WO2011122349A1

WO2011122349A1 - Mechanical joint structure for tubular steel piles

Info

Publication number: WO2011122349A1
Application number: PCT/JP2011/056270
Authority: WO
Inventors: 啓笠原; 規之川端; 正文田附; 剛男原田; 耕之吉田; 敏雄篠原; 重夫金井; ゆかり花田
Original assignee: 日鐵住金建材株式会社
Priority date: 2010-03-29
Filing date: 2011-03-16
Publication date: 2011-10-06
Also published as: JP2011208373A

Abstract

Provided is a joint structure that mechanically joins two tubular steel pipes by fitting together an inner joint pipe and an outer joint pipe that are fixed by welding to corresponding end surfaces of the two pipes, and keeps the two joint pipes together by inserting pins. An outer joint pipe (3) having a plurality of connecting holes (3a...) made in the peripheral wall thereof in the radial direction is fixed by welding to the end surface of one of the tubular steel piles (1). An end mounting bracket (4) is affixed by welding to the corresponding end surface of the other tubular steel pile (2), and to the other side of the end mounting bracket (4) an inner joint pipe (5) having a plurality of connecting holes (4a...) made in the peripheral wall thereof in the radial direction at positions that correspond with the connecting holes (3a) in the outer joint pipe (3) is affixed by welding. The inner joint pipe (5) can fit into the inside of the outer joint pipe (3). The inner joint pipe (5) is inserted into the inside of the outer joint pipe (3), and the connecting holes (3a and 5a) of the outer joint pipe (3) and the inner joint pipe (5) are brought into alignment and a connecting pin (6) is inserted therein, and processing to prevent the pin from being dislodged is performed, connecting the two tubular steel piles (1 and 2).

Description

Mechanical joint structure of steel pipe pile

This invention belongs to the technical field of joint structures in which inner joint pipes and outer joint pipes fixed by welding are fitted to corresponding end faces of steel pipe piles, and are pinned and connected mechanically in series.

Conventionally, many of the means for connecting steel pipe piles in series on site have been carried out by using on-site welded joints in which the ends of the steel pipe piles that are butted against each other are fixed by welding. However, in the field welding, there is a problem that the welding quality is easily influenced by the skill of the worker and the weather, and further, the field welding work is very troublesome, and the construction period is prolonged and the cost is increased. For this reason, recently, various joint structures connected by mechanical joints in place of on-site welding have been developed and already put into practical use.

For example, the mechanical joint structure of a steel pipe pile disclosed in the following Patent Document 1 is an outer surface in which a plurality of connecting holes 3a are formed in the peripheral wall on the upper end surface of the lower steel pipe pile 1 as shown in FIG. The joint pipe 3 is fixed in advance by welding a in the factory, and the lower end surface of the upper steel pipe pile 2 has an outer diameter close to the inner diameter of the outer joint pipe 3 and a plurality of connecting holes 5a. The inner joint pipe 5 is also fixed by welding b in the factory. At the site, the inner joint pipe 5 is fitted into the pipe of the outer joint pipe 3, the connecting

holes

3a and 5a of both pipes are matched, and the connecting pin 6 hits the locking member 5b in the connecting

holes

3a and 5a. Inserted, a set bolt 7 was inserted into the bolt through hole of the connecting pin 6, and the tip of the bolt 7 was screwed into the bolt hole of the locking member 5b and fastened to connect the two

steel pipe piles

1 and 2 It is a configuration.

JP 2006-37619 A JP 2009-138382 A

As described with reference to FIG. 8, the mechanical joint structure of the steel pipe pile disclosed in the above-mentioned Patent Document 1 is the outer joint pipe 5 fixed to the upper steel pipe 2 by factory welding. The outer peripheral surface of a thick steel pipe having a thickness corresponding to the dimensional difference S (for example, 25 mm) between the diameter and the inner diameter of the inner joint pipe 5 is extended over the fitting length L of the inner joint pipe 5 by, for example, a lathe. The outer diameter close to the inside of the joint pipe 3 is cut and manufactured, and the remaining non-cut portion 51 at the upper end is welded and fixed to the upper steel pipe pile 2 at the factory. However, the work of cutting about half of the thickness of the steel plate pipe with a lathe is very time consuming and time consuming, and a large amount of steel scrap is generated, resulting in great waste of the steel material. Disposal of waste also takes time and cost. Moreover, since the above-mentioned thick steel pipe becomes a special size, it is not easy to obtain and takes a long delivery time. Further, the production of the thick steel pipe has a problem that the unit price per weight is very high as compared with the production of the thin steel pipe.
The mechanical joint structure of a steel pipe pile disclosed in Patent Document 2 has the same problem because the basic configuration is almost the same as the mechanical joint structure of Patent Document 1.

Incidentally, in the so-called stamped joints disclosed in

Patent Documents

1 and 2 above, since both the inner surface of the outer joint pipe and the outer surface of the inner joint pipe are usually cut, The difference from the diameter, that is, the diameter difference is often set as small as 0.5 mm to 1.0 mm. Therefore, when the outer diameter and thickness of the outer joint pipe are determined, the outer diameter of the inner joint pipe is almost automatically set. decided. However, since the outer diameter of a steel pipe with a low unit price is standardized, when the steel pipe is used, the outer diameter of the inner joint pipe often does not match the inner diameter of the outer joint pipe. It is necessary to cut the outer surface of the inner joint pipe to a required diameter. In addition, there is a risk that some dimensional errors in the outer and inner diameters of the steel pipe are unavoidable during pipe making, and the cross-sectional shape is also not round due to the roundness error, so the inner joint pipe may not be inserted into the outer joint pipe. . For this reason, if the diameter difference between the two pipes is set to 0.5 mm to 1.0 mm as in the conventional case, both the inner surface of the outer joint pipe and the outer surface of the inner joint pipe must be machined with a lathe, resulting in a large cost increase. It becomes.

An object of the present invention is to provide a structure that allows easy manufacture of a mechanical joint structure of a steel pipe pile and to provide it at a low cost. More specifically, the outer joint pipe and the inner joint pipe can be configured by selecting and using steel pipes with the required outer diameter and thickness, thereby greatly reducing the labor of cutting the peripheral surface with a lathe. To provide a steel pipe pile mechanical joint structure, which can greatly reduce the cost.

As a means for solving the above-mentioned problems of the prior art, the mechanical joint structure of a steel pipe pile according to the invention described in claim 1 is:
In the mechanical joint structure of steel pipe piles that mechanically connect two steel pipe piles in series,
On the end face of one steel pipe pile, an outer joint pipe with a plurality of connecting holes drilled in the radial direction on the peripheral wall is fixed by welding,
An end fitting is fixed to the corresponding end face of the other steel pipe pile by welding, and can be fitted inside the outer joint pipe to the other side of the end fitting, and a connecting hole for the outer joint pipe is formed on the peripheral wall. The inner joint pipe with a plurality of connecting holes pierced in the radial direction in a matching arrangement is fixed by welding,
An inner joint pipe is inserted into the pipe of the outer joint pipe, the connecting holes of the outer joint pipe and the inner joint pipe are made to coincide with each other, a connection pin is inserted, and a drop prevention process is performed. It is characterized in that steel pipe piles are connected.

The invention described in claim 2 is a mechanical joint structure of a steel pipe pile according to claim 1,
A difference in diameter between the inner diameter of the outer joint pipe and the outer diameter of the inner joint pipe is formed in a range of 0.7% to 1.5% of the inner diameter of the outer joint pipe.

The invention described in claim 3 is the mechanical joint structure of the steel pipe pile according to

claim

1 or 2,
The shape of the end fitting is a disc shape or an annular shape.

In the mechanical joint structure of a steel pipe pile according to the present invention, the outer joint pipe 3 is fixed to the end face of one steel pipe pile 1 by factory welding, and the end fitting 4 is attached to the corresponding end face of the other steel pipe pile 2. Since the inner joint pipe 5 which is fixed by factory welding and can be fitted inside the outer joint pipe 3 on the other side of the end fitting 4 is also fixed by factory welding, the end fitting 4 and the outer metal The joint pipe 3 and the inner joint pipe 5 can be used by selecting and using steel pipes with the required outer diameter and thickness, and the peripheral surface cutting can be largely omitted, so that much labor and cost are greatly reduced. Therefore, an inexpensive mechanical joint structure can be provided.

It is a perspective view which decomposes | disassembles and shows the mechanical joint structure of the steel pipe pile which concerns on this invention. It is a perspective view which shows the mechanical joint structure of the steel pipe pile which concerns on this invention. It is sectional drawing which shows the mechanical joint structure of the steel pipe pile which concerns on this invention. (A) is the IV section enlarged view of FIG. (B) is an enlarged view showing a different configuration for welding the outer joint pipe to the steel pipe pile. FIG. 5 is a cross-sectional view taken along line VV in FIG. 2. It is a perspective view which shows the outer joint pipe | tube which provided the hole for connection in the staggered arrangement | positioning. It is sectional drawing which shows the Example from which the mechanical joint structure of the steel pipe pile which concerns on this invention differs. It is sectional drawing which shows the mechanical joint structure of the conventional steel pipe pile.

In the mechanical joint structure of a steel pipe pile according to the present invention, an outer joint pipe 3 in which a plurality of connecting holes 3a are formed in the peripheral wall in a radial direction is fixed to the end surface of one steel pipe pile 1 by welding a. The end fitting 4 is fixed to the corresponding end face of the steel pipe pile 2 by welding b, and can be fitted to the other side of the end fitting 4 inside the outer joint pipe 3. The inner joint pipe 5 in which a plurality of connecting holes 5a are formed in a radial direction in an arrangement that coincides with the connecting holes 3a is fixed by welding c.
The inner joint pipe 5 is inserted into the pipe of the outer joint pipe 3, the

connection holes

3a and 5a of both pipes are aligned, and the connection pins 6 are inserted into the

respective connection holes

3a and 5a to prevent the dropout treatment. The two

steel pipe piles

1 and 2 are connected.

Below, the structure and usage method of the mechanical joint structure of the steel pipe pile which concerns on this invention are demonstrated based on the illustrated example.
The mechanical joint structure of steel pipe piles shown in Figs. 1 to 5 is that the outer joint pipe 3 is welded at the factory to the upper end surface of the lower steel pipe pile 1 of the two upper and lower

steel pipe piles

1 and 2 to be connected in series. And is stuck. The end fitting 4 is welded to the corresponding lower end surface of the upper steel pipe pile 2, and the inner joint pipe 5 is similarly fixed to the other side surface (lower surface side) by factory welding. At the site, the inner joint pipe 5 of the upper steel pipe pile 2 is fitted into the outer joint pipe 3 of the lower steel pipe pile 1, and the inner and

outer joint pipes

5 and 3 are joined using the connecting pin 6, The two

steel pipe piles

1 and 2 are mechanically connected in series to complete the joint structure. Note that the mechanical joint structure of the present invention can be similarly implemented even with a configuration in which the configuration shown in FIG. 3 is turned upside down.

The configuration of each part will be described in more detail. The steel pipe piles 1 and 2 of the illustrated embodiment have an outer diameter of 216.3 mm and a thickness of 8.2 mm, and the upper end surface of the lower steel pipe pile 1 has the same outer diameter as the outer diameter of the steel pipe pile 1. As an example, the outer joint pipe 3 having four connecting holes 3a... Drilled in the radial direction at equal intervals is fixed to the peripheral wall by welding at the factory. As an example, the diameter of the connecting hole 3a is 48.5 mm.
The outer joint pipe 3 is processed and used by selecting a steel pipe having a required outer diameter and thickness. For example, the outer joint pipe 3 has a thickness of 14.7 mm and a length of 183.5 mm. Incidentally, the operation of welding the outer joint pipe 3 to the end face of the steel pipe pile 1 is performed in advance on the inner face of the outer joint pipe 3 in consideration of the root gap as shown in an enlarged view in FIG. The backing material 8a straddling is installed, and the butted portion is continuously welded in the circumferential direction from the pipe outer surface side. In the case of the illustrated example, a re-shaped groove is formed at the lower end of the outer joint pipe 3. When the backing material 8a and the below-mentioned

backing materials

8b and 8c are made of a material such as a steel plate, they can be removed after the welding and used repeatedly. As shown in FIG. 4 (B), the backing material 8a can be omitted by forming a protruding portion 3b protruding downward together with a reed groove at the lower end of the outer joint pipe 3. Moreover, it can implement similarly also in the structure which did not form a groove | channel in the lower end of the outer joint pipe | tube 3, and processed the ladle-shaped groove | channel in the upper end of the opposing steel pipe pile 1. Furthermore, it is possible to weld the outer joint pipe 3 or the steel pipe pile 1 without forming a groove. The same applies to the following embodiments.
The number of the connecting holes 3a is not limited to the four illustrated. For example, as shown in FIGS. 6 and 7, a plurality of configurations can be implemented, or even three can be implemented. Further, the shape of the connecting hole 3a is not limited to the circular shape shown in the figure, and for example, an elliptical shape or a quadrangular shape can be used.

On the other hand, the upper steel pipe pile 2 has an end fitting 4 made of an annular steel plate having the same outer diameter as the outer diameter of the steel pipe pile 2 on the lower end surface corresponding to the upper end face of the lower steel pipe pile 1. The upper surface is fixed by welding b in the factory. As an example, the end fitting 4 has an annular shape having a length t ₁ of 19 mm and a thickness t ₂ of 31.3 mm. The end fitting 4 may be manufactured by cutting a thick steel pipe into a short length, or may be manufactured by cutting a steel plate. Incidentally, the work of welding the end fitting 4 to the lower end surface of the upper steel pipe pile 2 is performed by previously installing a backing material 8b straddling the steel pipe pile 2 in consideration of the root gap on the upper surface of the end fitting 4. Welding is performed by processing a groove in the outer corner of the end fitting 4. In addition, it can implement similarly also in the structure which did not form a groove | channel in the outer corner of the edge part metal fitting 4, but processed the lathe-shaped groove | channel on the upper end of the opposing steel pipe pile 2.
The end fitting 4 is not limited to the illustrated annular shape. Although illustration is omitted, for example, a disk shape may be used. When manufacturing the end fitting 4 from a steel plate, the circular shape not only has a lower cutting cost than the annular shape, but also suppresses the cross-sectional shape of the end of the inner joint, thereby suppressing a decrease in the bending strength of the joint. There are benefits.

Four connecting holes 5a in the radial direction can be fitted on the lower surface of the end fitting 4 to the inside of the outer joint pipe 3, and arranged on the peripheral wall so as to coincide with the connecting holes 3a of the outer joint pipe 3. The drilled inner joint pipe 5 is fixed by welding c in a factory. In the operation of welding the inner joint pipe 5 to the lower surface of the end fitting 4, a backing material 8 c straddling the end fitting 4 is installed on the inner surface of the inner joint pipe 3 in consideration of the root gap in advance. The butt portion is continuously welded in the circumferential direction from the outer surface side.
Similarly to the outer joint pipe 3, the inner joint pipe 5 is also used by selecting a steel pipe having a required outer diameter and thickness. As an example, the dimensions of the inner joint pipe 5 are an outer diameter of 185 mm and a thickness of 14.7 mm while the inner diameter of the outer joint pipe 3 is 186.9 mm. Even if there is a difference in diameter between the inner diameter of the outer joint pipe 3 and the outer diameter of the inner joint pipe 5 (1.9 mm, the ratio of the diameter difference with the inner diameter of the outer joint is 1.02%), the bending moment strength of the joint portion can be reduced. The dimensions are within a range that can be sufficiently secured. In addition, the outer surface of the inner joint pipe 5 can be roughened to improve the fitting.
The inner joint pipe 5 is welded to the end fitting 4 by forming a re-shaped groove at the outer corner of the upper end portion.

The diameter difference between the inner diameter of the outer joint pipe 3 and the outer diameter of the inner joint pipe 5 is 0.7% of the inner diameter of the outer joint pipe 3 so as to omit the peripheral surface cutting of the outer joint pipe 3 and the inner joint pipe 5. % To 1.5% or less is preferable.
The reason is that by setting a large difference between the inner diameter of the outer joint pipe 3 and the outer diameter of the inner joint pipe 5, the standard outer diameter original pipe can be used as it is as the inner joint pipe 5, and the roundness error is further reduced. This is because it can be absorbed. Specifically, since the roundness of a general steel pipe is about 0.5%, the inner joint pipe 5 may not be inserted into the outer joint pipe 3 if the diameter difference is less than 0.7%. There is. Moreover, if the diameter difference is too large, the bending moment proof stress of the joint is reduced. According to the bending test conducted by the inventor, in the test in which the diameter difference between the

pipes

3 and 5 was set to 1.2%, the bending proof strength was about 2% lower. When the diameter difference was 1.8%, the diameter decreased by about 15%. Therefore, it has been found that the diameter difference between the

pipes

3 and 5 is preferably set to 0.7% or more and 1.5% or less of the inner diameter of the outer joint pipe 3. By providing a difference in diameter within the above range, one or both of the inner surface of the outer joint pipe 3 and the outer surface of the inner joint pipe 5 can be formed without cutting, and it is possible to prevent a decrease in the bending strength of the joint. it can.

The inner joint pipe 5 has a length of 159 mm. The length of the inner joint pipe 5 is preferably 0.6 to 1.2 times the outer diameter of the steel pipe pile 2. Therefore, if the outer diameter of the steel pipe pile 2 is 216.3 mm as described above, the length of the inner joint pipe 5 need only be in the range of 129.8 mm to 259.6 mm. The reason is outlined below.
When the compressive force and the tensile force are applied, the inner joint pipe 5 and the outer joint pipe 3 press each other in a direction perpendicular to the pipe axis direction so as to rotate in opposite directions. The pressing force becomes a couple and a moment is transmitted. Since this moment transmission amount is substantially proportional to the length of the inner joint pipe 5 (the length in which the inner joint pipe 5 and the outer joint pipe 3 overlap), a larger moment can be transmitted as the inner joint pipe 5 becomes longer. is there. For example, when the length of the inner joint pipe 5 is less than 0.6 times the outer diameter of the steel pipe pile 2, the moment generated by the twisting of the inner joint pipe 5 and the outer joint pipe 3 is the bending of the steel pipe pile 2. In order to reduce the moment proof strength to 30% or less and share the remaining moment for the transmission of the pin portion, it is necessary to increase the wall thickness of the joint pipe or increase the number of connecting pins 6 described later. Further, the bending rigidity of the joint portion is significantly lowered, which causes a design problem. On the other hand, when the length of the inner joint pipe 5 is 1.2 times or more the outer diameter of the steel pipe pile 2, the bending strength increases, but an effect commensurate with the increase in cost cannot be obtained. Therefore, the inner joint pipe 5 can be suitably implemented by setting the length of the outer diameter of the steel pipe pile 2 to 0.6 to 1.2 times.

As an example of the connection pin drop-off prevention process, in the embodiment shown in FIGS. 3 and 5, the inner surface of the inner joint pipe 5 is arranged so as to block all the inner openings of the connection holes 5a, and will be described later. A locking member 5b having a bolt hole 7a into which the screw 7 is screwed is also fixed by welding in a factory. However, the locking member 5b can also be implemented in a configuration in which the locking member 5b is traversed and fixed so as to block a part of the inner opening of the connecting hole 5a. In addition, as shown in the conventional example of FIG. 8, the locking member 5 can be implemented in a ring shape.

Next, the on-site connection work of the two steel pipe piles 1 and 2 will be described. As shown in FIG. 1, an inner joint pipe fixed to the lower end of a steel pipe pile 2 is suspended in a pipe of an outer joint pipe 3 fixed to the lower steel pipe pile 1 and opened upward with a pile driving machine or the like. Insert 5 and fit. Then, the connecting

holes

3a and 5a of the inner and outer

joint pipes

3 and 5 are made to coincide with each other, and the connecting

holes

3a and 5a are connected to the connecting

pins

3a and 5a having a slightly smaller diameter than the connecting

holes

3a and 5a ( In the illustrated embodiment, the cylindrical body) is inserted until it hits the locking member 5b in the inner joint pipe 5. Then, the screw shaft portion of the set bolt 7 is inserted into the bolt through hole 6a of the connecting pin 6, and the tip end portion of the screw shaft portion 7 is screwed into the bolt hole of the locking member 5b and fastened. The

piles

1 and 2 are connected. Although not shown in the figure, the head of the set bolt 7 is provided with a recess capable of accommodating the head of the set bolt 7 in the connecting pin 6 so that the head of the bolt 7 protrudes from the outer surface of the pipe. It can also be implemented in a configuration that is housed so that there is no such thing.

The manufacturing cost of the mechanical joint structure of the steel pipe pile of the above-described embodiment and the conventional mechanical joint structure of the steel pipe pile will be compared.
In the conventional mechanical joint structure of steel pipe piles, the outer joint pipe 3 has a roundness by cutting a standard steel pipe having an outer diameter of 216.3 mm, a thickness of 15 mm, and a length of 173.5 mm. The outer diameter is 216.3 mm, the thickness is 14.5 mm, and the length is 173.5 mm.
Also, as the inner joint pipe 5, a special steel pipe having an outer diameter of 216.3 mm, a thickness of 29.5 mm, and a length of 178 mm is cut and the size of the portion to be fitted into the outer joint pipe 3 is set. The outer diameter is 187.3 mm, the thickness is 14.5 mm, and the length is 159 mm. As described in paragraph [0005] above, the inner joint pipe 5 is a thick steel pipe having a thickness corresponding to the dimensional difference S between the outer diameter of the steel pipe piles 1 and 2 and the inner diameter of the inner joint pipe 5. This is because the outer peripheral surface of the inner joint pipe 5 needs to be cut to the outer diameter close to the inner side of the outer joint pipe 3 by, for example, a lathe, over the fitting length L of the inner joint pipe 5. The combined weight of the outer joint pipe 3 and the inner joint pipe 5 before cutting is 37.1 kg. Further, the amount of cutting by lathe processing of the outer joint pipe 3 and the inner joint pipe 5 is 1.599 × 10 ⁻³ m ³ .

On the other hand, the mechanical joint structure of the steel pipe pile of the present embodiment having the above dimensions is the outer joint pipe 3 having an outer diameter of 216.3 mm, an inner diameter of 188.3 mm, a thickness of 14.7 mm, and a length of 183. A steel pipe with a standard of 5 mm is used as it is. As the inner joint pipe 5, a steel pipe made of a standard standard having an outer diameter of 185 mm, a thickness of 14.7 mm, and a length of 159 mm is used as it is. The combined weight of the outer joint pipe 3 and the inner joint pipe 5 is 28.7 kg. Since the outer joint pipe 3 and the inner joint pipe 5 can omit the cutting process, the cutting amount is zero.
Therefore, in the mechanical joint structure of the steel pipe pile of the present embodiment, the total weight of the purchased steel material is reduced by 23% compared to the mechanical joint structure of the conventional steel pipe pile, and an inexpensive steel pipe can be purchased and used. Since the peripheral surface cutting can be largely omitted, it is possible to greatly reduce the labor and cost.

As different embodiments of the mechanical joint structure of the steel pipe pile according to the present invention, as shown in FIG. 7, the outer diameter of the outer joint pipe 3 and the outer surface of the end fitting 4 are allowed to prevent deterioration of peripheral friction. As a dimension, it can implement by the dimension which protrudes about 10 mm outward from the outer surface of the steel pipe pile 1. FIG. As an example, the outer diameter of the steel pipe piles 1 and 2 is 355.6 mm and the thickness is 12 and 7 mm, whereas the outer diameter of the outer joint pipe 3 is 365.1 mm, the thickness is 18.5 mm, and the length is The outer diameter of the end fitting 4 is 365.1 mm, the length t ₁ is 25 mm, and the thickness t ₂ is 40.6 mm.
As an example, the inner joint pipe 5 has an outer diameter of 323.9 mm, a thickness of 20 mm, and 267.5 mm, whereas the outer joint pipe 3 has an inner diameter of 328.1 mm. Even if there is a difference in diameter between the inner diameter of the outer joint pipe 3 and the outer diameter of the inner joint pipe 5 (4.2 mm, a diameter difference ratio of 1.28% from the inner diameter of the outer joint), the inner joint pipe 5 is It is a dimension within a range that can be inserted into the tube 3 and can sufficiently secure the bending moment proof stress of the joint portion.

As a further different embodiment of the mechanical joint structure of the steel pipe pile according to the present invention, when a large number of holes for connection are arranged in a row in the circumferential direction of the joint pipe, the loss area of the opening cross section becomes large, As shown in FIGS. 6 and 7, the configuration is provided in a staggered arrangement in the tube axis direction. In the embodiment shown in FIG. 7, the height dimensional difference between the centers of the connecting

holes

5a and 5a positioned above and below is 70 mm. That is, it is possible to prevent the defect area of the cross section of the opening from being reduced and reduce the various proof stresses of the joint.

Although the present invention has been described above based on the illustrated examples, the present invention is not limited to the above-described embodiments and examples. Various embodiments are possible within the scope of design changes and applications usually performed by those skilled in the art as necessary.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Steel pipe pile 3 Outer joint pipe 3a Connection hole 4 End metal fitting 5 Inner joint pipe 5a Connection hole 6 Connection pin

Claims

In the mechanical joint structure of steel pipe piles that mechanically connect two steel pipe piles in series,
On the end face of one steel pipe pile, an outer joint pipe with a plurality of connecting holes drilled in the radial direction on the peripheral wall is fixed by welding,
An end fitting is fixed to the corresponding end face of the other steel pipe pile by welding, and can be fitted inside the outer joint pipe to the other side of the end fitting, and a connecting hole for the outer joint pipe is formed on the peripheral wall. The inner joint pipe with a plurality of connecting holes pierced in the radial direction in a matching arrangement is fixed by welding,
An inner joint pipe is inserted into the pipe of the outer joint pipe, the connecting holes of the outer joint pipe and the inner joint pipe are made to coincide with each other, a connection pin is inserted, and a drop prevention process is performed. A mechanical joint structure for steel pipe piles, wherein the steel pipe piles are connected.
The diameter difference between the inner diameter of the outer joint pipe and the outer diameter of the inner joint pipe is formed in a range of 0.7% to 1.5% of the inner diameter of the outer joint pipe. The mechanical joint structure of steel pipe piles described in 1.
3. The mechanical joint structure for steel pipe piles according to claim 1 or 2, wherein the shape of the end fitting is a disc shape or an annular shape.