JP2020007904A - Concrete pile with double steel pipe, method for manufacturing the same, manufacturing device, pile head joint structure and jointed pile structure - Google Patents

Abstract

To provide a concrete pile with double steel pipe which secures a sufficient bending bearing force even at the end, a method for manufacturing a concrete pile with double steel pipe having a sufficient bending bearing force, a manufacturing device, a pile head joint structure and a jointed pile structure.SOLUTION: A concrete pile with a double steel pipe includes: an outer steel pipe; a first end plate; a second end plate; a hollow cylindrical inner steel pipe arranged inside in a radial direction of the outer steel pipe, and a hollow cylindrical concrete part which is arranged in contact with the outer steel pipe between the outer steel pipe and the inner steel pipe, and is composed of concrete; and a filling part arranged between the concrete part and the inner steel pipe. The inner steel pipe is configured so as to burden a tensile axial force when a bending moment acts on the concrete pile with double steel pipe, at least the first end of the inner steel pipe is configured so as to burden a larger tensile axial force when the first end of the inner steel pipe and the first end plate are fillet-welded when the tensile axial force acts on the inner steel pipe.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a hollow concrete pile with a double steel pipe, a method of manufacturing the same, a manufacturing apparatus, a pile head joint structure, and a joint pile structure.

A concrete pile with an outer steel pipe (SC pile), which is a kind of a ready-made pile, is generally constituted by an outer steel pipe and hollow cylindrical concrete covered with the outer steel pipe (for example, see Patent Document 1). .
On the other hand, Patent Document 2 discloses an SC pile in which a hollow inner steel pipe is arranged as a cylindrical reinforcing member in a hollow portion of the SC pile. According to the SC pile, even if peeling of concrete from the outer steel pipe due to buckling of the outer steel pipe and crushing occur, movement of the concrete piece to the hollow portion is prevented, and a sudden decrease in the strength of the SC pile is suppressed. You.

Japanese Patent No. 5,265,447 JP 2016-223207 A

When an SC pile as a ready-made pile is constructed by the embedding method, a hollow portion is required for the SC pile in order to reduce buoyancy generated in the SC pile. Therefore, it is difficult to use a solid SC pile in which a hollow portion is filled with a filler as disclosed in Non-Patent Documents 1 and 2 for the embedding method.
In this regard, according to the SC pile (concrete pile with double steel pipes (WSC pile)) disclosed in Patent Document 2, a hollow portion can be secured by providing the inner steel pipe, and the SC pile can be easily embedded. Applicable to It should be noted that “WSC” is a registered trademark, but the display of the registered trademark is omitted in this specification.
Moreover, since the SC pile disclosed in Patent Document 2 has an inner steel pipe, it has a larger bending strength than an SC pile having no inner steel pipe.
Here, the bending strength of the pile is generally measured by applying a downward load to the central portion in the axial direction while supporting both ends of the pile arranged horizontally. If the bending strength of the WSC pile is measured by such a measuring method, the bending strength becomes larger than that of the SC pile having no inner steel pipe by the amount of the inner steel pipe.
However, the bending strength at the end of the WSC pile is lower than that at the center in the axial direction of the WSC pile depending on the configuration of the inner steel pipe. This is because at the center of the WSC pile in the axial direction, the inner steel pipe bears the tensile axial force when the WSC pile is deformed at the time of measuring the bending strength, but at the end of the WSC pile, depending on the configuration of the inner steel pipe, However, it is not possible to sufficiently bear the tensile axial force.

In view of the above-mentioned circumstances, an object of the present invention is to provide a concrete pile with a double steel pipe in which sufficient bending strength is secured even at an end.
Another object of the present invention is to provide a method for manufacturing a concrete pile with a double steel pipe having a sufficient bending strength.
Another object of the present invention is to provide an apparatus for manufacturing a concrete pile with a double steel pipe having a sufficient bending strength.
Another object of the present invention is to provide a pile head joint structure for a concrete pile with a double steel pipe having a sufficient bending strength.
Another object of the present invention is to provide a joint pile structure of a concrete pile with a double steel pipe having a sufficient bending strength.

(1) A concrete pile with a double steel pipe according to at least one embodiment of the present invention,
A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow cylindrical cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
In a concrete pile with a double steel pipe comprising
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. It is configured to bear the power.

  According to the above configuration (1), when at least the first end of the inner steel pipe is fillet welded to the first end of the inner steel pipe and the first end plate when a tensile axial force acts on the inner steel pipe. By being configured to be able to bear a larger tensile axial force, the first end portion of the inner steel pipe can bear a sufficient tensile axial force even compared to the axially central portion of the inner steel pipe. For this reason, the concrete pile with the double steel pipe of the above configuration (1) has a sufficient bending strength not only at the axial center but also at the ends.

(2) In some embodiments, in the above configuration (1),
A first end of the inner steel pipe and the first end plate are joined via a first complete penetration groove weld,
The first full penetration groove weld is configured such that a tensile axial force acts when a tensile axial force acts on the inner steel pipe.

When fillet welding is performed between the first end of the inner steel pipe and the first end plate, a shear force acts on the fillet weld when a tensile axial force acts on the inner steel pipe. And, on the premise that the leg length of the fillet weld is set according to the thickness of the inner steel pipe, the throat thickness of the fillet weld is smaller than the thickness of the inner steel pipe.
On the other hand, when the first end portion and the first end plate of the inner steel pipe are joined via a full penetration groove weld and a tensile axial force acts on the full penetration groove weld, The cross-sectional area and the cross-sectional area of the full penetration groove weld can be made equal.
For this reason, the tensile yield strength of the full penetration groove weld becomes larger than the shear yield strength of the fillet weld and becomes substantially equal to the tensile yield strength of the inner steel pipe.
In consideration of the above circumstances, in the above configuration (2), the first end of the inner steel pipe and the first end plate are joined via the first full penetration groove welding portion, and the first full penetration opening is performed. It is configured such that a tensile axial force acts on the front welded portion, so that the first end portion of the inner steel pipe can bear a sufficient tensile axial force as compared with the central portion in the axial direction of the inner steel pipe. .

(3) In some embodiments, in the above configuration (2),
A second end of the inner steel pipe projects outside through a second opening of the second end plate.
According to the above configuration (3), since the second end of the inner steel pipe projects outside through the second opening of the second end plate, the inner steel pipe is directly or indirectly joined to the second end plate. When doing so, it can be easily fixed.

(4) In some embodiments, in any one of the configurations (1) to (3),
The first end plate or the second end plate has an injection hole for injecting the curable material to be the filling portion between the concrete portion and the inner steel pipe.
According to the above configuration (4), since the injection hole is provided in the first end plate or the second end plate, the curable material can be easily injected between the concrete portion and the inner steel pipe with a simple configuration. can do.

(5) In some embodiments, in the above configuration (4),
The first end plate or the second end plate has an air vent for discharging air during injection of the hardening material serving as the filling portion between the concrete portion and the inner steel pipe.
According to the above configuration (5), since the air vent hole is provided in the first end plate or the second end plate, the curable material can be easily formed with no gap between the concrete portion and the inner steel pipe with a simple configuration. Can be injected.

(6) In some embodiments, in the above configuration (4) or (5),
The first end plate or the second end plate has a discharge hole for discharging excess curable material during the injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. Have.
According to the above configuration (6), the first end plate or the second end plate is provided with a discharge hole, and by confirming the outflow of the curable material from the discharge hole, the concrete portion can be formed with a simple configuration. It can be easily determined whether or not the hardening material has been sufficiently filled between the inner pipe and the inner steel pipe.

(7) In some embodiments, in the above configuration (3),
The diameter of the second opening of the second end plate is larger than the outer diameter of the inner steel pipe,
A lid member is further provided between the inner steel pipe and a second opening of the second end plate.
According to the configuration (7), the second opening of the second end plate is larger in diameter than the outer diameter of the inner steel pipe, and a gap is secured between the second end plate and the inner steel pipe. Through the second opening of the end plate, the inner steel pipe can be easily inserted inside the concrete part. On the other hand, by attaching a cover member to the gap between the inner steel pipe and the second end plate, the gap between the second end plate and the inner steel pipe can be substantially closed, and a cylindrical shape is formed between the concrete part and the inner steel pipe. Space can be partitioned.

(8) In some embodiments, in the above configuration (7),
An outer surface of the second end plate is located outside an outer surface of the lid member in an axial direction of the inner steel pipe,
The lid member is fillet welded to the inner steel pipe and the second end plate.
According to the above configuration (8), even when the lid member is welded to the inner steel pipe and the second end plate, the fillet weld portion of the lid member formed by the fillet welding is directed outward from the outer surface of the second end plate. Projection can be prevented. For this reason, when connecting a concrete pile with a double steel pipe to another pile, the outer surface of the second end plate can be brought into direct contact with the end plate of another pile without interference of the cover fillet weld. it can.

(9) In some embodiments, in the above configuration (7) or (8),
The first end plate, the second end plate, or the lid member has an injection hole for injecting the curable material to be the filling portion between the concrete portion and the inner steel pipe.
According to the above configuration (9), since the injection hole is provided in the first end plate, the second end plate, or the lid member, the curable material can be filled between the concrete portion and the inner steel pipe with a simple configuration. Can be easily injected.

(10) In some embodiments, in the above configuration (9),
The first end plate, the second end plate or the lid member has an air vent hole for discharging air during injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. Have.
According to the above configuration (10), since the air vent hole is provided in the first end plate, the second end plate, or the lid member, the curable material can be filled between the concrete portion and the inner steel pipe with a simple configuration. It can be easily injected without gaps.

(11) In some embodiments, in the above configuration (9) or (10),
The first end plate, the second end plate, or the lid member is for discharging excess curable material during injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. With a discharge hole.
According to the above configuration (11), the first end plate, the second end plate, or the lid member is provided with the discharge hole, and by confirming the outflow of the curable material from the discharge hole, the configuration can be simplified. It can be easily determined whether the hardening material is sufficiently filled between the concrete portion and the inner steel pipe.

(12) In some embodiments, in the above configuration (1),
A first end of the inner steel pipe projects outside through a first opening of the first end plate.

  According to the above configuration (12), since the first end of the inner steel pipe projects outside through the first opening of the first end plate, it is possible to connect the first end of the inner steel pipe to an external member. it can. Then, by connecting the first end of the inner steel pipe to an external member, the first end of the inner steel pipe can bear a sufficient tensile axial force as compared with the central part in the axial direction of the inner steel pipe.

(13) In some embodiments, in the above configuration (1),
A tension fitting for connecting the first end plate to a first end of the inner steel pipe;
A first end of the inner steel pipe is joined to the tension fitting via a full penetration groove weld for tension,
The full penetration groove weld for tension is configured such that when a tensile axial force acts on the inner steel pipe, a tensile axial force acts.

  According to the above configuration (13), the first end portion of the inner steel pipe is joined to the tension fitting via the full penetration groove welding portion for tension, and the full penetration groove welding portion for tension is Since the tensile axial force acts on the inner steel pipe when the tensile axial force acts on the inner steel pipe, the first end of the inner steel pipe has a sufficient tensile axial force as compared with the central part in the axial direction of the inner steel pipe. Is bearable.

(14) In some embodiments, in the above configuration (1),
A tension fitting connected to a first end of the inner steel pipe;
The first end of the inner steel pipe can bear the tensile axial force via the tension fitting when a tensile axial force acts on the inner steel pipe.

  According to the above configuration (14), the first end of the inner steel pipe bears the tensile axial force via the tension fitting, so that the first end of the inner steel pipe is compared with the central part in the axial direction of the inner steel pipe. However, it is possible to bear a sufficient tensile axial force.

(15) In some embodiments, in any one of the configurations (1) to (12),
The first end of the inner steel pipe is configured to be connectable to an adapter member for attaching a fixing member for pile head connection.

  According to the above configuration (15), the first end of the inner steel pipe is connected to the first end of the inner steel pipe by connecting the adapter member for attaching the anchoring member for pile head connection to the first end of the inner steel pipe. It can be connected to members. Thus, the first end portion of the inner steel pipe can bear a sufficient tensile axial force as compared with the central portion in the axial direction of the inner steel pipe.

(16) In some embodiments, in any one of the configurations (1) to (15),
The second end of the inner steel pipe is configured to be connectable to another pile.

  According to the above configuration (16), by joining the second end of the inner steel pipe to another pile, the second end of the inner steel pipe can have a sufficient tensile axis as compared with the central part in the axial direction of the inner steel pipe. Can bear the power.

(17) In some embodiments, in any one of the configurations (1), (12), (13), (14), (15), and (16),
The second end of the inner steel pipe and the second end plate are joined via a second complete penetration groove weld,
The second complete penetration groove weld is configured such that a tensile axial force acts when a tensile axial force acts on the inner steel pipe.

  According to the above configuration (17), the second end portion of the inner steel pipe and the second end plate are joined via the second full penetration groove welding portion, and are joined to the second full penetration groove welding portion. It is configured such that a tensile axial force acts, whereby the second end portion of the inner steel pipe can bear a sufficient tensile axial force as compared with the central portion in the axial direction of the inner steel pipe.

(18) In some embodiments, in any one of the configurations (1) to (15),
A second end of the inner steel pipe is located closer to a first end of the inner steel pipe than the second end plate in an axial direction of the inner steel pipe,
An outer peripheral surface of the inner steel pipe is provided with a stopper for preventing a relative displacement of the filling portion in an axial direction of the inner steel pipe.

  According to the above configuration (18), even if the second end of the inner steel pipe is not joined to the second end plate, relative displacement of the inner steel pipe with respect to the filling portion is prevented by the stopper, so that When a tensile force or a compressive force acts on the outer steel pipe, the inner steel pipe can also bear the tensile force or the compressive force.

(19) In some embodiments, in any one of the configurations (1) to (18),
An outer fixing member joining portion for mechanically attaching the outer fixing member to the outer steel pipe is provided.

  According to the above configuration (19), since the outer steel pipe is provided with the outer fixing member joining portion, the outer fixing member can be easily attached to the outer steel pipe.

(20) A method for manufacturing a concrete pile with a double steel pipe according to at least one embodiment of the present invention,
A hollow cylindrical outer steel pipe, a first end plate having a first opening in the center, a second end plate having a second opening in the center having a larger diameter than the first opening, and an outer diameter smaller than the second opening. A step of preparing a hollow and cylindrical inner steel pipe having, and a lid member that can be disposed between the second opening and the inner steel pipe;
Attaching the first end plate to a first end of the outer steel pipe;
Attaching the second end plate to a second end of the outer steel pipe;
An uncured concrete is poured into the outer steel pipe to which the first end plate and the second end plate are attached, and a hollow cylindrical concrete portion made of concrete placed in contact with the outer steel pipe Forming a;
Inserting the inner steel pipe inside the concrete part through a second opening of the second end plate;
Welding a first end of the inner steel pipe and the first end plate;
Attaching the lid member to a gap between the inner steel pipe and the second end plate;
A step of injecting a curable material from an injection hole provided in the first end plate, the second end plate, or the lid member to form a filling portion between the concrete portion and the inner steel pipe;
Is provided.

  According to the configuration (20), since the second opening of the second end plate has a larger diameter than the first opening of the first end plate, the inner steel pipe can be easily inserted inside the concrete portion. On the other hand, by attaching the lid member to the gap between the inner steel pipe and the second end plate, a cylindrical space can be defined between the concrete part and the inner steel pipe. A filling portion is easily formed between the concrete portion and the inner steel pipe by injecting a curable material into the space from an injection hole provided in the first end plate, the second end plate, or the lid member. can do.

(21) A concrete pile with a double steel pipe according to at least one embodiment of the present invention, the concrete pile with a double steel pipe applied to the method for manufacturing a concrete pile with a double steel pipe according to the above configuration (20). The manufacturing apparatus of
In the step of inserting the inner steel pipe inside the concrete part, the load on the first end side of the inner steel pipe can be supported while allowing the inner steel pipe to move inside the horizontally arranged concrete part. It is.

  According to the above configuration (21), in the step of inserting the inner steel pipe inside the concrete part, the inner steel pipe is inserted inside the concrete part through the second opening of the second end plate by the production device for the concrete pile with the double steel pipe. It can be inserted smoothly and easily.

(22) A pile head joint structure of a concrete pile with a double steel pipe according to at least one embodiment of the present invention,
Concrete pile with double steel pipe,
An anchoring member attached to the end of the concrete pile with the double steel pipe,
A concrete block surrounding the fixing member,
The concrete pile with a double steel pipe,
A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow cylindrical cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
With
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. It is configured to bear the power,
The fixing member includes an inner fixing member for connecting a first end of the inner steel pipe to the concrete block.

According to the above configuration (22), by connecting the first end of the inner steel pipe to the concrete block via the inner fixing member, the first end of the inner steel pipe is compared with the central part in the axial direction of the inner steel pipe. However, it is possible to bear a sufficient tensile axial force. For this reason, the concrete pile with a double steel pipe has sufficient bending strength not only at the center but also at the ends.
In addition, by providing the inner fixing member in the concrete block, the bending strength of the concrete block (pile head joint) can be improved.

(23) In some embodiments, in the above configuration (22),
The inner fixing member is provided integrally with an inner surface of a first end of the inner steel pipe, and is configured by one or more protrusions protruding radially inward from an inner surface of the first end.
When the outer diameter of the concrete pile with the double steel pipe is D, the pile head of the concrete pile with the double steel pipe is embedded in the concrete block over a length of 0.5D or more and 3D or less,
The concrete block is attached to the one or more protrusions.

  According to the configuration (23), the pile head of the concrete pile with the double steel pipe is buried in the concrete block over a length of 0.5D or more and 3D or less, and the concrete block is attached to one or more protrusions. Due to the adhesion, the first end of the inner steel pipe can bear a sufficient tensile axial force. As a result, the concrete pile with the double steel pipe has sufficient bending strength not only at the center but also at the end, and a pile head joint having high bending strength can be realized.

(24) A joint pile structure of a concrete pile with a double steel pipe according to at least one embodiment of the present invention,
Concrete pile with double steel pipe as upper pile,
A lower pile connected to the upper pile,
With
The concrete pile with a double steel pipe,
A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow cylindrical cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
With
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. It is configured to bear the power,
A second end of the inner steel pipe is connected to the lower pile.

  According to the above configuration (24), by connecting the second end of the inner steel pipe to another pile, the second end of the inner steel pipe has a sufficient tensile strength as compared with the central part in the axial direction of the inner steel pipe. Axial force can be borne. For this reason, the concrete pile with a double steel pipe has sufficient bending strength not only at the center but also at the ends.

ADVANTAGE OF THE INVENTION According to this invention, the concrete pile with a double steel pipe whose sufficient bending strength is ensured also in the edge part is provided.
Further, according to the present invention, there is provided a method of manufacturing a concrete pile with a double steel pipe having a sufficient bending strength.
Further, according to the present invention, there is provided an apparatus for manufacturing a concrete pile with a double steel pipe having a sufficient bending strength.
Further, according to the present invention, a pile head joint structure of a concrete pile with a double steel pipe having sufficient bending strength is provided.
Further, according to the present invention, a joint pile structure of a concrete pile with a double steel pipe having a sufficient bending strength is provided.

It is a longitudinal section showing roughly composition of a concrete pile with a double steel pipe concerning one embodiment of the present invention. FIG. 2 is an enlarged view of a region II in FIG. 1. FIG. 3 is an enlarged view of a region III in FIG. 1. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. It is sectional drawing which shows schematically the WSC pile as another pile joined to the WSC pile as an upper pile. It is sectional drawing which expands and schematically shows the joint pile structure of the WSC pile which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows schematically the joint pile structure of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure for explaining the example of use of the WSC pile of Drawing 1. FIG. 14 is a sectional view schematically showing a PHC pile connectable to the WSC pile shown in FIG. 13. It is a sectional view showing roughly the pile head joint structure of the WSC pile concerning one embodiment of the present invention. It is sectional drawing which shows schematically the pile head joint structure of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. FIG. 30 is a sectional view schematically showing a pile head joint structure using the WSC pile of FIG. 29. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 2 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. FIG. 36 is a plan view schematically showing a first end plate of the WSC pile in FIG. 35. FIG. 36 is a plan view schematically showing a second end plate of the WSC pile in FIG. 35. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. It is a figure corresponding to FIG. 3 of the WSC pile which concerns on other embodiment of this invention. FIG. 41 is a schematic plan view of the second end plate side of the WSC pile of FIG. 40. FIG. 41 is a schematic plan view of a lid member used for the WSC pile in FIG. 40. FIG. 41 is a diagram for describing a use example of the WSC pile in FIG. 40. It is a figure corresponding to FIG. 1 of the WSC pile concerning other embodiments of the present invention. It is a flow chart for explaining a rough procedure of a manufacturing method of a WSC pile concerning an embodiment of the present invention. It is the schematic for demonstrating an example of an inner steel pipe insertion process. It is the schematic for demonstrating an example of a filling part formation process. It is a front view showing roughly the manufacturing device of the WSC pile concerning one embodiment of the present invention. FIG. 49 is a side view schematically showing the WSC pile manufacturing device of FIG. 48. FIG. 49 is a schematic diagram for describing a method of using the WSC pile manufacturing device in FIG. 48. FIG. 49 is a schematic diagram for describing a method of using the WSC pile manufacturing device in FIG. 48.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.
For example, the expression representing a shape such as a square shape or a cylindrical shape not only indicates a shape such as a square shape or a cylindrical shape in a strictly geometrical sense, but also an uneven portion or a chamfer within a range where the same effect can be obtained. A shape including a part and the like is also represented.

FIG. 1 is a longitudinal sectional view schematically showing a configuration of a concrete pile with a double steel pipe (hereinafter, also referred to as a WSC pile) 1 according to one embodiment of the present invention. FIG. 2 is an enlarged view of a region II in FIG. FIG. 3 is an enlarged view of a region III in FIG.
As shown in FIGS. 1 to 3, the WSC pile 1 </ b> A includes the outer steel pipe 3, the first end plate 5, the second end plate 7, the inner steel pipe 9, the concrete part 11, and the filling part 13. Have. In FIGS. 1 and 2, a plurality of reinforcing bars 14 are welded to the outer steel pipe 3 as fixing members (outer fixing members) for pile head joining.

The outer steel pipe 3 is hollow and has a cylindrical shape.
The first end plate 5 is attached to a first end of the outer steel pipe 3, and has a first opening 5a at the center. The first end 3a of the outer steel pipe 3 and the first end plate 5 are connected via a full penetration groove weld (outside complete penetration groove weld) 15 formed by full penetration groove welding. Have been. A backing 17 is provided on the inner surface side of the full penetration groove welding portion 15 for complete penetration groove welding.

  The second end plate 7 is attached to the second end of the outer steel pipe 3 and has a second opening 7a at the center. The second end 3b of the outer steel pipe 3 and the second end plate 7 are connected via a full penetration groove weld 15 formed by full penetration groove welding. The full penetration groove weld 15 extends over the entire circumference of the second end 3b of the outer steel pipe 3, but may be slightly interrupted. Note that a backing 17 is provided on the radially inner side of the full penetration groove welding portion 15 for complete penetration groove welding.

The inner steel pipe 9 has a hollow and cylindrical shape, and is arranged inside the outer steel pipe 3.
The concrete portion 11 is made of hollow cylindrical concrete, and is disposed between the outer steel pipe 3 and the inner steel pipe 9 in contact with the outer steel pipe 3.
The filling part 13 is arranged between the concrete part 11 and the inner steel pipe 9. The filling part 13 is made of grout or concrete such as cement or mortar, and is attached to the concrete part 11 and the inner steel pipe 9. That is, the filling section 13 may be made of a curable material.

For example, the concrete part 11 is formed by injecting concrete into the inside of the outer steel pipe 3 to which the first end plate 5 and the second end plate 7 are welded and curing after centrifugal molding. After the concrete portion 11 is formed, the filling portion 13 is configured by arranging the inner steel pipe 9 in the concrete portion 11 and then injecting a curable material between the inner steel pipe 9 and the concrete portion 11. Therefore, although not shown, for example, one or more injection holes for injecting the curable material into one or both of the first end plate 5 and the second end plate 7 are provided. The injection hole may be closed with a stopper or with a hardened curable material.
In addition, the formation method of the concrete part 11 and the filling part 13 is not limited to the said method, For example, after assembling the outer steel pipe 3, the 1st end plate 5, the 2nd end plate 7, and the inner steel pipe 9, these The concrete part 11 and the filling part 13 may be formed integrally by concrete-filling the inside of the container with vibration. That is, the concrete part 11 and the filling part 13 may be integrally formed.

  In the WSC pile 1A, the inner steel pipe 9 is configured to bear a tensile axial force when a bending moment acts on the WSC pile 1A. At least the first end 9a of the inner steel pipe 9 is more solid than when the fillet welding is performed between the first end 9a of the inner steel pipe 9 and the first end plate 5 when a tensile axial force acts on the inner steel pipe 9. Are also configured to be able to bear a large tensile axial force.

Specifically, the inner steel pipe 9 has substantially the same length as the outer steel pipe 3, and extends from the first end plate 5 to the second end plate 7. Then, the first end 9a of the inner steel pipe 9 and the first end plate 5 form a full penetration groove weld (first full penetration groove weld) 19 formed by full penetration groove welding. Connected through. The full penetration groove weld 19 connects the distal end face of the first end 9 a of the inner steel pipe 9 and the inner face of the first end plate 5, and extends over the entire circumference of the inner steel pipe 9. There may be some interruptions. A backing 21 is provided radially outside of the full penetration groove welding portion 19 for complete penetration groove welding.
On the other hand, the second end 9b of the inner steel pipe 9 and the second end plate 7 are connected via a fillet welded portion 23 formed by fillet welding. The fillet welded portion 23 connects the distal end surface of the second end 9 b of the inner steel pipe 9 and the inner peripheral surface of the second end plate 7, and extends over the entire circumference of the inner steel pipe 9. . However, the fillet weld 23 does not need to extend over the entire circumference, and may be partially interrupted.

Hereinafter, a method of manufacturing the WSC pile 1A will be described.
First, the first end plate 5 and the second end plate 7 are completely penetrated and welded to the outer steel pipe 3. Thereafter, concrete is injected into the outer steel pipe 3 and then centrifugally formed and cured to form a concrete portion 11. Then, the inner steel pipe 9 is inserted into the inside of the outer steel pipe 3 through the second opening 7a of the second end plate 7, and the first end 9a of the inner steel pipe 9 is completely penetrated into the first end plate 5 and bevel welded. The second end 9b of the inner steel pipe 9 is fillet welded to the second end plate 7. Thereafter, a filler is injected into a gap formed between the concrete portion 11 and the inner steel pipe 9 and hardened to form a filling portion 13. Thereby, the WSC pile 1A is completed.

  In order to insert the inner steel pipe 9, the second opening 7a of the second end plate 7 is larger in diameter than the inner steel pipe 9, and the inner steel pipe 9 is completely penetrated into the inner surface of the first end plate 5 to form a groove. For this purpose, the first opening 5 a of the first end plate 5 has a smaller diameter than the inner steel pipe 9. Furthermore, the rebar 14 is connected to the first end 3a of the outer steel pipe 3 at the construction site, for example, after the completion of the WSC pile 1A.

  According to the above-described WSC pile 1A, at least the first end 9a of the inner steel pipe 9 is connected to the first end 9a of the inner steel pipe 9 and the first end plate 5 when a tensile axial force acts on the inner steel pipe 9. Is configured to be able to bear a larger tensile axial force than when fillet welding is performed, so that the first end portion 9a of the inner steel pipe 9 has a sufficient tensile axial force even compared to the central portion of the inner steel pipe 9. Can bear. For this reason, the WSC pile 1A has a sufficient bending strength not only at the center in the axial direction but also at the end of the inner steel pipe 9 on the first end 9a side.

Here, when the first end 9a of the inner steel pipe 9 and the first end plate 5 are fillet welded, when a tensile axial force acts on the inner steel pipe 9, a shearing force acts on the fillet weld. Then, under the premise that the leg length of the fillet weld is set according to the thickness of the inner steel pipe 9, the throat thickness of the fillet weld is smaller than the thickness of the inner steel pipe 9.
On the other hand, the first end 9a of the inner steel pipe 9 and the first end plate 5 are joined via the full penetration groove weld 19, and a tensile axial force acts on the full penetration groove weld 19. In other words, when the front end surface of the first end portion 9a of the inner steel pipe 9 and the inner peripheral surface of the first end plate 5 are joined via a full penetration groove weld 19, the thickness of the inner steel pipe 9 or The cross-sectional area and the throat thickness or cross-sectional area of the full penetration groove weld 19 can be made equal.
For this reason, the tensile yield strength of the full penetration groove weld 19 becomes larger than the shear yield strength of the fillet weld and becomes substantially equal to the tensile yield strength of the inner steel pipe 9.

In consideration of the above circumstances, in the WSC pile 1A, the first end 9a of the inner steel pipe 9 and the first end plate 5 are joined via the full penetration groove welding portion 19, and the full penetration groove welding is performed. It is configured such that a tensile axial force acts on the portion 19, whereby the first end 9 a of the inner steel pipe 9 can bear a sufficient tensile axial force even compared to the axially central portion of the inner steel pipe 9. It is.
In the WSC pile 1A, the second end 9b of the inner steel pipe 9 and the second end plate 7 may not be connected.

Hereinafter, another embodiment of the present invention will be described. In the following description, configurations that are the same as or similar to those of the above-described embodiment will be given the same names or reference numerals, and descriptions thereof will be omitted or simplified.
FIG. 4 is a diagram corresponding to FIG. 3 of a WSC pile 1B according to another embodiment of the present invention. As shown in FIG. 4, the WSC pile 1B differs from the WSC pile 1A only in the means of connecting the second end 9b of the inner steel pipe 9 and the second end plate 7. In the WSC pile 1B, the outer peripheral surface of the second end 9b of the inner steel pipe 9 and the inner peripheral surface of the second end plate 7 are formed by a full penetration groove welding or a partial penetration groove welding. They are connected via a front welded portion 28. When a tensile axial force acts on the inner steel pipe 9, a shear force acts on the penetration groove weld 28.

In the manufacturing process of the WSC pile 1A, the WSC pile 1B connects the second end 9b of the inner steel pipe 9 and the second end plate 7 not by fillet welding but by full penetration groove welding or partial penetration groove welding. Can be manufactured.
The WSC pile 1B has the same operation and effect as the WSC pile 1A. However, the throat thickness of the penetration groove welding portion 28 can be greater than the thickness of the fillet weld portion 23 obtained by fillet welding the second end 9 b of the inner steel pipe 9 and the second end plate 7. . Therefore, the connection strength between the second end portion 9b of the inner steel pipe 9 of the WSC pile 1B and the second end plate 7 can be increased, and the second end of the inner steel pipe 9 of the WSC pile 1B can be compared with the WSC pile 1A. The tensile axial force that can be borne by the portion 9b can be increased.

FIGS. 5, 6, and 7 are diagrams corresponding to FIGS. 1, 2, and 3, respectively, of a WSC pile 1C according to another embodiment of the present invention.
As shown in FIGS. 5 to 7, the WSC pile 1 </ b> C differs from the WSC pile 1 </ b> A in that the first end 9 a of the inner steel pipe 9 projects outside through the first opening 5 a of the first end plate 5. ing. Therefore, the inner steel pipe 9 extends from the second end plate 7 to the outside through the first end plate 5 and is longer than the outer steel pipe 3.
To the first end 9a of the inner steel pipe 9, a reinforcing rod 29 as a fixing member (inner fixing member) for pile head joining can be attached. The reinforcing bar 29 is attached to the first end 9a of the inner steel pipe 9 by, for example, welding or mechanical bonding.
In the WSC pile 1C, the first end 9a of the inner steel pipe 9 is connected to the first end plate 5 via a fillet weld 30 formed by fillet welding. As long as the portion 9b and the second end plate 7 are connected as described below, the first end 9a and the first end plate 5 of the inner steel pipe 9 may not be connected.

  On the other hand, in the WSC pile 1C, the second end portion 9b of the inner steel pipe 9 has a full penetration groove welding portion (second full penetration groove welding) formed in the second end plate 7 by full penetration groove welding. ) 31 are connected. The full penetration groove weld 31 connects the distal end face of the second end 9b of the inner steel pipe 9 and the inner face of the second end plate 7 and extends over the entire circumference of the inner steel pipe 9. , May be interrupted somewhat. A backing 33 is provided on the radially outer side of the full penetration groove weld 31.

Hereinafter, a method of manufacturing the WSC pile 1C will be described.
In the method of manufacturing the WSC pile 1C, the inner steel pipe 9 is inserted into the outer steel pipe 3 through the first opening 5a of the first end plate 5, and the second end 9b and the second end plate 7 of the inner steel pipe 9 are completely melted. The method differs from the method of manufacturing the WSC pile 1A in that the first end portion 9a of the inner steel pipe 9 and the first end plate 5 are fillet welded.
In order to insert the inner steel pipe 9, the inner steel pipe 9 has a smaller diameter than the first opening 5 a of the first end plate 5, and completely connects the second end 9 b and the second end plate 7 of the inner steel pipe 9. The inner steel pipe 9 has a larger diameter than the second opening 7 a of the second end plate 7 for penetration groove welding. Further, the rebar 29 is connected to the first end 9a of the inner steel pipe 9 at the construction site, for example, after the completion of the WSC pile 1C.

According to the above-described WSC pile 1C, since the first end 9a of the inner steel pipe 9 projects outside through the first opening 5a of the first end plate 5, the first end 9a of the inner steel pipe 9 is connected to the outside. Can be connected to a member. Then, by connecting the first end 9a of the inner steel pipe 9 to an external member, the first end 9a of the inner steel pipe 9 can provide a sufficient tensile axial force even when compared to the axial center of the inner steel pipe 9. Can bear.
Further, according to the WSC pile 1C, the second end 9b of the inner steel pipe 9 and the second end plate 7 are joined via the second full penetration groove welding portion 31, and the second full penetration groove welding is performed. The configuration is such that a tensile axial force acts on the portion 31, whereby the second end 9 b of the inner steel pipe 9 can bear a sufficient tensile axial force even in comparison with the axially central portion of the inner steel pipe 9. It is.
Although the tensile yield strength is reduced, also in the WSC pile 1C, the second end 9b and the second end plate 7 of the inner steel pipe 9 are fillet welded and partially welded as shown in FIG. The connection may be made by a penetration groove welding or a full penetration groove welding. Further, the first end 9a of the inner steel pipe 9 can be connected to an external member, and if the first end 9a of the inner steel pipe 9 and the first end plate 5 are connected, the first end 9a of the inner steel pipe 9 can be connected. The second end 9b and the second end plate 7 need not be connected.

FIGS. 8, 9, and 10 are diagrams corresponding to FIGS. 1, 2, and 3, respectively, of a WSC pile 1D according to another embodiment of the present invention.
As shown in FIGS. 8 to 10, the WSC pile 1 </ b> D further includes a tension fitting 35 connected to the first end 9 a of the inner steel pipe 9, and the first end 9 a of the inner steel pipe 9 is It is joined to the fitting 35 via a full penetration groove weld (tensile full penetration groove weld) 37, and the complete penetration groove weld 37 is applied when a tensile axial force acts on the inner steel pipe 9. It is configured such that a tensile axial force acts.
The tensioning bracket 35 has a stepped cylindrical portion 35a and an outwardly directed flange portion 35b that are integrally formed, and the distal end surface of the first end 9a of the inner steel pipe 9 is completely formed on the stepped surface of the cylindrical portion 35a. Penetration groove welding is performed. The full penetration groove welded portion 37 extends over the entire circumference of the inner steel pipe 9, but may be slightly interrupted. The outward flange portion 35b is fixed to the first end plate 5 by, for example, a bolt in a state in which it contacts the outer surface of the first end plate 5.

In the method of manufacturing the WSC pile 1D, the inner steel pipe 9 is inserted into the outer steel pipe 3 through the first opening 5a of the first end plate 5, but the inner steel pipe 9 and the tension fitting 35 are inserted into the inner steel pipe 9. A full penetration groove welding may be performed beforehand, or a full penetration groove welding may be performed after the inner steel pipe 9 is inserted.
The tension fitting 35 may be connected to the first end plate 5 by fillet welding instead of a bolt. If the tension fitting 35 is fixed to the first end plate 5 by bolts or fillet welding, the WSC pile 1D can be easily manufactured. However, even if the tension fitting 35 is not fixed to the first end plate 5, the first end plate 5 is brought into contact with the outward flange 35 b of the tension fitting 35, so that the first end of the inner steel pipe 9. The portion 9a can bear the tensile axial force.

  According to the WSC pile 1D, the first end portion 9a of the inner steel pipe 9 is joined to the tension fitting 35 via the full penetration groove welding portion 37 for tension, and the full penetration groove welding portion for tension. 37 is configured so that the tensile axial force acts when the tensile axial force acts on the inner steel pipe 9, so that the first end 9 a of the inner steel pipe 9 is compared with the central part in the axial direction of the inner steel pipe 9. However, it is possible to bear a sufficient tensile axial force.

FIGS. 11 and 12 are diagrams corresponding to FIGS. 1 and 2 of a WSC pile 1E according to another embodiment of the present invention, respectively.
The WSC pile 1E is different from the WSC pile 1D in that the tension fitting 35 is mechanically joined to the inner steel pipe 9.
Specifically, a male screw is formed on the outer peripheral surface of the cylindrical portion 35a of the tension fitting 35 of the WSC pile 1E, and a female screw is formed on the inner peripheral surface of the first end 9a of the inner steel pipe 9. . By screwing the female screw of the first end 9a of the inner steel pipe 9 with the male screw of the tension fitting 35, the first end 9a of the inner steel pipe 9 is mechanically joined to the tension fitting 35.

In the method for manufacturing the WSC pile 1E, the inner steel pipe 9 is inserted into the outer steel pipe 3 through the first opening 5a of the first end plate 5, but the inner steel pipe 9 and the tension fitting 35 are inserted into the inner steel pipe 9. Mechanical joining may be performed beforehand, or mechanical joining may be performed after the inner steel pipe 9 is inserted.
According to the WSC pile 1E, the first end 9a of the inner steel pipe 9 is mechanically joined to the tension fitting 35, and the mechanical joining is such that when a tensile axial force acts on the inner steel pipe 9, the tensile axial force is reduced. Since it is configured to act, the first end 9a of the inner steel pipe 9 can bear a sufficient tensile axial force as compared with the central part of the inner steel pipe 9 in the axial direction.

FIGS. 13, 14, and 15 are diagrams corresponding to FIGS. 1, 2, and 3, respectively, of a WSC pile 1F according to another embodiment of the present invention.
As shown in FIGS. 13 to 15, the outer peripheral surface of the second end 9 b of the inner steel pipe 9 has a penetration groove weld 28 formed by full penetration groove welding or partial penetration groove welding. It is connected to the inner peripheral surface of the second end plate 7 via the same. The first end 9a of the inner steel pipe 9 is configured to be connectable to an adapter member 41 for mounting the fixing member 29 for pile head connection. The adapter member 41 has a hollow and cylindrical shape, and the fixing member 29 can be welded or mechanically joined to the outer peripheral surface of the adapter member 41.

The WSC pile 1F inserts the inner steel pipe 9 into the outer steel pipe 3 through the first opening 5a of the first end plate 5 or the second opening 7a of the second end plate 7, and connects the second end 9b of the inner steel pipe 9 with the second end 9b. It is manufactured by full penetration groove welding or partial penetration groove welding with the two end plates 7.
Further, the outer peripheral surface of the first end portion 9a of the inner steel pipe 9 and the inner peripheral surface of the first end plate 5 may be completely penetration groove welded or partially penetration groove welded. The outer peripheral surface of the first end 9a of the inner steel pipe 9 and the inner peripheral surface of the first end plate 5 are completely penetrated and opened, not the outer peripheral surface of the second end 9b and the inner peripheral surface of the second end plate 7. Pre-welding or partial penetration groove welding may be used. That is, the first end portion 9a or the second end portion 9b of the inner steel pipe 9 may be connected to the first end plate 5 or the second end plate 7 in consideration of the manufacturing process of the WSC pile 1F.

  According to the WSC pile 1F, the first end 9a of the inner steel pipe 9 is connected to the first end 9a of the inner steel pipe 9 by connecting the adapter member 41 for attaching the anchoring member 29 for joining the pile head. It can be connected to the fixing member 29 for joining. Thus, the first end portion 9a of the inner steel pipe 9 can bear a sufficient tensile axial force even when compared with the central portion of the inner steel pipe 9 in the axial direction.

  Further, in the WSC pile 1F, the first end 9a of the inner steel pipe 9 can be mechanically joined to the adapter member 41. Specifically, a female screw is formed on the inner peripheral surface of the first end 9 a of the inner steel pipe 9, and a male screw is formed on the outer peripheral surface of the adapter member 41. By screwing the female screw on the inner peripheral surface of the first end 9a of the inner steel pipe 9 and the male screw on the outer peripheral surface of the adapter member 41, the adapter member 41 can be easily attached to the first end 9a of the inner steel pipe 9. Connected.

Further, in the WSC pile 1F, the second end 9b of the inner steel pipe 9 is configured to be connectable to another pile.
For this reason, according to the WSC pile 1F, by joining the second end 9b of the inner steel pipe 9 to another pile, the second end 9b of the inner steel pipe 9 is compared with the central part in the axial direction of the inner steel pipe 9. Can also bear sufficient tensile axial force.

In the WSC pile 1F, the second end 9b of the inner steel pipe 9 can be mechanically connected to another pile. Specifically, a female screw is formed on the inner peripheral surface of the second end 9 b of the inner steel pipe 9.
On the other hand, FIG. 16 is a cross-sectional view schematically showing a WSC pile 1G as another pile (lower pile) joined to the WSC pile 1F as the upper pile. FIG. 17 is a cross-sectional view schematically showing an enlarged connection structure (joint pile structure of the WSC pile) between the WSC pile 1F and the WSC pile 1G.

As shown in FIGS. 16 and 17, in the WSC pile 1 </ b> G, the first end 9 a of the inner steel pipe 9 projects outside from the first opening 5 a of the first end plate 5. A male screw is formed on the outer peripheral surface of the first end 9 a of the inner steel pipe 9. The male screw of the WSC pile 1G can be screwed with the female screw of the second end portion 9b of the inner steel pipe 9 of the WSC pile 1F. 1G is mechanically joined.
According to the WSC pile 1F and the WSC pile 1G, the inner steel pipes 9 can be easily joined to each other by mechanically joining the inner steel pipes 9 to each other. Then, by connecting the inner steel pipes 9 to each other, the second end 9b of the inner steel pipe 9 of the WSC pile 1F and the first end 9a of the inner steel pipe 9 of the WSC pile 1G can sufficiently bear the tensile axial force. is there.

As shown in FIG. 17, the outer peripheral portion of the second end plate 7 of the WSC pile 1F and the outer peripheral portion of the first end plate 5 of the WSC pile 1F are completely penetrated or partially penetrated. Joined by welding. Therefore, the second end 3b of the outer steel pipe 3 of the WSC pile 1F and the first end 3a of the WSC pile 1G can sufficiently bear the tensile axial force.
The outer peripheral portion of the second end plate 7 of the WSC pile 1F and the outer peripheral portion of the first end plate 5 of the WSC pile 1F may be mechanically joined.

FIG. 18 is an enlarged cross-sectional view schematically showing a connection structure (joint pile structure of a WSC pile) between a WSC pile 1F as an upper pile and a WSC pile 1H as another pile (lower pile).
As shown in FIG. 18, in the WSC pile 1H, the first end 9a of the inner steel pipe 9 does not protrude from the first opening 5a of the first end plate 5, and the inside of the first end 9a of the inner steel pipe 9 It differs from the WSC pile 1G in that a female screw is formed on the peripheral surface. The inner steel pipe 9 of the WSC pile 1F and the inner steel pipe 9 of the WSC pile 1H are connected via a hollow and cylindrical connecting fitting 43. A male screw is formed on the outer peripheral surface of the connection metal fitting 43, and the male screw of the connection metal fitting 43 is a female screw of the second end 9b of the inner steel pipe 9 of the WSC pile 1F and the inner steel pipe 9 of the WSC pile 1H. Can be screwed with the female screw of the first end 9a, and by screwing these, the inner steel pipe 9 of the WSC pile 1F and the inner steel pipe 9 of the WSC pile 1H are connected.
According to the WSC pile 1F and the WSC pile 1H, the inner steel pipes 9 can be easily joined to each other by mechanically joining the inner steel pipes 9 by using the connection fitting 43.

FIG. 19 is a diagram corresponding to FIG. 2 of a WSC pile 1J according to another embodiment of the present invention.
In the WSC pile 1J shown in FIG. 19, the first end 9a of the inner steel pipe 9 protruding from the first opening 5a of the first end plate 5 is for attaching a reinforcing bar (inside anchoring member) 29 for joining the pile head. Mechanical connection with the adapter member 41 of FIG.
Specifically, in the WSC pile 1J, the inner steel pipe 9 is longer than the outer steel pipe 3, and the first end 9a of the inner steel pipe 9 projects outside from the first opening 5a of the first end plate 5. A male screw is formed on the outer peripheral surface of the first end 9a of the inner steel pipe 9. On the other hand, the adapter member 41 has a hollow cylindrical portion 41a having a hollow cylindrical shape, and an outward flange portion 41b formed integrally with the cylindrical portion 41a, and a female screw is formed on an inner peripheral surface of the cylindrical portion 41a. I have. The female screw of the cylindrical portion 41a of the adapter member 41 can be screwed with the male screw of the first end 9a of the inner steel pipe 9, and the outward flange 41b of the adapter 41 is bolted to the first end plate. 5 can be fixed.
Note that the adapter member 41 may be attached to the inner steel pipe 9 on site.

According to the WSC pile 1J, the first end 9a of the inner steel pipe 9 is connected to the first end 9a of the inner steel pipe 9 by connecting the adapter member 41 for attaching the inner fixing member 29 for pile head joining. It can be connected to the inner fixing member 29 for head joining. Thus, the first end portion 9a of the inner steel pipe 9 can bear a sufficient tensile axial force even when compared with the central portion of the inner steel pipe 9 in the axial direction.
In the WSC pile 1J, the adapter member 41 is fixed to the first end plate 5 by bolts, but may not be fixed. In addition, although the adapter member 41 has the outward flange portion 41b, it does not have to have it.

FIG. 20 is a diagram corresponding to FIG. 2 of a WSC pile 1K according to another embodiment of the present invention.
In the WSC pile 1K shown in FIG. 20, the first end 9a of the inner steel pipe 9 protruding from the first opening 5a of the first end plate 5 is provided with an adapter member 41 for attaching the reinforcing bar 29 for pile head joining. Welding is possible.
Specifically, in the WSC pile 1K, a step surface is formed on the outer peripheral surface of the hollow and cylindrical adapter member 41, and the tip end surface of the first end 9a of the inner steel pipe 9 is formed on the step surface of the adapter member 41. On the other hand, it is connected via a full penetration groove weld (a full penetration groove weld for an adapter) 45 formed by full penetration groove welding over the entire circumference. For complete penetration groove welding, the inner steel pipe 9 is longer than the outer steel pipe 3, and the end face of the first end 9 a of the inner steel pipe 9 projects from the first opening 5 a of the first end plate 5. I have. Further, the complete penetration groove welding portion 45 for the adapter may be slightly interrupted.

  According to the WSC pile 1K, the adapter member 41 for attaching the inner fixing member 29 for pile head joining is connected to the first end 9a of the inner steel pipe 9 via the full penetration groove welding portion 45 for the adapter. Thus, the first end 9a of the inner steel pipe 9 can be connected to the inner fixing member 29 for joining the pile head. Thus, the first end portion 9a of the inner steel pipe 9 can bear a sufficient tensile axial force even when compared with the central portion of the inner steel pipe 9 in the axial direction.

FIG. 21 is a diagram corresponding to FIG. 2 of a WSC pile 1L according to another embodiment of the present invention.
As shown in FIG. 21, in the WSC pile 1L, the cylindrical portion 35a of the tension fitting 35 projects outward, and a protrusion 47 as a fixing member for pile head joining is provided at the outer end of the cylindrical portion 35a. It differs from the WSC pile 1E in that it is provided. The protrusion 47 is made of, for example, a reinforcing bar welded to the outer end of the cylindrical portion 35a. In the case of the WSC pile 1L, it can be said that the tension fitting 35 constitutes the adapter member 41.

FIG. 22 is a diagram corresponding to FIG. 2 of a WSC pile 1M according to another embodiment of the present invention.
As shown in FIG. 22, the WSC pile 1M is provided with an outer fixing member joining portion 48 for mechanically attaching the reinforcing bar 14 as a fixing member (outer fixing member) for pile head joining to the outer steel pipe 3. In this point, it differs from the WSC pile 1F. Specifically, a male screw is formed as an outer fixing member joining portion 48 on the outer peripheral surface of the first end 3a of the outer steel tube 3 located on the first end 9a side of the inner steel tube 9. On the other hand, the plurality of reinforcing bars 14 are fixed to the outer peripheral surface of the cylindrical joining ring 49, and female threads are formed on the inner peripheral surface of the joining ring 49. The female screw of the joining ring 49 can be screwed with a male screw as the outer fixing member joining portion 48 of the outer steel pipe 3.
According to the WSC pile 1M, the outer fixing member 14 can be easily attached to the outer steel tube 3 by providing the outer fixing member joining portion 48 to the outer steel tube 3.

FIG. 23 is a diagram corresponding to FIG. 1 of a WSC pile 1N according to another embodiment of the present invention.
As shown in FIG. 23, in the WSC pile 1N, the second end portion 9b of the inner steel pipe 9 is not connected to the second end plate 7 and is separated, and a projection 51 is provided on the outer peripheral surface of the inner steel pipe 9. In that it differs from the WSC pile 1C. The protrusion 51 is made of, for example, a reinforcing bar welded to the inner steel pipe 9.

In the WSC pile 1N, the adhesion between the inner steel pipe 9 and the filling portion 13 is improved by embedding the protrusion 51 in the filling portion 13. For this reason, when a bending moment acts on the inner steel pipe 9, the second end 9b of the inner steel pipe 9 can sufficiently bear the bending moment as compared with the central part in the axial direction.
In the WSC pile 1N, the inner diameter of the second opening 7a of the second end plate 7 is larger than the outer diameter of the projection 51 in order to pass the inner steel pipe 9 having the projection 51, and the second end 9b of the inner steel pipe 9 is formed. An annular gap between the second end plate 7 and the second opening 7a forms a filler injection hole.
In addition, the protrusion 51 is not limited to a reinforcing bar. For example, when the inner steel pipe 9 is a spiral steel pipe, the protrusion 51 may be formed by a spirally extending welded portion. Alternatively, when the inner steel pipe 9 is formed of a striped steel plate, the protrusion may be formed by unevenness on the surface of the striped steel plate.

FIG. 24 is a view corresponding to FIG. 1 of a WSC pile 1P according to another embodiment of the present invention.
As shown in FIG. 24, the WSC pile 1P differs from the WSC pile 1A in that the first end 9a of the inner steel pipe 9 is configured to be mechanically connectable to the adapter member 41.
Specifically, a female screw is formed on the inner peripheral surface of the first end 9 a of the inner steel pipe 9, and a male screw is formed on the outer peripheral surface of the cylindrical portion 41 a of the adapter member 41. By screwing the female screw of the inner steel pipe 9 and the male screw of the adapter member 41, the first end 9a of the inner steel pipe 9 and the adapter member 41 can be mechanically joined.

According to the WSC pile 1P, the distal end face of the first end 9a of the inner steel pipe 9 is completely penetrated and welded to the inner face of the first end plate 5, and the adapter member 41 is attached to the first end 9a of the inner steel pipe 9. By joining and connecting the first end 9a of the inner steel pipe 9 to the fixing member 29, the first end 9a of the inner steel pipe 9 can bear a sufficient tensile axial force as compared with the central part in the axial direction. .
The second end 9b of the inner steel pipe 9 can be completely penetrated and welded to the inner surface of the second end plate 7 by welding the tip end face of the second end 9b of the inner steel pipe 9 like the WSC pile 1E shown in FIG. By forming a female screw on the inner peripheral surface of the end 9b, another WSC pile 1G can be mechanically joined to the second end 9b of the inner steel pipe 9.

FIG. 25 is a diagram for describing a usage example of the WSC pile 1A.
As shown in FIG. 25, the WSC pile 1 </ b> A may be capable of mechanically joining or welding the adapter member 41 for attaching the inner fixing member 29 for pile head joining to the first end plate 5. By attaching the inner fixing member 29 to the WSC pile 1A via the first end plate 5 in this manner, the first end 9a of the inner steel pipe 9 can bear a sufficient tensile axial force as compared with the central portion in the axial direction. It is.

FIG. 26 is a cross-sectional view schematically showing a PHC pile (prestressed high-strength concrete pile) 55 connectable to the WSC pile 1F shown in FIG. As shown in FIG. 26, the PHC pile 55 has a male screw 72 that can be mechanically joined to the inner steel pipe 9 of the WSC pile 1F. The male screw 72 is provided integrally with the first end plate 5 of the PHC pile 55.
When a pile mechanically connectable to the inner steel pipe 9 like the PHC pile 55 is connected to the WSC pile 1F, the second end 9b of the inner steel pipe 9 of the WSC pile 1F has a sufficient tension compared to the central part in the axial direction. Axial force can be borne. That is, the piles that can be connected to the WSC pile 1F to form the joint pile structure of the WSC piles are not limited to the WSC piles, but are SC piles (concrete piles with outer steel pipes), PHC piles, or PC piles ( (Prestressed concrete pile) or the like.

  In the PHC pile 55, a male screw is provided integrally with the first end plate 5, but a male screw may be provided separately and fixed to the first end plate 5 using a bolt or the like. In addition, a female screw may be provided integrally with the first end plate 5, and the WSC pile 1F and the PHC pile 55 may be connected using the connection fitting 43 as shown in FIG.

FIG. 27 is a cross-sectional view schematically showing a pile head joint structure (hereinafter, also simply referred to as a pile head joint structure) 60A of the WSC pile according to one embodiment of the present invention.
The pile head joint structure 60A includes a WSC pile 1C, an outer fixing member 14 and an inner fixing member 29 attached to ends of the WSC pile 1C, and a concrete block 62 surrounding the outer fixing member 14 and the inner fixing member 29. ing. The concrete block 62 is, for example, a pile cap or a footing, and the WSC pile 1C can support the upper structure via the concrete block 62.

According to the pile head joint structure 60A, the first end 9a of the inner steel pipe 9 is connected (rigidly joined) to the concrete block 62 via the inner anchoring member 29, so that the first end 9a of the inner steel pipe 9 is connected. However, a sufficient tensile axial force can be borne even in comparison with the central portion of the inner steel pipe 9 in the axial direction. For this reason, the WSC pile 1C has a sufficient bending strength not only at the center in the axial direction but also at the end on the concrete block 62 side.
In addition, by providing the inner fixing member 29 in the concrete block 62, the bending strength of the concrete block 62 (the bending strength of the pile head joint) can be improved.
In addition, although the pile head joint structure 60A had the WSC pile 1C, it may have the WSC piles 1F, 1J, 1K, 1L, 1M, 1N, 1P, and as shown in FIG. The WSC pile 1A may be provided as long as the fixing member 29 can be attached.

FIG. 28 is a cross-sectional view schematically illustrating a pile head joint structure 60B of a WSC pile according to another embodiment of the present invention. As shown in FIG. 28, the pile head joint structure 60B is different from the pile head joint structure 60A in that the pile head joint structure 60B does not have the outer fixing member 14.
According to the pile head joint structure 60B, since only the inner fixing member 29 connected so that a tensile axial force acts on the inner steel pipe 9 is surrounded by the concrete block 62, the concrete block 62 and the WSC pile 1C are connected. Semi-rigid connection is possible.

FIG. 29 is a view corresponding to FIG. 1 of a WSC pile 1Q according to another embodiment of the present invention.
As shown in FIG. 29, the WSC pile 1 </ b> Q has one or more, preferably two or more projections 74 attached to the inner surface of the first end 9 a of the inner steel pipe 9, and the first end 3 a of the outer steel pipe 3. Is different from the WSC pile 1A in that one or more, preferably two or more projections 76 are attached to the outer surface of the WSC pile 1A.
The projections 74 and 76 are each formed by an annular ring or an arc-shaped member, and are fixed to the inner surface of the first end 9a of the inner steel pipe 9 or the outer surface of the first end 3a of the outer steel pipe 3 by welding or bolts. I have. The protrusion 74 protrudes radially inward from the inner surface of the first end 9 a of the inner steel pipe 9, and the protrusion 76 protrudes radially outward from the outer surface of the first end 3 a of the outer steel pipe 3. When a plurality of projections 74 and 76 are attached, the projections 74 and 76 are arranged at intervals in the axial direction of the inner steel pipe 9 and the outer steel pipe 3.
In the WSC pile 1Q, the reinforcing bar 14 may be attached to the outer steel pipe 3 instead of the projection 76.

FIG. 30 is a cross-sectional view schematically showing a pile head joint structure 60C using the WSC pile 1Q.
In the pile head joint structure 60C, the pile head of the WSC pile 1Q is buried in the concrete block 62 by a length (inset depth) corresponding to the outer diameter D of the WSC pile 1Q. Since the concrete block 62 is attached to the projections 74 and 76, when the concrete block 62 is inclined by a horizontal force, the tensile axial force is applied to the first end 9 a of the inner steel pipe 9 and the first end 9 a of the outer steel pipe 3. Acts on end 3a. That is, the protrusions 74 and 76 constitute an inner fixing member and an outer fixing member for pile head joining, respectively.

According to the WSC pile 1Q, one or more projections 74 are provided on the inner surface of the first end 9a of the inner steel pipe 9, and the projections 74 are embedded in the concrete block 62, so that the first end 9a of the inner steel pipe 9 is provided. Can bear a sufficient tensile axial force as compared with the central portion in the axial direction. In addition, by not using the reinforcing bar 29, the overlaid reinforcing bars in the concrete block 62 are prevented, and the reinforcing bars are easily arranged.
In addition, the swallowing depth is not limited to 1D, and may be 0.5D or more and 3D or less. In this case, the one or more protrusions 74 and 76 are provided in the axial direction of the inner steel pipe 9 and the outer steel pipe 3 within a range of 0.5D or more and 3D or less from the upper end of the WSC pile 1Q.

FIG. 31 is a diagram corresponding to FIG. 2 of a WSC pile 1R according to another embodiment of the present invention. As shown in FIG. 31, the WSC pile 1R is different from the WSC pile 1A in that the first end plate 5 and the second end plate 7 are replaced with the backings 17, 21 separately from the first end plate 5, The difference is that a step is formed in the plate 5 and the second end plate 7, and the backing is integrally formed by the step of the first end plate 5 and the second end plate 7.
According to the WSC pile 1R, there is no need to prepare separate backings 17, 21 and the inner steel pipe 9 and the outer steel pipe 3 can be easily welded to the first end plate 5 and the second end plate 7. it can.

FIG. 32 is a view corresponding to FIG. 2 of a WSC pile 1S according to another embodiment of the present invention. As shown in FIG. 32, when the WSC pile 1S is compared with the WSC pile 1R, a female screw is formed on the inner surface of the first opening 5a of the first end plate 5, and the first end 9a of the inner steel pipe 9 is formed. A male screw is formed on the outer surface of the inner steel pipe 9, and the female screw and the male screw are screwed together to mechanically join the first end plate 5 and the first end 9a of the inner steel pipe 9.
According to the WSC pile 1S, the first end plate 5 and the first end 9a of the inner steel pipe 9 are mechanically joined to each other, so that the first end 9a of the inner steel pipe 9 is compared with the central part in the axial direction. It can bear a sufficient tensile axial force.

FIG. 33 is a diagram corresponding to FIG. 2 of a WSC pile 1T according to another embodiment of the present invention. As shown in FIG. 33, when compared with the WSC pile 1R, the WSC pile 1T has an outer peripheral surface of the first end 9a of the inner steel pipe 9 and an inner peripheral surface of the first opening 5a of the first end plate 5. Are connected via a partial penetration groove weld 82 formed by partial penetration groove welding.
According to the WSC pile 1T, by making the throat thickness of the partial penetration groove welding portion 82 sufficiently large, the first end plate 5 and the first end portion 9a of the inner steel pipe 9 are more fillet-welded than in the case of fillet welding. The first end portion 9a of the inner steel pipe 9 can bear a sufficient tensile axial force as compared with the central portion in the axial direction.

  FIG. 34 is a diagram corresponding to FIG. 2 of a WSC pile 1U according to another embodiment of the present invention. As shown in FIG. 34, in the WSC pile 1U, when compared with the WSC pile 1D, the tension fitting 35 has a disk shape, and a male tapered surface 35c is formed on the outer peripheral surface of the tension fitting 35, The difference is that a female tapered surface 5c is formed in the first opening 5a of the one end plate 5. The male tapered surface 35c of the tension fitting 35 contacts the female tapered surface 5c of the first end plate 5 from outside. Further, the tension fitting 35 is connected to the inner periphery of the tension fitting 35 via a complete penetration groove weld 37.

  According to the WSC pile 1U, since the male taper surface 35c of the tension fitting 35 abuts against the female taper surface 5c of the first end plate 5 from the outside, the first end 9a of the inner steel pipe 9 is axially centered. Thus, a sufficient tensile axial force can be borne. In addition, since the male tapered surface 35c of the tension fitting 35 abuts against the female tapered surface 5c of the first end plate 5 from the outside, regardless of the variation in the length of the inner steel pipe 9 and the processing accuracy, The male tapered surface 35c of the tension fitting 35 can be reliably brought into contact with the female tapered surface 5c of the first end plate 5. As a result, the first end 9a of the inner steel pipe 9 can surely bear a sufficient tensile axial force as compared with the central portion in the axial direction.

Further, since the male tapered surface 35c of the tension fitting 35 is in contact with the female tapered surface 5c of the first end plate 5 from the outside, the inner steel pipe 9 is surely arranged concentrically with the outer steel pipe 3. be able to.
Further, in the WSC pile 1U, the inner diameter of the first end plate 5 and the inner diameter of the concrete portion 11 are the same, and the difference between the outer diameter of the inner steel pipe 9 and the inner diameter of the first end plate 5 is large. Therefore, in the manufacturing process of the WSC pile 1U, the inner steel pipe 9 can be easily inserted inside the outer steel pipe 3.

FIG. 35 is a view corresponding to FIG. 1 of a WSC pile 1V according to another embodiment of the present invention. FIG. 36 is a diagram corresponding to FIG. 3 of the WSC pile 1V.
As shown in FIGS. 35 and 36, the WSC pile 1V is different from the WSC pile 1A in that the second end 9b of the inner steel pipe 9 projects outside through the second opening 7a of the second end plate 7. Is different.
According to the WSC pile 1V, since the second end 9b of the inner steel pipe 9 projects outside through the second opening 7a of the second end plate 7, the inner steel pipe 9 is directly or indirectly connected to the second end plate. 7 can be easily fixed. For example, in the WSC pile 1V, the inner steel pipe 9 and the second end plate 7 are joined by a fillet weld 23 formed by fillet welding.

FIG. 37 is a plan view schematically showing the first end plate 5 of the WSC pile 1V.
In some embodiments, as shown in FIG. 37, the first end plate 5 has an injection hole 84 for injecting a hardening material to be the filling portion 13 between the concrete portion 11 and the inner steel pipe 9. Have. The injection hole 84 is located between the concrete part 11 and the inner steel pipe 9 in the radial direction of the first end plate 5.
According to the above configuration, since the injection hole 84 is provided in the first end plate 5, the curable material can be easily injected between the concrete portion 11 and the inner steel pipe 9 with a simple configuration. .

In some embodiments, the first end plate 5 has an air vent 86 for evacuating air during injection of the hardening material to be the filling portion 13 between the concrete portion 11 and the inner steel pipe 9. The air vent hole 86 is located between the concrete part 11 and the inner steel pipe 9 in the radial direction of the first end plate 5. When the injection hole 84 is provided on one end side (first end plate 5), the air vent hole 86 is also preferably provided on one end side (first end plate 5). 86 are preferably arranged apart from each other in the diameter direction of the first end plate 5.
According to the above configuration, since the air vent hole 86 is provided in the first end plate 5, it is possible to easily inject the hardening material between the concrete portion 11 and the inner steel pipe 9 with no gap with a simple configuration. Can be.

FIG. 38 is a plan view schematically showing the second end plate 7 of the WSC pile 1V.
In some embodiments, as shown in FIG. 37, the second end plate 7 is capable of forming an excess hardening material during the injection of the hardening material serving as the filling portion 13 between the concrete portion 11 and the inner steel pipe 9. It has a discharge hole 88 for discharging the material. The discharge hole 88 is located between the concrete part 11 and the inner steel pipe 9 in the radial direction of the second end plate 7. When the first end plate 5 is provided with the injection hole 84 and the second end plate 7 is provided with the discharge hole 88, the injection hole 84 and the discharge hole 88 are connected to the first end plate 5 or the second end plate. 7 are preferably spaced apart from one another in the diametric direction. When the injection hole 84 is provided on one end side (first end plate 5) of the WSC pile 1V, the discharge hole 88 is provided on the other end side (second end plate 7) of the WSC pile 1V. Is preferred.

According to the above configuration, the discharge hole 88 is provided in the second end plate 7, and by confirming the outflow of the curable material from the discharge hole 88, the concrete portion 11 and the inner steel pipe 9 can be formed with a simple configuration. It can be easily determined whether or not the curable material has been sufficiently filled.
Note that the air vent hole 86 is for discharging air between the concrete portion 11 and the inner steel pipe 9, and the discharge hole 88 is for discharging surplus curable material. The excess curable material may be discharged together with the air through the through hole, and the air may be discharged together with the curable material through the discharge hole 88.

FIG. 39 is a view corresponding to FIG. 3 of a WSC pile 1W according to another embodiment of the present invention.
As shown in FIG. 39, in the WSC pile 1W, the diameter of the second opening 7a of the second end plate 7 is larger than the outer diameter of the inner steel pipe 9, and is disposed between the inner steel pipe 9 and the second end plate 7. The difference from the WSC pile 1V is that the cover member 90 further includes a covered lid member 90.

  According to the above configuration, the second opening 7a of the second end plate 7 is larger in diameter than the outer diameter of the inner steel pipe 9, and a gap is secured between the second end plate 7 and the inner steel pipe 9. The inner steel pipe 9 can be easily inserted into the concrete part 11 through the second opening 7a of the second end plate 7. On the other hand, by attaching a ring-shaped lid member 90 in a plan view to the gap between the inner steel pipe 9 and the second end plate 7, the gap between the second end plate 7 and the inner steel pipe 9 can be substantially closed. A cylindrical space can be defined between the concrete part 11 and the inner steel pipe 9.

In some embodiments, as shown in FIG. 39, the outer surface of the second end plate 7 and the outer surface of the lid member 90 are flush with each other, and the inner peripheral edge of the lid member 90 and the inner steel pipe 9 are fillet welded. The outer peripheral edge of the lid member 90 and the second end plate 7 are joined to each other by a fillet weld 23 formed by the following method. They are joined together by 92.
When the outer surface of the second end plate 7 and the outer surface of the lid member 90 are arranged flush with each other, the lid member groove welding portion 92 does not project from the outer surface of the second end plate 7 or the outer surface of the lid member 90. It is preferable to cut or grind after welding.

FIG. 40 is a diagram corresponding to FIG. 3 of a WSC pile 1X according to another embodiment of the present invention. FIG. 41 is a schematic plan view on the second end plate 7 side of the WSC pile 1X. FIG. 42 is a schematic plan view of the lid member 90 used for the WSC pile 1X.
As shown in FIG. 40, in the WSC pile 1X, the outer surface of the second end plate 7 is located outside the outer surface of the lid member 90 in the axial direction of the inner steel pipe 9, and the outer peripheral edge of the lid member 90 The second end plate 7 is different from the WSC pile 1W in that the second end plate 7 is joined by a cover member fillet weld 94 formed by fillet welding.

  According to the above configuration, even when the lid member 90 and the second end plate 7 are fillet-welded, the lid member fillet weld 94 formed thereby protrudes outward from the outer surface of the second end plate 7. Can be prevented. Therefore, when the WSC pile 1X is connected to another pile, the outer surface of the second end plate 7 can be brought into direct contact with the end plate or the like of another pile without interference of the lid fillet weld 94. .

In some embodiments, as shown in FIGS. 40 to 42, the discharge hole 88 is provided in the lid member 90 instead of the second end plate 7.
According to the above configuration, even if the second opening 7a of the second end plate 7 is larger in diameter than the outer diameter of the inner steel pipe 9 and the second end plate 7 does not have sufficient space, the discharge hole 88 is provided. Can be.
In the case where the radial length of the lid member 90 is short, the discharge hole 88 is formed by a notch provided on the outer peripheral edge of the lid member 90 as shown in FIG. When the cover member 90 is long, the discharge hole 88 may be formed by a through-hole separated from the outer peripheral edge of the lid member 90.

  In the above-described embodiment, the injection hole 84 and the air vent 86 are provided in the first end plate 5, and the discharge hole 88 is provided in the second end plate 7 or the cover member 90. The arrangement of the hole 86 and the discharge hole 88 is not limited to this, and the injection hole 84, the air vent hole 86, and the discharge hole 88 may be appropriately provided in the first end plate 5, the second end plate 7, or the lid member 90, respectively. Can be. Alternatively, the injection hole 84, the air vent hole 86, or the discharge hole 88 may be provided in the inner steel pipe 9. In this case, it is preferable that the injection hole 84 and the air vent hole 86 are provided at one end of the inner steel pipe 9, and the discharge hole 88 is provided at the other end of the inner steel pipe 9. In this case, in the filling section forming step S26 described later, the outer steel pipe 3 is horizontally positioned so that the injection hole 84 is located at the bottom of the inner steel pipe 9 and the air vent hole 86 and the discharge hole 88 are located at the top of the inner steel pipe 9. Alternatively, it is preferable to arrange them at an angle.

FIG. 43 is a diagram for describing a usage example of the above-described WSC pile 1X.
As shown in FIG. 43, when the WSC pile 1X is used as an upper pile and another pile, for example, a PHC pile 96 is connected under the WSC pile 1X, the second end 9b of the inner steel pipe 9 of the WSC pile 1X. Is inserted into the first opening 5a of the first end plate 5 of the PHC pile 96 with a gap. Then, the second end plate 7 of the WSC pile 1X and the first end plate 5 of the PHC pile 96 are joined to each other by welding or mechanical joining.
According to the above-described configuration, even if the second end 9b of the inner steel pipe 9 projects, the second end 9b of the inner steel pipe 9 is inserted into the first opening 5a of the first end plate 5 of another pile. Thus, the WSC pile 1X and other piles can be easily connected.
The other piles connected to the WSC pile 1X are not limited to PHC piles, and may be other WSC piles, SC piles, PC piles, or the like. When the WSC pile 1X is connected to another WSC pile, the diameter of the first opening 5a of the first end plate 5 of the other WSC pile is designed so as to receive the inner steel pipe 9 of the WSC pile 1X. .

FIG. 44 is a view corresponding to FIG. 1 of a WSC pile 1Y according to another embodiment of the present invention.
As shown in FIG. 44, in the WSC pile 1 </ b> Y, the second end 9 b of the inner steel pipe 9 is closer to the first end 9 a of the inner steel pipe 9 than the second end plate 7 in the axial direction of the inner steel pipe 9. , And is different from the WSC pile 1A in that a projection 51 is provided on the outer peripheral surface of the inner steel pipe 9. That is, the inner steel pipe 9 is shorter than the outer steel pipe 3 and the concrete part 11, and the projection 51 functions as a slip stopper for preventing the relative shift of the filling part 13 in the axial direction of the inner steel pipe 9.

  According to the above configuration, even if the second end 9 b of the inner steel pipe 9 is not joined to the second end plate 7, the relative displacement of the inner steel pipe 9 with respect to the filling portion 13 is prevented by the stopper. Therefore, when a tensile force or a compressive force acts on the outer steel pipe 3, the inner steel pipe 9 can also bear the tensile force or the compressive force.

  FIG. 45 is a flowchart illustrating a schematic procedure of a method of manufacturing a WSC pile (hereinafter, also simply referred to as a manufacturing method) according to an embodiment of the present invention. The manufacturing method is particularly suitable for manufacturing the WSC piles 1V, 1W, 1X.

As shown in FIG. 45, the manufacturing method includes a member preparing step S10, a first end plate attaching step S12, a second end plate attaching step S14, a concrete part forming step S16, an inner steel pipe inserting step S18, a lid member arranging step S20. , A tack welding step S22, a main welding step S24, and a filling portion forming step S26.
In the member preparation step S10, a hollow cylindrical outer steel pipe 3, a first end plate 5 having a first opening 5a at the center, and a second end plate having a second opening 7a having a diameter larger than the first opening 5a at the center. 7, a hollow cylindrical inner steel pipe 9 having an outer diameter smaller than the second opening 7a, and a lid member 90 that can be disposed between the second opening 7a and the inner steel pipe 9 are prepared.

In the first end plate attaching step S12, the first end plate 5 is attached to the first end 3a of the outer steel pipe 3 by welding.
In the second end plate attaching step S14, the second end plate 7 is attached to the second end 3b of the outer steel pipe 3 by welding.
In the concrete part forming step S16, unhardened concrete is poured into the outer steel pipe 3 to which the first end plate 5 and the second end plate 7 are attached, and then subjected to centrifugal molding and curing. A hollow cylindrical concrete part 11 made of concrete to be arranged is formed.

In the inner steel pipe insertion step S18, the inner steel pipe 9 is lifted by, for example, a portal crane or the like, and the inner steel pipe 9 is inserted into the concrete part 11 through the second opening 7a of the second end plate 7. At this time, the inner steel pipe 9 is inserted until the tip of the inner steel pipe 9 on the first end 9a side reaches the groove of the first opening 5a of the first end plate 5, and the tip of the inner steel pipe 9 is connected to the first end plate. Participate in 5 In the inner steel pipe insertion step S18, the concrete portion 11 does not have to be completely hardened, but only needs to be hardened to some extent.
In the lid member arranging step S20, the lid member 90 is externally fitted to the second end 9b of the inner steel pipe 9, and the lid member 90 is disposed in a gap between the inner steel pipe 9 and the second end plate 7. When the second end 9b of the inner steel pipe 9 is suspended by a portal crane or the like, the portal crane or the like is temporarily moved in order to move the lid member 90 to a gap between the inner steel pipe 9 and the second end plate 7. The inner steel pipe 9 is removed and the second end 9b side of the inner steel pipe 9 is placed on the second end plate 7. Then, when fitting the lid member 90 into the gap between the inner steel pipe 9 and the second end plate 7, the second end 9b of the inner steel pipe 9 is lifted again by a portal crane or the like.

In the tack welding step S22, the first end plate 5 and the first end 9a of the inner steel pipe 9 are temporarily welded to each other, and the second end plate 7 and the second end 9b side of the inner steel pipe 9 and the lid member 90 are joined together. Is temporarily welded. At the time of temporary welding, it is preferable that the second end 9b of the inner steel pipe 9 is suspended by a portal crane or the like.
In the main welding step S24, the first end 9a of the inner steel pipe 9 and the first end plate 5 are welded by partial penetration groove welding or complete penetration groove welding, and the lid member 90 is connected to the inner steel pipe 9 and the second end. Fillet welding is performed on the plate 7.
In the filling portion forming step S26, a curable material is injected from the injection hole 84 provided in the first end plate 5, the second end plate 7, or the cover member 90, and the space between the concrete portion 11 and the inner steel pipe 9 is filled. The part 13 is formed.

  When the injection hole 84 is provided in the first end plate 5, the vertical position of the injection hole 84 changes due to the rotation of the outer steel pipe 3 and the first end plate 5. It is preferable that the outer steel pipe 3 and the first end plate 5 are fixedly arranged so that the position of the injection hole 84 in the vertical direction at the time of S26 is the lowest. In other words, it is preferable that the outer steel pipe 3 and the first end plate 5 are fixedly arranged so that the injection hole 84 is located directly below the inner steel pipe 9 in the vertical direction.

  Similarly, when the first end plate 5 is provided with the air vent hole 86, the outer steel pipe 3 and the first end plate are arranged such that the vertical position of the air vent hole 86 is highest in the filling portion forming step S26. Preferably, 5 is fixedly arranged. In other words, it is preferable that the outer steel pipe 3 and the first end plate 5 are fixedly arranged so that the air vent hole 86 is located directly above the inner steel pipe 9 in the vertical direction.

  Further, similarly, when the second end plate 7 or the cover member 90 is provided with the discharge hole 88, the outer steel pipe 3 is set so that the position of the discharge hole 88 in the vertical direction is highest in the filling portion forming step S26. Preferably, the second end plate 7 or the lid member 90 is fixedly arranged. In other words, it is preferable that the outer steel pipe 3 and the second end plate or the cover member 90 are fixedly arranged so that the discharge hole 88 is located directly above the inner steel pipe 9 in the vertical direction.

  According to the above manufacturing method, since the second opening 7 a of the second end plate 7 is larger in diameter than the outer diameter of the inner steel pipe 9, the inner steel pipe 9 can be easily inserted inside the concrete portion 11. On the other hand, by attaching the cover member 90 to the gap between the inner steel pipe 9 and the second end plate 7, a cylindrical space can be defined between the concrete part 11 and the inner steel pipe 9. Then, by injecting a hardening material into the space from the first end plate 5, the second end plate 7, or the injection hole 84 provided in the lid member 90, the space between the concrete portion 11 and the inner steel pipe 9 is formed. The filling portion 13 can be easily formed.

FIG. 46 is a schematic diagram for explaining an example of the inner steel pipe insertion step S18.
As shown in FIG. 46, in the inner steel pipe insertion step S18, the steel pipe is suspended horizontally by a portal crane or the like in the concrete portion 11 provided inside the horizontally fixed outer steel pipe 3, or a forklift. The inner steel pipe 9 which is lifted horizontally by, for example, is inserted.
In the inner steel pipe insertion step S18, the second end 3b side of the outer steel pipe 3 may be slightly lifted so that the inner steel pipe 9 can easily enter.

FIG. 47 is a schematic diagram for explaining an example of the filling portion forming step S26.
As shown in FIG. 47, in the filling portion forming step S26, in a state where the outer steel pipe 3 is horizontally arranged, the curable material is predetermined through the injection hole 84 located below the inner steel pipe 9 in the vertical direction. Is injected at an injection pressure of. During the injection of the curable material, excess curable material is discharged from the discharge holes 88 and air is discharged from the air vent holes 86.
Note that pipes are connected to the air vent hole 86 and the discharge hole 88, respectively, so that the hardening material is sufficiently injected between the inner steel pipe 9 and the concrete portion 11, and the outlet of each pipe is connected to the inner edge of the concrete portion 11. Is positioned higher. Further, in the filling portion forming step S26, the outer steel pipe 3 may be arranged so that the discharge hole 88 side of the outer steel pipe 3 is higher than the injection hole 84 side so as not to cause air accumulation on the injection hole 84 side.
After filling with the curable material, the injection hole 84, the air vent hole 86, and the discharge hole 88 may be closed with plugs, respectively, or the curable material may be cured and closed as it is.

FIG. 48 is a front view schematically showing a WSC pile manufacturing apparatus (hereinafter, also simply referred to as a manufacturing apparatus) 100 according to an embodiment of the present invention. FIG. 49 is a side view schematically showing the manufacturing apparatus 100. FIG. 50 and FIG. 51 are schematic diagrams for explaining a method of using the manufacturing apparatus 100.
As shown in FIGS. 48 and 49, the manufacturing apparatus 100 includes a U-shaped chuck portion 102 in a side view, two legs 104 provided integrally with the chuck portion 102 and separated from each other, A shaft 106 is provided between the two legs 104, and, for example, two cylindrical rollers 108 rotatably attached to the shaft 106.

The chuck portion 102 has two parallel plate portions 102a and 102b spaced apart from each other, and the plate portion 102a is provided with a screw hole 102c. By arranging the end of the inner steel pipe 9 between the plate parts 102a and 102b and screwing the bolt 110 into the screw hole 102c, as shown in FIG. 50 and FIG. The end 9a can be gripped.
On the other hand, the two leg portions 104 protrude from the plate portion 102b in a direction opposite to the plate portion 102a, and are spaced apart from each other and arranged in parallel. The shaft 106 is arranged along the tangential direction of the inner steel pipe 9 when the manufacturing apparatus 100 is gripping the first end 9a of the inner steel pipe 9, so that the two rollers 108 It is arranged along the tangential direction of the steel pipe 9.

The manufacturing apparatus 100 described above is attached to the lower part of the first end 9a of the inner steel pipe 9 immediately before the inner steel pipe insertion step S18 of inserting the inner steel pipe 9 inside the concrete portion 11. For example, as shown in FIG. 50, two manufacturing apparatuses 100 are attached to the lower part of the first end 9a of the inner steel pipe 9. In this state, when the first end 9a of the inner steel pipe 9 is inserted into the inside of the concrete part 11, the rollable roller 108 comes into contact with the inner peripheral surface of the concrete part 11, and the gap between the concrete part 11 and the inner steel pipe 9 is formed. A gap is secured. Thus, the manufacturing apparatus 100 can support the load on the first end 9a side of the inner steel pipe 9 while allowing the inner steel pipe 9 to move inside the horizontally arranged concrete part 11.
Therefore, according to the manufacturing apparatus 100, the inner steel pipe 9 is smoothly inserted into the concrete part 11 through the second opening 7 a of the second end plate 7 in the inner steel pipe insertion step S <b> 18 of inserting the inner steel pipe 9 inside the concrete part 11. And it can be easily inserted.
When the first end 9a of the inner steel pipe 9 reaches the vicinity of the first end plate 5 or reaches a predetermined distance from the first end plate 5, for example, the first end 9a of the inner steel pipe 9 is 9a is removed while supporting it. Thereafter, with the first end 9a of the inner steel pipe 9 supported by a forklift or the like, the inner steel pipe 9 is inserted until the first end 9a of the inner steel pipe 9 reaches the first end plate 5.

Lastly, the present invention is not limited to the above-described several embodiments, but also includes a form in which the above-described embodiment is modified and a form in which these forms are appropriately combined. In particular, in each embodiment, the local configuration centering on the first end 9a of the inner steel pipe 9 and the local configuration centering on the second end 9b of the inner steel pipe 9 are obtained by connecting the inner steel pipe 9 to the outer steel pipe 3. Any combination is possible as long as it can be inserted inside and the inner steel pipe 9 can be positioned at least at one end with respect to the outer steel pipe 3.
Moreover, although the concrete part 11 mentioned above was unreinforced concrete, it may be reinforced concrete.

1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J, 1K, 1L, 1M, 1N, 1P, 1Q, 1R, 1S, 1T, 1U, 1V, 1W, 1X, 1Y Concrete with double steel pipe Pile (WSC pile)
3 outer steel pipe 3a first end 3b of outer steel pipe second end 5 of outer steel pipe 5 first end plate 5a first opening 5c female tapered surface 7 second end plate 7a second opening 9 inner steel pipe 9a first of inner steel pipe End 9b Second end 11 of inner steel pipe 11 Concrete part 13 Filling part 14 Reinforcing bar (outside anchoring member)
15 Full penetration groove weld (outside full penetration groove weld)
17 Backing 19 Full penetration groove weld (1st full penetration groove weld)
21 Backing 23 Fillet weld 28 Penetration groove weld 29 Reinforcing bar (inner fixing member)
30 Fillet weld 31 Full penetration groove weld (2nd full penetration groove weld)
33 Backing 35 Tension fitting 35a Cylindrical portion 35b Outward flange 35c Male tapered surface 37 Full penetration groove weld (tensile full penetration groove weld)
41 Adapter member 41a Cylindrical part 41b Outward flange 43 Connection metal fittings 45 Full penetration groove welding part (full penetration groove welding part for adapter)
47 Projection 48 Outside anchoring member joint 49 Joint ring 51 Projection 55 PHC pile 60A, 60B, 60C Pile head joint structure of concrete pile with double steel pipe (WSC pile) 62 Concrete block 72 Male screw 74 Projection (inner anchoring member)
76 Projection (outside fixing member)
78 Female screw 80 Male screw 82 Partial penetration groove welding portion 84 Injection hole 86 Air vent hole 88 Discharge hole 90 Cover member 92 Cover member groove welding portion 94 Cover member fillet welding portion 96 PHC pile 100 WSC pile manufacturing apparatus 102 Chuck parts 102a, 102b Plate part 102c Screw hole 104 Leg part 106 Shaft part 108 Roller 110 Bolt S10 Member preparation step S12 First end plate attaching step S14 Second end plate attaching step S16 Concrete part forming step S18 Inner steel pipe inserting step S20 Cover Member arrangement step S22 Temporary welding step S24 Main welding step S26 Filling part forming step

Claims (24)

A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow cylindrical cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
In a concrete pile with a double steel pipe comprising
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. A concrete pile with a double steel pipe, which is configured to bear a force. A first end of the inner steel pipe and the first end plate are joined via a first complete penetration groove weld,
2. The double steel pipe according to claim 1, wherein the first full penetration groove welded portion is configured such that a tensile axial force acts when a tensile axial force acts on the inner steel pipe. 3. With concrete pile. The concrete pile with double steel pipes according to claim 2, wherein a second end of the inner steel pipe projects outside through a second opening of the second end plate.   The said 1st end plate or the said 2nd end plate has an injection hole for inject | pouring the hardening material used as the said filling part between the said concrete part and the said inner steel pipe, The characterized by the above-mentioned. 4. The concrete pile with a double steel pipe according to any one of 3.   The first end plate or the second end plate has an air vent hole for discharging air during injection of a hardening material serving as the filling portion between the concrete portion and the inner steel pipe. The concrete pile with a double steel pipe according to claim 4.   The first end plate or the second end plate has a discharge hole for discharging excess curable material during the injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. The concrete pile with a double steel pipe according to claim 4 or 5, wherein the concrete pile is provided. The diameter of the second opening of the second end plate is larger than the outer diameter of the inner steel pipe,
The concrete pile according to claim 3, further comprising a cover member disposed between the inner steel pipe and the second end plate. An outer surface of the second end plate is located outside an outer surface of the lid member in an axial direction of the inner steel pipe,
The concrete pile with a double steel pipe according to claim 7, wherein the lid member is fillet welded to the inner steel pipe and the second end plate.   The first end plate, the second end plate, or the lid member has an injection hole for injecting the hardening material to be the filling portion between the concrete portion and the inner steel pipe. The concrete pile with a double steel pipe according to claim 7 or 8.   The first end plate, the second end plate or the lid member has an air vent hole for discharging air during injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. The concrete pile with a double steel pipe according to claim 9, comprising:   The first end plate, the second end plate, or the lid member is for discharging excess curable material during injection of the curable material serving as the filling portion between the concrete portion and the inner steel pipe. The concrete pile with a double steel pipe according to claim 9 or 10, wherein the concrete pile has a discharge hole. 2. The concrete pile with double steel pipes according to claim 1, wherein a first end of the inner steel pipe projects outside through a first opening of the first end plate. 3. A tension fitting connected to a first end of the inner steel pipe;
A first end of the inner steel pipe is joined to the tension fitting via a full penetration groove weld for tension,
2. The double steel pipe according to claim 1, wherein the full penetration groove weld for tension is configured such that a tensile axial force acts when a tensile axial force acts on the inner steel pipe. 3. With concrete pile. A tension fitting connected to a first end of the inner steel pipe;
A first end of the inner steel pipe is mechanically joined to the tension fitting;
2. The double end according to claim 1, wherein the first end of the inner steel pipe can bear a tensile axial force via the tension fitting when a tensile axial force acts on the inner steel pipe. 3. Concrete pile with steel pipe. The two ends according to claim 1, wherein the first end of the inner steel pipe is configured to be connectable to an adapter member for attaching a fixing member for pile head connection. Concrete pile with heavy steel pipe. The concrete pile with a double steel pipe according to any one of claims 1 to 15, wherein the second end of the inner steel pipe is configured to be connectable to another pile. The second end of the inner steel pipe and the second end plate are joined via a second complete penetration groove weld,
The said 2nd complete penetration groove welding part is comprised so that a tensile axial force may act, when a tensile axial force acts on the said inner steel pipe, The Claims 1, 12, 13, 14 characterized by the above-mentioned. The concrete pile with a double steel pipe according to Claim, 15 or 16. A second end of the inner steel pipe is located closer to a first end of the inner steel pipe than the second end plate in an axial direction of the inner steel pipe,
16. A stopper for preventing a relative displacement of the filling portion in an axial direction of the inner steel pipe on an outer peripheral surface of the inner steel pipe. 2. A concrete pile with a double steel pipe according to item 1. The concrete pile with a double steel pipe according to any one of claims 1 to 18, wherein an outer fixing member joining portion for mechanically attaching the outer fixing member to the outer steel pipe is provided. A hollow cylindrical outer steel pipe, a first end plate having a first opening in the center, a second end plate having a second opening in the center having a larger diameter than the first opening, and an outer diameter smaller than the second opening. A step of preparing a hollow and cylindrical inner steel pipe having, and a lid member that can be disposed between the second opening and the inner steel pipe;
Attaching the first end plate to a first end of the outer steel pipe;
Attaching the second end plate to a second end of the outer steel pipe;
An uncured concrete is poured into the outer steel pipe to which the first end plate and the second end plate are attached, and a hollow cylindrical concrete portion made of concrete placed in contact with the outer steel pipe Forming a;
Inserting the inner steel pipe inside the concrete part through a second opening of the second end plate;
Welding a first end of the inner steel pipe and the first end plate;
Attaching the lid member to a gap between the inner steel pipe and the second end plate;
A step of injecting a curable material from an injection hole provided in the first end plate, the second end plate, or the lid member to form a filling portion between the concrete portion and the inner steel pipe;
A method for producing a concrete pile with a double steel pipe, comprising: An apparatus for manufacturing a concrete pile with a double steel pipe applied to the method for manufacturing a concrete pile with a double steel pipe according to claim 20,
In the step of inserting the inner steel pipe inside the concrete part, the load on the first end side of the inner steel pipe can be supported while allowing the inner steel pipe to move inside the horizontally arranged concrete part. An apparatus for manufacturing a concrete pile with a double steel pipe. Concrete pile with double steel pipe,
An anchoring member attached to the end of the concrete pile with the double steel pipe,
A concrete block surrounding the fixing member,
The concrete pile with a double steel pipe,
A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow and cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
With
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. It is configured to bear the power,
The structure according to claim 1, wherein the anchoring member includes an inner anchoring member for connecting the first end of the inner steel pipe to the concrete block. The inner fixing member is provided integrally with an inner surface of a first end of the inner steel pipe, and is configured by one or more protrusions protruding radially inward from an inner surface of the first end.
When the outer diameter of the concrete pile with the double steel pipe is D, the pile head of the concrete pile with the double steel pipe is embedded in the concrete block over a length of 0.5D or more and 3D or less,
23. The joint structure according to claim 22, wherein the concrete block is attached to the one or more protrusions. Concrete pile with double steel pipe as upper pile,
A lower pile connected to the upper pile,
With
The concrete pile with a double steel pipe,
A hollow cylindrical outer steel pipe,
A first end plate attached to a first end of the outer steel pipe and having a first opening in the center;
A second end plate attached to a second end of the outer steel pipe and having a second opening in the center;
A hollow, cylindrical inner steel pipe arranged radially inward of the outer steel pipe,
A hollow cylindrical cylindrical concrete portion arranged between the outer steel pipe and the inner steel pipe in contact with the outer steel pipe, and made of concrete,
A filling portion disposed between the concrete portion and the inner steel pipe,
With
The inner steel pipe is configured to bear a tensile axial force when a bending moment acts on the concrete pile with the double steel pipe,
At least a first end of the inner steel pipe has a larger tensile axis when a tensile axial force acts on the inner steel pipe than when fillet welding is performed between the first end of the inner steel pipe and the first end plate. It is configured to bear the power,
The joint pile structure of a concrete pile with a double steel pipe, wherein a second end of the inner steel pipe is connected to the lower pile.

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