JP2847062B2 - Steel pipe pile - 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 in which, when a steel pipe pile is buried underground without vibration, a spiral blade cannot be rotated and propelled, and construction efficiency can be significantly improved.

[0002]

Conventionally, as a steel pipe pile for low-middle-rise structures buried in the ground with no earth removal, no noise, and no vibration, see, for example, Japanese Patent Publication No. 2-62848. As described above, there is known a structure in which a digging blade is provided at a lower end of a pile main body and a spiral wing is provided on an outer periphery of a lower part of the pile main body.
According to this steel pipe pile, the pile main body is erected substantially vertically on the ground where the pile is to be buried, and then the pile main body is rotated and propelled into the ground by an auger device. While excavating and softening the ground, the spiral blades penetrate into the unexcavated soil on the peripheral surface of the pile body, and the pile body is rotationally propelled and buried in the ground. In this embedding process, the strength of the soil acts as a reaction force on the upper portion of the spiral blade, so that the pile body is screwed into the ground without applying any particular pushing force only by applying a rotating force to the pile body. When the pile main body is screwed to a predetermined depth and buried, the pile main body is pushed away to the outer peripheral surface side of the pile main body, and the compressed earth and sand tightens the outer peripheral surface of the pile main body. A large supporting force is obtained by the reaction force of the lower soil.

However, in the process of screwing and embedding the pile body in the ground, as the ground becomes harder, the amount of rotation propulsion per rotation decreases and the rotation propulsion may become impossible. In some cases, even if a pushing load is applied together with the rotational force, the spiral blades do not cut into the ground, so that the rotation cannot be propelled, and it becomes difficult to fix the tip (lower end) of the pile body to a predetermined depth.

[0004] As a countermeasure in such a case, for example, when the ground becomes hard and the pile main body cannot be propelled into the ground, the pile main body is reversed and then forwardly rotated again to slightly advance, so that forward and reverse rotation is performed. There is a method of repeatedly pushing the pile body into the ground little by little, or increasing the rotational force applied to the pile body to push the pile body into the ground.

[0005] However, the means for propelling the pile body into the ground little by little by repeating normal rotation and reverse rotation has an extremely long construction time and has a serious problem in construction efficiency. Also, when increasing the rotational force, the rotational force cannot be increased until the maximum torsional stress of the pile body is exceeded, and the pile thickness is increased more than necessary to apply a large rotational force to the pile body. There is an uneconomical problem of increasing the size of the auger device.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steel pipe pile capable of improving construction efficiency without preventing a spiral blade from rotating and propelling.

[0007]

Means for Solving the Problems The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems, and has accomplished the present invention as follows.

When the pile body is rotated and driven underground, the excavated and softened earth and sand is extruded to the outer peripheral side of the pile body by the excavation blade at the lower end (tip) of the pile body, while the spiral blades are pushed. Penetrates into the earth and sand on the outer peripheral side of the pile body, and is propelled by one pitch during one rotation. At this time, in the first half rotation, the spiral wings penetrate into the ground on the outer peripheral side of the pile body to propel the pile body into the ground. The earth and sand on the lower end side of the pile body is pushed out to the outer peripheral side of the pile body and wraps around the bottom side of the spiral blade, is compressed by the spiral blade, and resists the propulsion of the spiral blade. On the ground, it is difficult to overcome this and propel the spiral wing, and it is considered that rotational propulsion becomes impossible. Also, even in the case of sandy ground with a large porosity, once the excavated and softened soil is compressed by the spiral blade, it is not as strong as the hard ground, but similarly resists the propulsion of the spiral blade, It is considered that the wing cannot be propelled for rotation.

[0009] Therefore, when a plate piece is provided on the bottom surface of the spiral blade so as to remove the earth and sand sneaking into the bottom surface side of the spiral blade,
Spiral blades can be rotated and propelled to bury the pile body in the ground without repeatedly propelling the pile body into the ground by repeating forward and reverse rotations or increasing the rotational force acting on the pile body. Was found.

[0010] The present invention has been made based on the above findings, and includes a pile body made of steel pipe, an excavation blade provided at a lower end of the pile body, and a pile diameter provided at a lower outer periphery of the pile body. A spiral wing having substantially twice the outer diameter, and a bottom of an intermediate portion between the start end and the end of the spiral wing, the radial direction of the pile body being
And a soil discharge plate, which is provided so as to extend in the direction, and is excavated and softened by the excavation blade, and discharges earth and sand which has wrapped around the bottom surface side of the spiral blade to the outside of the spiral blade. And

According to the steel pipe pile of the present invention, the pile main body is rotationally propelled so as to be screwed into the ground, so that the soil at the lower end side of the pile main body excavated and softened by the excavation blade is propelled by the pile main body. While extruding to the outer peripheral side of the pile, the spiral wing bites into the ground on the outer peripheral side of the pile main body and rotates, and the pile main body is buried in the ground, during this embedding process, the excavation blade softens the excavation, and the pile main body is propelled The earth and sand pushed out to the outer peripheral side of the main body and wrapping around the bottom side of the spiral blade is discharged to the outside of the spiral blade by the discharging plate.

[0012]

FIG. 1 is a front view showing an embodiment of a steel pipe pile according to the present invention, FIG. 2 is a bottom view thereof, and FIGS. 3 and 4 are partial front views showing another embodiment of a discharge plate. FIG. 5 is a graph of experimental data showing the relationship between the burial depth and the rotation torque when the steel pipe piles of FIGS. 1 and 2 are buried, and FIG. 6 is the same as FIG. 5 for the steel pipe piles without the earth removal plate. It is a graph of.

According to the steel pipe pile of the present embodiment, as shown in FIG. 1, a bottom plate 11 is provided at the lower end of a steel pipe pile body 10, and a pair of stepped excavating blades extending in the radial direction are provided on the bottom plate 11. 1
2, 12 are provided. On the outer periphery of the pile body 10, a substantially one-turn spiral blade 1 having an outer diameter of about twice the pile diameter is provided at a lower position thereof.
3, and a spiral wing 14 having a diameter substantially larger than that of the spiral wing 13 is provided at a predetermined position above the spiral wing 13 at an intermediate position. The spiral blade 1 is provided on the bottom surface of the spiral blade 13.
3 extends in the radial direction of the pile body 10 to the position of approximately one half of
From the inner edge to the outer edge of the spiral wing 13
An earth discharging plate 15 is provided so as to extend in the width direction of the spiral blade 13 (see FIG. 2) .

The bottom plate 11 is fixed to the lower end opening of the pile main body 10 by welding or the like, closes the lower end opening, and supports and fixes the excavating blades 12,12. This bottom plate 11
Acts to push out the soil at the lower end of the pile body 10 to the outer peripheral side of the pile body 10 when the pile body 10 is buried in the ground,
After the burial is completed, it will support the ground by receiving the reaction force from the ground. A hole may be provided in the center of the bottom plate 11, or the bottom plate 11 itself may be omitted. In this case, although the supporting force cannot be obtained by the bottom plate 11, when the pile body 10 is buried in the ground, the excavating blades 12, 1
The excavated and softened earth and sand due to 2 escapes into the pile body 10, so that the pile body 10 can be buried underground smoothly.

The excavating blades 12, 12 excavate and soften earth and sand on the lower end side of the pile body 10. In the embodiment shown in FIGS. 1 and 2, the excavating blades 12, 12 do not project perpendicularly to the bottom plate 11, but project in a state of being slightly inclined in directions opposite to each other. The excavating blades 12 and 12 are
Are formed stepwise so as to be higher on the center side and lower on the peripheral side of the bottom plate 11. Therefore, the pile body 1 is efficiently
The excavation and softening of the earth and sand on the lower end side of 0 can be performed. In addition,
As shown in FIGS. 1 and 2, instead of providing two excavating blades 12 and forming each of them in a stepped shape, a V-shaped excavating blade formed of one or a plurality of excavating blades may be provided.

The spiral blades 13, 14 bite into the unexcavated ground (soil and sand) on the outer peripheral side of the pile body 10 by rotating the pile body 10, and the strength of the soil is applied to the upper portions of the spiral blades 13, 14 as a reaction force. In order to work, there is a function of propelling the pile main body 10 into the ground at the time of burying in the ground (acts on the pile main body 10 without particularly applying a pressing force to the pile main body 10 so as to be pushed into the ground. It is buried underground by the rotational force.) After the burial is completed, it has the function of increasing the supporting capacity of the pile. In the present embodiment, two spiral blades 13 and 14 are provided, and the spiral blade 14 is formed to have a larger diameter than the spiral blade 13.
When buried, a large propulsive force is obtained, and after the burying is completed, a large supporting force is obtained. Further, since the upper spiral blade 14 is formed to have a larger diameter than the lower spiral blade 13, even if a pull-out force acts on the pile body 10, it can be resisted.
The pile main body 10 functions not only as a support pile but also as a reaction force pile by the spiral blades 13 and 14. The spiral blade may be only the spiral blade 13 provided on the outer periphery of the lower portion of the pile body 10, or a plurality of spiral blades may be arranged at a predetermined pitch from the lower portion to the upper portion of the pile body 10, Further, the pile wing may be formed so that the outer diameter of the spiral blade gradually increases from the lower part to the upper part.

The soil expulsion plate 15 is formed by excavating and softening the pile body 10 at the lower end side of the pile body 10 by the excavation blades 12, 12, and is pushed out to the outer peripheral side of the pile body 10 as the pile body 10 is propelled.
3 is prevented from getting round on the bottom side. In FIG. 1, the earth discharging plate 15 is extended in the radial direction of the pile main body 10, that is,
From the inner edge to the outer edge of the spiral blade 13, the entire width direction of the spiral blade 13 is
It shows a case where it is provided so as to extend over the body (see FIG. 2) . When the earth discharging plate 15 is provided at the start end of the spiral blade 13, it becomes a resistance when the spiral blade 13 bites into the ground, thereby preventing or difficulting the biting, and when it is provided at the end of the spiral blade 13. In this case, the earth and sand wrap around the bottom surface of the spiral blade 13 and the effect of providing the earth discharging plate 15 is lost. Therefore, it is necessary to provide the spiral blade 13 at an intermediate portion between the start end and the terminal end. However, as shown in FIG. It is not necessary to provide the spiral blade 13 at a position closer to the start end, or at a position closer to the end of the spiral blade 13 depending on the properties of the ground at the buried portion. FIG. 1 shows a case where the earth discharging plate 15 is provided so as to be inclined with respect to the bottom surface of the spiral blade 13 in the direction of rotation of the pile body 10 (the direction of rotation of the spiral blade 13). When the soil discharging plate 15 is tilted in the direction of the rotation propulsion of the spiral blade 13 in this way, the soil plate that acts on the bottom surface side of the spiral blade 13 with the rotation of the pile body 10 acts to cut the soil. Pile body 1
Since it is excluded on the outer peripheral side of 0, it is particularly suitable for highly viscous ground.

The earth discharging plate 15 may be provided on the bottom surface of the spiral blade 13 along the axis of the pile main body 10 as shown in FIG. Also, as shown in FIG.
May be inclined in the direction opposite to the rotational propulsion direction. In this case, since the earth and sand that is going to go to the bottom surface side of the spiral blade 13 is pushed out from the bottom surface of the spiral blade 13 by the earth discharging plate 15, it is suitable for sandy ground having a large porosity.

In FIG. 1 and FIG.
(To extend in the radial direction of the pile body 10)
From the inner edge to the outer edge of the spiral wing 13
It is installed to extend over the entire width of the spiral wing 13.
In addition, it is inclined in the direction of rotation of the pile body 10 (the direction of rotation of the spiral blade 13), and in a stepwise manner so as to be higher on the center side of the spiral blade 13 and lower on the peripheral edge side like the excavating blade 12. Although it is formed, it is not limited to this, and the size, shape, etc. of the earth discharging plate 15 are set according to the type, hardness, viscosity, porosity, etc. of the ground to be buried.

Next, a method for constructing the steel pipe pile will be described.

[0021] For example, after the steel pipe pile is set almost upright on the ground where the steel pipe pile is to be buried by the auger device, the pile body 1
When the pile main body 10 is rotated so as to be screwed into the ground by a rotary drive mechanism connected to the upper end of the lower excavator, the excavation blade 12 at the lower end,
The excavation and softening of the soil by 12 extrudes the soil on the lower end side of the pile body 10 toward the outer peripheral side of the pile body 10 as the pile body 10 is propelled, and the spiral wings 13 and 14 are placed on the ground on the outer peripheral side of the pile body 10. The pile body 10 is rotatably propelled into the ground using the strength of the earth and sand acting on the upper surfaces of the spiral blades 13 and 14 as a reaction force. In this embedding process, even if the earth and sand excavated and softened by the excavating blades 12 and 12 and pushed to the outer peripheral side of the pile body 10 by the propulsion of the pile body 10 wraps around the bottom side of the spiral blade 13, the earth discharging plate 15 This removes the sediment that has wrapped around.

More specifically, when the pile main body 10 is rotated once, the pile main body 10 is propelled into the ground by one pitch of the spiral blades 13 and 14, but at this time, the excavation blade is rotated by approximately half a rotation of the first half. The soil at the lower end side of the pile body 10 is excavated and softened by 12 and 12, and the soil is propelled by the pile body 10 so that the pile body 10
The spiral blades 13 and 14 are made to bite into the ground on the outer peripheral side of the pile body while being extruded and compressed to the outer peripheral side of the pile. The spiral wing 1 is pushed out to the outer peripheral side of the main body 10.
The earth and sand which has wrapped around the bottom surface side of 3 is removed by the earth discharging plate 15.

Therefore, there is no danger that the excavated and softened earth and sand will be compressed on the bottom surface of the spiral blade 13 and cannot be propelled in rotation. Even if the pile body 10 is buried and the ground becomes hard, there is no problem.

FIGS. 5 and 6 are graphs of experimental data obtained by measuring the relationship between the torque acting on the steel pipe pile and the burial depth of the steel pipe pile when the steel pipe pile is actually buried in the ground. FIG.
6 is a graph of experimental data using the steel pipe pile of the present embodiment shown in FIGS. 1 and 2, and FIG. 6 is a graph of experimental data using a steel pipe pile without a soil discharge plate.

In each case, the dimensions of the steel pipe pile used were a pile diameter of 190.7 mm, a wall thickness of 5.3 mm, and a blade diameter (diameter of a spiral blade).
Had a diameter of 400 to 500 mm and a length (total length) of 15 m. In each case, the maximum torsional torque was 3.5 ton · m. The rotation drive mechanism of the auger device rotates the steel pipe pile when the torsional torque acting on the steel pipe pile approaches the maximum torsional torque of 3.5 ton / m so that the torsional torque acting on the steel pipe pile does not exceed 3.5 ton ・ m. The steel pipe pile is configured to be rotated in a direction opposite to the propulsion direction (reversely) to prevent the steel pipe pile from being damaged.

As apparent from FIG. 5, in the steel pipe pile of this embodiment, even when the burial depth is deep, the torsional torque acting on the steel pipe pile exceeds the maximum torsional strength of the pile body, and the pile cannot be propelled. It was found that the steel pipe pile could be buried smoothly under the ground without alternately repeating normal rotation and reverse rotation of the steel pipe pile.

On the other hand, in the case where the earth discharging plate is not provided,
As is clear from FIG. 6, the torque acting on the steel pipe piles becomes larger than the maximum torsional strength of the pile body and the rotation cannot be propelled as the burial depth becomes deeper. It was found that they could not be buried underground unless they were repeated alternately.

In this embodiment, the maximum burial depth of the steel pipe pile is 1
The maximum burial depth of steel pipe piles was 15.28mm without the earth removal plate, compared to 5.31mm. Further, in this embodiment, the steel pipe pile is rotatably propelled in the ground without alternately repeating the forward rotation and the reverse rotation as in the case where the earth removal plate is not provided, and the burial time can be reduced by about 1 hour per 3 m. found.

[0029]

As described above, according to the present invention,
An earth discharging plate is provided on the bottom surface of the intermediate portion between the start end and the end of the spiral blade, and the earth and sand which has been excavated and softened by the cutting blade by the earth discharging plate and wrapped around the bottom surface side of the spiral blade is removed. Since the soil is discharged to the outside, the rotation of the spiral wing is smoothly propelled, and the construction efficiency can be greatly improved. Also,
Since the structure is provided with an earth removal plate, the existing steel pipe piles are hardly changed and cost is not increased.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of a steel pipe pile according to the present invention.

FIG. 2 is a bottom view of the same.

FIG. 3 is a partial front view showing another embodiment of a discharge plate.

FIG. 4 is a partial front view showing another embodiment of the earth discharging plate.

FIG. 5 is a graph of experimental data showing the relationship between the burial depth and the rotation torque when the steel pipe piles of FIGS. 1 and 2 are buried.

FIG. 6 is a graph of experimental data showing a relationship between a burial depth and a rotation torque when a steel pipe pile without a discharge plate is buried.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pile main body 11 Bottom plate 12 Drilling blade 13, 14 Spiral wing 15 Discharge plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) E02D 5/56

Claims (4)

(57) [Claims] 1. A pile body made of steel pipe, an excavation blade provided at a lower end of the pile body, and a substantially single turn provided on an outer periphery of a lower portion of the pile body and having an outer diameter approximately twice as large as a pile diameter. and the spiral wing, before the bottom surface of the intermediate portion between the start end and the terminal end of said spiral wrap
A soil discharge plate provided so as to extend in the radial direction of the pile main body, excavated and softened by the excavation blade, and discharges earth and sand that has wrapped around the bottom surface side of the spiral blade to the outside of the spiral blade. A steel pipe pile characterized by the following. 2. The steel pipe pile according to claim 1, wherein another spiral having a diameter larger than that of the spiral blade is provided at an upper position on the outer periphery of the pile body at a predetermined distance from the spiral blade. A steel pipe pile with wings. 3. The steel pipe pile according to claim 1, further comprising: a spiral wing having a diameter larger than that of the spiral wing, and having a diameter larger than that of the spiral wing, at an upper position of the outer periphery of the pile main body at a predetermined distance from the spiral wing. A steel pipe pile comprising a plurality of spiral wings, including spiral wings provided on a lower outer periphery of a pile main body, wherein the spiral wings are sequentially formed to have larger wing diameters toward an upper portion of the pile main body. 4. The steel pipe pile according to any one of claims 1 to 3, wherein the soil discharge plate is rotated with respect to a bottom surface of the spiral blade provided on a lower outer periphery of the pile body. A steel pipe pile characterized by being inclined in the direction of rotation, inclined in the direction opposite to the rotation direction, or hanging down along the axial direction of the pile body.