JPH10159086A - Screwing steel-pipe pile with blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screwing steel-pipe pile with a blade, by which large bearing capacity is acquired by the blade, in which no excessive bending stress is generated in a steel pipe by bending moment transmitted from the blade, which is manufactured easily and in which processing cost can be reduced. SOLUTION: The steel-pipe pile 1 has a steel pipe 2 with mounting sections 3a, 3b, in which front end sections are divided into the plural through a high stepped section in one and a low stepped section in the other in the circumferential direction and divided each section is formed by inclined planes towards the same direction at approximately the same angle, and a plurality of fan- shaped plates 11a, 11b, in which radii are made larger than the radius of the steel pipe 2 and the sum total of internal angles is formed so as to reach approximately 360 deg.. The adjacent one end sections of these fan-shaped plates 11a, 11b are abutted at that time, and combined with the mounting sections 3a, 3b of the steel pipe 2 so as to form the approximately spiral blade 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screwed steel pipe pile with wings, and more particularly, to a steel pipe pile having a plurality of fan-shaped flat wings attached to a tip end of a steel pipe to apply a rotational force to the steel pipe pile. The present invention relates to a winged screwed steel pipe pile that can be buried underground by earth removal.

[0002]

2. Description of the Related Art A screw-in type which is buried underground by the action of a screw by applying a rotating force to a steel pipe pile having a spiral wing or the like attached to the tip or side of the steel pipe by a driving device installed on the ground. Many steel pipe piles have been proposed in the past, and some of them have been put to practical use although they are intended for small-diameter piles. Hereinafter, an example of such a conventional screw-in type steel pipe pile will be described.

[0003] In the method of burying steel pipe piles described in Japanese Patent Publication No. 2-62848, a bottom plate is fixed to a lower end of a steel pipe pile main body, and an excavation blade is provided on the bottom plate, and a lower end of the pile main body is provided. A steel pipe pile, which has an outer diameter almost twice the outer diameter of the pile main body on its outer peripheral surface and is screwed into a pile with a large wing width, is screwed into soft ground. While pushing it into the ground, excavating and softening the soil at the tip of the pile body with the excavating blade at the lower end, causing the spiral wings to bite into the unexcavated soil on the side of the pile, and rotating the pile as a reaction force with the strength of the soil While propelling, excavated and softened earth and sand is extruded to the side of the pile and compressed, and the pile is screwed into the ground without discharging the earth (prior art 1).

A steel pipe pile described in Japanese Patent Application Laid-Open No. 7-292666 has a pair of spiral wings, each of which has a length of half a roll and an outer diameter of about 1.5 to 3 times the pile body. A plurality of steel pipe piles are fixed discontinuously relative to each other at the same height position on the outer peripheral surface of the lower end portion of the steel pipe pile with the same helical direction (prior art 2).

[0005] Further, a rotary press-fit steel pipe pile described in Japanese Patent Application Laid-Open No. 61-98818 has a structure in which a steel cylinder is provided at a lower portion thereof.
Providing a blade having a pushing inclined front surface extending in the vertical direction, and forming an annular drill head by fixing an inclined blade obliquely rising upward from a lower end portion of the inclined front surface toward the rear in the cylindrical body rotating direction, The lower end of the steel pipe pile is attached to the upper end of the drill head (prior art 3).
The spiral wings or inclined blades shown in these prior arts 1 to 3 function not only as screws at the time of construction, but also as supports for obtaining ground support force.

[0006]

The steel pipe pile according to the prior art 1 has a spiral blade having a bottom plate at the lower end of a steel pipe pile body and an outer diameter on its outer peripheral surface which is almost twice as large as the outer diameter of the pile main body. These functions as a support having a large area when a load of an overlying structure is applied to the steel pipe pile, and a large supporting force can be obtained. However, there is a problem that the manufacturing cost is high for the following reasons. (1) Both the bottom plate and the spiral blade must be attached to the pile body by welding. (2) Bending of a steel plate is necessary to form a spiral blade. (3) Since a dimensional error occurs in the spiral wing and the pile main body at the time of manufacture, it takes time and labor to attach the spiral wing to the pile main body.

[0007] Considering the case of a steel pipe having an outer diameter of 500 mm, the thickness of the spiral blade is about 40 mm according to a trial calculation by the inventors. Bending a thick steel plate in this way not only costs a great deal of money, but also inevitably causes a large error in the height direction and the radial direction of the spiral blade. Further, the steel pipe usually has an outer diameter error of 0.5 to 1.0% and has a slightly elliptical shape, so that it is difficult to mount the spiral blade on the outer circumference of the steel pipe. Further, since a large gap is formed between the outer peripheral surface of the steel pipe and the inner periphery of the spiral blade, not only good welding cannot be performed, but also a long time is required for welding.

In the steel pipe pile of the prior art 2, it is necessary to provide a bottom plate in order to obtain a large supporting force.
There is the problem (1) pointed out above. Further, according to the specification of the prior art 2, the present invention is directed to a small-diameter steel pipe pile having an outer diameter of about 100 to 200 mm. A problem similar to that of the prior art 1 occurs. That is, even if the spiral wound is a half-wound spiral blade, not only high cost is required for bending, but also a lot of time and labor are required for installation and welding work on the steel pipe due to manufacturing errors.

A common problem of the prior arts 1 and 2 is that a large bending moment is transmitted from the spiral blade to the steel pipe. In other words, when a large vertical load acts on the steel pipe pile, a large ground reaction force acts on the spiral wing, whereby the bending moment generated in the spiral wing is transmitted to the steel pipe, and the steel pipe near the root of the spiral wing causes buckling There is a problem. When the outer diameter of the steel pipe is as small as about 200 mm, since the outer diameter of the spiral blade is small, the generated bending moment is also small, and this is not a problem.
When it is about 0 mm, a bending moment that cannot be dealt with by design often occurs in practice.

The prior art 3 has a serious problem that since the tip of the steel cylinder does not have a lid, earth and sand cannot enter the steel pipe to obtain a large ground support force. Further, since the width of the inclined blade is small and the structure slightly projects inside and outside the tip of the steel cylinder, the inclined blade cannot be expected as a support having a large ground support force. Furthermore, in the prior art 3, since a steel cylinder with an inclined blade is manufactured and then fixed to the tip of the steel pipe, an increase in cost is inevitable.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is intended to solve the following problems. (1) A large ground support force can be obtained using the wings. (2) Do not generate excessive bending stress in the steel pipe due to the bending moment transmitted from the blade. (3) The steel pipe pile can be buried by screwing into a strong stratum. (4) The manufacturing is easy and the manufacturing cost can be reduced.

[0012]

[Means for Solving the Problems]

(1) In the screwed steel pipe pile with wings according to the present invention, the tip is circumferentially divided into a plurality of steps through a step which is higher on the other side and lower on the other side, and the divided individual parts are in the same direction at substantially the same angle. A steel pipe having a mounting portion formed by an inclined surface facing
The radius is larger than the radius of the steel pipe, and the sum of the internal angles is approximately 360
° and a plurality of fan-shaped flat plates formed so as to form an approximately spiral wing by bringing one adjacent end of these fan-shaped flat plates into contact with each other. It is a combination.

(2) One end of the adjacent fan-shaped flat plate contacted in (1) above was welded and joined. (3) The height of the higher one of the steps formed between the mounting parts of (1) is set to 0.1 to 0.3 of the outer diameter of the steel pipe.
Doubled.

(4) The plurality of fan-shaped flat plates of (1) are formed such that the sum of the internal angles is 320 ° to 400 °. (5) Further, a fan-shaped flat plate was connected to the mounting portion provided at the tip of the steel pipe of (1) by low-strength welding means.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows Embodiment 1 of a screwed steel pipe pile with wings according to the present invention.
It is a perspective view of. In the figure, 1 is a screwed steel pipe pile with wings (hereinafter simply referred to as a steel pipe pile), 2 is a steel pipe constituting the steel pipe pile 1, 11 a and 11 b are fan-shaped flat plates made of a steel plate and connected to the tip of the steel pipe 2, The wing 10 is configured.

At the tip of the steel pipe 2, as shown in FIG.
In the circumferential direction, the first and second steps 4a and 4b
A first mounting portion 3a (a distal end portion side of the steel pipe 2), which is formed by being divided and having an inclined surface facing in the same direction at substantially the same angle, and a second mounting portion 3b are provided. In addition, these first
The mounting portion 3b and the second mounting portion 3b are discontinuous but substantially spiral.

The height h of the first step portion 4a varies depending on the state of the ground penetrating the steel pipe pile 1, the outer diameter of the steel pipe 2, and the like, but generally h = 0.1 to 0.3D (D is the steel pipe 2). Diameter)
And the height h ₁ of the second step portion 4b is
The fan-shaped flat plates 11a and 11b constituting the wing 10 are formed slightly higher in thickness than the fan-shaped flat plates 11a and 11b. When the height h of the first step portion 4a is less than 0.1D, the penetration amount per rotation of the steel pipe pile 1 is significantly reduced, and when it exceeds 0.3D, the penetration amount per rotation is large. This is excessive, so that the torque for rotating the steel pipe pile 1 becomes excessively large, and furthermore, the thickness of the ground loosened by the wings 10 becomes large, so that the supporting force is slightly reduced.

As shown in FIG. 3, the blade 10 has a fan-shaped flat plate 11 obtained by dividing a circular steel plate or an elliptical steel plate having an outer diameter D1 (for example, D1 = 2D) larger than the outer diameter D of the steel pipe 2 into two parts from the center.
a, 11b. The size of the wing 10 varies depending on the state of the ground penetrating the steel pipe pile 1, the outer diameter of the steel pipe 2, and the like. However, the outer diameter of the steel pipe 2 is considered in consideration of the balance between the screwing workability and the supporting force. 1.5 of D
About 2.5 times is desirable.

A fan-shaped flat plate 1 is provided at the tip of such a steel pipe 2.
In order to form the wing 10 by combining the wings 1a and 11b, for example, the fan-shaped flat plate 11a is placed on the first mounting portion 3a and its straight edge is made to coincide with the upper end of the steps 4a and 4b. It is connected to the steel pipe 2 by welding or the like. Next, the fan-shaped flat plate 11b is placed on the second mounting portion 3b, and its straight edge is set to the step portions 4a,
4b and is connected to the steel pipe 2 by welding or the like.

At this time, the step portions 4a of the fan-shaped flat plates 11a and 11b are staggered, but the ends of the step portions 4b abut on substantially the same plane. In this state, both fan-shaped flat plates 1
If the stepped portions 4a (contact portions) of 1a and 11b are welded, the attachment of the fan-shaped flat plates 11a and 11b is completed, and the substantially spiral blade 10 is obtained. The above-mentioned assembling order shows one example, and can be changed as appropriate.

In the steel pipe pile 1 according to the first embodiment configured as described above, the two fan-shaped flat plates 11a and 11b are welded to the substantially spiral mounting portions 3a and 3b provided at the lower end of the steel pipe 2. To form a wing 10 and connect the wing 10 to a steel pipe 2
The blade 10 is largely protruded from the outer peripheral surface of the blade 10 so that the blade 10 that is close to a spiral blade as a whole can be configured. As a result, when a rotational force is applied to the steel pipe pile 1 at the time of screwing into the ground, the steel pipe pile 1 can be smoothly penetrated into the ground as in the case of the steel pipe pile to which the spiral wing is attached. In screwing, the wings 10 cut into the ground below and screw the steel pipe pile 1 into the ground, and the earth and sand below the steel pipe 2 is used as a fan-shaped flat plate 11a, 1
It excavates at the staggered portion 1b, extrudes it around the steel pipe 2, and exerts both functions of compressing it.

Further, after the construction, when functioning as a pile for supporting a vertical load by an overlying building or the like, the fan-shaped flat plates 11a and 11b are provided with a portion serving as a bottom plate for closing the lower end opening of the steel pipe 2 and a steel pipe. The entire area including the portion as the wing protruding from the outer periphery of 2 functions as a support, and a large ground support force can be obtained.

As described above, the blade 10 has both a function of protruding into the outer periphery of the steel pipe 2 and cutting into the ground, and a function as a bottom plate for closing the opening at the tip of the steel pipe 2. It is known that the ground bearing capacity of a steel pipe pile having a closed tip is proportional to the closed area.
When the radius of a, 11b is twice the radius of the steel pipe 2, the wing 1
The area of 0 is four times as large as the area without it, and a very large ground support force can be obtained.

The blade 10 of the steel pipe pile 1 according to the present invention
The fan-shaped flat plates 11 a and 11 constituting the steel pipe 2 and the blade 10 are configured to be attached to the tip of the steel pipe 2 instead of the outer peripheral surface.
The fan-shaped flat plates 11a and 11b can be easily and surely joined to the steel pipe 2 without being affected by the dimensional error in the production of b. In addition, it is necessary to bend like a conventional spiral blade. Absent. Therefore, even in the case of a steel pipe pile having an outer diameter of about 500 mm, the fan-shaped flat plates 11a and 11b can be manufactured at low cost.
The manufacturing cost of the steel pipe pile 1 can be reduced as a whole. Further, both fan-shaped flat plates 11
Since one end of each of a and 11b is welded to integrate them, the mechanical stability can be increased and the ground can be more smoothly penetrated.

Embodiment 2 In the present embodiment, the portion surrounded by the steel pipe 2 in the opening 12 formed by the discrepancy between the ends of the fan-shaped flat plates 11a and 11b constituting the blade 10 in Embodiment 1 is described. As shown in FIGS. 4 and 5, the fan-shaped flat plates 11a and 11b are closed tightly by the closing member 13 while being closed by the closing member 13 made of a steel plate or the like. This prevents the intrusion and improves the mechanical stability of the wing 10.

According to this embodiment, the fan-shaped flat plates 11a,
Opening 12 formed by staggering of ends of 11b
Of the steel pipe 2 can be completely prevented by closing the portion surrounded by the steel pipe 2 with the closing plate 13, so that all the sediment below the tip of the steel pipe pile 1 is Since it is extruded to the side of the steel pipe pile 1 and is compressed to become high-density earth and sand, it is possible to increase the ground support force due to friction of the peripheral surface of the steel pipe pile 1.

By the way, in order to receive a large ground reaction force by the wing 10, the wing 10 is required to have high rigidity. For example, the outer diameter of the steel pipe 2 is 500 mm, and the outer diameter of the wing 10 is 10 mm.
In the case of 00 mm, a large bending moment is generated in the wing 10 due to the ground reaction force. Therefore, it is required to use a steel plate having a thickness of about 40 mm in design, and this bending moment is transmitted to the steel pipe 2 so that the bending stress is reduced. Will happen.

However, as shown in FIG. 6, the wing 10 according to the present invention has a bending moment M generated by a ground reaction force acting on portions outside the fan-shaped flat plates 11a and 11b.
₁ , M ₄ and the bending moments M ₂ , M ₃ generated in the inner part cancel each other at the tip of the steel pipe 2, and as a result, the steel pipe 2 near the mounting part 3 of the fan-shaped flat plates 11 a, 11 b Is the bending moment M ₁ -M with a small difference between the two.
_{Since only 2} and M ₄ -M ₃ are transmitted, no excessive bending stress is generated in the steel pipe 2. Further, as shown in the second embodiment, when rigid joining is performed by the closing members 13 of the adjacent fan-shaped flat plates 11a and 11b, the bending moment is canceled and balanced at the joint with the steel pipe 2 in order to cancel the bending moment. Has little effect.

On the other hand, depending on the relationship between the outer diameter of the steel pipe 2 and the outer diameter of the blades 10 and the distribution of the ground reaction force, a large imbalance occurs in the bending moment applied to the inner and outer blades 10 of the steel pipe 2. It is also conceivable that a bending moment corresponding to the difference between the bending moments is applied to the steel pipe 2 and a large bending stress is generated in the steel pipe 2. Furthermore, even if the bending moments applied to the wing 10 cancel each other as described above,
When the wing 10 is relatively thin, the whole may be deformed by bending. In such a case, a secondary bending moment acts on the joint between the steel pipe 2 and the blade 10.

In such a case, as shown in FIG.
Simple welding 1 that does not melt into the entire cross-section, such as fillet welding or partial welding, at the tip of steel pipe 2 (mounting portions 3a, 3b)
4, or the fan-shaped flat plates 11a and 11 are formed by full-section penetration welding using a welding material having a lower yield strength than the material of the steel pipe 2 (hereinafter, both are referred to as low-strength welding means).
b, the weld may be intentionally yielded before the bending stress of the steel pipe 2 reaches an allowable value, so that no further bending moment is transmitted to the steel pipe 2.

As shown in FIG. 8, a steel material such as a welding material has a property that it does not break until it is considerably deformed even after yielding. Therefore, the blade 10 can maintain the tip of the steel pipe 2 even after yielding of the welded portion. It does not fall out of the department. Further, even if the welded part yields, the compressive force from the steel pipe 2 to the wing 10 is reliably transmitted, so that the wing 10 can function soundly as a support receiving the ground reaction force.

Embodiment 3 In each of the above embodiments, a circular steel plate or an elliptical steel plate is divided into two equal parts, and the fan-shaped steel plates 11a, 11a having a total interior angle of 360 °.
b, and one adjacent end thereof is brought into contact with the wing 1
In this embodiment, the sum of the internal angles of the fan-shaped flat plates 11a and 11b is smaller than 360 ° or larger than 360 °. 9 and 10 show that the sum of the inner angles of both fan-shaped flat plates 11a and 11b is smaller than 360 °, and a gap 18 is formed between the fan-shaped flat plates 11a and 11b. FIG.
FIG. 12 shows the sum of the internal angles of both fan-shaped flat plates 11a and 11b as 3
Fan-shaped flat plates 11a and 11
An overlap 19 is generated between b and b. In this case, for example, when attaching the fan-shaped flat plate 11b, the step portion 4 is required.
a groove 3c which is continuous with the mounting portion 3b is provided at the upper part of
A part of the fan-shaped flat plate 11b may be fitted into the groove 3c.

According to the results of field tests and numerical analysis conducted by the inventors, the two fan-shaped flat plates 11a, 11b
If the sum of the internal angles of the steel pipe piles 1 is smaller than 320 °, the penetration speed at the time of screwing in the steel pipe pile 1 will decrease, and the supporting force will decrease. Further, it was found that when the angle exceeds 400 °, the workability is deteriorated in the gravel ground having a large particle diameter. For this reason, the fan-shaped flat plates 11a and 11b constituting the wing 10
Is preferably in the range of 320 ° to 400 °.

FIG. 13 shows that when the steel pipe pile 1 is screwed and buried in the ground, the end of the wing 10 is prevented from being deformed.
One or a plurality of reinforcing steel plates 20 are attached to ends of the fan-shaped flat plates 11a and 11b on the rotation direction side. FIG. 14 shows that, in order to improve the screwing efficiency of the steel pipe pile 1, the ends of the fan-shaped flat plates 11 a and 11 b on the rotation direction side are
One or a plurality of excavating blades 21 for assisting excavation of the wing 10 are attached. In this case, the fan-shaped flat plate 11
The excavating blade 21 may be attached near the center of the a and 11b. The reinforcing steel plate 20 and the excavating blade 21 are not essential to the present invention.

FIG. 15 shows an example of an execution test when the steel pipe pile 1 according to the present invention is buried underground. The dimensions of the steel pipe 2 constituting the steel pipe pile 1 are an outer diameter D: 500 mm and a wall thickness. :
14 mm, length: 48.5 m, and the height h of the stepped portion 4a of the spiral attachment portion provided at the distal end portion was set to h: 0.125D. The wing 10 has an outer diameter of 1000 mm and a thickness of 40.
2 mm fan-shaped flat plates (sum of inner angles: 360 °) 11
a, 11b, and joined to the mounting portions 3a, 3b of the steel pipe 2 by low-strength welding means. Further, as a comparative example, a spiral wing (outer diameter: 1000 mm) manufactured by bending a single donut-shaped steel plate was simultaneously tested on a steel pipe pile joined to a lower outer periphery of a steel pipe having an outer diameter of 500 mm, and workability and workability were improved. The bearing capacity was compared.

The rotational force of the steel pipe pile was transmitted to the pile head by an auger 26 mounted on a base machine 25 shown in FIG. The ground at the test site is landfill sand up to a depth of 8 m from the surface, soft cohesive soil from 8 m to 43.5 m, 43.5 m
Below that was a layer of fine sand. The steel pipe pile 1 according to the present invention and the steel pipe pile for comparison were each screwed to a depth of 47 m. As a result, the steel pipe pile 1 according to the present invention and the steel pipe pile for comparison did not show any difference in screwing workability, and both were able to be buried smoothly. Then, a vertical loading test was performed using a hydraulic jack, and the supporting force of both was exactly the same.

As described above, when the steel pipe pile according to the present invention is buried in the ground by applying a rotational force to the steel pipe pile 1 and screwing it, the portion of the blade 10 outside the outer peripheral surface of the steel pipe 2 is subjected to the action of the screw. In the same manner as described above, the steel pipe pile 1 is propelled downward by a reaction force from the surrounding ground. Further, unlike the bottom plate shown in the prior art, the inner portion of the steel pipe 2 is arranged so that the edges of the fan-shaped flat plates 11a and 11b constituting the blade 10 are staggered. It has a function to excavate. Further, the steel pipe pile 1 can obtain a large supporting force due to the entire area of the wing 10. In addition, steel pipe pile 1
Is extruded to the side of the steel pipe 2 and is compressed, resulting in dense sediment.
In addition to the above supporting force, a large supporting force due to circumferential friction is obtained.

In the above description, two fan-shaped flat plates 11a, 3a are attached to the spiral mounting portions 3a, 3b provided at the lower end of the steel pipe 2.
Although the case where the wing 10 made of 11b is joined is shown, the wing 1
Spiral wings or flat wings may be attached to the outer periphery of the steel pipe above zero. Thereby, it can be said that the function to propel the steel pipe 2 downward and the support function are further improved. Further, the wing 10 is divided into two fan-shaped flat plates 11a and 11b.
Although the case of the configuration is shown, it may be configured by an even number of two or more fan-shaped flat plates. As the number increases, the shape of the blade 10 approaches the spiral blade. However, if the number increases, the connection between each fan-shaped flat plate and the mounting portion of the steel pipe 2 becomes mechanically unstable when a vertical force acts on the steel pipe pile 1. Therefore, at most four are desirable.

[0039]

【The invention's effect】

(1) In the screwed steel pipe pile with wings according to the present invention, the tip is circumferentially divided into a plurality of steps through a step which is higher on the other side and lower on the other side, and the divided individual parts are in the same direction at substantially the same angle. A steel pipe having a mounting portion formed by an inclined surface facing
The radius is larger than the radius of the steel pipe, and the sum of the internal angles is approximately 360
° and a plurality of fan-shaped flat plates formed so as to form an approximately spiral wing by bringing one adjacent end of these fan-shaped flat plates into contact with each other. And (2) welding and joining one end of the abutted adjacent fan-shaped flat plate of (1) above; (3)
Since the height of the higher one of the steps formed between the mounting parts in the above (1) is set to 0.1 to 0.3 times the outer diameter of the steel pipe, the following effects are obtained. Obtainable.

Since the entire blade having both the function of the bottom plate of the steel pipe and the spiral blade functions as a support when a vertical force is applied, a large supporting force can be obtained. The blade formed by arranging a plurality of fan-shaped flat plates substantially spirally at the tip of the steel pipe can provide the same screwing workability as when the spiral blade is provided. Since one end of the fan-shaped flat plate is welded and integrated, the mechanical stability can be increased.

In addition to the necessity of bending the steel plate for the manufacture of the wing, even if there is a dimensional error in the production between the fan-shaped flat plate and the steel pipe, the fan-shaped flat plate can be easily and reliably formed without being affected by the error. Can be mounted on For this reason,
The manufacturing cost of steel pipe piles can be reduced. Since the wing is attached to the tip of the steel pipe instead of the outer peripheral surface, the bending moment generated in the wing is transmitted to the steel pipe, so that an excessive bending stress is hardly generated.

(4) Since the sum of the internal angles of the plurality of fan-shaped flat plates in (1) is 320 ° to 400 °, good screwing workability and stable supporting force can be obtained. .

(5) Since the fan-shaped flat plate constituting the blade of the above (1) is connected to the steel pipe by low-strength welding means, even if an excessive bending moment is generated in the blade, the bending stress generated in the steel pipe. Can be suppressed to within an allowable value.

[Brief description of the drawings]

FIG. 1 is a perspective view of Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a tip portion of the steel pipe of FIG.

FIG. 3 is a perspective view of a fan-shaped flat plate constituting the wing of FIG. 1;

FIG. 4 is a perspective view of a second embodiment of the present invention.

FIG. 5 is an explanatory bottom view of FIG. 4;

FIG. 6 is an explanatory diagram of a bending moment applied to a wing.

FIG. 7 is an explanatory view showing an example of joining a blade to a steel pipe.

FIG. 8 is a diagram showing properties of a steel material such as a welding material.

FIG. 9 is a perspective view of a third embodiment of the present invention.

FIG. 10 is an explanatory bottom view of FIG. 9;

FIG. 11 is a perspective view of another example of the third embodiment.

FIG. 12 is an explanatory bottom view of FIG. 11;

FIG. 13 is a perspective view showing a state where a reinforcing steel plate is attached to the wing.

FIG. 14 is a perspective view showing a state where a digging blade is attached to a wing.

FIG. 15 is an explanatory view showing a construction example of a steel pipe pile according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Steel pipe 3a, 3b Attachment part 4a, 4b Step part 10 Blade 11a, 11b Fan-shaped flat plate 12 Opening 13 Closure member 14 Low-strength welding means (fillet welding) 18 Gap 19 Overlap

Claims (5)

[Claims] 1. A mounting part formed by dividing a distal end portion into a plurality of steps in a circumferential direction, one of which is high and the other of which is low, and each of the divided portions is formed by an inclined surface facing in the same direction at substantially the same angle. A steel pipe having a portion having a radius larger than the radius of the steel pipe, and a sum of internal angles of about 3
A plurality of fan-shaped flat plates formed so as to be at an angle of 60 °, and attaching the steel pipe so that one adjacent end of the fan-shaped flat plates abuts to form a substantially spiral wing. Screwed steel pipe pile with wings, characterized in that it is connected to a section. 2. The screwed steel pipe pile with wings according to claim 1, wherein one end of the adjacent fan-shaped flat plates abutted is welded and joined. 3. The step according to claim 1, wherein the height of the higher step of the step formed in the mounting portion is 0.1 to 0.3 times the outer diameter of the steel pipe. Screwed steel pipe pile with wings. 4. The sum of the internal angles of a plurality of fan-shaped flat plates is 320.
2. The screwed steel pipe pile with wings according to claim 1, wherein the pile is formed so as to have an angle of 400 ° to 400 °. 3. 5. The screwed steel pipe pile with wings according to claim 1, wherein a fan-shaped flat plate is connected to the mounting portion provided at the tip of the steel pipe by low-strength welding means.