| 摘要 |
A frangible insert that is inserted in a pre-positioned bushing in the wall of a manhole form from the convex, easily reached side of the inner form wall. A key in the insert is received in a keyway in the bushing in the form wall so that the insert is properly oriented in the form. Concrete is then poured into the form, enveloping and affixing the insert within the man hole wall. A weakened, frangible region is provided on the insert in a position immediately adjacent to the form wall so that after the concrete is cured, the manhole and form can simply be separated, causing the portion of the insert embedded in the concrete to separate from the insert portion in the form bushing.
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