JP2012117233A - Joint structure of steel pipe pile, and steel pipe pile with joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint structure of a steel pipe pile, which enables the upper and lower steel pipe piles to be connected together by simple work on a job site and which enables the high-accuracy and high-reliability connection of the steel pipe piles by making working of a joint part simply performed by a steel working manufacturer and the like, and the steel pipe pile with a joint.SOLUTION: A diameter-enlarged sleeve part 1a is provided at an end of one steel pipe pile 1A of two steel pipe piles 1 (1A and 1B) to be connected to each other, which are equal in diameter to each other, and an end 1b of the other steel pipe pile 1B is fitted into the sleeve part 1a. The sleeve part 1a has a diameter enlarged by applying axial compressive force while heating an end of a round steel pipe, which serves as a material for the one steel pipe pile 1A, by high-frequency induction heating.

Description

  The present invention relates to a joint structure in a steel pipe pile serving as a pile foundation for supporting a structure such as a building or a house, and a steel pipe pile with the joint.

When the steel pipe pile is press-fitted deeply into the ground, the length of one steel pipe pile is insufficient, so a plurality of pieces are sequentially connected while being press-fitted into the ground. The mutual connection of steel pipe piles is generally performed by welding. However, in-situ welding takes time and requires a welding engineer who is a special engineer. For this reason, a joint structure has been proposed in which a mechanically simple connection is made without using welding.
For example, a threaded joint structure (Patent Document 1, etc.) is proposed in which a screw member is factory welded to the end of a steel pipe pile and screwed in the field.

JP 2003-105751 A

The conventional threaded joint structure simplifies on-site construction compared to the one that performs on-site welding, but it requires screwing work, and it is necessary to rotate a long steel pipe pile, so the workability is sufficiently improved. is not. In addition, it is necessary to assemble the screw member by factory welding or the like, and accuracy and reliability such as centering at the time of assembly are not sufficient.
Conventionally, a technology has been proposed to heat a large-diameter material steel pipe and condense it into a tapered shape in order to connect steel pipe piles with different diameters, but this is simply a technique that eliminates the difference in diameter. It does not improve pile connection workability.

  The object of the present invention is to connect the upper and lower steel pipe piles with simple field work, and the joint part can be easily processed by a steel processing manufacturer, etc., and the steel pipe pile can be connected with high accuracy and reliability. It is providing the steel pipe pile with a joint structure, and a joint.

The joint structure of the steel pipe pile of this invention has a sheath pipe part expanded in diameter at the end of one steel pipe pile in two steel pipe piles of the same diameter connected to each other, and the end of the other steel pipe pile is The sheath pipe part is fitted to the sheath pipe part, and the diameter of the sheath pipe part is increased by applying an axial compressive force while heating the end part of the steel pipe as the material of the other steel pipe pile by high frequency induction heating. It has been made.
According to this configuration, the end of one steel pipe pile has an expanded sheath pipe part, and the end of the other steel pipe pile is fitted to the sheath pipe part. It can be connected only by itself, and workability is greatly improved. The sheath tube part is made by expanding the diameter of the end of the steel pipe that is the raw material by applying axial compressive force while heating by high-frequency induction heating, so it can be easily formed by steel processing manufacturers, etc. It is possible to achieve higher accuracy and reliability than those assembled with separate members.
A joint structure using a sheath pipe is common in fluid piping, but a fluid pipe having the same diameter as that used for a pile is a cast product, and a sheath pipe is formed at the end of a steel pipe. The method is not conventionally known. In this regard, in the case of a steel pipe, an outer diameter and an inner diameter are used for forming, and while being partially heated by high-frequency induction heating, an axial compressive force is applied and hot forming is performed partly in the length direction. Thus, it was found that it can be easily molded. From this, it is realizable to use a sheath pipe part for the joint structure of a steel pipe pile.

  It is preferable that a stepped surface with which the end surface of the other steel pipe pile abuts is provided inside the base end of the sheath pipe portion of the one steel pipe pile. By providing this step surface and bringing the end face of the other steel pipe pile into contact, the axial force in the compression direction can be transmitted satisfactorily. Moreover, after construction is completed, it is avoided that the contact portions of the upper and lower steel pipe piles gradually shift in the axial direction due to the load of the upper structure, etc., and settlement of the pile head due to the joint portion is prevented.

The steel pipe pile with a joint according to the present invention is configured such that one end portion of the steel pipe pile is a sheath pipe portion expanded to an inner diameter in which the other end portion can be fitted, and the sheath pipe portion is an end portion of the steel pipe which is a material of the steel pipe pile. Is expanded by applying an axial compressive force while being heated by high frequency induction heating.
According to the steel pipe pile with a joint having this configuration, as described above with respect to the joint structure of the steel pipe pile of the present invention, it can be connected by simply inserting it at the site of pile driving, and workability is greatly improved. The sheath tube part is made by expanding the diameter of the end of the steel pipe that is the raw material by applying axial compressive force while heating by high-frequency induction heating, so it can be easily formed by steel processing manufacturers, etc. It is possible to achieve higher accuracy and reliability than those assembled with separate members. The method of forming a sheath tube at the end of a steel pipe is not known in the past, but axial compression is performed while partially heating by high-frequency induction heating using a molding die with an outer diameter and an inner diameter. By applying force and hot forming part by part in the length direction, it can be easily formed.

  Also in this steel pipe pile with a joint, it is preferable to provide the level | step difference surface of the shape which the end surface of an other end part can contact | abut inside the base end in the said sheath pipe part. Thereby, the axial force in the compression direction can be transmitted satisfactorily. Moreover, after construction is completed, it is avoided that the contact positions of the upper and lower steel pipe piles gradually shift due to the load of the upper structure and the like, and the settlement of the pile head due to the joint portion is prevented.

The joint structure of the steel pipe pile of this invention has a sheath pipe part expanded in diameter at the end of one steel pipe pile in two steel pipe piles of the same diameter connected to each other, and the end of the other steel pipe pile is The sheath pipe part is fitted to the sheath pipe part, and the diameter of the sheath pipe part is increased by applying an axial compressive force while heating the end part of the steel pipe as the material of the other steel pipe pile by high frequency induction heating. Therefore, it is possible to connect the upper and lower steel pipe piles with simple on-site work, and the joint part can be easily processed by a steel processing manufacturer, etc., and a connection with high accuracy and reliability can be achieved.
The steel pipe pile with a joint according to the present invention is configured such that one end portion of the steel pipe pile is a sheath pipe portion expanded to an inner diameter in which the other end portion can be fitted, and the sheath pipe portion is an end portion of the steel pipe which is a material of the steel pipe pile. Is expanded by applying axial compressive force while being heated by high-frequency induction heating, so that the upper and lower steel pipe piles can be connected by simple field work, and the joint part can be processed It can be done easily by a manufacturer, etc., and a highly accurate and reliable connection can be made.

It is sectional drawing of the joint structure of the steel pipe pile which concerns on 1st Embodiment of this invention. It is a middle abbreviation sectional view of the steel pipe pile with a joint. It is explanatory drawing which shows the connection state of the steel pipe pile. It is explanatory drawing which shows the process of the sheath pipe part of the steel pipe pile. (A), (B) is a fragmentary sectional view of the joint structure of the steel pipe pile concerning other embodiments, respectively.

  A first embodiment of the present invention will be described with reference to FIGS. This steel pipe pile joint structure has a sheath pipe part 1a having an enlarged diameter at the end of one steel pipe pile 1A in two steel pipe piles 1 (1A, 1B) of the same diameter connected to each other. The end 1b of the steel pipe pile 1B is fitted to the sheath pipe 1a. The sheath pipe portion 1a is obtained by expanding the diameter of an end portion of a round steel pipe, which is a material of the one steel pipe pile 1A, by applying an axial compressive force while heating it by high frequency induction heating.

  The sheath pipe portion 1a has a cylindrical shape having an inner diameter with a gap for fitting work added to the outer diameter D of the steel pipe pile 1A, and the end face 1ba of the other steel pipe pile steel pipe pile 1B is located inside the base end. Is formed in the axial direction. The outer peripheral surface of the steel pipe pile 1A is formed in the enlarged diameter portion 1ab where the diameter of the proximal end of the sheath tube portion 1a, that is, the vicinity of the stepped surface 1aa is gradually increased in a tapered shape.

Although FIG. 1 showed the joint part of the two steel pipe piles 1A and 1B, the two steel pipe piles 1A and 1B have the same shape, and the upper steel pipe pile 1 in the joint part is connected to one steel pipe pile. 1A, and the lower steel pipe pile 1 was called the other steel pipe pile 1B.
As shown in FIG. 2, each steel pipe pile 1 is configured such that one end portion of a round steel pipe is formed into a sheath pipe portion 1 a that is expanded to an inner diameter to which the other end portion 1 b can be fitted. The sheath tube portion 1a has the above-described configuration.

  While placing such steel pipe piles 1 on the ground G as shown in FIG. 3, an arbitrary number of them are connected according to the required pile length.

  FIG. 4 shows an example of a method for manufacturing the steel pipe pile 1. A round steel pipe 1A as a raw material is fed in the length direction by the feeding device 11 toward the mold 12 on the guide 14. While performing this feeding, heating is performed by the coil 13 of the high-frequency induction heating device installed in front of the mold 12, and the heated portion is expanded in diameter by the mold 12. The feeding device 11 is, for example, a hydraulic cylinder or a motor driven type. The mold 12 includes a core portion 12a having an outer diameter formed in accordance with the inner diameter of the sheath tube portion 1a, a cylindrical surface 12b having an inner diameter formed in accordance with the outer diameter of the sheath tube portion 1a, and a steel pipe. And an end contact surface 12c. A compression force acts on the material steel pipe 1A by the pressurization of the feeding device 11 between the feeding device 11 and the portion where the material steel pipe 1A of the mold 12 contacts, and the heated portion of the material steel pipe 1A expands in diameter. When it is sent until it hits the steel pipe end contact surface 12c, the tip of the material steel pipe 11A is formed in the shape of the sheath pipe portion 1a.

  In the mold 12 shown in the figure, the stepped surface 1aa (FIG. 1) on the inner surface of the sheath tube portion 1a cannot be molded, and therefore is molded later with another mold (not shown). This formation may be performed by induction heating the material steel pipe 1A again separately from the heating, or may be formed continuously until the material steel pipe 1A cools. Moreover, you may make it perform simultaneously the expansion of the diameter of the sheath pipe part 1a, and shaping | molding of the said level | step difference surface 1aa by devising the shape of the metal mold | die 12. FIG.

According to the joint structure and the steel pipe pile 1 of this configuration, the end portion of one steel pipe pile 1A has a sheath pipe portion 1a having an enlarged diameter, and the end portion 1b of the other steel pipe pile 1B is connected to the sheath pipe portion 1a. Since it is fitted, it can be connected only by inserting at the pile driving site, and workability is greatly improved. The sheath tube portion 1a is formed by expanding the diameter of the end portion of the steel tube 1A, which is a material, by applying an axial compressive force while heating by high frequency induction heating. it can. Therefore, it can be made highly accurate and reliable as compared with the case where another member is assembled.
The joint structure using the sheath pipe portion 1a is common in fluid piping, but the fluid pipe having the same diameter as that used in the pile is a cast product, and the sheath pipe portion is formed at the end of the steel pipe. The method to do is not known conventionally. In this regard, in the case of a steel pipe, an axial compression force is applied while partially heating by high frequency induction heating using a mold for molding with an outer diameter and an inner diameter (for example, the mold 12 in FIG. 4). It was confirmed that it was possible to form easily by hot forming partly in the direction. Thereby, using the sheath pipe part 1a for the joint structure of the steel pipe pile 1 has been achieved.

  Since the stepped surface 1aa is provided inside the base end of the sheath tube portion 1a, the end surface 1ba of the other steel pipe pile 1B is brought into contact with the stepped surface 1aa, so that the compression direction can be improved after the completion of construction or in the pile driving process. The axial force can be transmitted well. In addition, it is avoided that the contact positions of the upper and lower steel pipe piles 1 and 1 gradually shift in the axial direction due to the load of the upper structure after the construction is completed, and settlement of the pile head due to the joint portion is prevented. The

Note that the sheath pipe portion 1a is not limited to the above-mentioned shape. For example, as shown in FIG. 5 (A), the ring-shaped separate member 3 is interposed, and the end face 1ba of the other steel pipe pile 1B is provided on the step surface 1aa. You may make it contact | abut. Further, as shown in FIG. 4B, the inner surface of the base end of the sheath tube portion 1a is a tapered surface portion 1ab, and the end surface 1ba of the other steel pipe pile 1B is in contact with the middle portion of the tapered surface portion 1ab. good.
Moreover, although each said embodiment used the sheath pipe part 1a downward, you may use the sheath pipe part 1a upward at the upper end of the steel pipe pile 1. FIG.

1 (1A, 1B) ... steel pipe pile 1a ... sheath pipe part 1aa ... step surface 1ab ... diameter-enlarged part 1b ... end D ... outer diameter

Claims (4)

  An end of one steel pipe pile in two steel pipe piles of the same diameter connected to each other has a sheath pipe portion whose diameter is increased, and the other steel pipe pile end is fitted to the sheath pipe portion. The joint structure of the steel pipe pile, in which the sheath pipe part is obtained by expanding the diameter of the end portion of the steel pipe, which is the material of the one steel pipe pile, by applying an axial compressive force while heating by high-frequency induction heating. .   The joint structure of the steel pipe pile which has in the level | step difference surface which the end surface of the other steel pipe pile contact | abuts inside the base end in the said sheath pipe part of said one steel pipe pile in Claim 1.   One end of the steel pipe pile is made into a sheath pipe part whose diameter is expanded to an inner diameter that allows the other end part to be fitted, and this sheath pipe part is heated while heating the end of the steel pipe that is the material of the steel pipe pile by high-frequency induction heating. A steel pipe pile with a joint that is expanded in diameter by applying axial compressive force. The steel pipe pile with a joint according to claim 3, wherein a stepped surface having a shape with which the end face of the other end can come into contact is provided inside the base end of the sheath pipe.

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