| 摘要 |
A collection of sheet-metal, flanged, arcuate panels is provided which panels can be assembled in belts of generally circular cross-section commencing from the bottom of the manhole to provide a complete form structure for casting a concrete liner with a minimum thickness of about three inches and including openings created by sectional cylindrical inserts, all of which can be assembled, then disassembled after the concrete liner has set. An extensive variety of panels to accomodate different shapes of manholes includes panels for forming right conical belts, for forming offset conical belts, and for forming wedge-shaped belts to make transitions between vertical and tilted sections of the manhole. A key-panel for these various belts is provided to prevent capture of the panels by the poured concrete liners which includes a relatively narrow portion with vertical flanges fixed at an angle to one another which angle diverges toward the center of the form structure. The methods include jacking the form structure after a part of the liner has been formed and poured to cause it to fit relative to the manhole and inlet pipes into the manhole, before pouring the remainder of the liner.
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