JP6242527B1 - Steel pipe joint structure for pile construction - Google Patents

Abstract

[PROBLEMS] To provide a steel pipe joint structure capable of transmitting a large rotational torque as a steel pipe joint structure for joining short steel pipes in a pile construction involving a process of inserting a steel pipe into the ground by rotary press fitting such as a steel pipe pile. provide. Flanges that can be bolted to each other are welded and fixed to the end of one steel pipe to be joined and the end of the other steel pipe, respectively, and each flange has a donut shape. A plurality of (two in the illustrated example) convex portions (fan-shaped convex portions 6) that can contact each other in the rotational direction are provided on the flange base portion (flange substrate 5). Since both the flanges 3 and 4 abut against each other at the convex portion 6, a large rotational torque can be transmitted even if the small-diameter bolts are bolted, unlike a structure in which flat plate flanges are bolted together. It is not necessary to widen the flange width protruding from the outer peripheral surface of the steel pipe. [Selection] Figure 3

Description

  The present invention relates to a steel pipe joint structure for pile construction in which short steel pipes are joined to each other in a pile construction involving a step of inserting a steel pipe into the ground by rotational press-fitting.

As a pile construction method, there are various methods involving a process of inserting a steel pipe into the ground by rotary press-fitting. As this type of pile construction method, for example, if steel pipe piles are constructed, the length required for steel pipe piles penetrating into the ground is usually hindered in transportation and construction. It has been practiced to weld steel pipes directly to form a single steel pipe pile.
This method of joining by welding has the following problems: welding engineers must be secured, quality control of the welded part is required, welding work takes a long time, and costs increase from these. Various steel pipe joint structures have been proposed.

The joining structure of patent document 1 (Unexamined-Japanese-Patent No. 2011-157731) is a flange joining structure which welds and fixes a flange to the edge part of a steel pipe, and joins flanges with a volt | bolt. This flange joint structure is a general flange joint structure. A flat flange with a bolt hole formed in a flange that is a simple donut-shaped flat plate is welded and fixed to the end of the steel pipe, and the flat flange is formed with a bolt through the bolt hole. They are fastened together and transmit rotational torque by the frictional force between both flanges.
In this patent document 1, in normal construction of steel pipe piles, the steel pipes must be rotationally press-fitted while excavating the ground, and a large force acts on the connection part between the steel pipes, so the steel pipes must be firmly connected to each other. In the background that the configuration of the connecting portion is complicated, the soil is improved to manufacture a soil cement, and a steel pipe pile is inserted into the soil cement (Patent Document 1). [0004].

  As a special flange joint structure, as shown in Patent Document 2 (Japanese Patent Laid-Open No. 2013-112953) and Patent Document 3 (Japanese Patent Laid-Open No. 2011-69072), an inclined meniscus flange is fixed to the pipe end by welding. There is also a special shape that joins meniscus flanges with bolts.

  In the joining structure of Patent Document 4 (Japanese Patent Laid-Open No. 2011-52396), a male threaded joint is attached to the end of one steel pipe and a female threaded joint is secured to the end of the other steel pipe at the factory. The two steel pipes are joined by screwing the male thread joint of the steel pipe and the female thread joint of the other steel pipe.

  The joining structure of patent document 5 (Unexamined-Japanese-Patent No. 2002-294694) is a joining structure where the edge part of two steel pipe piles is faced | matched mutually, and the steel pipe sleeve is attached to the state compressed in the radial direction on the outer side of the abutting part. . In this case, the material and / or cross-sectional shape of the steel pipe sleeve is selected so that the steel pipe sleeve is plastically deformed before the steel pipe. As a result, it is said that a considerably thick steel pipe such as a steel pipe pile can be joined very easily without using mechanical joining such as a screw type or welding joining.

  Many joining structures other than Patent Documents 1 to 5 have been proposed as joining structures other than welding joining. For example, there are Patent Document 6 (JP 2009-191522), Patent Document 7 (JP 2006-299665), Patent Document 8 (JP 2008-69611), Patent Document 9 (JP 2011-69071), and the like. Each of them employs a fairly complicated structure, and a description thereof will be omitted.

JP2011-117731A JP2013-112953A JP2011-69072A JP 2011-52396 A JP 2002-294694 A JP2009-191522 JP 2006-299665 A JP 2008-69611 A JP2011-69071

  In the case of the steel pipe joint structure of Patent Document 1 in which simple flat flanges welded and fixed to the ends of the steel pipe are joined with bolts, the rotational torque at the time of rotary press-fitting is transmitted by the frictional force between the flanges, but the frictional force between the flanges In order to increase this, it is necessary to increase the bolt tightening force. Therefore, if a large diameter bolt is used, it is necessary to enlarge the bolt hole. However, since the flange width protruding from the outer surface of the steel pipe cannot usually be made too wide, it may not be possible to use a large diameter bolt. is there. Even if a high-strength bolt is used, the strength may not be satisfied unless the diameter is increased.

Since the steel pipe joint structures of Patent Documents 2 and 3 are those in which the meniscus flange is inclined and fixed to the steel pipe by welding, the meniscus flange is appropriately inclined to the appropriate position of the steel pipe and accurately fixed by welding. That doesn't always seem easy, making it cumbersome and costly.
This joint structure seems to be expected to increase the driving force of excavation. However, if this is not particularly expected, it becomes unnecessarily complicated and it cannot be considered that a large rotational torque can be transmitted.

  The screw-type steel pipe joint structure of Patent Document 4 may be used only when rotating in the direction in which the screw is tightened when the rotary press-fitting method is used, but when reverse rotation is required (to pull out), the screw Can not be adopted because it loosens.

  The steel pipe joint structure of the steel pipe sleeve compression method of Patent Document 5 seems to be difficult to ensure the stability of the joint strength in the pipe axis direction and the rotation direction and to manage the joint strength.

  The complicated joint structures such as Patent Documents 6 to 9 increase the manufacturing cost of the parts to be used, and the construction is complicated and the construction cost is high.

  The present invention was made based on the above-mentioned background, does not require welding on the construction site, can transmit a large rotational torque at the time of rotational press-fitting, and the manufacturing cost of parts can be reduced. The purpose of the present invention is to provide a steel pipe joint structure for pile construction that does not require complicated construction and can reduce construction costs.

Invention of Claim 1 which solves the above-mentioned subject is a steel pipe joint structure for pile construction which joins short steel pipes in the case of pile construction with the process of penetrating a steel pipe into the ground by rotational press-fit,
The flanges that can be bolted to each other are welded and fixed to the end of one steel pipe to be joined and the end of the other steel pipe, respectively, and the flanges contact each other in the rotational direction on a donut-shaped flange base. Ri Na plurality of projections capable contact is formed, the plurality of convex portions of each flange, characterized in that both a sector convex portion forms a fan-shaped contour.

Claim 2 is the steel pipe joint structure for pile construction according to claim 1 , wherein each of the flanges is a flange base plate in which the donut-shaped flange base portion is a flat plate, and the flange base plate is spaced apart in the circumferential direction. The fan-shaped plate for forming the fan-shaped convex portion is fixed by welding.

Claim 3 is a steel pipe joint structure for pile construction according to claim 1 or 2 , wherein when the steel pipe pile is constructed by rotating and pressing the steel pipe pile into the ground, the short steel pipes constituting the steel pipe pile are joined together. It is a steel pipe joint structure.

Claim 4 is the steel pipe joint structure for pile construction according to claim 1 or 2 , wherein the casing steel pipe is rotationally press-fitted into the ground, the cement-based injection material is injected, and then the casing steel pipe is pulled out to construct the columnar ground improvement body. When doing, it is the steel pipe joining structure which joins the short steel pipes which comprise the said casing steel pipe.

  In pile construction performed by adopting the steel pipe joint structure of the present invention, when rotationally press-fitting a steel pipe into the ground, transmission of rotational torque at the joint between one steel pipe and the other steel pipe is a flange fixed to each end. However, each flange has a structure in which a plurality of convex portions that can contact each other in the rotational direction are formed on the donut-shaped flange base. It is performed at the convex part which touches. According to the rotational torque transmission by the convex portions that are in contact with each other, a very large rotational torque can be transmitted.

  Therefore, the bolt that connects the two flanges is not required to have a particularly strong tightening force for generating a large frictional force between the flanges, unlike a bolt that simply joins flat plate flanges as in Patent Document 1. Therefore, it is not necessary to use a large-diameter bolt and there is no need to open a large bolt hole in the flange. In the case of a steel pipe joint structure for pile construction, there is a case where the flange width protruding from the outer surface of the steel pipe may not be so wide that it is extremely advantageous not to require a large-diameter bolt. Further, not only the problem of the flange width but also the fact that only a small-diameter bolt is sufficient is advantageous in terms of parts cost, workability and other various points.

  Note that high-strength bolts are expensive, and tightening torque management (e.g., for example) may be possible by using high-strength bolts capable of strong tightening force instead of using large-diameter bolts. However, according to the present invention, the bolt can be inexpensive and no special tightening torque management is required.

  Unlike the method of welding and fixing the inclined meniscus flange to the steel pipe like the steel pipe joint structure of the meniscus flange method of Patent Documents 2 and 3, the steel pipe joint structure of the present invention is very simple even with the same flange joint method, Cost is also low. Moreover, a large rotational torque can be transmitted.

  Further, in the screw joint method of Patent Document 4, since the screw is loosened with respect to the rotation in the reverse direction, the transmission of rotational torque is limited to one direction. Rotational torque can be transmitted. Therefore, it is applicable also when implementing the pile construction method with the process of drawing out the steel pipe (casing steel pipe) once penetrated into the ground.

  In the steel pipe sleeve compression type steel pipe joint structure of Patent Document 5, it is difficult to ensure the stability of the joint strength in the pipe axis direction and the rotation direction and to manage the joint strength, but according to the steel pipe joint structure of the present invention, There is no problem at all, and the bonding strength in the rotational direction is clear.

  Unlike the joining structures that are expensive to manufacture parts, such as the complicated joining structures of Patent Documents 6 to 9 and the like, and the construction is complicated and the construction costs are high, the steel pipe joining structure of the present invention is extremely simple. The cost of parts is low, the construction is easy and the construction cost is low.

BRIEF DESCRIPTION OF THE DRAWINGS The steel pipe joining structure for pile construction of one Example of this invention is shown, (A) is a front view of the flange junction part of an upper and lower steel pipe, (B) is AA sectional drawing of (A). (A) is the figure shown in the state which separated before the flange part of an upper and lower steel pipe was bolted in FIG. 1 (a), (b) is a BB arrow line view of (a). 2A is a perspective view of the lower flange joint portion of FIG. 2A, and FIG. 2B is a perspective view of the upper flange joint portion of FIG. FIG. It is a figure for demonstrating the shape dimension of a flange, (A) is a top view of a flange, (B) is the perspective view. It is a perspective view which shows the flange which integrally casted the flange base part and the convex part (fan-shaped convex part). It is a top view which shows the Example of the flange which formed three fan-shaped convex parts in the flange base part. It shows a specific application example of the steel pipe joint structure for pile construction of the present invention. (I) When short steel pipes constituting the steel pipe pile are joined when constructing the steel pipe pile, (b) is a columnar shape The case where the short steel pipes which comprise a casing steel pipe are joined when constructing a ground improvement body is shown.

  Hereinafter, the form for implementing the steel pipe joining structure for pile construction of this invention is demonstrated with reference to drawings.

FIG. 1 shows a steel pipe joint structure 10 for pile construction according to one embodiment of the present invention, in which (A) is a front view of flange joints of upper and lower steel pipes 1 and 2, and (B) is A of (A). It is -A sectional drawing.
The flange 3 is welded and fixed to the lower steel pipe 1, and the flange 4 is welded and fixed to the upper steel pipe 2, and both the steel pipes 1 and 2 are flange-joined by tightening the flanges 3 and 4 with bolts 8.
FIG. 2 (a) is a diagram showing the state in which the flanges 3 and 4 of the upper and lower steel pipes are separated from each other before bolting in FIG. 1 (a), and (b) is a view taken along the line BB in FIG. It is.
3 (a) is a perspective view of the flange joint portion of the lower steel pipe 1 in FIG. 2 (a), and FIG. 3 (b) is a view showing the flange joint portion of the upper steel pipe 4 in FIG. FIG.

The two flanges 3 and 4 have the same shape as themselves, and as shown in FIG. 4, each flange 3 (4) is fan-shaped on a flange substrate (flange base) 5 which is a donut-shaped flat plate. This is a structure in which the sector plate 6 is fixed by welding as a convex portion. The welding and fixing may be performed, for example, on the outer periphery and inner periphery of the fan-shaped plate 6, but may be performed on both ends. 1 to 3, the fan-shaped plate 6 of the flange 3 of the lower steel pipe 1 is distinguished by 6a, and the fan-shaped plate 6 of the flange 4 of the upper steel pipe 2 is distinguished by 6b. In FIG. 2B, the fan-shaped plate 6 is shown by sand hatching.
Each fan-shaped plate 6 in the illustrated example has a planar shape obtained by roughly dividing a donut-shaped flat plate into four parts (divided into four equal parts), and the flanges 3 and 4 are configured such that the two fan-shaped plates 6 face each other on the flange substrate 5. It is a welded structure. Each sector plate 6 has a sector shape with an angle (θ = 88 °) slightly smaller than 90 ° so that the upper and lower sector plates 6 do not interfere with each other when the upper and lower flanges 3 and 4 are joined. A portion where the fan-shaped plate 6 is fixed to the flange substrate 5 by welding is also referred to as a fan-shaped convex portion 6 with the same reference numeral.
Eight bolt insertion holes 7 through which the bolts 8 are inserted are provided in the flanges 3 and 4 at equal intervals in the circumferential direction, and both the flanges 3 and 4 are bolted at two locations for each sector-shaped convex portion 6. . In the figure, the bolt insertion hole opened only in the flange substrate 5 and the bolt insertion hole opened in the fan-shaped convex portion 6 (two-layered portion) are indicated by the same reference numeral 7 without being distinguished. .
The dimension of each part of the flanges 3 and 4 of an Example is the outer diameter D = 320mm and the internal diameter d = 218mm. The plate thickness of the flange substrate 5 is 20 mm, the plate thickness of the sector plate 6 is also 20 mm, the hole diameter of the bolt insertion hole 7 is 23 mm, and the position of the bolt insertion hole 7 is a position with a radius R = 140 mm.
The sizes of the flanges 3 and 4 are those when the shaft diameter (steel pipe diameter) of the pile is 216.3 mm. For example, the outer diameters 267.4 mm, 318.5 mm, 355.6 mm, 406.4 mm, In the case of a large shaft diameter such as 457.2 mm, the flange size is a corresponding large diameter. Since the steel pipe joint structure of the present invention can transmit a large rotational torque, it is particularly effective when the shaft diameter is large.

In the pile construction performed by adopting the steel pipe joint structure 10 of the above-described embodiment, when the steel pipe is rotationally press-fitted into the ground, the transmission of the rotational torque at the joint between the lower steel pipe 1 and the upper steel pipe 2 is performed at each end. Are transmitted between the flanges 3 and 4 fixed to the respective portions. On the flange substrate 5 of the donut shape, a plurality of sector-shaped convex portions 6 that can contact each other in the rotation direction are formed. As a result, the rotational torque is transmitted by the fan-shaped convex portions 6 of the flanges 3 and 4 that are in contact with each other. According to the rotational torque transmission by the fan-shaped convex portions 6 that are in contact with each other, extremely large rotational torque can be transmitted.
According to the steel pipe joint structure 10 of the above-described embodiment, various effects as described in the paragraph “Effects of the Invention” can be achieved.

The steel pipe joint structure 10 described above can be used as a steel pipe joint structure that joins short steel pipes constituting the steel pipe pile when the steel pipe pile is constructed by rotating and pressing the steel pipe pile into the ground.
When constructing a steel pipe pile, for example, as shown in FIG. 7 (a), a steel pipe pile 21 in which a drilling head 20 having, for example, a drilling blade or an end plate with a drilling blade is welded and fixed to the tip of the steel pipe is not shown. It penetrates into the ground by rotating press with the device. In addition, although the excavation head 20 in the illustrated example uses an end plate with an excavation blade whose center is recessed toward the pile head side as an end plate with an excavation blade, of course, a flat end plate with an excavation blade may be used. (The same applies to the excavation head 40 in FIG. 7B described later).
Since the length required for the steel pipe used for the steel pipe pile is usually hindered in transportation and construction, a plurality of short steel pipes are used. However, the steel pipe joint structure 10 of the embodiment is a lower side that is the pile tip side. Are used for joining a short steel pipe 1 and a short steel pipe 2 on the upper side thereof. When it is necessary to add two or more short steel pipes, as shown by a two-dot chain line, a steel pipe 30 having the flange 3 welded and fixed to the lower end is further joined.

The steel pipe joint structure 10 described above is a short length which constitutes the casing steel pipe when the casing steel pipe is pulled into the ground and injected with cement-based injecting material, and then the casing steel pipe is pulled out to construct a columnar ground improvement body. It can be used as a steel pipe joint structure for joining steel pipes.
When the casing steel pipe is rotationally press-fitted into the ground, for example, as shown in FIG. 7 (b), the excavation having a structure that has a drilling blade, an end face plate with excavating blades, and the like at the tip of the casing steel pipe 41 and can be detached from the tip The head 40 is attached. The excavation head 40 rotates integrally with the casing steel pipe 41 when the casing steel pipe 41 is penetrated. However, when the casing steel pipe 41 is pulled out after being injected with a cement-based injection material, the casing steel pipe 41 is rotated in the reverse direction. Leaves the bottom of the borehole.
Also in this case, since it is usually necessary to join and use a short steel pipe as shown in the figure as the casing steel pipe 41, the lower short steel pipe 1 which is the front end side of the casing steel pipe and the short steel pipe on the upper side thereof as described above. The steel pipe 2 can be joined by the steel pipe joining structure 10 of the embodiment.

  In addition, as a case where the columnar ground improvement body is constructed, the steel pipe joining structure of the present invention can be applied as a structure for joining short steel pipes even in the case of a method of injecting soil cement or the like instead of the cement-based injecting material.

  The flanges 3 and 4 in the steel pipe joint structure 10 of the above-described embodiment are configured by welding and fixing a fan-shaped plate (fan-shaped convex portion 6) to a flange substrate (flange base) 5 which is a donut-shaped flat plate, as shown in FIG. Thus, the flange 3 ′ (4 ′) in which the flange base portion 5 ′ and the fan-shaped convex portion 6 ′ are integrally cast may be used.

The flanges 3 and 4 described with reference to FIGS. 1 to 4 have a planar shape in which a fan-shaped plate 6 serving as a fan-shaped convex portion is divided into four substantially (divided into four) doughnut-shaped flat plates, but the flange 3 "shown in FIG. As shown in (4 ″), the fan-shaped plate 6 ″ having a planar shape obtained by roughly dividing the donut-shaped flat plate into six parts (6 equal parts) may be used, and the number of divisions is not limited to these (the portion of the fan-shaped plate 6 ″ is Sandy hatching) The flange substrate is indicated by 5 ″.
Further, the fan-shaped convex portions that are in contact with each other are not necessarily limited to the structure in which they are in contact with each other as in the embodiment, but may be any one that makes contact so that rotational torque can be transmitted. The fan-shaped convex portions (fan-shaped plates having a fan-shaped angle of 88 °) 6 that can be fitted to each other as in the embodiment can particularly increase the rotational torque that can be transmitted. Since there may be a space on the rotation direction rear end side (the side opposite to the abutting side) of the four fan-shaped convex portions 6, an appropriate sector angle can be adopted.

1, 2 Steel pipe 3, 3 ', 3 "flange (lower steel pipe flange)
4, 4 ', 4 "flange (upper steel pipe flange)
5, 5 "flange substrate (flange base)
6, 6 ', 6 "fan-shaped plate (fan-shaped convex part)
7 Bolt insertion hole 8 Bolt 10 Steel pipe joint structure 20 Excavation head 21 (welded and fixed to the tip of the steel pipe pile) Steel pipe pile 40 Excavation head 41 (detachably attached to the end of the casing) 41 Casing steel pipe

Claims (4)

A steel pipe joint structure for pile construction that joins short steel pipes to each other during pile construction with a process of inserting the steel pipe into the ground by rotational press-fit,
The flanges that can be bolted to each other are welded and fixed to the end of one steel pipe to be joined and the end of the other steel pipe, respectively, and the flanges contact each other in the rotational direction on a donut-shaped flange base. Ri Na plurality of projections capable contact is formed, the plurality of convex portions of each flange, characterized in that both a sector convex portion forms a fan-shaped contour. Each of the flanges is a flange substrate in which the flange base is a donut-shaped flat plate, and is formed by welding and fixing a fan-shaped plate on the flange substrate to form the fan-shaped convex portions at intervals in the circumferential direction. steel joining structure for pile construction according to claim 1, wherein. 3. The pile construction structure according to claim 1, wherein the steel pipe pile has a steel pipe joint structure that joins short steel pipes constituting the steel pipe pile when the steel pipe pile is rotated and press-fitted into the ground. Steel pipe joint structure. A steel pipe joining structure that joins short steel pipes constituting the casing steel pipe when the casing steel pipe is constructed by rotating and press-fitting the casing steel pipe into the ground and injecting a cement-based injection material and then pulling out the casing steel pipe The steel pipe joint structure for pile construction according to claim 1 or 2, wherein

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