Pile head dresser, pile head dressing method, and, placement of

Details Pile head dresser, pile head dressing method, and, placement of Pile head dresser, pile head dressing method, and, placement of

1997-05-15

1999-10-05

Bagnell, David

Hydraulic and earth engineering

Foundation

Columnar structure

405243, 405249, 405255, 405257, 52301, 5274518, 249 51, E02D 534, E04B 116, E04C 518

Patent

active

059612533

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a pile head dresser which is mounted to the head of a steel cage of a cast-in-place concrete pile installed in the ground for making a foundation for civil engineering work, to a method of dressing the head of such a concrete pile, and to an improvement in placement of such a pile.
2. Description of Related Art
In common construction work, a variety of methods are used for driving and installing foundation piles. Among of them is a popular cast-in-place pile installation method.
The cast-in-place concrete pile installation method comprises drilling a round hole into a bearing base layer in the ground by an earth drilling technique, installing in the drilled round hole a steel cage consisting of a framework assembly of reinforcement bars, and filling the hole with a batch of concrete which is supplied through a tremie pipe having been inserted from above into the steel cage. A reinforced concrete pile is formed when the concrete is solidified.
In general, the batch of concrete is abundant thus having an extension of about 1 meter high above the steel cage of the concrete pile. The concrete pile with the extension is covered with refilling soil for curing.
After the curing of the concrete is completed, the soil is removed and the concrete extension is chipped off to expose the reinforcement bars at the top of the steel cage. The foundation of a building structure is then built on the concrete piles.
The chipping of the concrete extensions however creates unwanted sounds, vibrations and dust and is generally regarded as a public nuisance. Also, it may damage the reinforcement bars and cause labor accidents and industrial illnesses. The concrete extensions require a considerable amount of concrete and the chipping procedure increases the overall construction cost and time.
A method of eliminating the chipping procedure is disclosed in Japanese Patent Application 61-186616 (1986) where the concrete extensions are removed while the concrete, supplied through a tremie pipe, remains in a viscous fluid form before being solidified. The removal of the concrete is achieved by vacuum suction with a suction hose coupled to a heavy-duty vacuum pump. The method is only feasible with the use of a casing installed in the drilled hole and is not satisfactorily applicable to any different case where the drilled hole may easily collapse.
According to the method, the reinforcement bars are exposed and directly covered by refilling soil when the concrete extensions have been removed. Also, the removal of the concrete extensions requires a large machine which may easily damage the top of the exposed reinforcement bars. As the injured reinforcement bars have to be repaired with extra care and cost, the method is rather impractical.
To prevent such damage to the exposed reinforcement bars during the chipping or removal of concrete extensions, a reinforcement bar cap structure has been introduced as disclosed in Japanese Patent Application 58-153816 (1983).
The cap has a through hole provided in the center thereof for accepting and detachably coupling a tremie pipe. The cap comprises a closed double-wall structure of a doughnut shape having two separate rooms or spaces about the center hole which are defined by two, top and bottom, annular plates provided with apertures.
In use, joint bolts are inserted through the apertures of the top or bottom plate of the cap and threaded into sleeve joints of which rear ends are mounted to the uppermost ends of reinforcement bars of a steel cage so that the cap structure and the steel cage are tightly joined to each other. This is followed by introduction of a flow of concrete through a tremie pipe.
The flow of concrete into the steel cage is continued until the cap structure on the top of the steel cage is filled up. For curing the concrete in the steel cage, the steel cage and the cap are covered with refilling soil. When the concrete has been cured, the refilling soil is removed to expose the cap. The con

REFERENCES:
patent: 2571549 (1951-10-01), Dunning
patent: 3396546 (1968-08-01), Pleuger
patent: 3487646 (1970-01-01), Gatien
patent: 4040260 (1977-08-01), Pryke
patent: 4472085 (1984-09-01), Mohler
patent: 5359829 (1994-11-01), Voita
patent: 5423633 (1995-06-01), Verstraeten

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