JP2001003357A - Steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the infiltration of soil and sand and water without increasing penetration resistance when a rotary penetration type steel pipe pile is penetrated. SOLUTION: This steel pipe pile is penetrated into a ground by obtaining driving force in the penetration direction by a blade 2 by rotating a steel pipe 1 in which the blade 2 is installed at a front end section. The front end of the steel pipe is closed by a cap 3 while cutting blades 4 excavating the ground and pushing out excavated materials to the outside in the radial direction are mounted to the base of the cap 3 at that time. The cap 3 is formed in a conical shape in a form that the cap is bulged to the front end side of the steel pipe 3. The front end section of the steel pipe 1 is filled with concrete 5 supporting the cap 3 from the inside.

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 used as a support pile for a structure.

[0002]

2. Description of the Related Art In recent years, a rotary penetration type steel pipe pile as shown in FIG. 3 has been developed and put into practical use. In this method, two wing-like blades 2 are provided at the tip end of a steel pipe 1 in a spiral shape as shown in (a) or inclined in the opposite direction as shown in (b), and the steel pipe 1 is rotated to ground. Penetrating feather 2
The driving force in the penetration direction can be obtained. According to such a rotary penetration type steel pipe pile, not only is it possible to perform construction with low noise and low vibration, but also it is possible to obtain an effect of compacting the ground due to no earth removal, and to increase the supporting force by the blades 2.
It can be easily pulled out by rotating it in the reverse direction, so it is in widespread use.

[0003] Further, if the above-mentioned steel pipe pile is extended upward as it is, the pillar of the building can be provided as a steel pipe pillar integral with the steel pipe pile, so that the construction of piles, foundations, and underground skeletons can be rationalized. It is possible, and if the entire inside of the steel pipe piles and steel pipe columns is filled with concrete, the concrete structure becomes the same as the filled steel pipe concrete structure. Construction is possible, and this is also effective.

[0004]

In the meantime, the conventional rotary penetrating type steel pipe pile is usually penetrated with its tip open, so that at least the tip of the steel pipe 1 is filled with soil due to the penetration. And the underground water comes in. Therefore, when concrete is filled into the inside of the steel pipe 1 in order to form a filled steel pipe concrete structure as described above, it is necessary to extract earth and sand prior to that, but the work of extracting the earth and sand that has entered the steel pipe 1 is easy. Not something that can be done.

[0005] Incidentally, in order to prevent earth and sand from entering, it is sufficient to close the tip of the steel pipe 1. In some cases, this is done, but if the tip of the steel pipe 1 is simply closed, the penetration resistance is reduced. It is not possible to efficiently penetrate due to the increase, and it is not applicable especially when constructing a large-diameter steel pipe pile.

In view of the above circumstances, an object of the present invention is to provide an effective steel pipe pile capable of preventing earth and sand and water from entering without increasing penetration resistance.

[0007]

According to the present invention, there is provided a steel pipe pile having a structure in which a steel pipe provided with a blade at a tip portion is rotated to obtain a propulsive force in a penetration direction by the blade to penetrate the ground. The tip of the steel pipe is closed by a cap, and a cutting blade is provided on the bottom surface of the cap to excavate the ground and push excavated soil radially outward.

According to a second aspect of the present invention, in the first aspect of the present invention, the cap has a conical shape that bulges toward the distal end of the steel pipe.

According to a third aspect of the present invention, the tip of the steel pipe is filled with concrete for supporting the cap from inside.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the following embodiments are merely examples, and are not intended to limit the present invention.

FIGS. 1A and 1B show a steel pipe pile according to an embodiment of the present invention. FIG. 1A is a side view (partially sectional view) of a tip portion, and FIG. 1B is a bottom view. The steel pipe pile of the present embodiment has a spiral blade 2 at the tip of a steel pipe 1 like the conventional steel pipe pile shown in FIG. 3A, but a cap 3 is attached to the tip of the steel pipe 1. As a result, the tip of the steel pipe 1 is closed, and the cap 3 reliably prevents earth and sand and water from entering the steel pipe 1.

The cap 3 is formed, for example, by pressing a thin steel plate into a conical shape in which the central portion bulges downward, and is attached to the tip of the steel pipe 1 by welding or the like. Has a plurality of (four in the illustrated example) cutting blades 4 attached thereto, and these cutting blades 4 are rotated by rotation during penetration.
The ground is excavated, and the excavated soil is guided radially outward by the cutting blade 4 as shown by the arrow in the figure and is forcibly pushed out to the side of the steel pipe 1, thereby reducing the excavation resistance and the penetration resistance. It is capable of efficient penetration. In the illustrated example, four cutting blades 4 are attached to the cap 3.
By being slightly inclined with respect to the radius of the excavated soil, it is possible to reliably and efficiently extrude the excavated soil to the outside.

Further, concrete 5 is provided at the tip of the steel pipe 1.
The cap 5 is supported from the inside by the concrete 5 so that the cap 3 can sufficiently withstand digging resistance and penetration resistance. Reference numeral 6 denotes a steel plate that partitions the inside of the steel pipe 1, which may be welded into the steel pipe 1 to partition the tip of the steel pipe 1 and then fill the inside with concrete 5.

According to the above-mentioned steel pipe pile, since the tip of the steel pipe 1 is closed by the cap 3, soil and water do not enter the steel pipe 1 at the time of penetration. Therefore, when the entire inside of the steel pipe 1 is filled with concrete after the penetration to form a filled steel pipe concrete structure, it is not necessary to perform an operation of extracting soil and sand that has entered the steel pipe 1 as in the related art. It is particularly suitable for use in such cases.

If the tip of the steel pipe 1 is simply closed as described above, the penetration resistance may increase and it may not be possible to carry out the penetration efficiently. By providing the blades 4 and excavating the ground with the cutting blades 4 and extruding the excavated soil outward with the cutting blades 4, the penetration of the steel pipe 1 can be efficiently performed without any trouble despite the end of the steel pipe 1 being closed. And can be applied to large diameter piles.

Further, since the cap 3 is formed in a conical shape, the cutting edge 4 is formed in comparison with a case where the cap 3 is formed in a simple flat shape.
Excavation and excavation of excavated soil can be performed more reliably and efficiently, and an effect of preventing misalignment can be obtained since the penetration direction is naturally guided by the top of the cap 3.

Further, since the steel pipe 1 is filled with the concrete 5 to support the cap 3 from the inside, the cap 3 itself may be simple, and it is sufficient to press a thin steel plate as described above, for example. It can be manufactured at low cost. In addition, the concrete 5 reinforces the tip of the steel pipe 1 from the inside, thereby obtaining a local buckling prevention effect at the time of intrusion. In addition, since the tip load increases, the buoyancy can be reduced even in the case of receiving groundwater pressure, There is also an advantage that the posture stability at the time of penetration is improved.

Incidentally, when a conventional general steel pipe pile is penetrated by a normal auger machine or the like, the positioning accuracy in the horizontal direction (allowable range of misalignment) is generally about 30 to 50 mm. In the case of a mere steel pipe pile, such accuracy does not cause any particular problem.However, in the case where the steel pipe pile is extended upward and the steel pipe pillar is integrally provided on the upper part as described above, the positioning accuracy of the steel pipe pile remains unchanged. This will affect the accuracy of the steel tube column installation. In addition, since the embedding accuracy generally required for a pillar is stricter than that of a pile of about 5 to 10 mm, similar accuracy is required for a steel pipe pile.

In the steel pipe pile of the present embodiment, since the misalignment is prevented by the top of the cap 3, the positioning accuracy can be expected to be improved as compared with the conventional general steel pipe pile, but in order to perform the positioning with higher precision. It is conceivable to use a guide pipe 10 as shown in FIG. That is, a short pipe-shaped steel pipe having an inner diameter substantially equal to the outer diameter of the blade 2 of the steel pipe pile is used as the guide pipe 10, which is strictly positioned at the penetration position of the steel pipe pile, and the steel pipe pile is placed inside the pipe. If the tip of the steel pipe is inserted to start the penetration, the positioning of the steel pipe pile can be performed with high precision required for the pillar.

The steel pipe pile of the above embodiment is shown in FIG.
However, it is of course possible to provide two wing-like blades 2 shown in FIG. 3B or other types of blades instead of the spiral blades 2 shown in FIG. The number and the mounting position of are also arbitrary. Further, the shape of the cap 3, the number and shape of the cutting blades 4 attached to the cap 3, the mounting position, and the like are arbitrary, and may be set optimally in consideration of the condition of the ground. Further, it is preferable to fill the tip of the steel pipe 1 with the concrete 5 as in the above embodiment, but this is not a limitation. Of course, the steel pipe pile of the present invention is not only applied to the case where the entire interior is filled with concrete to form a filled steel pipe concrete structure,
It goes without saying that the hollow steel pipe pile may be used as it is.

[0021]

According to the first aspect of the present invention, since the tip of the steel pipe is closed by a cap and a cutting blade is provided on the bottom surface of the cap to excavate the ground and extrude the excavated soil radially outward, so that when the steel pipe is penetrated, In addition to being able to prevent soil and water from entering the inside, it can be applied to large-diameter piles without lowering the penetration efficiency, and it is applicable when the entire inside of a steel pipe pile is filled with concrete after penetrating. Best.

According to the second aspect of the present invention, since the cap is formed in a conical shape, the excavation by the cutting blade and the pushing of the excavated soil to the side can be performed reliably and efficiently, and the penetrating direction is automatically guided by the top of the cap. Therefore, the effect of preventing misalignment can be obtained.

According to the third aspect of the present invention, since the concrete supporting the cap from the inside is filled in the tip of the steel pipe, the cap itself can be simple and inexpensive, and the concrete has an effect of preventing local buckling of the tip of the steel pipe. There is also an advantage that the buoyancy reduction effect due to an increase in the tip load and the posture stability at the time of penetration are improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a distal end portion of a steel pipe pile according to an embodiment of the present invention.

FIG. 2 is a view showing a construction example of the steel pipe pile.

FIG. 3 is a view showing a distal end portion of a conventional general rotary penetration type steel pipe pile.

[Explanation of symbols]

 Reference Signs List 1 steel pipe 2 blade 3 cap 4 cutting blade 5 concrete

Claims (3)

[Claims] 1. A steel pipe pile having a structure in which a steel pipe provided with a blade at a tip portion is rotated to obtain a propulsive force in a penetration direction by the blade to penetrate a ground, and a tip of the steel pipe is closed by a cap. A steel pipe pile characterized by having a cutting blade for excavating the ground and pushing excavated soil radially outward on the bottom surface of the cap. 2. The cap according to claim 1, wherein the cap has a conical shape that protrudes toward the distal end of the steel pipe.
Steel pipe pile as described. 3. The steel pipe pile according to claim 1, wherein the tip of the steel pipe is filled with concrete for supporting the cap from inside.