| 摘要 |
Concrete liners are cast in manholes using a form structure (11) made up of a collection of sheet-metal, flanged, arcuate panels (13, 19). The panels (13, 19) are assembled in belts of generally circular cross-section commencing from the bottom of the manhole for casting a concrete liner with a minimum thickness of about three inches and including openings created by sectional cylindrical inserts (83, 85, 89), all of which can be assembled, then disassembled after the concrete liner has set. To accommodate different shapes of manholes the panels can be formed into right conical, offset conical, and wedge-shaped (31, 33) belts to make transitions between vertical and tilted sections of the manhole. A key panel (15, 16, 17) is provided to allow easy disassembly of the respective belts, each key panel including a relatively narrow portion (16) with vertical flanges forming an angle which diverges toward the center of the form structure. |
