JP2004293035A - Joint structure of steel pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of steel pipes capable of facilitating the construction with a simple structure at a low cost and having high reliability corresponding also to large tensile load. <P>SOLUTION: The joint structure of the steel pipes includes an outside joint pipe 1 having engaging sections 5a, 5b and 5c with a plurality of steps in the direction of the axis of the inner circumferential surface connected to one steel pipe 31 and an inside joint pipe 11 having engaged projection sections 16a, 16b and 16c with a plurality of steps having a diameter reducing function and engaged with the engaging sections 5a, 5b and 5c of the outside joint pipe 1 in the direction of the axis of the outer circumferential surface connected to the other pipe 32, and the inside joint pipe 11 is pressed inside of the outside joint pipe 11 to respectively engage the engaged projection sections 16a, 16b and 16c with the engaging sections 5a, 5b and 5c of the outside joint pipe 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a joint structure of a steel pipe, for example, a steel pipe pile, a precast concrete pile (a PHC pile, a PRC pile, an SC pile) in a pipe axis direction, and a method of joining steel pipes.
[0002]
[Prior art]
Steel pipe piles such as soil-cement synthetic steel pipe piles are generally constructed by welding and joining piles at construction sites.
However, in the case of welded piles, (1) the quality of the welded part depends on the skill of the welder, and (2) the construction depends on the weather. Had been rare.
[0003]
As an example of a joining structure of steel pipes not based on welding, a cylindrical connecting part having an outer diameter smaller than the diameter of the steel pipe is coaxially connected and fixed to a butt end of each steel pipe to be connected, and this cylindrical connecting part is fixed. A large number of screw holes are provided on the side surface of the cylindrical connection portion, and these cylindrical connection portions connected and fixed to each steel pipe are butted against each other, and the outer periphery of the two butted cylindrical connection portions is appropriately divided into an arc shape. Covering each divided piece with a divided cylindrical joint having a large number of bolt insertion holes, aligning each bolt insertion hole of this divided cylindrical joint with each screw hole of the cylindrical connection portion, and fitting these bolt insertion holes. The steel pipes are connected to each other by screwing a bolt end into a screw hole through a bolt and tightening, and each split cylindrical joint fixed to the cylindrical connection portion and a head of each tightened bolt are connected to the steel pipe. Than the outside diameter of There are those do not appear (e.g., see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-81304 (pages 2 to 4, FIG. 1)
[0005]
[Problems to be solved by the invention]
The steel pipe connection structure described in Patent Document 1 uses a split cylindrical joint separate from a steel pipe pile. In order to integrate the steel pipe pile, not only the upper joint and the lower joint are engaged but also the split cylindrical joint is used. High-precision manufacturing is required in consideration of the engagement between the joint and the upper and lower joints, making it difficult to manufacture and expensive. In addition, it is necessary to separately transport and attach the divided cylindrical joint, and the workability is poor.
Furthermore, when the diameter and thickness of the steel pipe joints are increased, the weight of the divided cylindrical joint increases, and the transportability and workability are further deteriorated, such as the necessity of bringing in new heavy equipment such as a crane. There are various problems.
[0006]
The present invention has been made in order to solve the above-described problems, and has a simple and easy-to-construct structure, can reduce costs, and furthermore, has a highly reliable steel pipe that can sufficiently cope with a large tensile load. It is an object of the present invention to provide a joint structure and a method for joining steel pipes.
[0007]
[Means for Solving the Problems]
(1) The joint structure of a steel pipe according to the present invention has a plurality of locking portions in the axial direction of the inner peripheral surface, has an outer joint pipe joined to one steel pipe, has a diameter reducing function, and has an outer periphery. A plurality of engagement projections are provided in the axial direction of the surface to be engaged with the engagement portions of the outer joint pipe, and an inner joint pipe joined to the other steel pipe is provided. The fitting tube is press-fitted so that the engaging projections are respectively locked to the locking portions of the outer joint tube.
[0008]
(2) A concave groove is provided on the inner peripheral surface or the outer peripheral surface between the large-diameter portion and the engagement projection of the inner joint pipe of (1).
(3) At the lower end of the inner joint pipe of the above (1) or (2), a fitting portion for fitting to a bolt provided on the outer joint pipe is provided.
[0009]
(4) An initial gap was provided between the outer joint pipe and the inner joint pipe in any of the above (1) to (3).
(5) The height of the second-stage or higher engagement projections of the plurality of engagement projections provided on the inner joint pipe according to any one of (1) to (4) is set to the first-stage engagement. It was formed lower than the height of the protrusion.
[0010]
(6) Further, the steel pipe joint structure according to the present invention has a diameter-expanding function, is provided with a plurality of locking portions in the axial direction of the inner peripheral surface, and has an outer joint steel pipe connected to one steel pipe. A plurality of engagement projections are provided in the axial direction of the outer peripheral surface to be engaged with the engagement portions of the outer joint pipe, and an inner joint pipe joined to the other steel pipe is provided in the outer joint pipe. The inner joint pipe is press-fitted so that the engagement protrusions of the inner joint pipe are locked to the locking portions of the outer joint pipe, respectively.
[0011]
(7) When the inner joint pipe is press-fitted into the outer joint pipe of the above (6), the distal end of the inner joint pipe abuts on the projecting step of the outer joint pipe and is provided on the upper outer periphery of the inner joint pipe. The gap was formed between the contact portion and the upper end of the outer joint pipe.
(8) Of the plurality of locking portions provided on the outer joint pipe of (6) or (7), the tip of the locking portion of the second or lower stage from the top is shifted from the tip of the uppermost locking portion. Formed on the outer wall side.
(9) The outer joint pipe of any of the above (1) to (8) and the inner joint pipe pressed into the outer joint pipe were integrally fixed by bolts.
[0012]
(10) The steel pipe according to any one of the above (1) to (9) is a steel pipe pile, and one of the inner joint pipe joined to the other steel pipe pile is placed inside the outer joint pipe joined to one steel pipe pile. The steel pipe pile was press-fitted by its own weight.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
In view of the problems such as the connection structure of steel pipes described in Patent Document 1 described above, the inventor of the present invention joined an outer joint pipe to one steel pipe of two steel pipes to be joined, and The inner joint pipe is joined to the steel pipe of the above, a locking part is provided in the circumferential direction of the inner wall of the outer joint pipe, and an engaging projection is provided on the outer wall of the inner joint pipe to be locked to the locking part. A plurality of slits are provided in the joint pipe to have a diameter reducing function, the inner joint pipe is press-fitted (or fitted) into the outer joint pipe, and the engaging projection is locked to the locking portion, and the two steel pipes are connected. A joint structure for joining was proposed.
Such a steel pipe joint structure is extremely useful because it has a simple structure, is easy to manufacture and construct, and can reduce costs.
[0014]
By the way, in such a steel pipe joint structure, when the steel pipe to be joined becomes thick, the height of the engaging projection of the inner joint pipe which resists a tensile load is increased, and the steel pipe overlaps with the locking part. Need to be larger. However, when the height of the engagement protrusion is increased, when the inner joint pipe having the diameter reducing function is press-fitted (or fitted) into the outer joint pipe, the amount of radial bending (reduced diameter) of the inner joint pipe is reduced. As a result, the press-in force increases. In addition, when the amount of bending of the inner joint pipe increases, the root portion is plasticized, which may cause a problem in strength.
[0015]
The present invention is configured so that it can sufficiently cope with a large tensile load in the above-described steel pipe joint structure, and will be described in detail below with reference to embodiments.
[0016]
[Embodiment 1]
FIG. 1 is a schematic diagram of a joint structure for a steel pipe, a part of which is shown in cross section according to Embodiment 1 of the present invention.
In the figure, J is a joint part for joining two steel pipes 31 and 32, and a lower end part is a cylindrical outer joint pipe 1 welded to one steel pipe 31 to be joined, and an upper end part is the other end. And a cylindrical inner joint pipe 11 which is welded to the steel pipe 32.
[0017]
The outer joint pipe 1 is formed so that its outer diameter is substantially equal to the outer diameter of the steel pipe 31, the inner peripheral surface of the upper end portion 2 is cut obliquely upward to provide an inclined surface 3, and the outer peripheral surface of the inner peripheral surface is formed. A recess 4 whose diameter is enlarged within a predetermined range is formed substantially below the central portion in the axial direction. Reference numerals 5a, 5b, and 5c denote first to third locking portions provided on the upper edge portion of the concave portion 4 and the inner peripheral surface above the recessed portion. FIG. However, it is sufficient that the plurality of locking portions 5a to 5c are simply referred to as 5 in the following description. Reference numeral 6 denotes a projecting step formed on the lower edge of the recess 4 to have an inner diameter substantially equal to the inner diameter of the inner joint pipe 11, and 7 denotes a plurality of bolt insertion holes provided in the circumferential direction of the recess 4.
[0018]
The inner joint pipe 11 is provided with an enlarged diameter part 12 having an outer diameter substantially equal to the outer diameter of the steel pipe 32 at an upper part, and a lower part of the enlarged diameter part 12 through a step part 13 (abutting part). A main body 14 having an outer diameter substantially equal to the inner diameter of the joint pipe 1 is provided. The main body 14 is provided with a plurality of slits 15 reaching the lower end from the step 13 at substantially equal intervals in the circumferential direction, whereby the main body 14 is divided in the circumferential direction and has a diameter reducing function. Having a plurality of divided pieces 14a.
[0019]
16a, 16b, 16c correspond to the first to third locking portions 5a to 5c of the outer joint pipe 1, and the first to third engaging projections projecting from the outer peripheral surface of each divided piece 14a. in its the upper surface perpendicular to the outer peripheral surface lower is provided with the inclined surface 17, the height H ₂ of up to the step portion 13 from the upper surface of the first engaging projection 16a, the outer joint pipe 1 second is formed to be almost equal from the first engaging portion 5a and the height H ₁ to the upper end 2 (in the following description, it may be referred to simply as 16 a plurality of engagement projections 16 a to 16 c). Reference numeral 18 denotes a bolt hole provided below the first engaging projection 16a of each split piece 14a. The bolt hole 18 is provided corresponding to the bolt insertion hole 7 of the outer joint pipe 1. Instead of the bolt hole 18, a bolt insertion hole may be provided, and a nut may be attached to the inner wall side.
[0020]
Next, an example of a construction procedure when the present invention is applied to joining of steel pipe piles will be described. The outer joint pipe 1 and the inner joint pipe 11 are welded to the ends of the steel pipe piles 31a and 32a to be joined in advance in a factory or the like, and these steel pipe piles 31a and 32a are transported to a construction site. Shall be.
[0021]
First, as shown in FIG. 2A, the steel pipe pile 31a to which the outer joint pipe 1 is joined is driven into the ground. When the driving is advanced and the steel pipe pile 32a, which is the upper pile, is connected, the steel pipe pile 32a, to which the inner joint pipe 11 is joined at the tip, is positioned and positioned on the steel pipe pile 31a, and the steel pipe pile 32a is positioned. As shown in FIG. 2 (b), the lower surface of the inner joint pipe 11 and the lower surface of the first engagement protrusion 16 a of the inner joint pipe 11 are lowered by the rolling force due to its own weight. Utilizing the inclined surface 17 provided, each divided piece 14a of the inner joint pipe 11 is bent to reduce the diameter of the main body portion 14 and inserted into the outer joint pipe 1.
[0022]
When the steel pipe pile 32a is continuously lowered, each of the divided pieces 14a of the inner joint pipe 11 is further bent and reduced in diameter, and the inner joint pipe 11 is formed such that the outer peripheral surface of the first engagement projection 16a is the inner periphery of the outer joint pipe 1. When the step 13 (contact portion) comes into contact with the upper end portion 2 of the outer joint pipe 1, the rolling down is stopped. At this time, the first to third engagement projections 16a to 16c are located corresponding to the first to third engagement portions 5a to 5c, respectively. The state at this time is shown in FIG.
[0023]
In this state, if the bolt 35 inserted into the bolt insertion hole 7 of the outer joint pipe 1 is screwed into each bolt hole 18 of the inner joint pipe 11 and tightened, as shown in FIG. The first to third engaging projections 16a to 16c are securely locked to the first to third locking portions 5a to 5c of the outer joint pipe 1 by abutting or approaching the inner wall of the pipe 1, The upper and lower steel pipe piles 31 a and 32 a are firmly joined via the outer joint pipe 1 and the inner joint pipe 11.
[0024]
In this case, when the inner joint pipe 11 has been pressed into the outer joint pipe 1, each of the divided pieces 14 a of the inner joint pipe 11 is plastically deformed inward and does not return to the original state (expanded in diameter). It is feared that there is. However, according to the results of many experiments conducted by the inventors, each of the divided pieces 14a basically returns to the original state without plastic deformation, and the engaging projections 16a to 16c are respectively engaged with the locking parts 5a to 5c. Was locked. However, in order to more reliably lock the engaging projections 16a to 16c to the locking portions 5a to 5c, it is necessary to fix both using the bolt 35.
[0025]
In the steel pipe piles 31a and 32a fitted as described above, the compressive load applied to the steel pipe pile 32a as the upper pile is transmitted through the step 13 of the inner joint pipe 11 and the upper end 2 of the outer joint pipe 1. It is transmitted to the pile 31a. Further, since the tensile load is transmitted to the steel pipe pile 31a via the plurality of engagement protrusions 16a to 16c of the inner joint pipe 11 and the plurality of locking parts 5a to 5c of the outer joint pipe 1, the tensile load is reduced. It is possible to respond sufficiently.
[0026]
According to the present embodiment, the inner joint pipe 11 can be press-fitted into the outer joint pipe 1 with a relatively small press force without particularly increasing the engagement protrusion 16, and the upper locking portions 5 a to 5 c can be pressed. Since the overlap between the projection 5c and the engagement projections 16a to 16c is increased, it is possible to sufficiently cope with a large tensile load as described above.
Also, the inner joint pipe 11 joined to the end of the steel pipe pile 32a is simply pressed into the outer joint pipe 1 by the weight of the steel pipe pile 32a and fixed with the bolt 35, without using other members and the like. Since the piles 31a and 32a can be joined, the structure is simple and the construction is extremely easy. Not only can the cost be reduced, but also the workability can be greatly improved.
[0027]
Further, since the outer diameter of the outer joint pipe 1 and the outer diameter of the large-diameter portion 12 of the inner joint pipe 11 are substantially equal to the outer diameters of the steel pipe piles 31a and 32a to be joined, the joint J becomes the outer periphery of the steel pipe piles 31a and 32a. Therefore, the steel pipe piles 31a, 32a can be driven into the ground with less penetration resistance.
If a large-diameter portion into which the head of the bolt 35 is inserted is provided in the bolt insertion hole 7 of the outer joint pipe 1, the head of the bolt 35 may protrude from the outer peripheral surface of the joined outer joint pipe 1. Therefore, the resistance to penetration into the ground can be further reduced. However, in this case, it is necessary to provide a hole for engaging a hexagon wrench or the like in the head of the bolt 35.
[0028]
In the above description, the case where the joint structure according to the present embodiment is used for joining the steel pipe piles 31a and 32a has been described. However, the present invention is not limited to this. The present invention can also be implemented. In this case, when the inner joint pipe 11 is press-fitted into the outer joint pipe 1, a press-fitting machine or the like may be required.
[0029]
[Embodiment 2]
FIG. 4 is a partial cross-sectional view of a joint portion of a steel pipe according to Embodiment 2 of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
This embodiment, the upper part of the inner peripheral surface of the inner joint tube 11, the width (height) is provided with a recessed groove 20 of the L ₂ (in the figure, a stepped portion of the edge on the groove 20 13 is shown.
FIG. 5 shows another example of the present embodiment. In this example, a concave groove 20 is provided at the upper part of the outer peripheral surface of the inner joint pipe 11 with its upper edge at the same position as the stepped part 13. It is a thing. The concave groove 20 shown in FIGS. 4 and 5 may be provided in another place as long as it is between the large-diameter portion 12 of the inner joint pipe 11 and the uppermost engaging projection 16c.
[0030]
The construction procedure of the joint portion J in the present embodiment is almost the same as that in the first embodiment, but a concave groove 20 is provided on the inner or outer peripheral surface of the inner joint pipe 11 to reduce the thickness of this portion. Since the rigidity is reduced by reducing the thickness, each divided piece 14a is easily bent, so that the press-in force can be reduced, and even in the large-diameter joint portion J, the inner weight of the steel pipe pile 32a joined to the inner joint pipe 11 causes The part 11 can be pressed into the outer joint part 1.
[0031]
As described above, the concave groove 20 can be provided at an appropriate position between the step 13 and the engaging projection 16 on the inner peripheral surface or the outer peripheral surface of the inner joint pipe 11, and as shown in FIG. since the bending moment increases according to the upper flange and the split pieces 14a distance L ₁ is longer groove 20 between the lower end portion of the groove 20, the deflection amount is increased in the diameter direction of the divided pieces 14a, which Accordingly, the press-in force becomes smaller. Further, according to the axial length of the groove 20 (width) L ₂ is longer, the force-insertion force is reduced.
[0032]
By the way, when the diameter of the joint portion J increases, the machining accuracy of the cutting process of the outer joint pipe 1 and the inner joint pipe 11 deteriorates. Therefore, it is necessary to select the plate thickness to be larger than the minimum plate thickness necessary for stress. Thereby, the amount of bending of the divided piece 14a of the inner joint pipe 11 is reduced, and the press-fitting force when press-fitting the outer joint pipe 1 is increased. For this reason, in order to suppress the pressing force to be equal to or less than the own weight of the upper steel pipe pile 32a, it is necessary to increase the axial length of the divided piece 14a of the inner joint pipe 11 so as to be easily bent. This not only increases the size of the joint J, but also increases the cost.
[0033]
In the present embodiment, a concave groove 20 is provided in the inner peripheral surface or the outer peripheral surface of the main body portion 14 (divided piece 14a) of the inner joint pipe 11, and the rigidity of this portion is reduced to facilitate bending. Can be suppressed to be equal to or less than the weight of the upper steel pipe pile 32a without increasing the axial length of the steel pipe pile 32a.
This not only reduces the cost of the joint portion J, but also eliminates the need to use a press-fitting machine or the like even in the case of a joint portion having a large diameter, thereby facilitating construction and improving workability.
[0034]
[Embodiment 3]
FIG. 6 is an explanatory view of a main part of a joint portion of a steel pipe according to Embodiment 3 of the present invention and an inner surface explanatory view of a split piece of an inner joint pipe.
In the present embodiment, as shown in FIG. 6, a bolt hole 18 is provided instead of the plurality of bolt insertion holes 7 provided in the outer joint pipe 1 of the first embodiment (FIG. 1), and In place of the bolt hole 18 provided in each of the divided pieces 14a, an inverted U-shaped fitting portion 21 opened at the lower end is provided. The case where the locking portion 5 of the outer joint pipe 1 and the engagement protrusion 16 of the inner joint pipe 11 are provided in two stages is shown. At the tip of the threaded portion of the bolt 35, a polygonal locking hole 36 such as a hexagon is provided so that the bolt 35 can be rotated from the outside.
[0035]
In the construction of the present embodiment configured as described above, the steel pipe pile 31a to which the outer joint pipe 1 is joined is driven into the ground to connect the upper steel pipe pile 32a (not shown). At this time or in advance, as shown in FIG. 7A, the tip of the bolt 35 is screwed into the bolt hole 18 of the external joint pipe 11 from inside.
Then, the steel pipe pile 32a, to which the inner joint pipe 11 is joined at the distal end, is lowered by the rolling force due to its own weight, and as shown in FIG. 7 (b), the fitting section provided on each divided piece 14a of the inner joint pipe 11 21 is fitted to a bolt 35 attached to the outer joint pipe 1. At this time, the engagement projections 16a and 16b of the inner joint pipe 11 are located corresponding to the engagement parts 5a and 5b of the outer joint pipe 1.
[0036]
Then, for example, an L-shaped hexagon wrench is engaged with the locking hole 36 provided at the tip of the screw portion of the bolt 35 from the outside of the outer joint pipe 1 to further tighten the bolt 35. The steel pipe piles 31a and 32a are firmly joined via the outer joint pipe 1 and the inner joint pipe 11, respectively.
The effect of this embodiment is almost the same as that of the first embodiment.
[0037]
[Embodiment 4]
When slit 15 is provided in inner joint pipe 11 as in Embodiments 1 to 3, when welded to steel pipe pile 32a, the tip side of each split piece 14a is deformed outward due to thermal deformation due to welding. (Diameter expansion). For this reason, if the outer diameter of the inner joint pipe 11 is formed substantially equal to the inner diameter of the outer joint pipe 1, the outer diameter of the split piece 14a of the inner joint pipe 11 at the time of press-fitting into the outer joint pipe 1 becomes larger than the initial diameter. Since press-fitting increases, press-fitting may not be possible with the weight of the upper pile (steel pipe pile 32a) alone.
[0038]
For this reason, in the present embodiment, as shown in FIG. 8, the outer diameter of the inner joint pipe 11 is made slightly smaller than the inner diameter of the outer joint pipe 1 in accordance with the amount of deformation due to welding. An initial gap g is provided between the inner wall of the joint pipe 1 and the outer wall of the inner joint pipe 11. Thereby, even if each of the divided pieces 14a of the inner joint pipe 11 is deformed outward by welding, it is possible to prevent an increase in press-in force, and the inner joint pipe 11 can be connected to the upper pile (steel pipe) without using a special external force. The pile 32a) can be pressed into the outer joint pipe 1 by its own weight.
[0039]
When the steel pipe piles 31a and 32a to be joined are thick, it is necessary to increase the height (projection length) of the engagement projections 16a to 16c so as to withstand the tensile load. With such a configuration, when the inner joint pipe 11 is pressed into the outer joint pipe 1, the amount of deformation (diameter reduction) of each of the divided pieces 14a in the radial direction increases, and the weight of the upper pile (steel pipe pile 32a) is reduced. In order to press-fit it, it is necessary to increase the length of the split piece 14a in the axial direction to make it easier to deform in the radial direction. However, in this case, there is a problem that not only the size of the joint is increased, but also the cost is increased.
[0040]
In such a case, by providing an initial gap g between the inner wall in the outer joint pipe 1 and the outer wall of the inner joint pipe 11 as in the present embodiment, the inner joint pipe 11 is inserted into the outer joint pipe 1. During the press-fitting, the amount of deformation of the divided pieces 14a to the inside can be small, and joining can be performed with a small press-fit.
[0041]
According to the present embodiment, an initial gap is provided between the inner wall of the outer joint pipe 1 and the outer wall of the inner joint pipe 11, and the inner joint pipe 11 is press-fitted into the outer joint pipe 1, and then the inner joint pipe 11 is bolted. The split piece 14a of the pipe 11 is drawn toward the outer joint pipe 1 to be deformed outward, and the locking projections 16a to 16c are locked to the locking parts 5a to 5c, thereby securely joining the steel pipe piles 31a and 32a. And can sufficiently withstand a large tensile load. At this time, an initial stress is generated at the base of the split piece 14a of the inner joint pipe 11 due to the drawing in of the bolt 35, but since the drawing amount is small, the influence of the initial stress on the joint strength is extremely small.
[0042]
By the way, in the above-described first to fourth embodiments, the engaging projections 16a to 16c of the inner joint pipe 11 are securely locked to the locking portions 5a to 5c of the outer joint pipe 1 by the bolt 35, or The case has been described in which the inner joint pipe 11 having an initial gap with the outer joint pipe 1 is deformed outward to securely lock the engaging projections 16a to 16c with the locking parts 5a to 5c. Also has the following functions.
[0043]
When a tensile load is applied to a steel pipe pile installed underground by being joined by the outer joint pipe 1 and the inner joint pipe 11, the tensile load is transmitted from the inner joint pipe 11 to the lower steel pipe pile via the outer joint pipe 1. However, since the plurality of slits 15 are provided in the inner joint pipe 11, the split pieces 14a are easily deformed inward (in the diameter reducing direction) by a tensile load. When the tensile load increases and the amount of deformation of the inner joint pipe 11 to the inside increases, the engagement protrusions 16a to 16c of the inner joint pipe 11 move to the locking portions 5a of the outer joint pipe 1 as shown by broken lines in FIG. To 5c.
[0044]
According to the present invention, as described above, by fixing the outer joint pipe 1 and the inner joint pipe 11 with the bolts 35, even if a large tensile load is applied to the inner joint pipe 11, deformation to the inside is restricted. Therefore, it is possible to prevent the engaging projections 16a to 16c from being disengaged from the locking portions 5a to 5c, and to withstand a large tensile load.
[0045]
[Embodiment 5]
FIG. 10 is a schematic diagram of a joint structure of a steel pipe showing a part according to a fifth embodiment of the present invention in cross section. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
In each of the above embodiments, the inner joint pipe 11 is provided with the slit 15 so as to have a diameter reducing function, and the inner joint pipe 11 is press-fitted into the outer joint pipe 1 so that the engaging projection 16 is engaged with the engaging portion. 5 shows a case where the outer joint pipe 1 is provided with a slit so as to have a diameter increasing function, and the inner joint pipe 11 is press-fitted into the outer joint pipe 1 to engage with the outer joint pipe 1. The projections 16a, 16b are locked to the locking portions 5a, 5b.
[0046]
In FIG. 10, a plurality of slits 9 are provided in the circumferential direction of the main body 8 of the outer joint pipe 1 at substantially equal intervals and open to the upper end and reach the lower step 6. A plurality of divided pieces 8a having a diameter expanding function are formed by being divided in the circumferential direction. The bolt insertion hole 7 is provided above the uppermost locking portion 5b. Further, a bolt hole 18 is provided in the upper part of the cylindrical main body 14 in the inner joint pipe 11 so as to correspond to the bolt insertion hole 7 of the outer joint pipe 1. The bolt hole 18 may be a bolt insertion hole, and a nut may be attached to the inner wall surface by welding.
[0047]
Next, an example of a construction procedure in a case where the present embodiment is applied to joining of steel pipe piles will be described. It is assumed that the outer joint pipe 1 and the inner joint pipe 11 are welded to the ends of the steel pipe piles 31a and 32a to be joined in advance in a factory or the like.
[0048]
As shown in FIG. 11 (a), when the steel pipe pile 31a to which the outer joint pipe 1 is joined is driven into a state where the steel pipe pile 32a which is the upper pile is joined, the inner joint pipe 11 is joined to the tip. The steel pipe pile 32a thus positioned is positioned above the steel pipe pile 31a and is lowered by the rolling force of the steel pipe pile 32a by its own weight, and is provided at the upper end of the outer joint pipe 1 as shown in FIG. Utilizing the inclined surface 3 and the inclined surface 17 provided below the lowermost engagement projection 16a of the inner joint pipe 11, each of the divided pieces 8a of the outer joint pipe 1 is bent outward to form a main body. 8 is expanded and inserted into the outer joint pipe 1.
[0049]
When the steel pipe pile 32a is continuously lowered, the first (lowest) engagement projection 16a of the inner joint pipe 11 is lowered along the inner peripheral surface of the outer joint pipe 1, and each divided piece 8a of the outer joint pipe 1 is lowered. When the step portion 13 (contact portion) comes into contact with the upper end portion 2 of the outer joint pipe 1, the reduction is stopped. The state at this time is shown in FIG.
[0050]
In this state, if the bolt 35 inserted into the bolt insertion hole 7 of the outer joint pipe 1 is screwed into the bolt hole 18 of the inner joint pipe 11 and tightened, as shown in FIG. Abuts or approaches the outer wall of the inner joint pipe 11, the plurality of engaging projections 16 a, 16 b are respectively engaged with the engaging portions 5 a, 5 b, and the upper and lower steel pipe piles 31 a, 32 a are connected to the outer joint pipe 1. And through the inner joint pipe 11.
[0051]
In the present embodiment, substantially the same effect as in the case of Embodiment 1 can be obtained. However, since the lower inner peripheral surface of the main body 8 of the outer joint pipe 1 is provided with the concave portion 4, The rigidity of this portion is reduced, and each divided piece 8a can be easily bent as in the case of the second embodiment.
[0052]
Embodiment 6
As in the fifth embodiment, a slit 9 is provided in the outer joint pipe 1 to form a plurality of divided pieces 8a, and when the inner joint pipe 11 is press-fitted, the outer joint pipe 1 is expanded in diameter. In a joint structure fixed at 35, when a compressive load acts on the upper pile (steel pipe pile 32a), this compressive load is applied to the step (abutting portion) 13 of the inner joint pipe 11 and the upper end of the outer joint pipe 1. 2 and transmitted to the lower pile (steel pipe pile 31a). In this case, since the outer joint pipe 1 is provided with the slit 8a, there is a possibility that the split piece 8a may cause buckling failure.
[0053]
In the present embodiment, as shown in FIG. 13, in a state where the joint between the outer joint pipe 31 a and the inner joint pipe 11 is completed, the distal end 11 a of the inner joint pipe 11 is connected to the projecting step 6 of the outer joint pipe 1. together they are brought into contact is obtained by the provided clearance g ₁ between the step portion 13 and the upper portion 2 of the outer joint pipe 1 of the inner joint tube 11.
With this configuration, the compressive load is transmitted from the distal end 11a of the inner joint pipe 11 to the lower pile (steel pipe pile 31a) via the projecting step 6 of the outer joint pipe 1, and the upper end 2 of the outer joint pipe 1 is formed. Since no compressive load is applied to, there is no risk that each of the divided pieces 8a will cause buckling failure.
[0054]
Embodiment 7
Incidentally, as described above, in the present invention having a plurality of engagement projections 16 on the inner joint tube 11 having a reduced diameter function, as shown in FIG. 14, for example, the same height (projection length) engagement of h ₁ When the joint portions 16a, 16b, and 16c are provided, when the inner joint pipe 11 is press-fitted into the outer joint tube 1, the first to third engagement protrusions 16a to 16c are sequentially arranged on the outer joint tube 1. When the uppermost engaging projection 16c comes into contact with the inner wall of the outer joint pipe 1 because it slides down on the inner wall and falls, the amount of bending of each divided piece 14a is restricted by the height of the engaging projection 16c. b ₁ is maximized, since they must be pressed into the inner joint tube in this state, a large fitting force P ₁ becomes necessary.
[0055]
This embodiment, in order to solve the above problem, as shown in FIG. 15, the second stage or more engaging projections 16b, the height of 16c (the projection length) h _2, h _3, bottom it is obtained by forming lower than the height h ₁ of the projection 16a of the.
Thereby, when the inner joint pipe 11 is press-fitted into the outer joint pipe 1, only the lowermost engagement protrusion 16 a is always in sliding contact with the inner wall of the outer joint pipe 1 from the start of press-fitting to the final stage. It descends, and the second and higher engaging projections 16 a and 16 c do not hit the inner wall of the outer joint pipe 1. Therefore, deflection of b ₂ of the split pieces 14a is regulated to the height h ₁ of the bottom of the projection 16a become much smaller, so the same as the case of providing the engaging projections 16 one step The inner joint pipe 11 can be pressed into the outer joint pipe 1 with a small rolling force.
[0056]
Form odor of this embodiment, as shown in FIG. 16 (a), 2-stage or more engaging projections 16b, 16c to the same height _{h 2,} and the height h of the bottom of the projection 16a may be lower than _1, or, as shown in FIG. 16 (b), 2-stage or more engaging projections 16b, the height _h 2, _{h 3} and 16b at the bottom of the projection 16a high it is lower than h _1, and may be made successively lower with increasing upwards.
[0057]
Further, when the slit 9 is provided in the outer joint pipe 1 and the inner joint pipe 11 is press-fitted therein as in the fifth embodiment, as shown in FIG. To the height h of all the outer joint pipes 1 corresponding to the locking portions 5a to 5c of the outer joint pipe 1 to which the engaging projections 16a to 16c are locked. Positions b and c (hereinafter, referred to as distal ends) of the engaging surfaces of the engaging portions 5b and 5a below the two-step surface are in contact with the inner wall 1b of the uppermost engaging portion 5c. It is provided at positions b and c (positions on the outer wall side) lower than the part a.
[0058]
In each of the above embodiments, the steel pipe pile 31a to which the outer joint pipe 1 is joined is driven into the ground, and the steel pipe pile 31a to which the inner joint pipe 11 is joined to the steel pipe pile 31a is lowered by its own weight. Although the case of joining has been described, the steel pipe pile 32a to which the inner joint pipe 11 is joined is cast into the ground, and the steel pipe pile 31a to which the outer joint pipe 1 is joined is lowered by its own weight to bring the outer joint pipe 1 inside. The steel pipe piles 32a and 31a may be joined by fitting and joining to the joint pipe 11.
[0059]
【The invention's effect】
According to the present invention, the inner joint pipe having a diameter decreasing function is press-fitted into the outer joint pipe, and the plurality of engagement projections are respectively engaged with the plurality of engagement parts of the outer joint pipe. Since the overlap with the engaging projection is increased, it is possible to sufficiently cope with a large tensile load. Moreover, the structure is simple, the construction is easy, the cost can be reduced, and a highly reliable steel pipe joint structure can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a joint structure for a steel pipe, a part of which is shown in cross section according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram illustrating an example of a procedure for installing the joint structure according to the first embodiment;
FIG. 3 is a partially omitted longitudinal sectional view showing a state where two steel pipes are joined by the joint structure of the first embodiment.
FIG. 4 is a longitudinal sectional view of a joint structure of a steel pipe with a part omitted according to a second embodiment of the present invention.
FIG. 5 is a longitudinal sectional view in which a part of another example of the second embodiment is omitted.
FIG. 6 is an explanatory view of a main part of a joint structure for a steel pipe according to Embodiment 3 of the present invention and an inner surface explanatory view of a split piece of an inner joint pipe.
FIG. 7 is an explanatory diagram of an example of a construction procedure according to a third embodiment.
FIG. 8 is an explanatory diagram of a main part of a steel pipe joint structure according to a fourth embodiment of the present invention.
FIG. 9 is an explanatory diagram of functions of bolts according to the first to fourth embodiments.
FIG. 10 is a schematic diagram of a joint structure for a steel pipe, a part of which is shown in cross section according to a fifth embodiment of the present invention.
FIG. 11 is an explanatory diagram illustrating an example of a construction procedure according to the fifth embodiment.
FIG. 12 is a partially omitted cross-sectional view showing a state where two steel pipes are joined by a joint structure according to a fifth embodiment.
FIG. 13 is an explanatory diagram of a main part of a joint structure for a steel pipe according to a sixth embodiment of the present invention.
FIG. 14 is an explanatory diagram of a main part of a joint structure for a steel pipe according to a seventh embodiment of the present invention.
FIG. 15 is an explanatory diagram of a main part of a steel pipe joint structure according to a seventh embodiment of the present invention.
FIG. 16 is an explanatory diagram of a main part of a joint structure for a steel pipe according to a seventh embodiment of the present invention.
FIG. 17 is an explanatory diagram of main parts of a joint structure for a steel pipe according to Embodiment 7 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer joint pipe 2 Upper end part 5a, 5b, 5c Locking part 7 Bolt insertion hole 8, 14 Main body part 11 Inner joint pipe 12 Large diameter part 13 Step (contact part)
8a, 14a Split pieces 9, 15 Slits 16a, 16b, 16c Engagement projection 18 Bolt hole 20 Concave groove 21 Fitting part 31, 32 Steel pipe 31a, 32a Steel pipe pile 35 Bolt

Claims (10)

An outer joint pipe having a plurality of stages of locking portions in the axial direction of the inner peripheral surface and joined to one steel pipe,
It has a diameter reducing function, and has an inner joint pipe joined to the other steel pipe, provided with a plurality of stages of engaging projections that are engaged with the engaging portions of the outer joint pipe in the axial direction of the outer peripheral surface. ,
A joint structure for steel pipes, wherein the inner joint pipe is press-fitted into the outer joint pipe, and the engaging projections are respectively engaged with the engaging portions of the outer joint pipe. The joint structure for a steel pipe according to claim 1, wherein a concave groove is provided on an inner peripheral surface or an outer peripheral surface between the large diameter portion of the inner joint pipe and the engagement protrusion. The joint structure for a steel pipe according to claim 1, wherein a fitting portion that fits with a bolt provided on the outer joint pipe is provided at a lower end of the inner joint pipe. The joint structure for a steel pipe according to any one of claims 1 to 3, wherein an initial gap is provided between the outer joint pipe and the inner joint pipe. The height of the second-stage or higher engaging projections of the plurality of stages of the engaging projections provided on the inner joint pipe is lower than the height of the first-stage engaging projections. Item 5. A joint structure for a steel pipe according to any one of Items 1 to 4. An outer joint steel pipe having a diameter increasing function, provided with a plurality of locking portions in the axial direction of the inner peripheral surface, and connected to one steel pipe,
A plurality of engagement projections are provided in the axial direction of the outer peripheral surface for engagement with the engagement portions of the outer joint pipe, and an inner joint pipe joined to the other steel pipe,
A joint structure for steel pipes, wherein the inner joint pipe is press-fitted into the outer joint pipe so that engagement projections of the inner joint pipe are respectively engaged with engaging portions of the outer joint pipe. When the inner joint pipe is press-fitted into the outer joint pipe, a tip portion of the inner joint pipe comes into contact with a projecting step of the outer joint pipe, and a contact portion provided on an upper outer periphery of the inner joint pipe and the outer joint pipe The steel pipe joint structure according to claim 6, wherein a gap is formed between the steel pipe and the upper end of the pipe. The tip of the second or lower locking portion from the top of the plurality of locking portions provided on the outer joint pipe is formed closer to the outer wall than the tip of the uppermost locking portion. Item 8. A joint structure for a steel pipe according to item 6 or 7. The steel pipe joint structure according to any one of claims 1 to 8, wherein the outer joint pipe and the inner joint pipe press-fitted in the outer joint pipe are integrally fixed by bolts. The steel pipe is a steel pipe pile, and an inner joint pipe joined to the other steel pipe pile is press-fitted into an outer joint pipe joined to one steel pipe pile by its own weight of one of the steel pipe piles. Item 10. A joint structure for a steel pipe according to any one of Items 1 to 9.

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