JP2003176535A - Steel pipe pile and its construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe pile and its construction method that can improve tip bearing power to the ground. <P>SOLUTION: This steel pipe pile 1 is provided with a shaft pipe 3 made of a steel pipe with at least one spiral blade 2 spirally projected from the outer periphery near the tip 3a, and an inner pipe 6 made of a steel pipe with an outer diameter slightly smaller than the inner diameter of the shaft pipe 3, provided with at least one excavating piece 4 protrusively on one face side 5a of a bottom plate 5 whose other face side 5b is stuck to the tip 6a, and inserted in the shaft pipe 3 with the excavating piece 4 turned to the tip 3a side of the shaft pipe 3. <P>COPYRIGHT: (C)2003,JPO

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 for preventing uneven settlement of a house or the like on soft ground and a method of constructing the same.

[0002]

2. Description of the Related Art As is well known, as a method of preventing uneven settlement of a house or the like in soft ground and a method of transmitting an upper load to the ground, for example, a rotary penetration method for steel pipe piles without problems such as noise and vibration. There is.

In this rotary penetration method, as shown in FIGS. 11 and 12, a spiral blade 2 is provided in a spiral shape on the outer periphery near the tip 3a. For example, a triangular plate-shaped excavation piece 4 is projected on one surface side 5a. In many cases, the steel pipe pile 51 including the shaft pipe 3 made of a steel pipe having the other surface side 5b of the bottom plate 5 provided fixed to the tip 3a is used. At the time of construction, it is general that the head 51b of the steel pipe pile 51 is pressed or supported by a heavy machine to be rotated and penetrate into the ground. After the rotary penetration, due to the ground reaction force (tip supporting force) received by the tip 51a of the steel pipe pile 51 including the spiral blade 2 and the frictional force (peripheral surface friction force) generated between the steel pipe pile 51 and the ground. It has a structure that gains supportive power.

[0004]

However, in the conventional steel pipe pile 51 as described above, when the amount of penetration of the steel pipe pile 51 per revolution is smaller than the revolution pitch P of the spiral blade 2 when the steel pipe pile 51 is rotationally penetrated into the ground. A part of the ground that remains undisturbed by the spiral wing 2 is generated. In addition, a portion that remains undisturbed by the excavated piece 4 also occurs. Therefore, if a load is applied to the steel pipe pile 51, harmful subsidence may occur in supporting a house or the like, and there is a problem that the tip supporting force for the ground is not so large.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a steel pipe pile capable of improving the tip supporting force for the ground and a construction method thereof.

[0006]

In order to achieve the above object, a steel pipe pile according to a first aspect of the present invention comprises a steel pipe shaft tube in which at least one spiral blade is provided in a spiral shape on the outer periphery near the tip, and Made of steel pipe with an outer diameter slightly smaller than the inner diameter of the shaft pipe, the other side of the bottom plate having at least one drilling piece projecting on one surface side is fixed to the tip, and the drilling piece is placed inside the shaft pipe on the tip side of the shaft pipe. And an inner tube inserted toward the end.

A construction method of claim 2 is the construction method of the steel pipe pile according to claim 1, wherein the steel pipe pile is rotationally penetrated to a predetermined depth of the ground in a state where the excavated piece is projected from the tip of the shaft pipe. After that, move the steel pipe pile up and down while rotating,
A crushed soil portion is provided by crushing the ground near the tip of the steel pipe pile, the tip of the shaft pipe is located at a predetermined height in the crushed soil portion, and the inner pipe is pulled out from the shaft pipe. By press-fitting and hardening it, an improved soil portion is provided at the tip of the shaft tube.

In the construction method of claim 3, the height from the bottom surface of the crushed soil portion to the tip of the shaft tube when the mortar is press-fitted is equal to or greater than the outer diameter of the spiral blade.

According to a fourth aspect of the present invention, the mortar is press-fitted into the crushed soil portion, and the mortar is hardened while being filled inside the tip of the shaft tube.

According to a fifth aspect of the construction method, the mortar is
The Monken inserted into the shaft tube is pressed into the crushed soil portion by free fall.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the conventional technique are designated by the same reference numerals.

As shown in FIGS. 1 to 3, in a steel pipe pile 1 according to this embodiment, a shaft pipe 3 made of steel pipe in which a spiral blade 2 is provided in a spiral shape on the outer periphery near a tip 3a, and this shaft The outer diameter of the pipe 3 is slightly smaller than the inner diameter of the pipe 3.
The other surface side 5b of the bottom plate 5 protruding from the
The shaft pipe 3 is provided with an excavation piece 4 and an inner pipe 6 inserted toward the tip 3a side of the shaft pipe 3.

The shaft tube 3 has, for example, an outer diameter of about 10 to several tens of c.
It is made of a circular tubular steel pipe having a wall thickness of m and a wall thickness of several mm, and is formed in a long length of several m to several tens of m.

The spiral blade 2 is made of, for example, a steel plate, and is provided in a spiral shape by welding or the like on the outer periphery of the shaft tube 3 near the tip 3a. In this embodiment, only one round is made, but it is not limited to this, and more rounds may be made. The number of spiral blades 2 is not limited to one, and a plurality of spiral blades 2 may be provided so as to project along the length direction of the shaft tube 3.

The inner pipe 6 is made of a circular tubular steel pipe similar to the shaft pipe 3, but has an outer diameter slightly smaller than the inner diameter of the shaft pipe 3, and the excavation piece 4 is formed in the shaft pipe 3. 3 is inserted into and taken out toward the tip 3a side. The length of the inner pipe 6 may be substantially the same as that of the shaft pipe 3, but is not particularly limited, and in a state where the excavated piece 4 is projected from the tip 3a of the shaft pipe 3 when the ground 7 is rotationally penetrated. The length may be such that the inner pipe 6 and the shaft pipe 3 can be simultaneously rotated by a heavy machine or the like.

The bottom plate 5 is made of, for example, a disc-shaped steel plate, and the excavation piece 4 is projected on one side 5a by welding or the like, and the other side 5b is fixed to the tip 6a of the inner pipe 6 by welding or the like. Has been done. The excavated piece 4 is made of, for example, a triangular plate-shaped steel plate, but the shape, size, number, protruding position, protruding angle, etc. of the excavated piece 4 are not particularly limited and can be appropriately changed as necessary. is there.

Next, a method of constructing the steel pipe pile 1 constructed as described above will be described. When constructing the steel pipe pile 1, first, as shown in FIG. 4, the steel pipe pile 1 is rotationally penetrated to a predetermined depth of the ground 7 with the excavated piece 4 protruding from the tip 3 a of the shaft pipe 3. In this case, the shaft tube 3 and the inner tube 6 may be simultaneously rotated in the same direction by a heavy machine or the like. Alternatively, the shaft tube 3 and the inner tube 6 may be rotated while being fixed by a conventionally known fixing means.

Then, as shown in FIG. 5, the steel pipe pile 1 is moved up and down while being rotated by a heavy machine or the like, and the ground 7 near the tip 1a of the steel pipe pile 1 is crushed to provide a crushed soil portion 8. In this case, the steel pipe pile 1 may be rotated or moved in an appropriate direction, and a predetermined range of the ground 7 may be crushed by the spiral blade 2 to form the crushed soil portion 8.

Further, as shown in FIGS. 6 and 7, for example, the steel pipe pile 1 is moved upward so that the tip 3a of the shaft pipe 3 is located at a predetermined height in the crushed soil portion 8, and then the shaft pipe 3 is moved. To inner tube 6
Pull out. The timing of pulling out the inner pipe 6 from the shaft pipe 3 is not particularly limited, and it may be pulled out after moving only the shaft pipe 3 upward, or the inner pipe 6 may be pulled out.
The shaft tube 3 may be moved upward after pulling out.

Then, as shown in FIGS. 8 and 9, after the mortar 9 is put into the crushed soil portion 8 through the shaft tube 3, the mortar 9 is inserted into the shaft tube 3 through the wire rope 10 or the like so as to freely fall and pull up. Mortar 9 by the Monken 11 etc.
Is pressed into the crushed soil portion 8. At the time of press fitting, the periphery of the crushed soil portion 8 may be compressed outward so that the crushed soil portion 8 expands as in this embodiment. The mortar 9 is
It can be pressed into the crushed soil section 8 by compressed air,
According to the free fall of the Monken 11, like this embodiment, there is an advantage that it can be easily press-fitted with a large load.

After press-fitting, the mortar 9 is hardened by leaving it for a predetermined period of time to form an improved soil portion 12 at the tip 3a of the shaft tube 3, as shown in FIG. The head portion 3b of the shaft tube 3 may be cut off by a predetermined length as necessary, and then the upper plate 13 made of a disc-shaped steel plate may be fixed by welding or the like. The foundation such as the cloth foundation 14 may be installed above the shaft tube 3 by a conventionally known method. Here, if the height from the bottom surface 8d of the crushed soil portion 8 to the tip 3a of the shaft tube 3 when the mortar 9 is pressed in is equal to or greater than the outer diameter of the spiral blade 2, the improved soil portion 12 having a sufficient height can be formed. At the same time, there is an advantage that the mortar 9 can be easily press-fitted. Also, while pressing the mortar 9 into the crushed soil portion 8,
If the mortar 9 is cured while being filled inside the tip 3a of the shaft tube 3, the tip 3a of the shaft tube 3 will improve the soil portion 12.
Since it is surely buried in the structure, there is an advantage that the shaft tube 3 and the improved soil portion 12 are not likely to be displaced.

By providing the improved soil portion 12 at the tip 3a of the shaft tube 3 in this manner, the tip supporting force for the ground 7 becomes large, so that the subsidence amount should be kept small even if a load is applied to the shaft tube 3. The advantage is that

[0023]

As described above, according to the invention of claim 1, since the shaft pipe and the inner pipe are provided, it can be suitably used as a steel pipe pile for providing an improved soil portion at the tip of the shaft pipe. .

According to the second aspect of the invention, since the improved soil portion is provided at the tip of the shaft tube as described above, the tip supporting force for the ground becomes large, and therefore the sinking of the shaft tube even when a load acts on it. The amount can be kept small.

According to the invention of claim 3, the height from the bottom surface of the crushed soil portion to the tip of the shaft tube when the mortar is press-fitted is equal to or larger than the outer diameter of the spiral blade, so that the improved soil portion having a sufficient height can be obtained. It can be formed and it is easy to press mortar.

According to the fourth aspect of the present invention, since the mortar is pressed into the crushed soil portion and the mortar is hardened in a state where the mortar is filled inside the tip end of the shaft tube, the tip end of the shaft tube is surely placed in the improved soil portion. There is no risk of the shaft tube and the improved soil being misaligned.

According to the invention of claim 5, the mortar is press-fitted into the crushed soil portion by free fall of the Monken, so that the mortar can be easily press-fitted with a large load.

[Brief description of drawings]

FIG. 1 is a partially omitted front view of a steel pipe pile according to an embodiment.

FIG. 2 is a bottom view of the steel pipe pile.

FIG. 3 is a front view of the inner pipe with a part thereof omitted.

FIG. 4 is a partially omitted cross-sectional view showing a state after the steel pipe pile is rotationally penetrated to a predetermined depth of the ground.

FIG. 5 is a partially omitted cross-sectional view showing a state after the crushed soil portion is provided.

FIG. 6 is a partially omitted cross-sectional view showing a state after the steel pipe pile has been moved upward.

FIG. 7 is a partially omitted cross-sectional view showing a state where an inner pipe is pulled out from a shaft pipe.

FIG. 8 is a partially omitted cross-sectional view showing how mortar is put into the crushed soil portion.

FIG. 9 is a partially omitted cross-sectional view showing how mortar is press-fitted into the crushed soil portion.

FIG. 10 is a partially omitted cross-sectional view showing a state after the improved soil portion is provided at the tip of the shaft tube.

FIG. 11 is a partially omitted front view of a conventional example.

FIG. 12 is a bottom view of a conventional example.

[Explanation of symbols] 1 steel pipe pile 1a tip 2 spiral wings 3-axis tube 3a tip 4 excavated pieces 5 bottom plate 5a One side 5b Other side 6 inner tube 6a tip 7 ground 8 crushed soil 8d bottom 9 Mortar 11 Monken 12 improved soil

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshitake Onishi             Sekisui Ha, 1-188 Oyodo-Naka, Kita-ku, Osaka-shi             Inside Us Co., Ltd. (72) Inventor Junsaburo Yamada             1-13-3 Senba Nishi, Minoh City, Osaka Prefecture F-term (reference) 2D041 AA02 BA12 BA13 BA35 BA52                       CA05 DB02 FA03 FA07 FA13                       FA14                 2D050 AA06 AA16 BB07 CA05 CB05                       CB13

Claims (5)

[Claims] 1. A shaft pipe made of a steel pipe in which at least one spiral blade is projected in a spiral shape on the outer periphery near the tip, and a steel pipe having an outer diameter slightly smaller than the inner diameter of the shaft pipe, and at least one excavated piece. The steel pipe pile, wherein the other surface side of the bottom plate protruding from the one surface side is fixed to the tip, and the inner pipe is inserted into the shaft pipe so that the excavated piece is inserted toward the front end side of the shaft pipe. 2. The method for constructing a steel pipe pile according to claim 1, wherein the steel pipe pile is rotationally penetrated to a predetermined depth of the ground in a state where the excavated piece is projected from the tip of the shaft pipe, and then the steel pipe pile is installed. While rotating, it moves up and down to provide a crushed soil portion by crushing the ground near the tip of the steel pipe pile, the tip of the shaft pipe is located at a predetermined height in the crushed soil portion, and the inner pipe is moved from this shaft pipe. A method for constructing a steel pipe pile, characterized in that an improved soil portion is provided at the tip of the shaft tube by press-fitting and hardening mortar in the crushed soil portion in the pulled-out state. 3. The method for constructing a steel pipe pile according to claim 2, wherein the height from the bottom surface of the crushed soil portion to the tip of the shaft pipe when the mortar is press-fitted is equal to or larger than the outer diameter of the spiral blade. 4. The method for constructing a steel pipe pile according to claim 2, wherein the mortar is press-fitted into the crushed soil portion and hardened in a state where the mortar is filled inside the tip of the shaft pipe. 5. The method for constructing a steel pipe pile according to claim 2, wherein the mortar is press-fitted into the crushed soil portion by free fall of a Monken inserted in the shaft pipe.