JP2004218341A - Steel pipe pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe pile reducible in initial settlement. <P>SOLUTION: An annular collar part 3 for receiving support pressure is provided at the outer periphery near the tip of a steel pipe 2, and at least a lower face 3a of the collar part 3 is provided with a plurality of cutting edges 4 of a plate shape at suitable spaces in a circumferential direction, with one end of each abutting on the outer peripheral surface of the steel pipe 2 and with the other end extending to the peripheral edge part of the collar part 3. The support pressure can thereby be received in plane by the whole lower face of the collar part to reduce the initial settlement. It is preferable that the other end 4a of the cutting edge 4 is projected slightly outward from the peripheral edge part of the collar part 3. The upper face of the collar part 3 is also provided with a plurality of cutting edges 5 of a plate shape at suitable spaces in the circumferential direction, with one end of each abutting on the outer peripheral surface of the steel pipe 2 and with the other end extending to the peripheral edge part of the collar part 3. It is preferable that the direction of the cutting edges 5 of the upper face is opposite to that of the cutting edges of the lower face. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steel pipe pile, and more particularly to a steel pipe pile in which an initial settlement amount is suppressed.
[0002]
[Prior art]
The most basic construction method of pile foundation work is to directly hit and drive a pile using a drop hammer.However, since this hammering method is a major social problem as noise pollution, A pile method is being developed. As a typical example, a twisted steel pipe pile method of screwing a steel pipe pile into the ground and burying it has been proposed.
[0003]
This construction method includes, for example, a relatively light-weight (required ground strength of 5 tf / m ² or less) building such as a wooden two-story or three-story house, and a soft ground that may cause land subsidence in the future. It is adopted as a ground reinforcement method when building on such residential ground. In particular, when there is a strong ground (support layer) relatively shallower than the ground surface (around -5.0 m to 15 m), and the entire upper part contains soft ground or corroded soil, the above-described method is used. Often adopted.
[0004]
Generally, a steel pipe pile used in this method is provided with a spiral excavating blade (also referred to as a spiral blade) on the outer periphery of a tip portion of a commercially available steel pipe (see, for example, JP-A-7-292666). ). The steel pipe pile is rotated and driven by an auger motor while applying a predetermined load, so that the steel pipe pile is screwed into the ground until it reaches the support layer and is buried (placed). In this steel pipe pile, the load of the building is supported by mainly receiving the supporting pressure (reaction force) from the supporting layer on the lower surface of the excavating blade, and the sinking of the building is prevented.
[0005]
[Patent Document 1]
JP-A-7-292666 [0006]
[Problems to be solved by the invention]
However, in the steel pipe pile, the support layer is roughened by the excavation by the excavation blade, and the excavation blade is spirally inclined. There was a problem that the initial settlement amount was large.
[0007]
The present invention has been made in consideration of the above circumstances, and has as its object to provide a steel pipe pile capable of reducing the initial settlement amount.
[0008]
[Means for Solving the Problems]
Among the present invention, the invention of claim 1 is provided with an annular flange portion for receiving a supporting pressure on an outer periphery near a tip of the steel pipe, and at least a lower surface of the flange portion has one end in contact with the outer peripheral surface of the steel pipe and the other end. A plurality of plate-shaped cutting blades extending to the peripheral edge of the flange are provided at appropriate intervals in the circumferential direction.
[0009]
The invention according to claim 2 is characterized in that the other end of the cutting blade slightly protrudes outside the peripheral edge of the flange.
[0010]
In the invention of claim 3, a plurality of plate-shaped cutting blades having one end in contact with the outer peripheral surface of the steel pipe and the other end extending to the peripheral edge of the flange are also provided on the upper surface of the flange at appropriate intervals in the circumferential direction. The direction of the cutting blade on the upper surface is opposite to the direction of the cutting blade on the lower surface.
[0011]
The invention according to claim 4 is characterized in that a tip portion of the steel pipe is closed by an end plate, and a triangular blade is protruded from a lower surface of the end plate.
[0012]
According to a fifth aspect of the present invention, the tip end of the steel pipe is provided with a tip end having a thickness greater than that of the steel pipe, and sediment is introduced into the end end of the tip end to consolidate the pipe. And a taper portion is provided.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Drawing 1 is a figure showing the steel pipe pile concerning an embodiment of the invention, (a) is a side view, (b) is a side view seen from the right side of (a), (c) is from below (a). FIG. 2 is a view showing the tip of the steel pipe pile, (a) is a sectional view, (b) is a view seen from below (a), and FIG. 3 is (a) a support layer reaching portion. It is the figure seen from the upper part which shows the effect | action of the lower cutting blade when the steel pipe pile is reversely rotated, and FIG.
[0014]
In FIG. 1, 1 is a steel pipe pile, and 2 is a steel pipe constituting the steel pipe pile 1. An annular, preferably annular annular flange 3 for receiving a supporting pressure is provided on the outer periphery near the distal end of the steel pipe 2. In the illustrated example, the outer diameter of the flange 3 is, for example, about twice the outer diameter of the steel pipe 2. At least on the lower surface 3 a of the flange 3, a plurality of plate-like cutting blades 4 having one end in contact with the outer peripheral surface of the steel pipe 2 and the other end extending to the peripheral edge of the flange 3 are arranged at appropriate intervals in the circumferential direction. Approximately four, two in the illustrated example. More specifically, one side surface (left side when viewed from the tip) of one end (base end) of the cutting blade 4 is in contact with the outer peripheral surface of the steel pipe 2, and the other end (tip) 4 a of the cutting blade 4 is It extends tangentially.
[0015]
In the case of the embodiment, a plurality of plate-like cutting blades 5 having one end in contact with the outer peripheral surface of the steel pipe 2 and the other end extending to the peripheral edge of the flange 3 are also provided on the upper surface 3b of the flange 3 at appropriate intervals in the circumferential direction. About two to four sheets are provided, and two sheets are provided in the illustrated example. The cutting blades 4, 5 are formed of the same material as the steel pipe 2, for example, a steel plate. The cutting blades 4, 5 are formed in a substantially right-angled triangle, that is, tapered 6 so that the height gradually decreases from one end on the side in contact with the steel pipe 2 to the other end on the peripheral edge side of the flange 3. Thereby, the penetration resistance or torque at the time of rotary excavation is reduced.
[0016]
The cutting blades 4, 5 are symmetrically arranged with the steel pipe 2 interposed therebetween in a state of standing upright on the lower surface 3 a or the upper surface 3 b of the flange 3. The other end of the cutting blade 4 on the lower surface 3a of the flange 3 in order to excavate the ground with a diameter slightly larger than the flange 3 in order to suppress the flange 3 from becoming a resistance to the excavation of the steel pipe pile 1. 4 a slightly protrudes outside the peripheral edge of the flange 3. The flange 3 is attached to the steel pipe 2 by welding, and the cutting blades 4 and 5 are fixed to the flange 3 and the steel pipe 2 by welding.
[0017]
Further, the direction of the cutting blade 5 on the upper surface 3b of the flange portion 3 is opposite to the direction of the cutting blade 4 on the lower surface 3a. That is, one side (left side as viewed from the tip) of one end (base end) of the lower cutting blade 4 is in contact with the outer peripheral surface of the steel pipe 2, whereas the upper cutting blade 5 is at one end ( The other side surface (the right side when viewed from the distal end) of the base end is in contact with the outer peripheral surface of the steel pipe 2, and the directions of the upper and lower cutting blades 4, 5 are reversed. When the steel pipe pile 1 is screwed into the ground and driven, the steel pipe pile 1 is placed in the direction of the arrow (clockwise) in FIG. 1, and in the case of FIG. 3A, in the direction opposite to the arrow (counterclockwise). Rotate (forward rotation). As a result, the earth and sand excavated by the cutting blade 4 on the lower surface 3a is pushed radially outward. When the steel pipe pile 1 reaches the support layer, the steel pipe pile 1 is reversely rotated in the direction of the arrow as shown in FIGS. While being compacted, the excavated earth and sand is pressed against the hole wall of the excavation hole by the cutting blade 5 on the upper surface and is compacted so as not to collapse. When the steel pipe pile 1 is pulled out, as shown in FIG. 3B, the steel pipe pile 1 is pulled up while rotating in the reverse direction in the direction of the arrow, so that the cutting blade 5 on the upper surface 3b pushes the soil outward in the radial direction. It is possible to easily pull out the steel pipe pile 1 while doing so.
[0018]
The distal end of the steel pipe 2 is closed by a circular end plate 7 as shown in FIG. 2 to receive a supporting pressure. Further, in order to prevent the steel pipe pile 1 from being misaligned at the time of rotating excavation, a triangular blade 8 having an isosceles triangular shape whose vertex coincides with the axis of the steel pipe 2 is protruded from the lower surface of the end plate 7. I have. The end plate 7 is formed in a disk shape having the same diameter as the inner diameter or the outer diameter of the steel pipe 2, and is attached to the lower end of the steel pipe 2 by welding. The triangular blade 8 is welded and fixed to the lower surface of the end plate 7 in a vertically upright state. In addition, as the steel pipe pile 1, a discharge hole 9 for discharging a solidifying agent, for example, cement milk, which is pumped through the steel pipe 2 into the end plate 7, is provided on the end plate 7, and the discharge hole 9 is opened and closed from the outside. The check valve 10 may be provided so that the soil quality of the soft ground can be improved and strengthened.
[0019]
Next, the operation of the steel pipe pile having the above configuration will be described. The steel pipe pile 1 is held at its upper end by a rotary driving device (auger motor) mounted on a working machine (not shown) so as to be able to move up and down, and is set upright toward the ground. 1 (c) is rotationally driven by the rotary driving device while applying the load. The ground is cut or excavated by the rotation of the triangular blade 8 and the cutting blade 4 on the lower surface 3a of the flange 3 due to the rotation of the steel pipe pile 1, and the excavated earth and sand is compacted while being pushed radially outward by the cutting blade 4. And pressed against the hole wall.
[0020]
The steel pipe pile 1 is screwed into the ground in this way, and excavation work is continued while the steel pipe 2 is sequentially added to the upper end of the steel pipe pile 1 by welding until the tip of the steel pipe pile 1 reaches the support layer. When the tip of the steel pipe pile 1 reaches the support layer, the steel pipe pile 1 is appropriately rotated in the reverse direction, and the cutting blade 4 on the lower surface 3a of the flange 3 as shown in FIG. The lower soil may be gathered inward to consolidate the soil, and the cutting blade 5 on the upper surface 3b of the flange 3 may push the soil above the flange 3 outward to consolidate, as shown in FIG. . In this way, the casting (burial) of the steel pipe pile 1 is completed.
[0021]
According to the steel pipe pile 1, an annular flange 3 for receiving a supporting pressure is provided on the outer circumference near the tip of the steel pipe 2, and at least a lower surface 3 a of the flange 3 has one end in contact with the outer peripheral surface of the steel pipe 2 and the other end. Is provided with a plurality of plate-shaped cutting blades 4 extending to the peripheral edge of the flange portion 3 at appropriate intervals in the circumferential direction, so that the entire lower surface of the flange portion 3 can receive the support pressure from the support layer in a planar manner. In addition, the initial settlement amount can be reduced as compared with a conventional steel pipe pile which receives a supporting pressure with a helically arranged excavating blade. In this case, since the other end 4a of the cutting blade 4 slightly protrudes outside the peripheral edge of the flange 3, the ground can be dug smoothly without the flange 3 being caught.
[0022]
A plurality of plate-like cutting blades 5 having one end in contact with the outer peripheral surface of the steel pipe 2 and the other end extending to the peripheral edge of the flange 3 are also provided on the upper surface 3b of the flange 3 at appropriate intervals in the circumferential direction. Since the direction of the cutting blades 5 on the upper surface 3b is opposite to the direction of the cutting blades 4 on the lower surface 3a, the steel pipe pile 1 is excavated by rotating forward and the steel pipe pile 1 is inverted when reaching the support layer. By rotating the soil, the cutting blades 4 on the lower surface 3a can compact the soil into the inside of the flange portion 3, and the cutting blades 5 on the upper surface 3b press the excavated soil against the hole wall of the drilling hole to consolidate so as not to collapse. When the steel pipe pile 1 is to be pulled out, the steel pipe pile 1 is easily pulled out by pushing up the steel pipe pile 1 while rotating it in the reverse direction, while pushing the soil and sand toward the hole wall side by the cutting blade 5 on the upper surface 3b. Can be. Further, since the distal end of the steel pipe 2 is closed by the end plate 7 and the triangular blade 8 protrudes from the lower surface of the end plate 7, the lower surface of the end plate 7 receives the supporting pressure from the support layer. In addition, the triangular blade 8 eliminates misalignment and makes it possible to dig straight underground.
[0023]
FIG. 4 is a cross-sectional view showing another example of the tip of the steel pipe pile. In this embodiment, the same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted. The steel pipe pile 1 is provided with a tip pipe part 11 having a greater thickness than the steel pipe 2 at the tip of the steel pipe 2. A tapered portion 12 for introducing earth and sand into the inside of the distal end pipe 11 and closing it tightly is provided at the distal end of the distal end pipe 11. The outer diameter of the tip tube 11 is substantially the same as the outer diameter of the steel pipe 2.
[0024]
An annular flange 3 for receiving a supporting pressure is provided on the outer periphery near the distal end of the distal end pipe portion 11, and at least a lower surface 3 a of the flange 3, in the illustrated example, upper and lower surfaces 3 a, 3 b have one end formed of a steel pipe. A plurality of plate-shaped cutting blades 4, 5 which are in contact with the outer peripheral surface of the flange 3 and whose other end extends to the peripheral edge of the flange 3 are provided at appropriate intervals in the circumferential direction. Further, a half-angle blade is attached to the distal end portion of the distal end pipe portion 11 by welding. With the steel pipe pile configured as described above, the same effect as in the above embodiment can be obtained. Further, in particular, according to the steel pipe pile 1, a distal pipe 11 having a greater thickness than the steel pipe is provided at the distal end of the steel pipe 2, and earth and sand is applied to the distal end of the distal pipe 11. Since the tapered portion is provided for introducing and closing the inside of the steel pipe, the tip of the steel pipe can be easily closed with the earth and sand.
[0025]
As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to the above embodiments, and various design changes and the like can be made without departing from the gist of the present invention. is there.
[0026]
【The invention's effect】
In short, according to the present invention, the following effects can be obtained.
[0027]
(1) According to the first aspect of the present invention, an annular flange for receiving a supporting pressure is provided on the outer periphery near the distal end of the steel pipe, and at least the lower surface of the flange has one end in contact with the outer peripheral surface of the steel pipe and the other end. Since a plurality of plate-shaped cutting blades extending to the peripheral edge of the flange portion are provided at appropriate intervals in the circumferential direction, supporting pressure can be received on the entire lower surface of the flange portion in a planar manner, and the initial settlement amount can be reduced. Can be.
[0028]
(2) According to the second aspect of the invention, since the other end of the cutting blade slightly protrudes outside the peripheral edge of the flange, the ground can be dug smoothly without the flange being caught. it can.
[0029]
(3) According to the third aspect of the present invention, a plate-like cutting blade having one end also in contact with the outer peripheral surface of the steel pipe and the other end extending to the peripheral edge of the flange is provided at an appropriate interval in the circumferential direction. A plurality is provided, and since the direction of the cutting blade on the upper surface is opposite to the direction of the cutting blade on the lower surface, the steel pipe pile is excavated by rotating forward and the steel pipe pile is reversely rotated when reaching the support layer. By doing so, it is possible to compact the earth and sand inward of the flange by the cutting blade on the lower surface and to press the excavated earth and sand against the hole wall of the drill hole by the cutting blade on the upper surface and to consolidate so as not to collapse, When pulling out the steel pipe pile, the steel pipe pile can be easily pulled out by pulling up the steel pipe pile while rotating it in the reverse direction.
[0030]
(4) According to the invention of claim 4, since the tip of the steel pipe is closed by the end plate and the triangular blade is protruded from the lower surface of the end plate, the lower surface of the end plate receives the supporting pressure. It is possible to excavate straight underground without misalignment by the triangular blade.
[0031]
(5) According to the fifth aspect of the present invention, the tip of the steel pipe is provided with a tip pipe thicker than the steel pipe, and the tip of the tip pipe is filled with earth and sand inside the tip pipe. Since the tapered portion for introducing and closing tightly is provided, the front end of the steel pipe can be easily closed tightly with earth and sand.
[Brief description of the drawings]
FIG. 1 is a view showing a steel pipe pile according to an embodiment of the present invention, wherein (a) is a side view, (b) is a side view as viewed from the right side of (a), and (c) is a lower side of (a). FIG.
FIGS. 2A and 2B are views showing a tip portion of a steel pipe pile, where FIG. 2A is a cross-sectional view and FIG.
FIG. 3 (a) is a top view showing the operation of the lower cutting blade when the steel pipe pile is reversely rotated at the support layer reaching portion, and FIG. 3 (b) is a top view showing the operation of the upper cutting blade. FIG.
FIG. 4 is a cross-sectional view showing another example of the tip portion of the steel pipe pile.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Steel pipe 3 Flange part 4 Cutting blade 5 Cutting blade 7 End plate 8 Triangular blade 11 Tip tube part 12 Taper part

Claims (5)

An annular flange for receiving a supporting pressure is provided on the outer periphery near the tip of the steel pipe, and a plate-shaped cutting in which one end is in contact with the outer peripheral surface of the steel pipe and the other end is extended to the peripheral edge of the flange at least on the lower surface of the flange. A steel pipe pile comprising a plurality of blades provided at appropriate intervals in a circumferential direction. 2. The steel pipe pile according to claim 1, wherein the other end of the cutting blade slightly protrudes outside a peripheral edge of the flange. 3. A plurality of plate-shaped cutting blades, one end of which is in contact with the outer peripheral surface of the steel pipe and the other end of which is extended to the peripheral edge of the flange, are also provided at appropriate intervals in the circumferential direction on the upper surface of the flange. The steel pipe pile according to claim 1, wherein a direction is opposite to a direction of the cutting blade on the lower surface. The steel pipe pile according to any one of claims 1 to 3, wherein a tip portion of the steel pipe is closed by an end plate, and a triangular blade is protruded from a lower surface of the end plate. At the tip of the steel pipe, a tip pipe having a thickness greater than that of the steel pipe is provided, and at the tip of the tip pipe, a taper section is provided for introducing earth and sand into the inside of the tip pipe to close it tightly. The steel pipe pile according to any one of claims 1 to 3, wherein the steel pipe pile is provided.

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