JP2011094358A - Joint pipe for steel pipe pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint pipe for a steel pipe pile, which can obtain high joint strength by welding, and which enables upper and lower piles to be easily joined together without being restricted by a construction site. <P>SOLUTION: Characteristically, this joint pipe 1 for joining the upper and lower piles of the steel pipe pile includes: an axial intermediate portion 2 with the largest outside diameter; a first diameter-reduced portion 3 which is formed in such a manner as to continue into each of both ends of the intermediate portion 2, and the outside diameter of which is smaller than that of the intermediate portion; and a second diameter-reduced portion 4 which is formed in such a shape as to continue into an end of the first diameter-reduced portion 3 via an annular step surface 6 perpendicular to an axial line, the outside diameter of which is smaller than that of the first diameter-reduced portion 3 and approximately equal to an inside diameter of the steel pipe pile, and into which the steel pipe pile is to be fitted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a joint pipe for steel pipe piles, and more particularly to a joint pipe for connecting an upper pile and a lower pile.

  Steel pipe piles are widely known as one of the pile types used for pile foundations. The pile generally supports the load of the structure by the tip support force and the peripheral surface friction force. However, when the depth of the support layer for obtaining the tip support force is deep, the piles must be added sequentially. That is, at the construction site, it is necessary to use the pile already embedded in the ground as the lower pile and connect the upper pile to this.

  Conventionally, as a method of connecting the lower pile and the upper pile, a method using a bolt and a nut or a method using welding is known. Among these methods, when welding the upper pile and the lower pile of the steel pipe pile by welding, it is difficult to attach a backing metal to the inside of the groove. For this reason, a cylindrical backing metal having a plurality of protrusions on the outer periphery as disclosed in Patent Documents 1 and 2 has been proposed. According to this prior art, since the lower end of the upper pile and the upper end of the lower pile are locked above and below the protrusion, a gap for welding is formed between the lower end of the upper pile and the upper end of the lower pile, Welding can be performed with the backing metal applied.

  However, in this prior art, since a plurality of protrusions enter the gap to be welded, the welding of the upper and lower piles must be incomplete at the protrusions. In particular, when the thickness of the steel pipe pile is thin, the ratio of the projection length dimension of the projection to the thickness dimension increases, and the projection portion is likely to be incompletely welded.

  Patent Document 3 discloses a technique for welding upper and lower piles without using a backing metal. This prior art is provided with a narrowed portion having a tapered surface at the lower end portion of the upper pile and a pile connecting portion connected to this, and by fitting the pile connected portion to the lower pile, the narrowed portion is used for welding. A groove is formed.

  However, in this prior art, in order to fit the lower end of the upper pile to the lower pile, the thickness of the upper pile must be larger than the thickness of the lower pile. Increasing the thickness of the upper pile is effective from the viewpoint of increasing the horizontal strength of the pile, as described in the same document. In the case of sequential joining, the thickness of the pile becomes unnecessarily large as it goes upward, so it is inappropriate as a technique used in such a construction site.

Japanese Patent Laid-Open No. 11-158866 JP 2009-203730 A JP-A-2005-76415

The present invention has been made based on the technical background as described above, and achieves the following object.
The objective of this invention is providing the joint pipe of the steel pipe pile which can obtain the high joining strength by welding, and can join an upper and lower pile easily, without being restrict | limited to a construction site.

The present invention employs the following means in order to achieve the above object.
That is, this invention is a joint pipe for joining an upper pile and a lower pile of a steel pipe pile,
An axially intermediate portion with the largest outer diameter,
A first reduced diameter portion formed continuously at both ends of the intermediate portion and having an outer diameter smaller than the outer diameter of the intermediate portion;
The end of the first reduced diameter portion is formed continuously through an annular step surface perpendicular to the axis, the outer diameter is smaller than the first reduced diameter portion and substantially equal to the inner diameter of the steel pipe pile, The steel pipe pile joint pipe is provided with a second reduced diameter portion to be fitted.

  More specifically, the end of the intermediate portion and the first reduced diameter portion are connected via an annular tapered surface.

  According to the joint pipe of the present invention, the second reduced diameter portion connected to the first reduced diameter portion via the annular step surface is formed, and the steel pipe pile is fitted to the second reduced diameter portion. The end face of the steel pipe pile is locked to the annular step surface and does not enter any more, and a gap for welding of a predetermined size can be secured. Therefore, high joint strength by welding can be obtained. In addition, since the second reduced diameter portion functions as a backing during welding, molten metal does not flow out into the joint pipe, and welding defects can be prevented from occurring.

It is a front view showing an embodiment of a joint pipe by this invention. It is a top view of the thing of the embodiment. It is a figure which expands and shows the A section of FIG. It is sectional drawing which shows the connection state of an upper pile and a lower pile. It is a figure which expands and shows the B section of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a steel pipe pile joint pipe 1 according to the present invention includes an axial intermediate portion 2, first reduced diameter portions 3 and 3 respectively connected to both ends of the intermediate portion 2, and a first reduced size. Second diameter-reduced portions 4 and 4 connected to the ends of the diameter portions 3 and 3 are provided.

  The intermediate part 2 is a part with the largest outer diameter, and the outer diameter is substantially equal to the outer diameter of the steel pipe pile (upper pile and lower pile) connected via the joint pipe 1 (see FIG. 4). The first reduced diameter portions 3 and 3 are portions whose outer diameter is smaller than the outer diameter of the intermediate portion 2, and are connected to both ends of the intermediate portion 2 via the annular tapered surface 5. The second reduced diameter portions 4 and 4 are portions whose outer diameter is smaller than the outer diameter of the first reduced diameter portion 3, and the outer diameter is substantially equal to the inner diameter of the steel pipe pile. Thus, it continues to the end of the first reduced diameter portion 3 via the annular step surface 6 perpendicular to the axis. The steel pipe pile is fitted to the second reduced diameter portion 4 (see FIG. 4).

  The joint pipe 1 is formed by cutting out the outer circumference of a short steel pipe having a thickness equal to the thickness of the intermediate portion 2 by cutting, so that the first and second reduced diameter portions 3 and 4, the annular tapered surface 5 and the annular step Formed to have surface 6. The inner diameter of the joint pipe 1 is equal over the entire axial direction.

  Next, the connection method of the upper pile and the lower pile of the steel pipe pile using the said joint pipe 1 is demonstrated with reference to FIG. At one end of the steel pipe piles that are sequentially connected at the construction site, the joint pipe 1 is joined in advance at the factory by welding. That is, the joint pipe 1 is joined at the factory to the upper end of the steel pipe pile that is already buried in the ground at the construction site and becomes the lower pile 10, and the work of welding the upper pile 11 to the joint pipe 1 is performed at the construction site. . Hereinafter, the joining work at the construction site will be described, but the joining work at the factory is exactly the same.

  In order to join the upper pile 11 to the joint pipe 1, first, the lower end portion of the upper pile 11 is fitted to the second reduced diameter portion 4 as shown in an enlarged manner in FIG. 5. Since the inner periphery of the lower end surface 11a contacts and locks the annular step surface 6, the upper pile 11 thus fitted does not enter any more. Thereby, an annular gap of a predetermined size, that is, a route interval for welding, is formed between the lower end surface 11 a of the lower pile 11 and the tapered surface 5. Welding 12 is performed over the entire circumference of the joint pipe 1 so as to fill this gap. Thereby, the upper pile 11 is joined to the joint pipe 1, and as a result, the upper pile 11 is connected to the lower pile 10.

  According to the above-described joint pipe 1, the second reduced diameter portion 4 connected to the first reduced diameter portion 3 via the annular step surface 6 is formed, and the steel pipe piles 10, 11 are formed in the second reduced diameter portion 4. Therefore, the end surfaces of the steel pipe piles 10 and 11 are locked to the annular step surface 6 and do not enter any more, and a gap for welding of a predetermined size can be secured. Therefore, high joint strength by welding can be obtained. Further, since the second reduced diameter portion 4 functions as a backing at the time of welding, the molten metal does not flow out into the joint pipe, and it is possible to prevent welding defects from occurring.

  In the above embodiment, the tapered surface 5 is formed between the end of the intermediate portion 2 and the first reduced diameter portion 3, and during this time, like the annular step surface 6, an annular step perpendicular to the axis of the joint pipe 1 is provided. It may be a surface. In this case, an annular taper surface is provided on the end surfaces of the steel pipe piles 10 and 11 except for a contact portion with the annular step surface 6.

DESCRIPTION OF SYMBOLS 1 Joint pipe 2 Middle part 3 1st reduced diameter part 4 2nd reduced diameter part 5 Annular taper surface 6 Annular level difference surface 10 Steel pipe pile (lower pile)
11 Steel pipe pile (upper pile)

Claims (2)

A joint pipe for joining an upper pile and a lower pile of steel pipe piles,
An axially intermediate portion with the largest outer diameter,
A first reduced diameter portion formed continuously at both ends of the intermediate portion and having an outer diameter smaller than the outer diameter of the intermediate portion;
The end of the first reduced diameter portion is formed continuously through an annular step surface perpendicular to the axis, the outer diameter is smaller than the first reduced diameter portion and substantially equal to the inner diameter of the steel pipe pile, A steel pipe pile joint pipe, comprising: a second reduced diameter portion to be fitted.   The joint pipe of a steel pipe pile according to claim 1, wherein the end of the intermediate portion and the first reduced diameter portion are connected via an annular tapered surface.

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