JP6644452B1 - A connecting member for a different diameter steel pipe pile and a steel pipe pile using the same. - Google Patents

Abstract

[PROBLEMS] A steel pipe pile of a different diameter that can easily cope with various diameter differences between an upper pile and a lower pile, can be manufactured at a low cost, and is easily applicable to both a head pile and a bottom pile. A connection member is provided. A steel pipe pile having different diameters is used when vertically connecting a large-diameter steel pipe pile and a small-diameter steel pipe pile. A steel large-diameter short pipe 3 to which the large-diameter steel pipe pile 51 is welded and connected to one side of the circular flat plate 2 which is the pile connection member 1 and is at least not smaller in diameter than the outer diameter of the large-diameter steel pipe pile 51. The pipe end is fixed to the entire circumference by welding on the inner and outer surfaces, and the other end of the circular flat plate 2 is fixed by welding the pipe end of the steel small-diameter short pipe 4 to which the small-diameter steel pipe pile 52 is connected by welding to the inner and outer faces. Become. [Selection diagram] FIG.

Description

  The present invention is also applicable to a case where a steel pipe pile installed on the ground by a rotary press-fitting method is applied to a steel pipe connection portion of a steel pipe pile installed by connecting steel pipe piles having different diameters up and down to construct a head pile. The present invention relates to a connecting member for a different-diameter steel pipe pile which can easily cope with a case where an expanded bottom pile is constructed, and a steel pipe pile constructed using the same.

When a steel pipe pile formed by vertically connecting steel pipe piles having different diameters is used, for example, a threaded joint structure is used as a connecting member for connecting a large-diameter steel pipe pile and a small-diameter steel pipe pile. Patent Document 1).
The screw type joint structure of Patent Literature 1 will be described using the reference numerals in Patent Literature 1. When an upper threaded joint member 4 of a female thread is welded and fixed to the upper end of a lower diameter steel pipe pile 1c on the small diameter side, an upper steel pipe on a large diameter side is formed. The lower threaded joint member 5 of the male screw 5a is welded and fixed to the lower end of the pile 1b, and the lower threaded joint member of the upper steel pipe pile 1b on the large diameter side is attached to the female thread 4a of the upper threaded joint member 4 of the lower diameter steel pipe pile 1c. 5 is a structure in which the male screw 5a is screwed and fastened.

  In addition, the joint structure of Patent Document 2 will be described using the reference numerals in Patent Document 2, and a lower pipe special portion 3 of a short pipe having the same diameter as the lower pipe is fixed to the upper end of the lower steel pipe pile 2 having a small diameter by welding. The upper special pile portion 5 of the short pipe is externally fitted to the lower special pile portion 3 at a slightly shifted position and fixed by welding, and the lower end of the upper steel pipe pile 4 on the large diameter side is fixed to the upper pile special portion 3. After narrowing to the same diameter as the diameter of the portion 5 (same diameter as the diameter of the lower steel pipe pile 2), it is placed on the upper end surface of the upper pile special portion 5, and the upper end of the upper pile special portion 5 is placed on the upper side. This is a joint structure in which the steel pipe pile 4 is fixed by welding to the vicinity of the narrowed lower end.

JP-A-2003-105755 JP 2013-234561

The screw-type joint structure of Patent Document 1 requires screw processing, which is complicated and costly.
The joint structure of Patent Document 2 is complicated in that it is necessary to reduce the lower end of the upper steel pipe pile 4 to the same diameter as the upper pile special part 5 (the same diameter as the lower steel pipe pile 2). Yes, and it is considered difficult to greatly reduce the diameter, so it can be used only in the case of a slight difference in diameter.

  The present invention has been made on the basis of the above background, and has a structure that does not require threading, drawing, and the like, and can easily cope with various diameter differences between the upper pile and the lower pile, and is inexpensive. It is an object of the present invention to provide a different-diameter steel pipe pile connecting member that can be manufactured in a different diameter steel pipe pile connecting member. And a steel pipe pile using the same.

The invention of claim 1 that solves the above-mentioned problem is that steel pipe piles installed on the ground by a rotary press-fitting method in which a tip member that exerts a propulsive force by rotation is fixed to a tip of a shaft portion made of a steel pipe, have different diameters from each other. When the steel pipe piles are installed by connecting the steel pipe piles vertically, a different diameter steel pipe pile connection member used when vertically connecting the large-diameter steel pipe pile and the small-diameter steel pipe pile,
On one side of a circular flat plate that is not at least smaller in diameter than the outer diameter of the large-diameter steel pipe pile, the pipe end of the steel large-diameter short pipe to which the large-diameter steel pipe pile is welded and connected is welded to the entire circumference both on the inner and outer surfaces. And
A small-diameter short pipe made of steel to which the small-diameter-side steel pipe pile is welded and connected to the other side surface of the circular flat plate is welded and fixed to the entire inner and outer surfaces.

Claim 2 is the connecting member of different diameter steel pipe pile according to claim 1, wherein the outer diameter of the large diameter short pipe is D1, the inner diameter is d1, the outer diameter of the large diameter steel pipe pile is D2, and the inner diameter is d2, When the outside diameter of the small diameter short pipe is D3, the inside diameter is d3, and the outside diameter of the small diameter side steel pipe pile is D4, and the inside diameter is d4,
The relationship between the diameter of the large diameter short pipe and the diameter of the large diameter steel pipe pile is D1 ≧ D2, and d1 ≦ d2,
The relationship between the diameter of the small-diameter short pipe and the diameter of the small-diameter-side steel pipe pile is D3 ≧ D4 and d3 ≦ d4.

  A third aspect of the present invention is the connecting member for a steel pipe pile having a different diameter according to the first or second aspect, wherein the outer diameter of the circular flat plate is the same as the outer diameter of the large-diameter short pipe.

  According to a fourth aspect of the present invention, in the connecting member of the different diameter steel pipe pile according to the first or second aspect, the circular flat plate has a flange portion projecting radially outward from an outer peripheral surface of the large-diameter short pipe.

  A fifth aspect of the present invention is characterized in that, in the connecting member of the different diameter steel pipe pile according to the fourth aspect, the circular flat plate has an inclined surface portion that is inclined upside down in the flange portion.

The invention according to claim 6 is a steel pipe pile constructed as a head pile using the different-diameter steel pipe pile connection member according to any one of claims 1 to 5,
The large-diameter-side steel pipe pile is an upper end of the pile, and the small-diameter-side steel pipe pile is a lower side thereof.

The invention of claim 7 is a steel pipe pile constructed as an expanded pile using the different diameter steel pipe pile connection member of any one of claims 1 to 5,
The large-diameter steel pipe pile is located at the lower end of the pile, and the small-diameter steel pipe pile is located at the upper end thereof.

The invention of claim 8 is a steel pipe pile constructed as an expanded pile using the different diameter steel pipe pile connection member of claim 7,
The tip member that exerts the propulsion force fixed to the tip of the large-diameter steel pipe pile that is the lower end of the pile is turned upside down with respect to a flange portion that is an outer portion from the outer peripheral surface of the large-diameter steel pipe pile. Having an inclined surface portion, comprising an end plate made of a disk, and a plate-shaped excavation blade with a sharp tip fixed vertically to the lower surface center of the end plate,
The end face plate has a circular center hole at the center thereof, and the excavating blade has a notch at the edge on the end face side thereof facing the center hole.

ADVANTAGE OF THE INVENTION According to the different diameter steel pipe pile connection member of this invention, processes, such as a screw process and a drawing process, are unnecessary, and manufacture is easy and can be manufactured at low cost.
Also, high strength can be easily secured as a connecting member for a different diameter steel pipe pile requiring strength.
Further, it is possible to easily cope with various diameter differences between the upper pile and the lower pile.
Further, according to the connecting member of the different diameter steel pipe pile, by using the steel pipe pile upside down, it is possible to easily cope with the construction of the steel pipe pile of the expanded bottom pile even when the steel pipe pile of the expanded pile is constructed.
A pile (head pile) with a large diameter on the pile head side (large-diameter steel pipe pile) has a high horizontal force (shear force) and bending moment acting on the pile head side due to the shaking of the earthquake. Adopt to ensure resistance. The lower part of the pile, whose main purpose is to secure the vertical bearing capacity, is made small in diameter (small diameter steel pipe pile) in terms of economy.
In addition, a pile (extended bottom pile) with a large diameter (large diameter steel pipe pile) at the bottom of the pile that penetrates into the hard ground has a greater friction force on the peripheral surface than a small diameter pile and has a pile bottom (or a wide flange). Adopted to increase the vertical support force by the tip member). Since it is uneconomical to increase the diameter of the intermediate portion having a low N value, the intermediate portion is made to have a small diameter (small diameter steel pipe pile).

It is a perspective view of the connection pipe member of a different diameter steel pipe pile of one example of the present invention (in addition, upper and lower steel pipe piles are shown by two-dot chain lines). FIG. 2 is a front view of a partial cutout of the different diameter steel pipe pile connection member of FIG. 1. It is a figure which shows the state which connected the upper and lower steel pipe piles mutually via the said different diameter steel pipe pile connection member, and is a front view of the partial notch in the case of constructing a head pile (hatching of the cross-sectional part was omitted). It is a perspective view of a different diameter steel pipe pile connection member of other examples of the present invention. FIG. 5 is a front view of a partial cutout of the different diameter steel pipe pile connection member of FIG. 4. It is a perspective view of a different diameter steel pipe pile connection member of yet another example of the present invention. It is a front view of the different diameter steel pipe pile connection member of FIG. It is a perspective view at the time of constructing an expanded pile using the different diameter steel pipe pile connection member of FIG. 1 and 2 upside down (in addition, the upper and lower steel pipe piles are shown by two-dot chain lines). It is a figure explaining the construction steel pipe pile which connected and connected the upper and lower steel pipe piles using the different diameter steel pipe pile connection member shown in FIGS. 1 and 2, (a) is when constructing an expanded steel pipe pile, (B) is a construction drawing of a steel pipe pile in the case of constructing a steel pipe pile with an expanded bottom pile, and (c) is a construction drawing of a steel pipe pile in the case of constructing both a steel pipe pile of a head pile and a steel pipe pile of a bottom pile. (A) is a side view of the backing ring, (b) is a plan view, (C) is a perspective view. FIG. 11 is a diagram showing a case where the upper and lower steel pipe piles are connected via the different diameter steel pipe pile connection members shown in FIGS. 1 and 2 using the backing ring of FIG. 10 and corresponds to FIG. 3. FIG. 9 is an enlarged view of the tip member attached to the lower end of the constructed steel pipe pile, where (A) is a front view and (B) is a side view (the figure in FIG. 9).

  Hereinafter, embodiments for implementing a connecting member for steel pipe piles of different diameters and a steel pipe pile according to the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a different-diameter steel pipe pile connecting member 1 of one embodiment of the present invention (in addition, upper and lower steel pipe piles are indicated by two-dot chain lines), and FIG. 2 is a different-diameter steel pipe pile connecting member of FIG. 1 is a front view of a partial cutout of FIG.
The different-diameter steel pipe pile connecting member 1 is used for vertically connecting steel pipe piles having different diameters in a rotary press-fitting method in which a steel pipe as a pile body is rotationally press-fitted into the ground.
This different diameter steel pipe pile connecting member 1 is fixed to the upper surface of the circular flat plate 2 by welding the entire end of the steel large diameter short pipe 3 to which the upper large diameter steel pipe pile 51 is welded and connected to the inner and outer surfaces. The lower end of the circular flat plate 2 has a structure in which the pipe end of the small-diameter short pipe 4 made of steel to which the lower small-diameter steel pipe pile 52 is connected by welding is fixed to the inner and outer surfaces by welding.

The welding connection between the large-diameter and short pipe 3 and the circular flat plate 2 is a fillet welding on the inner surface on the entire circumference. Note that fillet welding with a groove may be used. The outer surface side is full-length fillet welding in which a groove is provided on the entire circumference of the large-diameter short pipe 3 side.
The welding connection between the small-diameter short pipe 4 and the circular flat plate 2 is such that the inner surface side of the small-diameter short pipe 4 is full-length fillet welding. Note that fillet welding with a groove may be used. The outer surface side of the small-diameter short pipe 4 is fillet welding on the entire circumference with a groove provided on the entire circumference.

FIG. 3 is a view showing a state in which upper and lower steel pipe piles 51 and 52 are connected via the above-mentioned different diameter steel pipe pile connection member 1 (hatching showing a cross section is omitted).
As shown in FIG. 9A, the different diameter steel pipe pile connection member 1 constructs a head pile (that is, a steel pipe pile in which the steel pipe pile on the pile head side is larger in diameter than the steel pipe pile on the lower side). In this case, the upper large-diameter steel pipe pile 51 and the lower small-diameter steel pipe pile 52 are welded to each other via the different-diameter steel pipe pile connecting member 1.
In FIG. 9A, the small-diameter steel pipe pile directly welded to the different-diameter steel pipe pile connecting member 1 is indicated by reference numeral 52. Steel pipe piles of the same diameter are connected by welding. The entire installed steel pipe pile is shown as a construction steel pipe pile 61.

2 and 3, for example, the outer diameter D1 of the large diameter short pipe 3 is 273 mm, the plate thickness t1 is 15 mm, the inner diameter d1 is 243 mm, and the outer diameter D3 of the small diameter short pipe 4 is FIG. 219 mm, plate thickness t3 is 15 mm, inner diameter d3 is 189 mm, outer diameter D5 of circular flat plate 2 is 273 mm (same diameter as outer diameter D1 of large diameter short tube 3), and plate thickness t5 is 16 mm.
The large diameter steel pipe pile 51 welded and fixed to the upper side of the different diameter steel pipe pile connecting member 1 in the illustrated example has, for example, an outer diameter D2 of 267.4 mm, a plate thickness t2 of 9.3 mm, and an inner diameter d2 of 248.8 mm. is there. The small-diameter-side steel pipe pile 52 welded and fixed to the lower side has, for example, an outer diameter D4 of 216.3 mm, a plate thickness t4 of 8.3 mm, and an inner diameter d4 of 199.7 mm.
The height H of the large-diameter short tube 3 and the small-diameter short tube 4 is 150 mm.
The outer diameter of the steel pipe pile targeted in the present invention may be, for example, 101.6 mmφ to 457.2 mm. However, considering the entire circumference welding of the inner surface of the small-diameter short pipe 4 of the different-diameter steel pipe pile connecting member 1, welding is performed. As a small diameter size that can be easily worked when performing manual welding work with a rod, for example, 216.3 mmφ or more is preferable. In addition, due to various conditions, it is usually preferable that the large-diameter size is within 318.5 mm.

The present invention is applied to a rotary press-fitting method in which a steel pipe as a pile body is pressed into the ground by rotary press-fitting, and as shown in FIGS. 9 (a), (b) and (c), At the lower ends of the steel pipe piles 61, 61A, 61B, a tip member 70 that exerts a propulsive force by rotation is fixed.
This tip member 70 is shown in detail in FIGS. 12 (a) and (b), and shows an end plate 71 welded and fixed to a tip surface of a shaft portion (steel pipe pile) 61, and a lower surface of the end plate 71. A plate-shaped excavation blade 72 having a sharp tip is vertically fixed to the center by welding.
The end face plate 71 has, on a flange portion 73 that is an outer portion of the outer peripheral surface of the shaft portion 61, an inclined surface portion inclined upside down, that is, an inclined surface portion 74 inclined upward and a inclined surface portion 75 inclined downward. are doing. The inclined surface portions 74 and 75 of the end face plate 71 which are inclined in the upside-down direction exert a propulsive force by rotation at the time of rotational press-fitting.
The end plate 71 of the tip member 70 has a circular center hole 76 at its center.
The digging blade 72 has a pentagonal house shape having two sides 72a parallel to each other on the end face plate side (the side fixed by welding to the end face plate) and a tip end portion 72b having a triangular shape. Has a notch 72c opening toward the center hole 76. The shape (inner edge shape) of the notch 72c of this embodiment has a width the same as the diameter of the center hole 76, and has a pentagon substantially similar to the pentagon which is the entire contour of the excavating blade 72.
According to the tip member 70, the center hole 76 formed in the center of the end face plate 71 and the notch 72 c formed on the side of the excavating blade 72 influence each other and cooperate with each other, so that the pressure is released. Without impairing the excavated soil, a certain blocking effect due to the excavated soil penetrating into the pipe can be achieved to secure the supporting force.

FIG. 4 and FIG. 5 show another example of the connecting member 21 of different diameter steel pipe piles.
This different diameter steel pipe pile connecting member 21 is different in that a circular flat plate 22 has a flange portion 22a which protrudes radially outward from the outer peripheral surface of the large diameter short tube 3.
When the pipe diameter of the large-diameter steel pipe pile 51 is large, the large-diameter small-diameter short pipe 3 (shown in FIGS. 4 and 5 with the same size as FIGS. 1 and 2) is welded by the flange portion 22. Can be fixed.
In addition, when the soil depth position of the different-diameter steel pipe pile connecting member 21 at the time of completion of the construction of the steel pipe pile has a constant N value, the flange portion 22a of the different-diameter steel pipe pile connecting member 21 has a vertical supporting force. And a constant contribution to increase pullout resistance.
In addition, since the end face plate 71 of the above-mentioned tip member 70 has already stirred the soil at the time of rotary press-fitting, even if there is a wide flange portion 22 in the different diameter steel pipe pile connecting member 21, the pile is to be press-fitted. There is no particular problem.

FIG. 6 and FIG. 7 show a different-diameter steel pipe pile connecting member 31 of still another embodiment.
The different-diameter steel pipe pile connecting member 31 has a flange portion 32 in which the circular flat plate 32 protrudes radially outward from the outer peripheral surface of the large-diameter short tube 3 similarly to the circular flat plate 22 in FIGS. 4 and 5. The difference is that the flange portion 32 is provided with inclined surface portions 32aa and 32ab which are inclined upside down.
The flange portion 32 of the different-diameter steel pipe pile connection member 31 has the same action as the flange portion 22 of the different-diameter steel pipe pile connection member 21 shown in FIGS. 12 has substantially the same effect as the inclined surfaces 74 and 75 of the distal end member 70 described above with reference to FIG. Can be increased.
In addition, since the large diameter flange 32 exists in this different diameter steel pipe pile connection member 31 similarly to the above-mentioned different diameter steel pipe pile connection member 21, even when the pipe diameter of the large diameter side steel pipe pile 51 is large, A large-diameter large-diameter short tube 3 (shown in FIGS. 6 and 7 with the same size as FIGS. 1 and 2) can be fixed by welding.

FIG. 8 shows a case where the different diameter steel pipe pile connecting member 1 of FIG. 1 is used upside down.
That is, a large-diameter steel pipe pile 51 ′ is provided below the different-diameter steel pipe pile connecting member 1 and a small-diameter steel pipe pile 52 ′ is provided above, and the expanded bottom pile (large-diameter side) shown in FIG. The steel pipe pile 61 (61A) having the steel pipe pile 51 ') is constructed.
A pile (extended bottom pile) having a large diameter (large-diameter steel pipe pile 51 ′) at the bottom of the pile penetrating into the hard ground has a greater peripheral friction force and a lower pile (or a wider flange) than a small diameter pile. It is effective to increase the vertical support force of the tip member), while it is uneconomical to increase the diameter of the lower intermediate portion where the peripheral frictional force is not so much expected. Pile of small diameter (small diameter steel pipe pile). In such a case, the structure of FIG. 8 is preferable.

  FIG. 9C shows an embodiment of a steel pipe pile 61 (61B) employing both a head-expanded pile (large-diameter steel pipe pile 51) and an expanded pile (large-diameter steel pipe pile 51 ').

FIG. 10 is a back view used when welding the large diameter steel pipe pile 51 to the large diameter short pipe 3 of the different diameter steel pipe pile connection member 1 or when welding the small diameter steel pipe pile 52 to the small diameter short pipe 4. A backing ring 81 used as a backing is shown.
This backing ring 81 is not a closed circular ring but a so-called C-shaped ring having a notch (gap) 81d therein. Although there is a slight difference in diameter, the upper large-diameter portion 81a and the lower small-diameter in FIG. The portion 81b is an integral part that is continuous via the step portion 81c. For example, it can be manufactured by bending a strip-shaped elongated steel plate into a circular shape.

The backing ring 81 used when welding the large-diameter steel pipe pile 51 to the large-diameter short pipe 3 of the different-diameter steel pipe pile connection member 1 will be described. The outer diameter D6 of the large-diameter portion 81a is the large-diameter steel pipe pile. The outer diameter D7 of the small diameter portion 81b is slightly larger than the inner diameter d1 of the large diameter short tube 3 (fitting tightly, that is, the cut 81d). ), The diameter is elastically reduced and the fitting is tight.
Therefore, when the small-diameter portion 81b of the backing ring 81 is fitted into the large-diameter short pipe 3, the step 81c is placed on the inner step between the large-diameter steel pipe pile 51 and the large-diameter short pipe 3. The small-diameter portion 81b fits tightly with the large-diameter short tube 3.
In this state, the large-diameter steel pipe pile 51 can be welded to the large-diameter short pipe 3 of the different-diameter steel pipe pile connection member 1 with a backing metal.

If described as a backing ring 81 'used when the small diameter short pipe 4 of the different diameter steel pipe pile connecting member 1 is welded to the small diameter side steel pipe pile 52 (the illustrated backing ring 81' is upside down). The outer diameter D6 of the large diameter portion 81a is slightly smaller than the inner diameter d4 of the small diameter steel pipe pile 52 (there is a gap), and the outer diameter D7 of the small diameter portion 81b is slightly larger than the inner diameter d3 of the small diameter short tube 4. (Tightly fit. That is, the diameter is elastically reduced due to the presence of the cut 81d and tightly fitted).
In this case, the small-diameter portion 81b of the backing ring 81 'is fitted in advance on the inner surface of the small-diameter short pipe 4 of the different-diameter steel pipe pile connecting member 1. As described above, the small-diameter portion 81b is elastically reduced in diameter due to the presence of the cut 81d and tightly fits into the inner surface of the small-diameter short tube 4, so that the small-diameter portion 81b is elastically held in the small-diameter short tube 4 having the downward opening. Yes (does not fall).
In this state, the large diameter portion 81a of the backing ring 81 'elastically attached to the small diameter short pipe 4 is inserted into the small diameter steel pipe pile 52, and the lower end face of the small diameter short pipe 4 and the small diameter side steel pipe pile 52 are inserted. The small diameter short pipe 4 and the small diameter side steel pipe pile 52 can be welded with a backing metal by abutting the upper end face.

DESCRIPTION OF SYMBOLS 1 Different diameter steel pipe pile connection member 2, 22, 32 Circular flat plate 22a, 32a (Circular flat plate) flange 3 Large diameter short tube 4 Small diameter short tube 51 Large diameter steel pipe pile 52 Small diameter steel pipe pile 61, 61A, 61B Steel pipe Pile (shaft)
70 Tip Member 71 End Plate 72 Drilling Blade 73 (End Plate) Flange 81 (81 ′) Backing Ring 81a Large Diameter Portion
81b Small diameter portion 81c Stepped portion 81d Notch

Claims (8)

A steel pipe pile installed on the ground by a rotary press-fitting method in which a tip member that exerts propulsive force by rotation is fixed to the tip of a shaft part made of a steel pipe, and steel pipe piles of different diameters are connected vertically to each other. In the case of a pile, a different diameter steel pipe pile connecting member used when vertically connecting the large diameter steel pipe pile and the small diameter steel pipe pile,
On one side of a circular flat plate that is not at least smaller in diameter than the outer diameter of the large-diameter steel pipe pile, the pipe end of the steel large-diameter short pipe to which the large-diameter steel pipe pile is welded and connected is welded to the entire circumference both on the inner and outer surfaces. And
A different-diameter steel pipe pile connecting member, wherein a pipe end of a steel small-diameter short pipe to which the small-diameter side steel pipe pile is welded and connected to the other side surface of the circular flat plate is fixed by welding all over the inner and outer surfaces. The outer diameter of the large-diameter short pipe is D1, the inner diameter is d1, the outer diameter of the large-diameter steel pipe pile is D2, the inner diameter is d2, the outer diameter of the small-diameter short pipe is D3, and the inner diameter is d3. When the outer diameter of the side steel pipe pile is D4 and the inner diameter is d4,
The relationship between the diameter of the large diameter short pipe and the diameter of the large diameter steel pipe pile is D1 ≧ D2, and d1 ≦ d2,
2. The different diameter steel pipe pile connection member according to claim 1, wherein the diameter relation between the small diameter short pipe and the small diameter side steel pipe pile is D3 ≧ D4 and d3 ≦ d4. Claim 1 or 2 different diameter steel pipe piles connecting member of, wherein the outer diameter of the circular flat plate is the same diameter as the outer diameter of the large径短long tube. The said circular flat plate has the flange part which protruded to the radial direction outer side from the outer peripheral surface of the said large diameter short pipe, The different diameter steel pipe pile connection member of Claim 1 or 2 characterized by the above-mentioned .   The said circular flat plate is provided with the inclined surface part which mutually inclines in the up-down direction in the said flange part, The different diameter steel pipe pile connection member of Claim 4 characterized by the above-mentioned.   It is a steel pipe pile constructed as a head pile using the different diameter steel pipe pile connection member according to any one of claims 1 to 5, wherein the large diameter steel pipe pile is a pile upper end side, and the small diameter steel pipe pile is a pile. A steel pipe pile being a lower side.   It is a steel pipe pile constructed as an expanded bottom pile using the different diameter steel pipe pile connection member according to any one of claims 1 to 5, wherein the large-diameter steel pipe pile is at the lower end of the pile, and the small-diameter steel pipe pile is A steel pipe pile, being an upper side. It is a steel pipe pile constructed as an expanded bottom pile using the different diameter steel pipe pile connection member according to claim 7,
The tip member that exerts the propulsion force fixed to the tip of the large-diameter steel pipe pile that is the lower end of the pile is turned upside down with respect to a flange portion that is an outer portion from the outer peripheral surface of the large-diameter steel pipe pile. Having an inclined surface portion, comprising an end plate made of a disc, and a plate-shaped excavation blade with a pointed tip fixed vertically to the lower surface center of the end plate,
The steel pipe pile according to claim 1, wherein the end plate has a circular center hole at a center portion thereof, and the excavating blade has a notch at an edge portion of the end plate side facing the center hole.

Images