JPH11241337A - Screw-type steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of an excessive stress by providing a steel pipe and a fitting member which is larger in wall thickness or strength than the steel pipe, and equipped with a blade, and fitting a lower end part of the steel pipe or one of the fitting member into the other for joining. SOLUTION: A lower end part of a steel pipe 2 is fitted from an upper part into a fitting member 3 to a lower end of which steel blades 11a, 11b are fitted, and the fitting member 3 is welded to the steel pipe 2 to form a steel pipe pile 1. In embedding the steel pipe pile 1, the steel pipe pile 1 is turned by the drive of a turning apparatus to propel the steel pipe by the screwing action of blades 10, and embed the pipe in the ground. The steel blades 11a, 11b having the function of blocking the tip part of the steel pipe pile 1 and the propelling blades, function as a support body when the perpendicular force is applied by an overburden structure, etc. The fitting member is arranged on a part to which the bending moment generated in the blades 10 of the steel pipe pile 1 is transmitted. Thus, a large load bearing capacity of ground can be obtained by making use of the blades, and no excessive stress is transmitted to the steel pipe pile even when a large bending moment is transmitted from the blades.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw-in type steel pipe pile having wings, and more particularly, to a steel pipe pile using a thick-walled mounting member or a high-strength mounting member for a blade mounting portion. And a screw-in type steel pipe pile that can be buried underground with no earth removal.

[0002]

2. Description of the Related Art There have been many methods of embedding a steel pipe pile underground by applying a rotating force to a steel pipe pile having a wing plate attached to a tip portion or a side face of the steel pipe by a machine installed on the ground, and by a screw action. It has been proposed and some of them have been put to practical use, although they are intended for small diameter piles. Here, three inventions considered to be related to the present invention will be described below.

[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 the steel pipe pile body, an excavation blade is provided on the bottom plate, and the lower end of the pile body is provided on the outer peripheral surface. A steel pipe pile, which has a wing with a large wing width and almost twice the outer diameter of the pile body and is screwed into a pile, is screwed into soft ground. Pressing, excavating and softening the soil at the tip of the pile body with the excavating blade at the lower end, making the spiral wings bite into the unexcavated earth and sand on the side of the pile, and excavating while rotating and driving the pile as a reaction force against the strength of the soil The softened soil is extruded to the side of the pile and compressed, and the pile is screwed into the ground without discharging the soil (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 during construction but also as a support for obtaining a large ground reaction force.

[0006]

In the steel pipe piles of the prior arts 1 and 2, when the vertical force acts on the steel pipe pile due to the weight of the mounted structure or the seismic force after the completion of the construction, the spiral wing is strongly opposed to the ground on the lower surface of the wing. Receive strength. As a result, a large bending moment is generated at the root of the spiral blade, and this is transmitted to the steel pipe to generate a large bending stress. This bending stress is, as described in the specification of the prior art 2, when the outer diameter of the steel pipe is 100 mm.
A steel pipe pile having a small diameter of about 200 mm does not pose a serious problem in practical use. However, a steel pipe pile having an outer diameter of 500 to 600 mm, which is widely used, poses a serious design problem.

[0007] The outer diameter of the spiral blade is, as shown in the prior arts 1 and 2, 2 mm of the outer diameter of the steel pipe in terms of construction or supporting force.
It is said to be about twice as good. Here, the outer diameter of the steel pipe is 20
Compare 0mm steel pipe pile and 600mm steel pipe pile. Now, the outer diameter of each spiral wing is 40 times, which is twice the outer diameter of the steel pipe.
Assuming 0 mm and 1200 mm, the width of the spiral blade, that is, (wing outer diameter−steel pipe outer diameter) / 2, is 100 mm and 300 mm, respectively.
Becomes If the ground reaction force per unit area acting on the spiral blade is the same, the bending moment per unit circumference acting on the root of the spiral blade is proportional to the square of the width of the spiral blade.
The steel pipe having an outer diameter of 600 mm is about 9 times as large as the steel pipe having an outer diameter of 200 mm. For this reason, a very thick spiral blade is required.

On the other hand, a bending moment is transmitted from the spiral blade to the steel pipe near the root of the spiral blade, and a bending stress is generated. The magnitude of the bending moment transmitted to the steel pipe varies depending on the dimensions of the steel pipe, but is about 50 to 100% of the bending moment generated at the root of the spiral blade. For example, an outer diameter of 600
In the case of a steel pipe of mm, a bending moment of about 50 to 100% of the bending moment value of the spiral blade which requires a thickness of 40 mm or more by design acts on the steel pipe near the root of the spiral blade. Outer diameter 600
In the case of a steel pipe of mm, the wall thickness of the commonly used steel pipe is 5
It is about 12 mm, and the bending stress of the steel pipe caused by the ground reaction force greatly exceeds the design allowable bending stress of the steel pipe. To cope with this, the wall thickness is
Although it is conceivable to use steel pipes up to three times as large, the cost is remarkably increased, and it is unavoidable to design practically.

Further, the steel pipe pile of the prior art 3 has an important problem that a large ground supporting force cannot be obtained because the steel cylindrical body does not have a lid at the tip end thereof. Due to its narrow structure and a structure that slightly projects into and out of the tip of the steel cylinder, the inclined blade cannot be expected as a support having a large ground support force.

The present invention has been made to solve the above-mentioned problems, and has as its object to obtain the following screw-in type steel pipe pile. (1) A large ground support force can be obtained using the wings. (2) Do not generate excessive stress on the steel pipe pile due to the bending moment transmitted from the wing. (3) The steel pipe pile can be buried by screwing into the strong ground.

[0011]

SUMMARY OF THE INVENTION A threaded steel pipe pile according to the present invention has a steel pipe and a wall thickness greater than the wall thickness of the steel pipe or greater than the strength of the steel pipe. And a mounting member to which one of the lower end portion of the steel pipe and the mounting member is fitted into the other and integrally joined.

[0012] Further, a substantially R-shaped wing mounting portion is provided at the lower end of the mounting member. Further, the above-mentioned mounting member was formed by bending a substantially strip-shaped steel plate. Further, the above-mentioned wing was constituted by a flat steel wing.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in order to receive a large ground reaction force by the wings of a steel pipe pile, the wings are required to have high rigidity. For example, when the outer diameter of the steel pipe is 500 mm and the outer diameter of the wing is 1000 mm, a large bending moment is generated on the wing due to the ground reaction force, and therefore, it is required to use a steel plate having a thickness of about 40 mm in design. The bending moment is transmitted to the steel pipe to generate a large bending stress. Depending on the relationship between the outer diameter of the steel pipe and the outer diameter of the wing and the distribution of the ground reaction force, the magnitude of the above bending moment causes a large imbalance in the bending moment applied to the inner and outer wings of the steel pipe, It is conceivable that this is transmitted to the steel pipe, and a large bending moment is transmitted to the steel pipe as shown in FIG.

According to the present invention, by using a steel plate having a thickness greater than the wall thickness of a steel pipe or a steel plate having a strength greater than the strength of a steel pipe in a portion of a steel pipe pile affected by bending stress, The stress generated in the portion affected by the bending stress is set within the allowable stress.
Hereinafter, embodiments of the present invention will be described.

[Embodiment 1] FIG. 1 shows Embodiment 1 of the present invention.
It is a perspective view of the screw type steel pipe pile which concerns on. In the figure,
1 is a threaded steel pipe pile (hereinafter simply referred to as a steel pipe pile), 2
Is a steel pipe constituting the steel pipe pile 1, and a steel wing 11a, 11b constituting a wing 10 is attached to a lower end of the steel pipe pile 3, and a lower end of the steel pipe 2 is fitted and joined to form a steel pipe pile 1 together with the steel pipe 2. An attachment member.

The mounting member 3 is a steel plate having a thickness t ₂ larger than the thickness t ₁ of the steel pipe 2 and a width (or length) slightly longer than the outer peripheral length of the steel pipe 2, or a strength larger than the strength of the steel pipe 2. FIG. 2 shows a steel plate having a width (or length) slightly longer than the circumference of the steel plate 2.
As shown in the figure, a parallelogram-shaped steel plate 7a cut diagonally
To produce The steel plate 7a is bent as shown by the arrow to form a cylindrical shape, and both ends thereof are welded and joined, as shown in FIG. This allows
At the upper and lower ends of the mounting member 3, a stepped portion 5 corresponding to the pitch P of the imaginary spiral line forms a substantially L-shaped (spiral) blade 1.
A mounting portion 4 of zero is formed. In this case, the inner diameter D ₂ of the mounting member 3 is formed substantially equal to or slightly larger than the outer diameter D of the steel pipe 2.

FIG. 4 shows a steel plate 7b cut into a trapezoidal shape shown in FIG.
To form a cylindrical mounting member 3 by bending
A spiral mounting portion 4 having a pitch P is formed at the lower end, and the upper end is substantially horizontal. The steel plate constituting the mounting member 3 is not limited to a parallelogram or a trapezoid, but may be a rectangular or other substantially strip.

In this case, the pitch P formed by the steps 5 varies depending on the state of the ground in which the steel pipe pile 1 is buried, the outer diameter D of the steel pipe 2, and the like.
It is desirably about D (D is the outer diameter of the steel pipe 2) (the same applies to the following embodiments). This pitch P
Is less than 0.1, the penetration amount per rotation of the steel pipe pile 1 is reduced, and if it exceeds 0.6D, the penetration amount per rotation becomes too large. Since the torque becomes excessive and the excavation depth of the steel wings 11a and 11b increases, the supporting force may decrease.

The thickness t ₂ of the mounting member 3 and its length L are:
Considering the assumed ground reaction force, it will be determined by numerical analysis. First, regarding the thickness t ₂ , for example, the outer diameter D of the steel pipe 2 is 500 mm, and the diameter D _{4 of the} blade 10 is 1
When a vertical load of 500 t is applied at 000 mm, in a normal steel pipe, the portion where only the axial force is applied falls within the yield stress (2400 kgf / cm ² ) at a thickness of 14 mm. In order to keep the stress of the portion where the gas acts on within an allowable value, a steel pipe having a thickness of about 20 mm is required. For this reason, the method of attaching the blade 10 directly to the steel pipe by increasing the thickness of the steel pipe becomes uneconomical.

Therefore, as described above, if a mounting member 3 having a thickness t ₂ larger than the thickness t _{1 of the} steel pipe 2 or a mounting member having a strength greater than the strength of the steel pipe 2 is used in a portion where the bending moment acts, Since it is not necessary to increase the overall thickness of the steel pipe 2, it is economical and can sufficiently cope with a large bending moment. Further, since the mounting member 3 is simply formed by bending and welding a steel plate cut into a substantially rectangular shape as described above, various sizes can be used according to the applied load.

Next, according to the FEM analysis performed by the inventors, the length L of the mounting member 3 differs depending on the ground reaction force, but is generally 0.3 D or more (D is the outer diameter of the steel pipe 2). (The same applies to the following embodiments). In the above description, the case where the mounting member 3 is manufactured by bending a substantially strip-shaped steel plate is shown. However, the inner diameter is substantially equal to or slightly larger than the outer diameter of the steel pipe 2, and the thickness of the steel pipe 2 is increased. A steel pipe having a thickness greater than the wall thickness or a steel pipe having a strength greater than the strength of the steel pipe 2 is cut into a predetermined length L, and a lower end thereof is cut off in a spiral shape with a pitch P, so that an attachment member having a structure substantially as shown in FIG. May be configured.

The blade 10, as shown in FIG. 5, a circular steel plate 11 or an oval steel having an outer diameter D ₄ is divided into two from the center to form a flat steel blade 11a, 11b, the straight edge Is mounted on a line passing through the center from the step portion 5 of the mounting portion 4 of the mounting member 3 and joined to the mounting portion 4 by welding to form a substantially spiral shape as a whole. In this case, the space formed by the straight edges of the steel wings 11a and 11b at the tip of the mounting member 3 may be closed by the closing member. The outer diameter D ₄ of the blade 10 is generally (the same applies in the embodiments below) of about 1.5 to 3.0 times is desirable for the outer diameter D of the steel pipe 2.

Further, in the present embodiment, the case where the blade 10 is constituted by the two steel blades 11a and 11b whose sum of the internal angles is 360 ° is shown, but the circular steel plate 11 is divided into three equal parts and four equal parts. Then, a plurality of steel blades having a total inner angle of 360 ° may be attached to the tip of the attachment member 3 so as to form a substantially spiral shape as a whole, and the blade 10 may be configured. As the number of steel wings increases, the shape becomes closer to a spiral shape.
If the number of sheets is sufficient, if the number of sheets is too large, the function as a screw is reduced, and the blade mounting structure becomes unstable, and the time required for mounting is increased, which is uneconomical.

In this embodiment, a steel wing 1 is provided at the lower end.
The lower end of the steel pipe 2 is fitted into the mounting member 3 to which 1a and 11b are mounted from the upper portion to a predetermined position, and the upper edge of the mounting member 3 and the outer peripheral surface of the steel pipe 2 are welded and joined together, The steel pipe pile 1 is configured. In this case, when joining the mounting member 3 and the steel pipe 2, the steel pipe 2 is fitted in the mounting member 3, so that it is stable, and the upper edge of the mounting member 3 and the steel pipe 2 can be welded. It can be easily and reliably joined. If a stopper for positioning when the steel pipe 2 is fitted into the mounting member 3 is provided on the outer peripheral surface of the steel pipe 2 or the inner peripheral surface of the mounting member 3, the vertical load is more reliably transmitted to the distal end portion. be able to. Further, the steel wing 11 is attached to the mounting member 3.
If the attachment member 3 and the steel pipe 2 are joined before the attachment of a and 11b, the upper edge of the attachment member 3 and the outer peripheral surface of the steel pipe 2, and the inner peripheral surface or lower edge of the attachment member 3 and the lower end of the steel pipe 2 The parts can be reliably integrated by welding.

When the steel pipe pile 1 is buried, as shown in FIG. 6, the pile head is connected to a rotary drive device 31 mounted on the construction machine 30, and the rotary drive device 31 is driven to rotate the steel pipe pile 1. Then, it is propelled and buried in the ground by the screw action of the wing 10. At this time, most of the tip opening of the steel pipe pile 1 (therefore, the tip opening of the mounting member 3) is mostly made of the steel wing 1
Since it is closed by 1a and 11b, the earth and sand hardly enters the steel pipe pile 1.

According to the present embodiment configured as described above, the steel wings 11a and 11b having both functions of closing the opening at the tip end of the steel pipe pile 1 and propulsion wings are provided by the vertical force generated by the overlying structure or the like. Functions as a support during the action of the slab, and a large ground support force can be obtained. Further, since the mounting member 3 is provided at a portion of the steel pipe pile 1 where the bending moment generated in the wing 10 is transmitted, the bending stress generated in the mounting member 3 can be kept within an allowable value. It does not transmit the bending moment caused by 10. Further, the provision of the mounting member 3 allows the use of a steel pipe 2 having a normal thickness, and the mounting member 3 can be manufactured without wasting a small number of processing portions, thereby reducing costs.

[Embodiment 2] FIG. 8 shows Embodiment 2 of the present invention.
It is a perspective view of. In the first embodiment, using about equal to or mounting member 3 is slightly larger inner diameter D ₂ and the outer diameter D of the steel pipe 2, there is shown the case where welded by fitting the steel pipe 2 to the mounting member 3, this embodiment form, using the mounting member 3 of the inside diameter D ₁ substantially equal to or more outer diameter slightly smaller D ₃ of the steel pipe 2, the steel pipe 2 is fitted to the outer periphery of the mounting member 3, the lower edge portion of the steel pipe 2 and the mounting The outer peripheral surface of the member 3 is welded to form the steel pipe pile 1. The operation and effect of the present embodiment are the same as those of the first embodiment, and a description thereof will be omitted.

Third Embodiment Next, various modifications of the first and second embodiments will be described. FIG. 9 is a perspective view showing a first modification, in which steel wings 11 a and 11
b. The attachment member 3 is shown in FIGS.
As shown in FIG. 1 (FIG. 10 is upside down for ease of explanation), one of rectangular steel plates 8 slightly longer than the outer peripheral length of the steel pipe 2 (or slightly shorter than the inner peripheral length of the steel pipe 2). The central portion of the long side of the steel plate 8 is formed as a stepped portion 5b having a height of one half of the pitch P of the imaginary spiral line described above.
Is bent to form a cylindrical shape as shown in FIG. 10, and two L-shaped mounting portions 4a and 4b are formed at the lower end thereof. Alternatively, two rectangular steel plates may be shifted from each other and joined to each other, and then bent into a cylindrical shape to form two rectangular-shaped mounting portions 4a and 4b. Further, the steel plate 8 may have a parallelogram shape or a trapezoidal shape, and further, the end of the steel pipe may be cut in a sawtooth shape to form the mounting member 3.

The mounting portions 4a, 4b of the mounting member 3 as described above
When steel wings 11a and 11b as shown in FIG. 5 are attached by welding and a steel pipe 2 is fitted to the mounting member 3, the steel pipe pile 1 is formed. The operation and effect of this modification are almost the same as those of the first and second embodiments.

FIG. 12 is a perspective view of a second modified example, in which a blade 10 made of square steel blades 21a and 21b is provided at the lower end of the mounting member 3. As shown in FIG. Note that an example is shown in which the mounting member 3 is the same as the mounting member 3 of the first and second embodiments.

The wing 10 is, for example, a square steel wing 2 obtained by dividing a square steel plate 21 shown in FIG.
Since it is composed of 1a and 21b, it has a very simple structure. The combined size of the steel wings 21a and 21b varies depending on the state of the ground in which the steel pipe pile 1 is buried, the outer diameter of the steel pipe 2, and the like. In general, the outer diameter D of the steel pipe 2 is 1.5 to 3 times. It is desirably about 0.0 times. Here, the steel wing 21
The sizes of a and 21b refer to the length L of the diagonal line of the steel plate 21 shown in FIG. The steel wings 21a and 21b may be configured by dividing a triangular steel plate into two.

The operation and effect of the steel pipe pile 1 with wings according to this modification are almost the same as those of the above-described embodiments, but in this modification, when the steel pipe pile 1 penetrates into the ground, Since the side surface of the excavation in the rotation direction is formed by the corners (maximum size portions) of the steel wings 21a and 21b, the rear side surface of the tip surface portion tends to separate from the excavated ground.
That is, the steel wings 21a and 21b have a flank behind the excavated portion. For this reason, the friction resistance at the time of penetration can be reduced as compared with a steel pipe pile having an outer circumferential arc-shaped wing in which the side surface at the rear of the excavated portion constantly contacts the excavated ground wall surface.

FIG. 14 shows another example of this modification.
In this example, instead of the square steel wings 21a and 21b, triangular steel wings 21c and 21d obtained by cutting a square steel plate at diagonal lines and dividing the steel plate into two parts are attached to the distal end portion of the mounting member 3. is there. The function of this example is almost the same as that of the example of FIG.

FIG. 15 shows still another example of this modification, in which steel wings 21e and 21f are formed by dividing a hexagonal steel plate into two parts. The function of this example is almost the same as that of the example of FIG. 12, but by making the blade 10 closer to a circle, the supporting force characteristics are improved as compared with the square steel blade.

In the above description, the case where the steel wings 21a to 21f are formed by dividing a triangular, quadrangular or hexagonal steel plate into two parts is shown. For example, an eight-sided or more polygonal steel plate is divided into two parts. To form a steel wing. Further, in the above description, the case where the steel wing is formed by dividing the polygonal steel plate into two parts is shown. May be sequentially attached to three or more attachment portions provided in the above.

FIG. 16 is a perspective view of a third modification. In this example, a square steel pipe 2a is used for the steel pipe, and the mounting member 3 is used.
Is a square. In manufacturing the mounting member 3, for example, four rectangular steel plates or L-shaped steel plates having inclined lower ends are welded in a square shape to form a substantially spiral mounting portion 4a at the lower end. . The size D (corresponding to the outer diameter of the steel pipe 2 in the first embodiment) of the square steel pipe 2a in the present modification refers to the length of a diagonal line of the square steel pipe.

The operation and effect of the steel pipe pile 1 according to the present modification are almost the same as those of the above embodiments, but when the steel pipe 2 is a steel pipe pile 1 made of a normal steel pipe (round shape), Since the entire peripheral surface of the steel pipe 2 is in sliding contact with the ground, the peripheral surface friction is large and a large torque is required. On the other hand, in the case of the square steel pipe 2a, when the screw is screwed, the corner of the square steel pipe 2a mainly comes into contact with the surrounding ground, so that the peripheral friction is small, so that the screwing torque can be reduced.

FIG. 17 is a perspective view of a fourth modification, in which the steel pipe pile 1 is constituted by a ribbed steel pipe 2b. That is, a steel plate having a plurality of ribs 2c provided on the surface is bent by rolling, for example, to form spiral ribs 2c on the outer peripheral surface. The pitch P of the rib 2c is substantially the same as the pitch P of the spiral virtual line of the first embodiment. In this case, the mounting member 3 includes the first or second embodiment.
The mounting member 3 described in the above is used.

The operation and effects of this modification are almost the same as those of the above embodiments, but when screwed into the ground, the helical rib 2c also contributes to propulsion. it can.

In the first and second embodiments, the circular steel plate or the elliptical steel plate is divided into a plurality of equal parts to form steel wings 11 a to 11 b having a total inner angle of 360 °. Although the case where the blade 10 is configured by being attached is shown, in this modification, the sum of the internal angles of the steel blades 11a and 11b is formed smaller than 360 ° or larger than 360 °.
18 and 19 show a fifth modification, in which the steel wing 1
The sum of the inner angles of 1a and 11b is smaller than 360 °, and a gap 13 is formed between the steel blades 11a and 11b. 20 and 21 show the case where the sum of the inner angles of the steel blades 11a and 11b is larger than 360 °.
An overlap 14 occurs between a and 11b. In this case, for example, in mounting the steel wing 11b, a groove 4c continuous with the mounting portion 4 is provided above the step portion 5, and a part of the steel plate 11b is fitted into the groove 4c. Good.

According to the results of field tests and numerical analysis conducted by the inventors, the steel wing 11
If the sum of the inner angles of a and 11b is smaller than 320 °, the penetration speed at the time of screwing in the steel pipe pile 1 will decrease, and the tip supporting force after embedding will decrease. In addition, when it exceeds 400 °, it has been found that in the gravel ground having a large particle size, the gravel is clogged between the blades 10 and the workability is deteriorated. For this reason, it is desirable that the sum of the internal angles of the steel blades 11a and 11b constituting the blade 10 be in the range of 320 ° to 400 °.

In this case, each steel wing 11 constituting the wing 10
It is not necessary to make all the inner angles of a and 11b equal, and they may be slightly different. Also, the gap 13 or the overlap 14 is set to 1
It is not necessary to concentrate on the place, the adjacent steel wings 11a, 1
1b may be provided as appropriate. Furthermore, steel wings 11a,
The number of 11b is not limited to two, but may be three or more (this embodiment can be implemented in other embodiments).

[Fourth Embodiment] FIG. 22 is a perspective view of a fourth embodiment of the present invention. In the present embodiment, a closing member 15 is attached to a distal end of a cylindrical mounting member 3a whose upper and lower ends are substantially parallel, and a blade 10 made of steel blades 12a and 12b is provided on the outer periphery. The mounting member 3a has an inner diameter substantially equal to or slightly larger than the outer diameter of the steel pipe 2, or an outer diameter substantially equal to or slightly smaller than the inner diameter of the steel pipe 2, and a thicker steel pipe than the thickness of the steel pipe 2, or A steel pipe having a strength greater than the strength of the steel pipe 2 is cut into a predetermined length, and a closing member 15 is attached to the tip of the steel pipe 2 by welding to close the opening at the tip. The mounting member 3a may be manufactured by bending a steel plate.

As shown in FIG. 23, the wing 10 has an outer diameter D ₆ larger than the outer diameter of the steel pipe 2 (for example, D ₆ = 2D) and an inner diameter D _6.
5 is a donut-shaped flat steel plate 12 approximately equal to the outer diameter of the steel pipe 2
Is divided into two from the center to form flat steel wings 12a and 12b. The steel wings 12a and 12b follow a spiral virtual line having a pitch P assumed on the outer peripheral surface of the mounting member 3a. To form a substantially spiral wing 10 as a whole. Then, the steel pipe 2 is inserted or fitted into the attachment member 3a having the wings 10 on the outer periphery, and the steel pipe 2 is joined by welding, whereby the steel pipe pile 1 is formed.

In this embodiment, the sum of the internal angles is 360
The case where the wing 10 is constituted by two steel wings 11a and 11b of the same angle is shown, but the donut-shaped flat steel plate 11 is divided into three equal parts.
The blade 10 may be configured by dividing into four equal parts and attaching a plurality of steel blades having a total inner angle of 320 ° to 400 ° to the outer periphery of the mounting member 3a so as to form a substantially spiral shape as a whole. .
As the number of steel blades increases, the shape becomes closer to a spiral shape. However, in actual construction, four blades are sufficient. If the number is too large, the function as a screw decreases and the blade mounting structure becomes unstable. However, it is uneconomical only because the installation time is increased.

FIG. 24 shows another example of the present embodiment. The flat steel blades 12a and 12b shown in FIG. 23 are arranged on the outer peripheral surface of the mounting member 3a along the imaginary spiral line. They are mounted at different angles and in different directions. The length L ₁ of the mounting member 3a in this embodiment, according to the inventors of the embodiment the FEM analysis, varies depending subgrade reaction generally 0.7D (D is the outer diameter of the steel pipe 2) to above It is desirable that the mounting position of the wing 10 is within 1D from the tip of the mounting member 3a in terms of the screwing work of the steel pipe pile 1 and the supporting force performance. FIG. 22,
FIG. 24 shows a case where one stage of wings 10 is provided on the mounting member 3a. However, two or more stages of wings 10 may be provided.

[Fifth Embodiment] FIG. 25 is a perspective view of a fifth embodiment of the present invention.
This is the same as in the first embodiment. In the present embodiment, the wing 10
Above, flat steel wings 12a and 12b as shown in FIG. 23 are formed on the outer peripheral surface of the steel pipe 2 at substantially the same angle as the wing 10 along the spiral imaginary line of the pitch P in directions different from each other. The wing 20 (upper wing) is provided by being attached. Note that, as in the case of FIG. 22 of the fourth embodiment, the upper blade 20 may be attached so that the steel blades 12a and 12b form a spiral continuously along the spiral virtual line.

According to the present embodiment, when the steel pipe pile 1 is screwed into the ground, the upper wing 20 greatly contributes to propulsion and improves the propulsion force, so that the screwing torque can be reduced. The upper wing 20 may be provided in a plurality of stages on the steel pipe pile 1, and may be applied to other embodiments. Since the upper wing 20 is provided above the steel pipe pile 1 and the ground reaction force applied thereto is relatively small, the upper wing 20 can be directly attached to the steel pipe 2. In some cases, a mounting member may be provided on the mounting portion of the upper wing 20 as well.

[Embodiment 6] As the outer diameter of the steel pipe 2 increases, the outer diameter of the blade 10 also increases as described above, and accordingly, the thickness of the blade 10 also increases. As a result, for example, FIG.
When the steel pipe pile 1 is screwed into the ground by the construction machine 30 as shown in FIG. 1, a large resistance due to the ground is applied to the ends in the rotation direction of the steel wings 11a, 11b and the like. You may not be able to penetrate the ground. For this reason, there is a problem that the construction machine 30 must be enlarged. In the present embodiment, in order to solve such a problem, the cut-in portions (ends on the rotation direction side) of the steel wings 11a and 11b and the like are cut off at an acute angle to provide an inclined surface, thereby adding to the end portions. It reduces the resistance of the ground, makes it easier to penetrate into the ground, and reduces the torque. Note that, instead of the inclined surface, a digging blade for assisting digging may be attached to a biting portion such as the steel wings 11a and 11b. When screwing the steel pipe pile 1 into the ground and embedding it, the steel wings 11a, 11b are prevented from being deformed at their ends.
A reinforcing member may be attached to the bite portion such as b. This embodiment can be implemented in other embodiments.

In the above description, the case where the wing attached to the attachment member or the steel pipe is constituted by a plurality of flat steel wings has been described, but one or a plurality of wings bent along the spiral virtual line are shown. Spiral wings.

[0051]

The screw-in type steel pipe pile according to the present invention has a steel pipe and a thickness greater than the thickness of the steel pipe or greater than the strength of the steel pipe, and the wing is attached to the tip or the outer peripheral surface. With a mounting member, either the lower end of the steel pipe or the mounting member is fitted into the other and joined together, so a large ground support force is obtained using the wing, and a large bending moment is transmitted from the wing. Even so, excessive stress is not transmitted to the steel pipe pile. In addition, since either the steel pipe or the mounting member is fitted into and joined to the other, the joining operation is easy. Further, it is economical because it is not necessary to increase the thickness of the entire steel pipe.

Further, since a substantially wing-shaped wing mounting portion is provided at the lower end of the mounting member, the wing can be securely mounted at a predetermined position, and the number of working steps can be reduced.

Further, since the mounting member is formed by bending a substantially strip-shaped steel plate, the material can be used without waste, and the structure is simple and there is little processing.
Cost can be reduced.

Further, since the blades are formed of flat plate-like steel blades, manufacture and attachment to the mounting member are extremely easy, and the number of manufacturing and mounting steps can be greatly reduced.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram for explaining the production of the mounting member of FIG. 1;

FIG. 3 is a perspective view of the mounting member of FIG. 1;

FIG. 4 is a perspective view of another example of a mounting member.

FIG. 5 is an explanatory diagram of the wing of FIG. 1;

FIG. 6 is an explanatory view of a construction example of a screw-in type steel pipe pile according to the present invention.

FIG. 7 is an explanatory diagram of a stress distribution of a steel pipe due to a ground reaction force applied to a steel wing.

FIG. 8 is a perspective view of Embodiment 2 of the present invention.

FIG. 9 is an explanatory diagram of a first modification of the first and second embodiments according to the third embodiment of the present invention.

FIG. 10 is a perspective view of the mounting member of FIG. 9;

FIG. 11 is an explanatory diagram for explaining the production of the mounting member of FIG. 9;

FIG. 12 is a perspective view of a second modified example.

FIG. 13 is an explanatory view of the steel wing of FIG.

FIG. 14 is a perspective view of another example of the second modified example.

FIG. 15 is a perspective view of another example of the second modified example.

FIG. 16 is a perspective view of a third modified example.

FIG. 17 is a perspective view of a fourth modified example.

FIG. 18 is a perspective view of a fifth modified example.

FIG. 19 is a bottom view of FIG. 18;

FIG. 20 is a perspective view of another example of the fifth modified example.

FIG. 21 is a bottom view of FIG. 20;

FIG. 22 is a perspective view of a fourth embodiment of the present invention.

FIG. 23 is an explanatory view of the steel wing of FIG. 22.

FIG. 24 is a perspective view of another example of the fourth embodiment.

FIG. 25 is a perspective view of Embodiment 5 of the present invention.

[Explanation of symbols]

Reference Signs List 1 steel pipe pile 2 steel pipe 3, 3a mounting member 4, 4a, 4b blade mounting portion 10 blade 11a, 11b, 12a, 12b, 21a to 21f steel blade

Claims (4)

[Claims] 1. A steel pipe, comprising: a steel pipe; and a mounting member having a thickness greater than the thickness of the steel pipe or a strength greater than the strength of the steel pipe, and a wing attached to a tip end or an outer peripheral surface thereof. A screw-in type steel pipe pile, wherein one of the part and the mounting member is fitted into the other and integrally joined. 2. The screw-in type steel pipe pile according to claim 1, wherein a substantially wing-shaped wing mounting portion is provided at a lower end portion of the mounting member. 3. The screw-in type steel pipe pile according to claim 1, wherein the mounting member is formed by bending a substantially strip-shaped steel plate. 4. The screw-in type steel pipe pile according to claim 1, wherein the blade is formed of a flat steel blade.