JP2021116590A - Bottom-expanded steel pipe pile and bottom-expanded integrated steel pipe - Google Patents

Abstract

To provide a bottom-expanded steel pipe pile that can form a large bottom-expanded part with a simple structure, can realize a large bearing capacity, and can exert a large propulsive force when rotationally press-fitting.SOLUTION: A bottom-expanded steel pipe pile comprises a shaft steel pipe 2, a bottom-expanded steel pipe 3 having a diameter larger than that of the shaft steel pipe joined to a lower end of the shaft steel pipe, and a tip member 4 joined to the lower end thereof and exerting excavation propulsion force. The tip member comprises an end face plate 10 fixed to the lower end surface of the bottom-expanded steel pipe and having inclined surface portions inclined upside down, and a plate-shaped excavation blade 31 fixed vertically to the lower surface thereof. The excavation blade has a notch 31a that opens facing a center hole 32 formed in the center of the end face plate. A joint structure between the shaft steel pipe and the bottom-expanded steel pipe is a joint structure in which a circular flat plate 21 is welded and fixed to the upper end of the bottom-expanded steel pipe, a short pipe 5 having a diameter equal to or slightly larger than the diameter of the shaft steel pipe and thicker than the shaft steel pipe is welded and fixed to the upper surface thereof, and the upper end of the short pipe and the lower end of the shaft steel pipe is welded and joined.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bottom-expanded steel pipe pile constructed by a rotary press-fitting method and a bottom-expanded portion integrated steel pipe used as a bottom-expanded side portion of the bottom-expanded steel pipe pile.

The expanded bottom pile method is adopted in the cast-in-place concrete method, but it is also adopted in the steel pipe pile by the rotary press-fitting method (Patent Documents 1, 2, 3, 4). Each patent document will be described below using the respective reference numerals.

The bottom-expanded steel pipe pile 1 of Patent Document 1 has a structure in which a bottom-expanded plate 3 made of a substantially square steel plate is attached to the tip surface of a steel pipe (pile steel pipe) 2, and the bottom-expanded plate 3 faces upward and downward with an inclined surface portion 31 by cutting. The inclined surface portion 32 is formed.

The bottom-expanded steel pipe A of Patent Document 2 has a configuration in which a bottom conical bottom support blade 2'is connected to a small-diameter steel pipe 1 which is a shaft steel pipe by an inclined reinforcing material 3'.

The rotary press-fitting expanded bottom steel pipe pile 1 of Patent Document 3 is a short for connection having a bottom expanding plate 4 and an excavation blade 5 and a tip excavating blade 6 formed as a notch portion of the bottom expanding plate 4 at the tip portion of the pile body 2. It has a configuration in which a pipe 3 is provided.

The bottom-expanded steel pipe pile A of Patent Document 4 includes a bottom-expanded portion 2 fixed to the lower end of the steel pipe 1 which is the main body of the steel pipe pile, and a press-fitting portion 3 fixed to the lower end of the bottom-expanded portion 2.
In the bottom expanding portion 2, a plurality of heat-meltable synthetic resin bags 13 filled with a water reaction expansion material 12 are arranged inside and outside the recess 6 of the intermediate steel material 5, and are attached to a mounting plate 4 fixed to the lower end portion of the steel pipe 1. Each bag 13 is surrounded by a plurality of curved pressing plates 8 whose upper ends are connected so as to be swingable, and the outer periphery of the lower portion of each pressing plate 8 is bound by a heat-meltable synthetic resin band 14. Is formed.
As the press-fitting portion 3, a forehead excavation blade 17 and an excavation drill 18 are provided.

JP 2006-127267 JP-A-2002-212947 JP 2006-177101 JP-A-2002-339352

In all of Patent Documents 1 to 4, the bottom-expanded plate 3 (Patent Document 1), the bottom-expanded support wing 2'(Patent Document 2), the bottom-expanded plate 4 (Patent Document 3), and the bottom-expanded portion are directly attached to the pile body steel pipe (shaft steel pipe). 2 (Patent Document 4) is provided, and a sufficiently large bottom-expanded portion cannot be formed.
Further, Patent Document 4 has a special structure in which a plurality of heat-meltable synthetic resin bags 13 filled with a water reaction expansion material 12 are arranged, and cannot be easily manufactured.

By the way, under the present applicant, we have developed a bottom-expanded steel pipe pile that can form a sufficiently large bottom-expanded portion with a simple structure and can obtain a large bearing capacity, and a bottom-expanded portion integrated steel pipe, and applied for a patent. (Patent application 2019-119163 (filed on June 26, 1st year of Reiwa)).
According to this bottom-expanded steel pipe pile, it is possible to form a sufficiently large bottom-expanded portion with a simple structure and obtain a large bearing capacity. There is also the aspect that a large driving force is required.

The present invention has been made based on the above background, and it is possible to form a sufficiently large bottom-expanded portion with a simple structure, to obtain a large bearing capacity, and to provide a large propulsion when the pile is rotationally press-fitted. It is an object of the present invention to provide a bottom-expanded steel pipe pile capable of exerting force and a bottom-expanded portion integrated steel pipe.

The bottom-expanded steel pipe pile of the invention of claim 1 that solves the above problems includes a shaft steel pipe that is a pile steel pipe main body, a bottom-expanded steel pipe having a diameter larger than that of the shaft steel pipe joined to the lower end of the shaft steel pipe, and the bottom-expanded steel pipe. It is a bottom-expanded steel pipe pile by the rotary press-fitting method, which consists of a circular bottom-expanded part joined to the lower end of the pipe and at the same time a tip member that exerts excavation propulsion force.
_{A circular end face plate having a diameter D 0 larger than the diameter d 1} of the bottom expansion side steel pipe is welded and fixed to the lower end surface of the bottom expansion side steel pipe, and the tip member projects outward from the outer circumference of the bottom expansion side steel pipe in the end face plate. It is a configuration in which inclined surface portions that are inclined upside down from each other are formed on the flange portion.
Junction structure between said shaft steel pipe the拡底side steel pipe, circular flat plate of the拡底side the same diameter as the steel tube diameter d ₁ is fixed by welding to the upper end of the拡底side steel pipe, the shaft steel tube diameter d on the upper surface of the circular flat plate ₂ the same diameter or the short tube of the thick than the shaft steel pipe with a large diameter than 2mm fixed by welding, the length of the short tube is the inner surface welding is possible lengths for the circular flat plate, said short tube It is a joint structure in which the upper end of the steel pipe and the lower end of the shaft steel pipe are welded together.
Further, the end face plate is provided with a plate-shaped excavation blade having a pointed tip vertically fixed in the center of the lower surface thereof, and has a circular center hole in the center of the end face plate, and the excavation blade has an edge on the end face plate side. The portion is characterized by having a notch that opens facing the central hole.

A second aspect of the present invention is the expanded steel pipe pile according to the first aspect, wherein the excavating blade has a pentagonal house shape having both sides parallel to each other on the end face plate side and a triangular tip side thereof.

The invention of claim 3 is a bottom-expanded steel pipe integrated with a bottom-expanded steel pipe used in the construction of a bottom-expanded steel pipe pile by a rotary press-fitting method.
A steel pipe with a larger diameter and a thicker wall than the shaft steel pipe, which is a pile body steel pipe, with a tip member that exerts excavation propulsion at the same time as a circular bottom-expanded part fixed at the lower end.
A circular flat plate of the same diameter as the拡底side steel tube diameter d ₁ which is welded and fixed to the upper end of the拡底side steel pipe,
_{A short pipe having the same diameter as the shaft steel pipe diameter d 2} or a large diameter within 2 mm and thicker than the shaft steel pipe, which is welded and fixed to the upper surface of the circular flat plate, is provided, and the length of the short pipe is the same as that of the circular flat plate. On the other hand, the length is such that inner surface welding is possible.
In the tip member, a circular end face plate is welded and fixed to the lower end surface of the bottom-expanded steel pipe, and an inclined surface portion inclined upside down is formed on a flange portion of the end face plate that projects outward from the outer circumference of the bottom-expanded steel pipe. It is a structure that has been made
Further, the end face plate is provided with a plate-shaped excavation blade having a pointed tip vertically fixed in the center of the lower surface thereof, and has a circular center hole in the center of the end face plate, and the excavation blade has an edge on the end face plate side. The portion is characterized by having a notch that opens facing the central hole.

According to the bottom-expanded steel pipe pile of the present invention, the shaft steel pipe, which is the main body of the pile steel pipe, is not directly joined to the tip member that exerts excavation propulsion force at the same time as the circular bottom-expanded portion, but has a larger diameter than the shaft steel pipe. Since the structure is joined to the tip member with the bottom-expanded side steel pipe interposed therebetween, the outer diameter of the end face plate of the tip member, which is a circular bottom-expanded portion, can be made large, and a large bearing capacity can be obtained as a bottom-expanded steel pipe pile. It becomes.
That is, if the outer diameter of the end face plate is simply increased in order to obtain a large bearing capacity as a bottom-expanded steel pipe pile, and if the small diameter shaft steel pipe is directly welded and fixed to the large diameter end face plate, it will be in a narrow area in the center of the end face plate. Since the concentrated load acts, the end face plate (tip member) does not always work effectively as the bottom expansion part in terms of its rigidity, but the concentrated load is relaxed because the bottom expansion side steel pipe that is welded and fixed to the end face plate has a large diameter. , Acts effectively as a bottom expansion part.

As described above, it is possible to form a sufficiently large bottom-expanded portion with a simple structure and obtain a large bearing capacity, but by having a large bottom-expanded portion, a large propulsive force is provided when the pile is rotationally press-fitted. Desired. but,
The structure has a circular center hole in the center of the end face plate, and the excavation blade fixed to the center of the lower surface of the end face plate has a notch that opens facing the center hole, so that the propulsive force is not impaired. Can be improved.
That is, the center hole provided in the central portion of the end face plate acts as a pressure relief to reduce the pressure from the excavated soil on the end face plate at the time of rotational press fitting. That is, it has the effect of reducing the resistance of the excavated soil and improving the propulsive force (improvement of workability).
In this case, even if the excavation blade is located in the center hole of the end face plate, since it has a notch that opens facing the center hole, it does not prevent the excavated soil from entering the center hole (inside the steel pipe) so much. That is, the notch provided in the excavation blade exerts a control action against the invasion of the excavated soil into the central hole (inside the steel pipe).
In this way, the center hole drilled in the center of the end face plate and the notch formed on the excavation blade side interact with each other and act in cooperation with each other, so that the excavated soil can be removed without impairing the depressurizing action. Supporting power can be secured by exerting a certain blocking effect by invading the pipe.

Further, the shaft steel pipe and the bottom-expanded side steel pipe have a structure in which they are joined by welding and fixing to a circular flat plate welded and fixed to the upper end of the bottom-expanded side steel pipe, and a short pipe thicker than the shaft steel pipe is interposed. It is possible to secure the strength of the joint portion of the different diameter pipe with the steel pipe on the expanded bottom side.

Even when it is difficult to propel the end face plate due to gravel, boulders, or other minor underground obstacles in the ground, as in claim 2, the pentagonal house-shaped excavation blade is fixed to the lower surface of the end face plate. Smooth end face plate propulsion is possible, and workability is improved.

According to the invention of claim 3, at the construction site, the bottom-expanded steel pipe pile is constructed by welding and connecting the shaft steel pipe to the short pipe of the bottom-expanded integrated steel pipe already manufactured at the factory. Can be joined with high joining strength, and the construction efficiency at the site is significantly improved.

It is a figure which showed the expanded steel pipe pile of one Example of this invention by partial omission of two places in the length direction. It is an enlarged view of the part A of FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is sectional drawing of the main part CC of FIG. It is a figure which showed only the excavation blade in FIG. (A) is an enlarged cross-sectional view of a main part of part B in FIG. 1, and (b) is a cross-sectional view of DD in (a). It is the figure which showed the part of the bottom-expanded part integrated steel pipe 7 in FIG. 1 without omitting the length (the figure which showed alone as the Example of the bottom-expanded part integrated steel pipe of claim 3).

Hereinafter, a mode for carrying out the bottom-expanded steel pipe pile of the present invention and the bottom-expanded portion integrated steel pipe used as the bottom-expanded side portion of the bottom-expanded steel pipe pile will be described with reference to the drawings.

FIG. 1 is a view showing an expanded steel pipe pile according to an embodiment of the present invention with two partial omissions in the length direction. 2 is an enlarged view of part A of FIG. 1, FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 4 is a cross-sectional view of a main part CC of FIG.
As shown in these figures, the bottom-expanded steel pipe pile 1 of the embodiment includes a shaft steel pipe 2 which is a pile steel pipe main body, a bottom-expanded steel pipe 3 joined to the lower end of the shaft steel pipe 2, and a lower end of the bottom-expanded steel pipe 3. It is composed of a tip member 4 which is joined to a circular bottom and at the same time exerts an excavation propulsive force.
The bottom-expanded side steel pipe 3 of the embodiment is connected to the shaft steel pipe 2 via a thick short pipe 5 having substantially the same diameter as the shaft steel pipe 2.
As shown in FIG. 7, the portion of the bottom-expanded side steel pipe 3, the tip member 4, and the short pipe 5 is called the bottom-expanded integrated steel pipe 7, but with respect to the shaft steel pipe length, the short pipe 5 is regarded as a part of the shaft steel pipe 3. ..

As shown in FIGS. As shown in FIG. 3, the end face plate 10 provided with the plate-shaped drilling blade 31 having a sharp tip has a diameter D ₀ larger than _{the diameter d 1} of the bottom-expanded steel pipe 3.
The flange portion 12, which is a portion outside the outer peripheral surface of the bottom-expanded steel pipe 3, has a notch 13 extending from the peripheral edge of the end face plate toward the center, and is inclined upside down on both sides of the notch 13 in the diameter direction of the end face plate. Inclined surface portions 14a and 14b are formed. The upwardly inclined inclined surface portion is indicated by reference numeral 14a, and the downwardly inclined inclined surface portion is indicated by 14b. The inclined surface portions 14a and 14b of the end face plate 10 inclined in the upside-down direction exert a propulsive force by rotation at the time of rotational press-fitting.
In the illustrated example, the inclined surface portions 14a and 14b inclined in the vertical direction are provided on both sides in the diametrical direction, but they may be provided on only one side.

The end face plate 10 has a circular center hole 32 at the center thereof.
As shown in FIGS. 2 to 5, the excavation blade 31 is a pentagonal house having both sides 31b parallel to each other on the end face plate side (the side welded and fixed to the end face plate) and the tip end side portion 31c having a triangular shape. It has a shape (a typical pentagonal house shape) and has a notch 31a that opens facing the center hole 32 of the end face plate 10. The shape (inner edge shape) of the notch 31a of this embodiment has the same width as the diameter d4 of the center hole 32, and is a pentagon that is substantially similar to the pentagon that is the overall contour of the excavation blade 31 (strictly pentagon). Does not have to be).

As described above, the shaft steel pipe 2 is connected to the bottom expansion side steel pipe 3 via the short pipe 5. FIG. 6 shows the details of the joint structure 20 between the shaft steel pipe 3 and the bottom-expanded side steel pipe 3.
A circular flat plate 21 having the same diameter as the _{expanded bottom steel pipe diameter d 1} is welded and fixed to the upper end of the expanded bottom steel pipe 3, and the same diameter (d ₃ ) or slightly as _{the diameter d 2 of the shaft steel pipe 2 is attached to the upper surface of the circular flat plate 21.} The short pipe 4 having a large diameter and thicker than the shaft steel pipe 2 is welded and fixed, and the upper end of the short pipe 4 and the lower end of the shaft steel pipe 3 are welded and joined.
The short pipe 5 is welded and fixed to the upper surface of a circular flat plate 21 previously welded and fixed to the bottom-expanded side steel pipe 3 by full-circumferential fillet welding on both the inner and outer surfaces, but the outer surface side is full-circumferential fillet welding with a groove. .. As a result, a welded joint having sufficiently high strength is performed.

When the bottom-expanded steel pipe pile 1 is rotationally press-fitted into the ground by a pile driver having a rotary press-fitting drive unit, the end face plate 10 of the tip member 4 exerts propulsive force in a manner in which its inclined surface portions 14a and 14b bite into the soil. ..

According to the above-mentioned expanded bottom steel pipe pile 1, the shaft steel pipe, which is the main body of the pile steel pipe, is not directly joined to the tip member that exerts excavation propulsive force at the same time as the circular bottom expanded portion, and has a diameter larger than that of the shaft steel pipe 2. Since the structure is joined to the tip member 4 with the bottom-expanded side steel pipe 3 interposed therebetween, the outer diameter of the end face plate 10 of the tip member 4 which is a circular bottom-expanded portion can be made large, and a large bearing capacity can be provided as a bottom-expanded steel pipe pile. It becomes possible to obtain.
That is, if the outer diameter of the end face plate is simply increased in order to obtain a large bearing capacity as a bottom-expanded steel pipe pile, and if the small diameter shaft steel pipe is directly welded and fixed to the large diameter end face plate, it will be in a narrow area in the center of the end face plate. Since a concentrated load acts, the end face plate (tip member) does not necessarily work effectively as a bottom expansion portion in terms of its rigidity, but in the bottom expansion steel pipe pile 1 of the present invention, the bottom expansion side steel pipe fixed by welding to the end face plate 10 Since 3 has a large diameter, the concentrated load is relaxed and effectively acts as a bottom-expanded portion.

In a steel pipe pile, when the maximum construction depth of, for example, 130 times the steel pipe pile diameter (shaft steel pipe diameter) is possible depending on the ground conditions, the bottom-expanded side steel pipe 3 having a diameter larger than that of the shaft steel pipe 2 exists on the pile tip side. Therefore, it is possible to further increase the maximum construction depth. In that case, depending on the ratio of the bottom-expanded side steel pipe length (bottom-expanded side steel pipe ratio) to the total length of the expanded-bottomed steel pipe pile (sum of the shaft steel pipe length and the bottom-expanded side steel pipe length), the material is compared with the steel pipe pile having the same total pile length. The cost (steel material cost) can be saved.

That is, if the length L of the bottom-expanding side steel pipe 3 is too short, the effect of providing the bottom-expanding side steel pipe (the effect that the maximum construction depth can be deepened) cannot be obtained, and if it is too long, the maximum construction depth is deepened. Even if it can be done, the material cost (steel material cost) becomes too high and there is no point in adopting it in terms of cost effectiveness. Therefore, it is advisable to carry out a loading test to obtain an appropriate length (ratio of steel pipes on the expanded bottom side) that can obtain high cost effectiveness. This makes it possible to construct a bottom-expanded steel pipe pile that saves material cost (steel material cost) as compared with a steel pipe pile having the same total diameter.
If the length L of the bottom-expanded steel pipe 3 is _{5 to 20% of the total length L 0} of the bottom-expanded steel pipe pile 1, a load test can be performed to obtain an appropriate bottom-expanded steel pipe ratio that can obtain high cost effectiveness. It is possible.

Further, the portion of the tip member 4 which is the excavated portion of the bottom-expanded steel pipe pile 1 will be described. An excavation blade 31 having a circular center hole 32 in the center of the end face plate 10 and fixed to the center of the lower surface of the end face plate 10 The configuration having the notch 31a that opens toward the center hole 32 makes it possible to improve the propulsive force without impairing the supporting force.
That is, the center hole 32 provided in the central portion of the end face plate 10 acts as a depressurization to reduce the pressure from the excavated soil on the end face plate 10 at the time of rotational press fitting. That is, it has the effect of reducing the resistance of the excavated soil and improving the propulsive force (hence, the improvement of workability).
In this case, even if the excavation blade 31 is located in the center hole 32 of the end face plate 10, the excavated soil has a notch 31a that opens facing the center hole, so that the excavated soil does not enter the center hole (inside the steel pipe). It doesn't interfere so much. That is, the notch 31a provided in the excavation blade 31 exerts a control action against the invasion of the excavated soil into the central hole (inside the steel pipe).
In this way, the center hole 32 formed in the central portion of the end face plate 10 and the notch 31a formed on the side of the excavating blade 31 interact with each other and act in cooperation with each other without impairing the depressurizing action. , It is possible to secure the bearing capacity by exerting a certain blocking effect by the excavated soil invading the pipe.
As described above, in the present invention, the propulsive force can be improved by the configuration in which the excavation blade 31 fixed to the center of the lower surface of the end face plate 10 has a notch 31a that opens facing the center hole 32. By having a large bottom-expanded portion (tip member 4), it is possible to cope with a large propulsive force required when a pile is rotationally press-fitted.

Further, even when it is difficult to propel the end face plate 10 due to gravel, boulders, or other minor underground obstacles in the ground, the structure in which the pentagonal house-shaped excavation blade 31 is fixed to the lower surface of the end face plate 10 makes it smooth. End face plate propulsion becomes possible and workability is improved.
Further, since the shape of the notch 31a of the excavation blade 31 is a pentagonal house shape similar to the pentagonal house shape of the excavation blade 31, the pentagonal house-shaped excavation blade 31 has the action of loosening the soil and the action of the notch 31a (of the excavated soil). The control action against intrusion into the central hole (inside the steel pipe) works in cooperation with each other, and the effect of improving the propulsive force without impairing the supporting force can be further enhanced.
The shape (inner edge shape) of the notch 31a of the embodiment is substantially similar to the shape of the excavation blade 31, but the triangular portion may be, for example, a semicircular arc shape. Further, the width of the notch 31a is appropriately adjusted to the diameter of the center hole 32 as in the embodiment, but it does not necessarily have to be adjusted (the width may be slightly wider or narrower).

For the dimensions of each part of the bottom-expanded steel pipe pile 1 of the present invention, the size range of a general steel pipe pile constructed by the rotary press-fitting method can be adopted. It is advisable to select the diameter / plate thickness / length, the diameter / plate thickness / length of the expanded bottom steel pipe, and the diameter / plate thickness of the end face plate.

When constructing the bottom-expanded steel pipe pile of the present invention, the tip member 4 can be welded and fixed to the lower end of the bottom-expanded side steel pipe 3 and the short pipe 5 can be welded and fixed to the upper end in advance at the factory. FIG. 7 shows only the bottom-expanded portion integrated steel pipe 7 in which the bottom-expanded side steel pipe 3, the tip member 4, and the short pipe 5 are integrated.
By manufacturing the bottom-expanded portion integrated steel pipe 7 in advance at the factory, the bottom-expanded steel pipe pile 1 is constructed by welding and connecting the shaft steel pipe 2 to the short pipe 5 of the bottom-expanded portion integrated steel pipe 7 at the construction site. , The shaft steel pipe 2 and the bottom-expanded side steel pipe 3 can be joined with high joining strength, and the construction efficiency at the site is remarkably improved.

1 Expanded bottom steel pipe pile 2 Shaft steel pipe 3 Expanded bottom steel pipe 4 Tip member
5 Short pipe 7 Expanded bottom integrated steel pipe
10 End face plate 12 Brim portion 13 Notch portion 14a (inclined upward) Inclined surface portion
14b Inclined surface portion 20 (inclined downward) Join structure 21 (joint structure) Circular flat plate 31 Excavation blade 31a Notch 32 Center hole

Claims (3)

A shaft steel pipe that is a pile steel pipe body, a bottom-expanded steel pipe having a diameter larger than that of the shaft steel pipe joined to the lower end of the shaft steel pipe, and a circular bottom-expanded portion joined to the lower end of the bottom-expanded steel pipe, and excavated at the same time. It is a bottom-expanded steel pipe pile by the rotary press-fitting method, which consists of a tip member that exerts propulsive force.
_{A circular end face plate having a diameter D 0 larger than the diameter d 1} of the bottom expansion side steel pipe is welded and fixed to the lower end surface of the bottom expansion side steel pipe, and the tip member projects outward from the outer circumference of the bottom expansion side steel pipe in the end face plate. It is a configuration in which inclined surface portions that are inclined upside down from each other are formed on the flange portion.
Junction structure between said shaft steel pipe the拡底side steel pipe, circular flat plate of the拡底side the same diameter as the steel tube diameter d ₁ is fixed by welding to the upper end of the拡底side steel pipe, the shaft steel tube diameter d on the upper surface of the circular flat plate ₂ the same diameter or the short tube of the thick than the shaft steel pipe with a large diameter than 2mm fixed by welding, the length of the short tube is the inner surface welding is possible lengths for the circular flat plate, said short tube It is a joint structure in which the upper end of the steel pipe and the lower end of the shaft steel pipe are welded together.
Moreover, the end face plate is provided with a plate-shaped excavation blade having a pointed tip vertically fixed in the center of the lower surface thereof, and has a circular center hole in the center of the end face plate, and the excavation blade has an edge on the end face plate side. A bottom-expanded steel pipe pile having a notch in the portion that faces the central hole. The steel pipe pile according to claim 1, wherein the excavating blade has a pentagonal house shape having both sides parallel to each other on the end face plate side and a triangular tip side thereof. Bottom-expanded steel pipe used for construction of bottom-expanded steel pipe piles by the rotary press-fitting method.
A steel pipe with a larger diameter and a thicker wall than the shaft steel pipe, which is a pile body steel pipe, with a tip member that exerts excavation propulsion at the same time as a circular bottom-expanded part fixed at the lower end.
A circular flat plate of the same diameter as the拡底side steel tube diameter d ₁ which is welded and fixed to the upper end of the拡底side steel pipe,
_{A short pipe having the same diameter as the shaft steel pipe diameter d 2} or a large diameter within 2 mm and thicker than the shaft steel pipe, which is welded and fixed to the upper surface of the circular flat plate, is provided, and the length of the short pipe is the same as that of the circular flat plate. On the other hand, the length is such that inner surface welding is possible.
In the tip member, a circular end face plate is welded and fixed to the lower end surface of the bottom-expanded steel pipe, and an inclined surface portion inclined upside down is formed on a flange portion of the end face plate that projects outward from the outer circumference of the bottom-expanded steel pipe. It is a structure that has been made
Further, the end face plate is provided with a plate-shaped excavation blade having a pointed tip vertically fixed in the center of the lower surface thereof, and has a circular center hole in the center of the end face plate, and the excavation blade has an edge on the end face plate side. An expanded bottom integrated steel pipe having a notch in the portion that faces the central hole.

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