JPH10140560A - Composite knotted pile and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite knotted pile which is provided with enough support strength and cracking strength required as a knotted pile and a cross section which is simple and easy to manufacture with high efficiency and a manufacturing method thereof. SOLUTION: Concrete 5 is filled into a knotted steel pipe 2 having a knot- shaped projection 3 with a specified spacing in the longitudinal direction. The knotted steel pipe 2 is integrated with the concrete 5 in the inner surface by centrifugal molding and vapor curing and so forth, thereby forming a composite knotted pile 1 in steel concrete composite structure whose surface is covered with a steel plate. An end plate 4 made of a steel plate or the like is mounted on both ends of the composite knotted pile 1. The knotted steel pipe 2 protects the surface of the concrete 5 therewith and enhances cracking strength of the concrete, which makes it possible to omit the arrangement of PC bars or reinforced bars used for a prior art knotted pile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite knot pile composed of concrete used as a foundation pile, mainly a friction pile, and a steel plate covering the surface thereof, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As ready-made piles, friction piles such as ordinary concrete piles, steel pipe piles, steel-concrete composite piles, and other cylindrical prefabricated piles, as well as knotted piles that are expected to have a peripheral bearing capacity rather than a horizontal strength capacity are used. is there.

FIG. 4 shows a typical form of a conventional knotted pile 11, which is often made of hollow prestressed concrete having a knotted projection 13 on its outer periphery.

The manufacturing method in that case is roughly as follows.

[0005] Several PC bars 16 are bundled, and the hoop bars 17 are spot-welded to form a reinforcing bar cage.

[0006] The above reinforcing cage is placed in a lower mold frame giving a semicircular shape, filled with unhardened concrete 15, and centrifuged.

[0007] The centrifugally molded product is subjected to steam curing in a steam curing tank.

In order to prevent the pile concrete 15 from cracking, prestress is introduced into the PC bars 16.

[0009] Further, as a concrete formwork of the nodal pile, for example, there is one disclosed in Japanese Patent Publication No. Sho 62-53323. The gazette disclosed in this publication incorporates an inner mold that forms a half-circle corresponding to the inside of a half-cylindrical mold that can be split and opened, and that forms a node molding part and a body molding part. In the mold, the inner mold is made of reinforced plastic or the like, the body molding is formed thick, and the entire outer periphery is inscribed in the cylindrical mold.

[0010]

In the structure of the conventional knotted pile, in order to prevent the pile from cracking, the diameter and the number of reinforcing bars are changed and the prestress amount is determined to manufacture the pile. However, the manufacturing process is complicated, such as the arrangement of PC bars and reinforcing bars and the introduction of prestress.

Further, particularly in the case of a knotted pile, it is difficult to reinforce the knotted portion, and there is a possibility that a crack or the like may be generated in the knotted portion during handling.

[0012] Further, the knotted pile as a friction pile usually expects a peripheral bearing force rather than a horizontal strength, and is used in a portion where bending does not act so much or in a usage method where bending does not act much (for example, a plurality of piles). (For example, a lower pile in the case of adding a pre-made pile in the longitudinal direction), the arrangement of the reinforcing bars may be useless in terms of efficiency.

The present invention has been made to solve the above-mentioned problems, has a simple structure, is easy to manufacture, and has an efficient cross section having the necessary bearing strength and cracking strength as a nodal pile. It is an object of the present invention to provide a composite knot pile and a method of manufacturing the same.

[0014]

According to a first aspect of the present invention, there is provided a composite knot pile having a knot which is mainly composed of concrete and has knots on its outer periphery. It is a steel-concrete composite structure covered with steel plates.

The steel plate is mainly for improving the crack resistance of the knotted concrete portion, and functions as a PC bar or a reinforcing bar in a conventional concrete knotted pile.

The most basic structure is a structure in which a steel plate covers the entire periphery of a concrete knotted pile in the form of a steel pipe, and end plates are provided at both ends.
That is, it is possible that only a part is covered with a steel plate or a part is replaced with a reinforcing bar or the like.

According to a second aspect of the present invention, there is provided a method of manufacturing a composite knotted pile, wherein one of the composite knotted piles is provided with unhardened concrete in a knotted steel pipe having a knotted projection. The present invention is characterized in that a steel pipe and concrete are integrated by centrifugal molding.

For centrifugal forming itself, a method similar to a conventionally performed method can be used, and in this case, a steel tube with a knot can be considered as a scrap frame. The unhardened concrete filled in the knotted steel pipes penetrates tightly into the knotted projections of the knotted steel pipe by rotating the knotted steel pipe around the axis by the centrifugal molding device, and further integrates with the knotted steel pipe. Can be increased.

For example, the formwork described in JP-B-62-53323 described in the section of the prior art is used as it is, and the above-described knotted steel pipe is set in the inner formwork and filled with concrete. It is also possible to carry out centrifugal molding by using the existing equipment.

[0020]

FIG. 1 shows an embodiment of the present invention, in which a surface of a knot pile having knots at predetermined intervals in a longitudinal direction is covered with a steel plate to form a composite knot pile 1 of a steel concrete composite structure. .

In this example, the surface of the composite knot 1 is made up of a knotted steel pipe 2 having a knot-like projection 3 itself, and the concrete knot 1 integrated with the inner peripheral surface thereof. Is formed. In the figure, reference numeral 4 denotes an end plate made of a steel plate or the like.

The jointed steel pipe 2 protects the surface of the concrete 5 and functions as a PC bar or a reinforcing bar for improving the crack resistance of the concrete. It is possible to omit the arrangement of the PC bars and the reinforcing bars which have caused the cost increase.

FIGS. 2 and 3 show an embodiment of a method of manufacturing the composite knot pile 1 of FIG. 1. The composite knot pile 1 can be manufactured by the following procedure.

Concrete 5 is filled into a knotted steel pipe 2 having knotted projections 3 formed at predetermined intervals in advance in accordance with the outer peripheral shape of the composite knotted pile 1. The filling is performed by a screw feeder 6 or the like having a diameter that can be inserted into the knotted steel pipe 3.
When the concrete 5 has been filled to a certain extent, the screw feeder 6 continues to fill the concrete 5 while gradually pulling it out, and then attaches the end plate 4 to the other end.

The knotted steel pipe 2 filled with the uncured concrete 5 is put into a mold of a centrifugal molding device 8, and the concrete 5 is centrifugally formed by rotating the mold. In the drawing, reference numeral 7 denotes a gasket (packing) interposed between the inner surface of the mold of the centrifugal molding device 8 and the knotted steel pipe 2.

At the stage where the concrete 5 exhibits a certain level of strength, it is removed from the mold of the centrifugal molding device 8 and steam curing is performed.

It should be noted that, while using the jointed steel pipe 2 as a discarded frame, a concrete-compound composite pile in which the concrete 5 and the jointed steel pipe 2 are integrated is formed. Centrifugal forming apparatus 8 similar to the conventional method of manufacturing knotted piles except that the introduction of prestress into
Therefore, it is possible to manufacture the composite knot pile 1 of high quality efficiently by the same method.

As a method of manufacturing the jointed steel pipe 2 used here, a steel plate in which the projections of the joints are pressed in advance is sequentially formed into a U-shape, an O-O-E system, and the like.
Pressing into a letter shape, after seam welding, adjusting the shape (if necessary, a separate plate may be provided) or welding a short steel pipe and a ring-shaped steel material that forms a node,
There is a method of sequentially connecting them in the longitudinal direction.

The above is the manufacturing method using the knotted steel pipe 2. In addition to this, for example, a knot-shaped steel pipe having a filler inside is provided on the outer circumference of a conventional straight-pipe concrete composite pile without knots. It is also conceivable to fix the ring made of steel and use it as a knot of the compound knot.

Further, the composite knot pile 1 of the present invention does not necessarily have to be hollow, and may be a solid composite knot pile which is not formed by the centrifugal molding method.

[0031]

[Effect of the Invention] Since the steel plate is arranged on the outer peripheral surface of the knotted pile, necessary crack resistance can be secured even if the reinforcing bars are omitted,
In addition, since the concrete of the knot portion does not appear on the surface, damage to the knot portion during handling can be prevented.

Since the steel plate on the outer peripheral surface has the function of a PC reinforcing bar or a reinforcing bar as a concrete reinforcing bar in the conventional knotted pile, it has conventionally been troublesome to form a reinforcing cage or to arrange a PC reinforcing bar. The step of introducing the stress can be omitted, thereby reducing the manufacturing cost.

The steel plate itself forms a concave-convex steel pipe having knots, and the knots are filled with concrete, thereby constraining the concrete and ensuring integration with the concrete.

By previously manufacturing a knotted steel pipe having knotted projections, the knotted steel pipe functions as a discarding frame,
Centrifugal molding can be easily performed.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a composite knotted pile according to the present invention, in which (a) is a front view in which a middle part in a longitudinal direction is omitted (right half is a cross-sectional view), and (b) is a cross-sectional view taken along line AA. FIG.

FIG. 2 is a cross-sectional view schematically showing how concrete is filled into a knotted steel pipe in one embodiment of the production method of the present invention.

FIG. 3 is a cross-sectional view schematically showing a state of centrifugal molding in one embodiment of the manufacturing method of the present invention.

FIG. 4 is a front view (the right half is a cross-sectional view) of the upper part of a node pile showing a typical mode of a conventional node pile.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Composite knotted pile, 2 ... Knotted steel pipe, 3 ... Knotted projection, 4 ... End plate, 5 ... Concrete, 6 ... Screw feeder, 7
... gasket, 8 ... centrifugal molding device, 11 ... conventional knot,
13 ... node-like projection, 14 ... end plate, 15 ... concrete, 1
6 ... PC muscle, 17 ... Hoop muscle

Claims (2)

[Claims] 1. A composite, wherein a part or the entire outer peripheral surface of a knotted pile mainly made of concrete and having knots on its outer periphery is covered with a steel plate provided with irregularities corresponding to the knots. Knotty pile. 2. A method of manufacturing a composite knotted pile, comprising: filling unhardened concrete in a knotted steel pipe having a knotted projection; and integrating the steel pipe and concrete by centrifugal molding.