>Method and apparatus are provided herein for forming inverts in the manhole base of a manhole assembly using a single pour technique. In the single pour technique, the invert is formed simultaneously with the formation of the manhole base through the steps of first providing a mold having a hollow interior space for forming the manhole base to be cast therein. Rings are then mounted within the interior space of the mold to define openings to be provided in the side-walls of the manhole base being cast in the mold, the rings having central openings defining the central axis of the openings to be formed in the manhole base being cast. A mold member is then disposed in the mold, the mold member defining an interior surface of a floor of the manhole base being cast and having raised portions supported thereon defining an invert to be provided in the floor of the manhole base, the mold member having openings at the end walls of the raised portions, the centres of the openings lying on a line parallel to the longitudinal axis of its associated raised portion. Finally, a reciprocating activating means is activated thereby slidably to extend movable alignment members through each opening in the invert forming mold member and through an opening in an associated one of said mounting rings, thereby precisely to align the center of each ring along the longitudinal axis of a respective one of the raised portions preparatory to casting.</p> |
