JP3168500B2 - Steel pipe pile and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe pile with a spiral bottom plate, which is used as a foundation pile for a structure constructed in an urban area and which is propelled and rotated without vibration and without vibration.

[0002]

2. Description of the Related Art In recent years, a construction method has been adopted in which a pile is buried in the ground with no earth removal, no noise, and no vibration using a steel pipe pile provided with a spiral blade on the outer peripheral surface of the tip. In this steel pipe pile, a drilling blade is protruded from the bottom plate at the tip of the pile body, and a spiral wing having a radius more than twice the radius of the pile body is protruded from the outer peripheral surface near the tip over substantially one turn. The foundation pile,
By rotating as if screwing into the soft ground, excavating and softening the soil at the tip of the pile body by the excavation blade, while making the spiral wings bite into the undigged soil on the side of the pile body,
It is rotated and propelled underground using the strength of the soil as a reaction force.

[0003]

However, according to the conventional steel pipe pile, when the pile main body has a large diameter, the amount of sediment softened by the excavation blade and extruded to the side surface of the pile main body increases. As the diameter of the pile body increases, the thickness of the spiral wing also increases, making it difficult for the side of the pile body to dig into the undigged earth and sand, resulting in compression of the earth and sand at the tip of the pile body. In some cases, it became difficult to rotate the pile body.

[0004] After the steel pipe pile is buried, while the load supporting the building acts on the pile main body, the load also acts on the spiral wing equally with the pile main body. Has a bending moment. However, since the spiral wing is joined to the outer peripheral surface near the tip of the pile main body, this bending moment also acts near the weld, which is the joint between the spiral wing and the pile main body, and becomes the maximum at this part Therefore, the thickness of the pile body must be set thick to withstand this. This thickness is nearly twice as large as the thickness that can withstand the vertical load (compression load) acting on the pile body, and there is a problem that the material cost increases in the case of a long steel pipe pile.

Therefore, according to the present invention, even if the pile body has a large diameter, the pile body can be easily propelled into the ground, and the wall thickness of the pile body can be made as small as possible to reduce the material cost. An object of the present invention is to provide a steel pipe pile with a spiral bottom plate that can be achieved and a method for manufacturing the same.

[0006]

The steel pipe pile according to the present invention comprises:
Spiral the tip of the tubular pile body along the outer periphery of the tip
Notch in the shape of the tip of the spirally cut pile body
It has a diameter about twice as large as the pile body along the
And a spiral bottom plate serving as an excavating blade is fixed.

[0007] In addition, the earth and sand flow into the pile body on the spiral bottom plate.
It is provided with a sediment entrance that allows entry.

In addition, the tip of the tubular pile body is
Spiral cuts along the outer circumference for almost one round,
Radial direction on an annular disk with a diameter of about twice the pile body
Into the spiral disk of the pile body
Dig formed by bending along the notched tip surface
A spiral bottom plate also serving as a cutting blade is welded to the tip end surface of the pile body.
It is formed by

Further , the method for manufacturing a steel pipe pile according to the present invention comprises:
Extend the tip of the tubular pile body along the outer circumference of the tip.
A process of spirally notching over one round and a radius
Cut in the direction, and the annular disc is spirally wound on the pile body.
Drilling blade by bending along the tip surface
Forming a dual-purpose spiral bottom plate;
Welding the spiral bottom plate to the surface.
is there.

[0010]

According to the steel pipe pile of the present invention, a rotary push-in drive device is attached to the upper end of the pile main body, and when the pile main body is rotated while pressing the pile main body to the underground side by the drive, the spiral bottom plate at the tip of the pile main body is formed. The excavation blade softens earth and sand, and the steel pipe pile is rotationally propelled and embedded in the ground. After the steel pipe pile is buried, the supporting load of the building acts on the pile body and the spiral bottom plate, respectively, and the ground reaction force (vertical reaction force) against this load acts on the spiral bottom plate and the pile body, respectively. I do. A bending moment also acts on the spiral bottom plate by this reaction force. However, since the spiral bottom plate is fixed to the tip of the pile main body, the bending moment of the spiral bottom plate does not act on the pile main body.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 and FIG. 2 show an embodiment of the present invention. FIG. 1 is a perspective view of the steel pipe pile of the present invention with a part omitted, and FIG. 2 is a perspective view of a spiral bottom plate of the steel pipe pile shown in FIG.

As shown in FIGS. 1 and 2, the steel pipe pile of this embodiment is provided with a spiral bottom plate 11 having a diameter about twice the diameter of the pile body 10 at the tip of the tubular pile body 10 and also serving as an excavating blade. It is configured to be fixed over almost one turn.

That is, the tip portion of the tubular pile body 10 is spirally cut along the outer periphery of the tip over substantially one round. On the other hand, the spiral bottom plate 11 also serving as a digging blade is shown in FIG.
As shown in FIG. 2, a circular disk having a diameter about twice as large as the pile main body 10 is cut in a radial direction reaching the center of the circular disk, and the circular disk is cut into a spirally cut end surface of the pile main body 10. It is formed by bending along the line. Then, a steel pipe pile shown in FIG. 1 is formed by welding a spiral bottom plate 11 also serving as an excavating blade to the tip end surface of the spirally cut pile main body 10.

The thickness of the spiral bottom plate 11 is determined by the diameter of the pile body 10 and the hardness of the ground in which the steel pipe pile is embedded. The spiral bottom plate 11 is provided with a closing plate 12 which closes a gap between the start end and the end, and a pile body 10 is provided at the center thereof.
An earth and sand entry hole 13 is provided to allow earth and sand to enter the inside.

According to the steel pipe pile of the above embodiment, the pile body 10
Is erected on the ground to be buried, and a rotating push-in drive device (not shown) is attached to the upper end thereof, and the pile body 10 is rotated while pressing the pile body 10 into the ground by the drive. 11 is a pile body 1 as an excavation blade
The excavation and softening of the soil at the tip of 0 extrudes to the side of the pile body 10, and the steel pipe pile is rotationally propelled and embedded in the ground.

In this embedding operation, the spiral bottom plate 11 functions as a spiral blade and an excavating blade, so that the bite into the ground is good, and even if the diameter of the pile body 10 is increased as in the related art, the lower end side of the pile body 10 There is no risk of compressing the earth and sand, and the rotation of the steel pipe pile is smoothly promoted. Therefore, construction can be performed even on hard ground, which has been difficult in the past, and a large supporting force can be obtained.

After the steel pipe pile is buried, the load supported by the building acts on the pile body 10 and the spiral bottom plate 11, while the vertical reaction force of the ground against this load causes the pile body 10 and the spiral bottom plate to react. 11 respectively. A compressive force acts on the pile body 10 due to the supporting load and the vertical reaction force in the opposite direction. A bending moment acts on the spiral bottom plate 11 by a vertical reaction force. However, unlike the conventional spiral blade, the bending moment of the spiral bottom plate 11 does not act on the pile main body 10 because the spiral bottom plate 11 is fixed to the tip end surface of the pile main body 10.
In other words, although a bending moment acts on the spiral bottom plate 11 by a vertical reaction force, only a compressive force acts on the pile body 10. For this reason, the pile main body 10 only needs to have a wall thickness that can withstand the compressive force, and it is not necessary to set the wall thickness of the pile main body 10 nearly twice as thick as in the related art in order to withstand the bending moment. Therefore, the wall thickness can be reduced by approximately 50% as compared with the conventional steel pipe pile.

FIGS. 3 and 4 show another embodiment of the steel pipe pile according to the present invention. FIG. 3 is a front view of another steel pipe pile according to the present invention with a part thereof omitted, and FIG. 2 is a side view of the steel pipe pile. In the drawings, the same portions as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

In another embodiment, the spiral bottom plate 11 has
The drilling blades 14, 14 having stepped blades are connected to the spiral bottom plate 1
1 is fixed so as to extend diametrically from the center and to be inclined at an angle of 40 ° to 45 ° with respect to the bottom surface of the spiral bottom plate 11. Here, the inclination angle with respect to the bottom surface of the spiral bottom plate 11 is set in this manner for the following reason. That is, the inclination angle of the excavating blade 14 with respect to the bottom surface of the spiral bottom plate 11 is 4
If the angle is smaller than 0 °, sufficient excavation capacity cannot be obtained, and if the angle is larger than 45 °, the excavation ability increases, but the resistance to excavation becomes too large, which is not preferable.
This is because in the range of 40 ° to 45 °, the resistance to excavation does not increase, and a desired excavation ability can be obtained.

According to this other embodiment, the spiral bottom plate 11 and the excavating blades 14 and 14 excavate and soften the earth and sand at the tip of the pile body 10 during the embedding work of the steel pipe pile. It can be performed in a short time, and the construction time can be reduced. Further, the excavating blades 14 and 14 function as ribs for reinforcing the spiral bottom plate 11, and the thickness of the spiral bottom plate 11 can be set to be thin.

In each of the above embodiments, the pile body 10
A grout ejection hole may be provided at the tip of the grout so that cement milk is ejected from the grout ejection hole during excavation. Further, an air ejection hole may be provided.

[0023]

According to the steel pipe pile of the present invention as described in the foregoing, the distal end surface of the cut out pile body helically, so as to along which have a diameter of about twice the pile body, Spiral wings
Since the spiral bottom plate acting as a drilling blade is fixed, the excavation softening of the soil at the tip of the pile body can be promoted, and even if the pile body has a large diameter, it can be easily propelled into the ground and the pile body can be easily propelled. Since the bending moment does not act on the joint portion between the pile body and the spiral bottom plate, it is possible to reduce the material cost by reducing the thickness of the pile body as much as possible.

[Brief description of the drawings]

FIG. 1 is a partially omitted perspective view of a steel pipe pile according to the present invention.

FIG. 2 is a perspective view of a spiral bottom plate of the steel pipe pile shown in FIG.

FIG. 3 is a front view showing another steel pipe pile of the present invention with a part thereof omitted.

FIG. 4 is a side view of the steel pipe pile of FIG. 3;

[Explanation of symbols]

 10 Pile body 11 Spiral bottom plate 14 Drilling blade

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-98818 (JP, A) JP-A-5-287740 (JP, A) Jpn. Field (Int.Cl. ⁷ , DB name) E02D 5/54 E02D 5/56 E02D 5/72

Claims (4)

(57) [Claims] 1. A tip portion of a tubular pile body is spirally notched along the outer periphery of the tip, and is approximately twice as large as the pile body along the tip surface of the spirally cut pile body. steel pipe piles have a diameter, and wherein the formed of a fixed spiral bottom plate serving as a helical blade and digging edge. 2. The penetration of earth and sand into the pile body on the spiral bottom plate.
2. An allowable sediment entrance is provided.
Steel pipe pile as described. 3. The method according to claim 3, wherein the tip portion of the tubular pile body is placed outside the tip portion.
It is cut out spirally over almost one round along the circumference, and a circular plate having a diameter of about twice the diameter of the pile body is formed radially.
Direction, and insert the circular disk into the spiral shape of the pile body.
Formed by bending along the notched tip surface
A spiral bottom plate also serving as an excavating blade is formed by welding to a tip end surface of the pile main body.
Steel pipe pile. 4. The method according to claim 4, wherein the tip portion of the tubular pile body is placed outside the tip portion.
A step of spirally notching over substantially one circumference along the circumference, and making a radial cut in the annular disk, and
Bending along the spirally cut end of the pile body
Forming a spiral bottom plate also serving as a drilling blade , and welding the spiral bottom plate to a tip end surface of the pile main body.
And a method for manufacturing a steel pipe pile.