JP2002212948A - Foundation pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral blade at one end of a metal pipe for producing a foundation pile easier and further improving the driving performance. SOLUTION: A thicker meat portion of a metal pipe 1 where the thickness of meat is made larger at one end side 1a and the pipe end surface 2 is made to a spiral surface, from a spiral pipe end face 2 to a radial direction, the thick blade at the root portion 3a is extended and formed in one body by casting, and excavating blades 4...4 extruded in the axial direction are protruded as one body in the configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast iron foundation pile having a spiral blade at one end.

[0002]

2. Description of the Related Art For example, Japanese Patent Publication No. 02-62648 discloses a metal foundation pile having a spiral blade at the tip.
JP-A-9-324420, JP-A-11-2698
A foundation pile as disclosed in Japanese Patent No. 75 is known.

[0003]

Of the above, the Japanese Patent
The "steel pipe pile" described in 2-62648 is a steel pipe pile in which a spiral blade (spiral blade) is attached to the outer periphery of a bottomed pipe end, and a drilling blade is protruded from a bottom plate in the axial direction of the steel pipe. However, since the spiral blades and the bottom plate are attached to the end of the metal tube by welding, there is a disadvantage that the cost is high.

Further, since the steel pipe pile described in this publication has a bottom, there is a problem that the bottom plate becomes a resistance and it becomes difficult to excavate. In addition, the spiral blades that exert the forward force when excavating into the ground are formed by processing a single plate into a spiral shape and welding it to a steel pipe with a certain thickness, so that the spiral blade The strength of the blade itself and the mounting strength to the steel pipe that becomes the pile are not enough, and after being buried underground as a foundation pile,
There is also a problem that the load supporting strength of the spiral blade is not sufficient.

The "screw-in type steel pipe pile" disclosed in Japanese Patent Application Laid-Open No. 9-324420 is one in which a spiral plate is attached to the lower surface of the tip of a steel pipe by welding means. However, there is a drawback that the temporary fixing work is required, the production is troublesome, and the cost is high.

In addition, since there is no excavation blade at the tip of the steel pipe pile, excavation into the ground has to rely only on the screw advancing force of the spiral strip, so that the excavation efficiency is poor. The “rotating buried open-end pile” disclosed in Japanese Patent Application Laid-Open No. H11-269875 has a tubular pile tip with an open end, so that there are few problems such as difficulty of excavation like two people, but the spiral blade is In addition, since it is attached to the outer periphery of the end of the steel pipe by welding, there is a problem that the production is troublesome and expensive.

[0007] The present invention solves the above-mentioned problems and facilitates the production of a foundation pile having a spiral blade at one end of a metal tube,
Moreover, it was made to improve the excavation performance.

[0008]

According to a first aspect of the present invention, there is provided a foundation pile having a helical surface at an end portion of a thickened metal tube having a helical surface. A spiral wing having a thick root portion is integrally formed by casting, and a digging blade projecting in the axial direction is integrally formed on an end surface of the helical pipe of the metal pipe. It is.

Therefore, in the foundation pile according to the present invention, since the metal pipe as the main body and the spiral blade at the tip end thereof are integrated by casting, the pipe main body and the spiral blade are formed at once in a casting mold. Can be manufactured. In addition, since both the one end side of the pipe and the root portion of the spiral blade extending in the radial direction are thickened, the supporting strength of the spiral strip blade supporting the embedded foundation pile is increased. And a large supporting force for the upper structure.

Further, at the time of excavation, the earth and sand is excavated and softened by the excavation blade on the pipe end surface, so that the excavation can be easily performed.
There is an effect that the verticality of the pile is improved by the ease of excavation by the excavation blade.

[0011]

Next, an embodiment of the present invention will be described. FIG. 1 is a partially broken front view of a foundation pile according to an embodiment of the present invention, and FIG. 2 is a partially broken left side view of FIG.

In FIG. 1, reference numeral 1 denotes a metal tube constituting a pile body, for example, a cast iron tube manufactured by centrifugal casting or the like. As shown in the drawing, one end 1a of the metal tube 1 has a thickness T larger than the thickness t of the normal straight tube portion 1b, and the tube end surface 2 of the thick tube wall portion 1a is also shown in FIG. The spiral blade 3 is formed into a spiral surface, and further extends in a radial direction from the tube end surface 2 so that the thickness of the root portion 3a is greater than the thickness of the radially outer portion 3b. I have.

Further, excavating blades 4 are integrally provided on the pipe end face 2 so as to extend in the axial direction of the metal pipe 1. The digging blades 4... May be formed integrally with the metal pipe 1 by casting, similarly to the spiral blades 3. However, the block-shaped digging blades 4. Alternatively, the pipe end face 2 may be formed so as to protrude from the spiral blade 3 by the height of the block-shaped excavating blade, and after the mold is removed, the excavating blades 4 and 4 may be cut out.

In the above embodiment, the thickness T of the thick portion at one end 1a is twice as large as the thickness t of the normal straight pipe portion 1b.
It is three times as thick. With such a thickness, it is possible to obtain a strength that can withstand the severe use conditions at the time of excavation and the weight of the building after burial.

The extended diameter D of the spiral strip 3 is about 1.5 to 2.5 times the diameter d of the straight pipe portion 1.
If it is less than 1.5 times, the excavating power by the spiral strip cannot be sufficiently obtained, and the supporting force by the spiral blades 3 in the ground after burial becomes insufficient. On the other hand, if it is larger than 2.5 times, the supporting force of the spiral blade 3 in the ground increases, but the excavation resistance increases and it becomes difficult to excavate.

The diameter D of the spiral strip 3 in the above numerical range is preferably about 1.9 to 2.2 times the straight pipe section 1b.
Next, how to use the foundation pile will be described.

A straight pipe 1 having a length of about 4 meters, a diameter of about 120 mm, a thickness of 6 mm, and a thickness T at one end 1a of 16 mm over a length of about 140 mm, and a thick portion 1b
A spiral blade 3 having an outer diameter of 250 mm, having a maximum thickness h of 16 mm at the root portion on the outer periphery and tapered from there, and having a constant thickness of 9 mm from the outer diameter of 194 mm. In addition, a foundation pile 1 was prepared by casting four excavating blades 4... 4 at the pipe end as shown in FIGS.

The pile was set upright on the ground surface and rotated.
When the pile 1 is driven to rotate around the axis, the excavation blade 4 on the pipe end face,
When the spiral blades 3 reached the surface of the ground, the wings 4 began to dig into the ground and began to dig into the ground.

The pile was excavated in the ground by applying a rotational force around the shaft in this way. However, the ground was swept up by the excavation blades 4 and 4 to soften the ground, and the excavation was smoothly performed. Along with this, the foundation pile 1 also dug into the ground in a substantially vertical state.

The foundation pile after being buried underground is buried in a state where the spiral blade at the tip is spread in the ground, so that it has sufficient supporting strength even on soft ground.

[0021]

As described above, in the foundation pile of the present invention, the metal pipe as the main body and the spiral blade at the tip end thereof are integrated by casting, so that the pipe main body and the spiral blade are integrated. Can be formed at once in a casting mold, which facilitates production. Also, since the wall thickness at one end side of the pipe and the root part of the spiral blade extending radially are thickened, after embedding,
The strength of the helical blade supporting the foundation pile to which the amount of building material is added increases, and the vertical bearing capacity after burial is buried.
At the same time, the parts that do not require strength other than those described above can be thinned, so that the mass of the entire foundation pile can be reduced.

Further, at the time of excavation, the earth and sand is excavated and softened by the excavation blade on the pipe end surface, so that the excavation can be easily performed.
There is an effect that the verticality of the pile is also improved by the ease of excavation by the excavation blade.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a foundation pile according to an embodiment of the present invention.

FIG. 2 is a left side view of FIG.

FIG. 3 is a bottom view of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal pipe 1a Thick wall part 2 Spiral pipe end surface 3 Spiral blade 3a Root part of spiral blade 4 Excavation blade

Claims (1)

[Claims] 1. A metal tube having a thicker wall at one end, wherein a tube end surface of the thicker portion is a spiral surface, and a thicker spiral shape at a root portion in a radial direction from the spiral tube end surface. A foundation pile, the blades of which are integrally extended by casting, and a drilling blade projecting in the axial direction is integrally provided on an end surface of the spiral tube of the metal tube.