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