JPH10102489A - Screw steel pipe pile with blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw steel pipe pile which can obtain a large bearing power by a blade, generates no excess bending stress in a steel pipe by bending moment transmitted from the blade, facilitate manufacture, and can reduce the working cost. SOLUTION: A screw steel pipe pile with the blade has a steel pipe 2, in which a mounting section 3 is formed by notching a front end section in an approximately spiral shape, and two or three fan-shaped plates 11a, 11b, in which radii are larger than the radius of the steel pipe 2 and which are formed so that the sum total of interior angles reaches approximately 360 deg.. These fan-shaped plates 11a, 11b are combined with the mounting section 3 of the steel pipe 2 so that adjacent edge sections are abutted mutually by the mounting section 3 and an approximately spiral blade 10 is molded.

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 that 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,
Some of them are intended for small diameter piles, but they have been put into practical use. 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 the lower end of a steel pipe pile body, a digging blade is provided on the bottom plate, and an outer periphery of the lower end of the pile body is provided. A spiral wing for screwing a pile with a large wing width, which has an outer diameter almost twice as large as the outer diameter of the pile body on the surface, is rotated so that a steel pipe pile projecting over almost one turn is screwed into soft ground. While pushing into the ground, the excavation blade at the lower end excavates and softens the earth and sand at the tip of the pile body, and makes the spiral wings bite into the unexcavated earth and sand on the side of the pile. While extruding and softening the excavated softened soil to the side of the pile,
The pile body is screwed into the ground without earth removal (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 of the prior art 1 has a bottom plate at the lower end of a steel pipe pile body and a spiral blade having an outer diameter almost twice as large as the outer diameter of the pile body on the outer peripheral surface. These are mounted and function as a support having a large area when a load of an overlying structure acts on 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 according to the 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) The screwed steel pipe pile with wings according to the present invention is formed such that the sum of the inner diameter and the steel pipe whose radius is larger than the radius of the steel pipe is substantially 360 ° with the steel pipe in which the mounting portion is formed by notching the tip end substantially spirally. It has two or three fan-shaped flat plates formed, and these fan-shaped flat plates are attached to the mounting portion of the steel pipe such that adjacent edges thereof abut on the mounting portion to form a substantially spiral wing. It is a combination.

(2) The screwed steel pipe pile with wings according to the present invention is a steel pipe having a mounting portion formed by cutting off the tip substantially in a spiral shape, and a sum of the inner angles of the steel pipe is larger than the radius of the steel pipe and is 320 °. It has two or three fan-shaped flat plates formed so as to form an angle of about 400 °, and these fan-shaped flat plates are connected to a steel pipe mounting portion so as to form a substantially spiral blade.

(3) The step caused by one rotation of the steel pipe of the spiral mounting part provided on the steel pipe of (1) or (2) is set to 0.1 to 0.4 times the outer diameter of the steel pipe.

(4) A fan-shaped flat plate was attached to the attachment portion provided at the tip of the steel pipe of (1) or (2) by low-strength welding means.

[0016]

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.
A mounting portion 3 of the blade 10 which is cut out in a substantially spiral shape is provided. The height of the step portion 4 forming the mounting portion 3, that is, the step h generated by one rotation of the steel pipe pile 1 is determined by the steel pipe pile. Although it depends on the state of the ground that penetrates 1 and the outer diameter of the steel pipe 2, it is generally desirable that h = about 0.1 to 0.4 D (D is the outer diameter of the steel pipe 2). This step h is 0.1D
If it is less than 1, the penetration amount per rotation of the steel pipe pile 1 is significantly reduced, and if it exceeds 0.4D, the penetration amount per rotation becomes too large, so that the torque for rotating the steel pipe pile 1 is small. Since the thickness of the ground becomes excessive and the thickness of the ground loosened by the wings 10 increases, the supporting force slightly decreases.

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 D ₁ (for example, D ₁ = 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.

FIGS. 4 and 5 are a perspective view and a bottom view showing another example of the present embodiment. In this example, the wing 10 is made of a circular steel plate or an elliptical steel plate having an outer diameter D ₁ larger than the outer diameter D of the steel pipe 2.
It is composed of divided fan-shaped flat plates 11a, 11b, 11c.

The fan-shaped flat plate 11 constituting the above-mentioned wing 10
a, 11b or 11a, 11b, 11c (hereinafter 11a-
11c) is preferably two or three. As the number increases, the shape of the wing 10 approaches the spiral wing, but when the number increases, when the vertical force acts on the steel pipe pile 1, each of the fan-shaped flat plates 11a to 11
Since the connecting portion between c and the mounting portion 3 of the steel pipe 2 becomes linear,
It becomes mechanically unstable.

Such fan-shaped flat plates 11a to 11c are:
The edge (straight edge in the case of two fan-shaped flat plates 11a to 11c, the tip end in the case of three fan-shaped flat plates 11a to 11c) is positioned at the approximate center of the steel pipe 2 and is mounted on the mounting portion 3, and the adjacent fan is placed. Shape flat plate 11
The edges of a to 11c abut on each other at the mounting portion and are connected to the mounting portion 3 of the steel pipe 2 by welding or the like, and the steel pipe pile 1 is configured.
In this case, the vicinity of the contact portions of the adjacent fan-shaped flat plates 11a to 11c may be joined by welding to increase the mechanical stability. Then, for example, as shown in FIG. 18, the auger 26 is connected to an auger 26 mounted on a base machine 25.
And is screwed into the ground by the screw action of the wing 10 and buried. At this time, most of the opening at the tip end of the steel pipe 2 is closed by the fan-shaped flat plates 11 a to 11 c, so that sediment hardly enters the steel pipe 2.

Embodiment 2 This embodiment is different from Embodiment 1 in that, in the opening 12 formed by the difference between the edges of the two or three fan-shaped flat plates 11 a to 11 c constituting the wing 10, As shown in FIGS. 6 and 7, the portion surrounded by 2 is closed by a closing member 13 made of a steel plate or the like.
The edges of a to 11c are rigidly joined by the closing member 13, thereby improving the mechanical stability of the wing 10 that prevents complete intrusion of earth and sand.

In the steel pipe pile 1 according to the first embodiment configured as described above, two or three fan-shaped flat plates 11a to 11c are welded to a substantially spiral mounting part 3 provided at the lower end of the steel pipe 2. To form the wing 10 and connect the wing 10 to the 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 piles 1 into the ground, and the earth and sand below the steel pipes 2 are fed into the fan-shaped flat plates 11a to 11a.
It excavates at the staggered portion 1c, extrudes it around the steel pipe 2, and exerts both the function of compressing it.

Further, after construction, when functioning as a pile for supporting a vertical load by an overlying building or the like, the fan-shaped flat plates 11a to 11c include 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 １１11c is twice the radius of the steel pipe 2, the wing 10
Is four times as large as the case without this, and a very large ground support force can be obtained.

As shown in the second embodiment, the portion of the opening 12 formed by the discrepancy between the ends of the fan-shaped flat plates 11a to 11c, which is surrounded by the steel pipe 2, is closed.
By blocking with 3, intrusion of earth and sand into the steel pipe 2 can be completely prevented, so that all earth and sand below the tip of the steel pipe pile 1 is pushed out to the side of the steel pipe pile 1 and compressed. Since the soil becomes high in density, the ground support force due to the peripheral friction of the steel pipe pile 1 can be increased.

The wing 10 of the steel pipe pile 1 according to the present invention is
Since the structure is such that the steel pipe 2 is attached not to the outer peripheral surface but to the tip end, the fan-shaped flat plates 11 a to 11 constituting the steel pipe 2 and the blade 10 are formed.
The fan-shaped flat plates 11a to 11c can be easily and surely joined to the steel pipe 2 without being affected by the dimensional error in the production of c. 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 to 11c can be manufactured at low cost.
The manufacturing cost of the steel pipe pile 1 can be reduced as a whole.

By the way, in order to receive a large ground reaction force by the blade 10, the blade 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. 8, the wing 10 has bending moments M ₁ and M ₄ generated by the ground reaction force acting on the outer portions of the fan-shaped flat plates 11a and 11b.
The bending moments M ₂ and M ₃ generated in the inner part cancel each other out at the tip of the steel pipe 2, and as a result, the difference between the two in the steel pipe 2 near the mounting part 3 of the fan-shaped flat plates 11 a and 11 b. Small bending moments M ₁ -M ₂ and M ₄ -M ₃
Is transmitted, no excessive bending stress is generated in the steel pipe 2. Further, as shown in the second embodiment, when the rigid joining is performed by the closing members 13 of the adjacent fan-shaped flat plates 11a to 11c, 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 blade 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.
A simple weld 14 that does not melt into the entire cross-section, such as fillet welding or partial welding, or a full cross-sectional penetration using a welding material having a lower yield strength than the material of the steel pipe 2 into the tip portion (mounting portion 3) of the steel pipe 2 The fan-shaped flat plates 11a to 11c are attached by welding (hereinafter, referred to as a low-strength welding means), and the welded portion is intentionally yielded before the bending stress of the steel pipe 2 reaches an allowable value. May not be transmitted.

As shown in FIG. 10, 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.

As shown in FIG. 11, a plurality of block-shaped steel slabs 16 are welded to the lower end portion of the outer peripheral surface of the steel pipe 2 instead of the above-mentioned welding, and the fan-shaped flat plate 11 is attached.
A U-shaped steel plate 17 is welded and arranged on the upper surfaces of a to 11c so as to face each of the steel slabs 16 and surround the periphery thereof. The hinge means 15) and the fan-shaped flat plates 11a to 11c may be attached to the tip of the steel pipe 2.

Since the steel pipe pile 1 to which the wings 10 are attached in this manner has a structure capable of transmitting a vertical force and a shearing force, the steel pipe pile 1 can be screwed into the steel pipe pile 1 in terms of burying workability and supporting function after the completion of the building. There is no problem at all. On the other hand, wing 10
Is not transmitted to the steel pipe 2, so that no bending stress is generated in the steel pipe 2.

Embodiment 3 In each of the above embodiments, a circular steel plate or an elliptical steel plate is divided into two or three equal parts, and the sum of the internal angles is 360 °.
1a to 11c are formed, and the adjacent edges are abutted by the mounting portion 3 to form the wing 10. However, in the present embodiment, the sum of the inner angles of the fan-shaped flat plates 11a to 11c is calculated. It is formed smaller than 360 ° or larger than 360 °. 12 and 13 show respective fan-shaped flat plates 11a to 1a.
The sum of the inner angles of 1c is smaller than 360 °, and a gap 18 is formed between the fan-shaped flat plates 11a and 11c. 14 and 15 show the fan-shaped flat plates 11a to 11a.
The sum of the internal angles of c is greater than 360 °, and an overlap 19 occurs between the fan-shaped flat plates 11a and 11c.
In this case, for example, in mounting the fan-shaped flat plate 11c, a groove 3a continuous with the mounting portion 3 is provided above the step portion 4, and a part of the fan-shaped flat plate 11c is fitted into the groove 3a. I just need.

According to the results of field tests and numerical analysis performed by the inventors, the fan-shaped flat plates 11a to 11c
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 to 11c constituting the wing 10
Is preferably in the range of 320 ° to 400 °.

In this case, it is not necessary to make all the internal angles of the fan-shaped flat plates 11a to 11c constituting the wing 10 equal.
It may be slightly different. In addition, the gap 18 or the overlap 19
Does not need to be concentrated in one place;
It may be provided as appropriate between 1a to 11c.

FIG. 16 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. 17 shows, in order to improve the screwing efficiency of the steel pipe pile 1, at the ends of the fan-shaped flat plates 11 a and 11 b on the rotation direction side.
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. 18 shows an example of an execution test when the steel pipe pile 1 according to the present invention is buried in the ground. 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: 45.5 m, and the step h of the spiral attachment portion provided at the tip was h: 0.125D. The wing 10 has an outer diameter of 1000 mm and a thickness of 40 mm.
11a, 11 fan-shaped flat plates (sum of inner angles: 360 °)
b, and joined to the mounting portion 3 of the steel pipe 2 by low-strength welding means. For comparison, a spiral blade (outer diameter 1000 mm) manufactured by bending one donut-shaped steel plate
Was simultaneously tested on a steel pipe pile joined to the lower periphery of a steel pipe having an outer diameter of 500 mm to compare the workability and the bearing capacity.

The torque 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 was landfill sand from the ground surface to a depth of 8 m, soft clay soil from 8 m to 38 m, and fine sand from 38 m below. Both the steel pipe pile 1 according to the present invention and the steel pipe pile for comparison were screwed to a depth of 44 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, in the steel pipe pile according to the present invention, when the steel pipe pile 1 is buried in the ground by applying a rotational force to the steel pipe pile 1 by screwing, 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 or three fan-shaped flat plates 11a to 11a are attached to the spiral mounting portion 3 provided at the lower end of the steel pipe 2.
Although the case where the wing 10 made of 11c 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.

[0043]

【The invention's effect】

(1) The screwed steel pipe pile with wings according to the present invention is formed such that the sum of the inner diameter and the steel pipe whose radius is larger than the radius of the steel pipe is substantially 360 ° with the steel pipe in which the mounting portion is formed by notching the tip end substantially spirally. It has two or three fan-shaped flat plates formed, and these fan-shaped flat plates are attached to the mounting portion of the steel pipe such that adjacent edges thereof abut on the mounting portion to form a substantially spiral wing. (2) or two or three fan-shaped flat plates formed so that the radius is larger than the radius of the steel pipe and the sum of the internal angles is 320 ° to 400 °, and these fan-shaped flat plates are combined. Is connected to the mounting portion of the steel pipe so as to form a substantially spiral wing, the following effects can be obtained.

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 in a substantially spiral shape at the tip of the steel pipe can provide the same insertion workability as in the case where the spiral blade is provided.

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.

(3) Since the step caused by one rotation of the steel pipe of the mounting portion provided on the steel pipe of (1) or (2) is set to 0.1 to 0.4 times the outer diameter of the steel pipe, each fan shape is obtained. In combination with the sum of the inner angles of the flat plates being 320 ° to 400 °, good screwing workability and stable supporting force can be obtained.

(4) Since the fan-shaped flat plate constituting the blade 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 is kept within an allowable value. Can be suppressed.

[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 another example of the first embodiment.

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

FIG. 6 is a perspective view of Embodiment 2 of the present invention.

FIG. 7 is an explanatory bottom view of FIG. 6;

FIG. 8 is an explanatory diagram of a bending moment applied to a wing.

FIG. 9 is an explanatory diagram showing an example of joining a blade to a steel pipe.

FIG. 10 is a diagram showing properties of a steel material such as a welding material.

FIG. 11 is a diagram showing another example of joining a blade to a steel pipe.

FIG. 12 is a perspective view of a third embodiment of the present invention.

FIG. 13 is an explanatory bottom view of FIG. 12;

FIG. 14 is a perspective view of another example of the third embodiment.

FIG. 15 is an explanatory bottom view of FIG. 14;

FIG. 16 is a perspective view showing a state in which a reinforcing steel plate is attached to the wing.

FIG. 17 is a perspective view showing a state where a digging blade is attached to a wing.

FIG. 18 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 3 Attachment part 10 Blade 11a, 11b, 11c Fan-shaped flat plate 12, 18 Opening 13 Closure member 14 Low strength welding means (fillet welding) 15 Hinge means 19 Overlap

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masahiro Hayashi 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (4)

[Claims] 1. A steel pipe having a mounting portion formed by notching a tip portion in a substantially spiral shape, and a sum of inner angles of the steel pipe being larger than a radius of the steel pipe being substantially 36.
Two or three fan-shaped flat plates formed so as to be 0 °, and these fan-shaped flat plates are brought into contact with adjacent edges at the mounting portion to form a substantially spiral wing. Screwed steel pipe pile with wings, wherein the pile is connected to a mounting portion of the steel pipe as described above. 2. A steel pipe having a mounting portion formed by notching a tip portion in a substantially spiral shape, wherein a radius is larger than a radius of the steel pipe and a sum of internal angles is 320 °.
And two or three fan-shaped flat plates formed so as to form an angle of about 400 °, and these fan-shaped flat plates are connected to the mounting portion of the steel pipe so as to form a substantially spiral blade. Screwed steel pipe pile with wings. 3. The step formed by one rotation of the steel pipe of the spiral mounting portion provided on the steel pipe is reduced by 0.1% of the outer diameter of the steel pipe.
The screwed steel pipe pile with wings according to claim 1 or 2, wherein the pile is set to 0.4 times. 4. 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.