Retrievable plug for bored cased foundation pile - has boring teeth and seals foot of casing tube whilst being able to move for concrete to pass

摘要

The retrievable plug (1) is for use with bored and cased in situ concrete foundation piles. The plug seals the foot of the tubular casing (5) as it penetrates during boring and may replace prior irretrievable plugs. The plug (1) has e. g. teeth (7, 8) to assist boring and may be displaced axially relative to the casing by virtue of rods (2) sliding in sleeves (3). The plug may have two slide-rods (2, 2') each guided in a sleeve (3, 3') which is mounted externally on the casing (5). The ends of the rods are returned (4) to form stops limiting plug displacement. The displacement may be such to permit the injection of concrete as the casing is withdrawn. The plug may be edge rebated to centre (6) in the end of the casing (5) and may, as an alternative be cruciform with cable retention.