JP2884266B2 - Compacted piles such as cast-in-place concrete piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a structure constructed by excavating the ground, such as the construction of an embedded pile using a cast-in-place concrete pile or a ready-made concrete pile, or the construction of a continuous underground wall. The present invention relates to compacted piles, such as cast-in-place concrete piles, which are used in the construction of cast-in-place concrete piles or the like for the purpose of compacting the ground at the tip of the structure and increasing the bearing capacity.

[0002]

2. Description of the Related Art Conventionally, in the construction of cast-in-place concrete piles and the like, it has been a problem that excavation loosens the tip ground and lowers the tip support force.
In the construction method described in Japanese Patent Publication No. 9, a construction method has been proposed in which after the skeleton concrete exhibits strength, a compaction pile is penetrated into the tip ground to compact the tip ground and increase the supporting force. The compacted piles described in the above-mentioned publications are roughly classified into compacted piles of a rotary press-fitting type and compacted piles of a driving or pushing-in type according to the difference in the penetration method.

[0003]

As described above, the technical idea of a compacted pile which penetrates into the extremity ground loosened by excavation and compacts the ground to increase the supporting force is already known. However, the shape and structure of compacted piles, which have excellent penetration performance as a specific technology and compaction performance at the tip ground, should be left as an unsolved technical problem. is there.

Accordingly, it is an object of the present invention to efficiently compact the tip ground loosened by excavation, and to provide a compacted pile satisfying the following functions. (1) Able to penetrate into a dense sand layer, gravel layer or gravel layer with almost no soil removal. (2) The ground directly below the tip of the main body pile, which can be mainly compacted on the side of the penetrated compaction pile. (3) Even when the compacted pile is to be penetrated in a short time, it does not require excessive mechanical force (thrust and torque) and has excellent penetration performance.

[0005]

As means for solving the above-mentioned problems of the prior art, compacted piles such as cast-in-place concrete piles according to the present invention, in particular, compacted piles of the drive-in type or the push-in type, are cast-in-place concrete. It has a length L of the same level as the tip diameter of the pile or the like, the diameter d ₂ about 5~30cm the tip, the upper end portion diameter d ₁ is about 10～60Cm, as a whole about 1 / 5-1 / 20 Characterized in that it is formed in a tapered shape with a gradient θ.

Next, as shown in FIG. 1 or FIG. 10, an embodiment of the compaction pile of the rotary press-fitting type according to the present invention is based on the shape, structure and dimensional specifications of the compaction pile of the driving or pushing-in type. In addition, a plurality of tip cutters 3 protruding forward from the pile tip surface along its outer peripheral surface are attached to the tip portion of the pile, and at one or more locations on the outer peripheral surface of the tapered portion 1. The side cutter 4 is provided with a dimension specification and arrangement in which the maximum diameter d _{3 of the} cutting edge is smaller than the diameter d ₁ of the upper end of the pile,
Further, a spiral ridge 5 is provided in a range not exceeding 1/2 of the total length L of the tapered portion 1 upward from the tip of the pile.

[0007]

Since the compacted pile of the present invention is formed in a tapered shape as a whole, the penetration performance is very good (compare FIG. 3 and FIG. 4). The effect of compacting the tip ground is great (see FIG. 2). In other words, the loosening of the ground due to excavation occurs most near the bottom of the excavation hole (near the tip of the pile), and the degree of loosening tends to decrease from that position in the depth direction. The compacted pile ultimately has the largest penetration volume into the part where the looseness is large, and inevitably has a large effect of compacting mainly the side ground, so the compacting effect corresponds to the change in the depth direction of the loosening of the ground. No waste.

Since the length L of the compaction pile is approximately the same as the diameter of the tip of a cast-in-place concrete pile or the like, the compaction pile has an excellent compacting effect on the tip ground loosened by excavation. This is because it has been confirmed that the region in which the ground is significantly loosened due to excavation is from the tip of a cast-in-place concrete pile or the like to a depth approximately equal to the tip diameter of the pile. The reason why the tapered portion 1 of the compacted pile is formed into a tapered shape with a gradient of about 1/5 to 1/20 as a whole is that the compacted pile has a tapered pile in comparison of compaction performance with a parallel pile having an equal diameter (FIG. 2). This is because superiority (compaction effect by wedge action) was confirmed.

The tip cutter 3 used in the compaction pile of the rotary press-fitting type is capable of rotatingly cutting a dense sand layer or gravel soil to improve the penetration performance of the compaction pile (FIG. 5). Side cutter 4
Reduces the frictional resistance between the soil and the tapered portion 1 generated when the compacted pile penetrates into the tip ground to a certain depth by the rotary cutting of the ground, thereby improving the penetration performance ( (Fig. 6).

The soil particles cut by the above-mentioned tip cutter 3 and the maximum diameter d _{3 of the} cutting edge are determined by the upper end diameter d _{1 of the} compacted pile.
The soil particles cut by the side cutter 4 having a size smaller than (the maximum diameter of the tapered portion 1) are pressed against the side ground by the tapered portion 1 in the process of ascending along the tapered portion 1 and upward. Does not cause earth removal. Accordingly, the compaction efficiency is reduced due to the discharge of the compaction pile and the deterioration of the quality of the cement milk or the like filled in the guide pipe or the like, which is often caused by the removal of the compaction pile, is prevented.

Due to the so-called screw action of the spiral ridge 5,
The penetration of the compacted pile is improved (FIG. 7). Since the spiral ridge 5 is provided in a length range not exceeding １ ／ below the entire length L of the tapered portion 1, it is possible to prevent the soil from being discharged when the compaction pile penetrates.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 shows an embodiment of a compaction pile of the rotary press-fitting type. The total length L of the tapered portion 1 is, for example, about the same as the tip diameter of a cast-in-place concrete pile (usually about 1 m to 4 m). I have. The tip diameter d ₂ and the upper end portion diameter d ₁ of the compaction pile, taking into account the respective construction of the good, the former d ₂ is about 5 to 30 cm, the latter d ₁ is about 10～60Cm, have tapered The portion 1 is formed in a tapered shape having a gradient of about 1/5 to 1/20. This compacted pile is usually manufactured by a casting method of cast iron or cast steel. At the upper end of the compaction pile, a connecting portion 2 having the same diameter as the upper end diameter d ₁ (maximum diameter) of the tapered portion 1 and having a length of about 5 to 30 cm is provided.
A rotating shaft having a length reaching from the ground to the tip ground of the main body pile is attached to the connecting portion 2 so that the rotating force can be transmitted, and after use, the rotating shaft can be separated by, for example, an operation of reversing the rotating direction. You.

The tip cutter 3 at the tip of the pile has a tip diameter d ₂ (d ₂ ) approximately along the outer peripheral surface of the tip of the compacted pile (that is, along the slope of the tapered portion 1). 〓
A plurality of them are attached in a structure protruding forward by about 5 to 30 cm). In FIG. 1A, a cutter simply provided on the tip of the pile, or vice versa.
This is because the penetrability is far superior to that of a cutter that does not protrude to the pile tip surface as in the model shown in FIG. 1C.

Next, on the outer peripheral surface of the tapered portion 1, there are provided a plurality of side cutters 4 having a size specification and an arrangement in which the maximum diameter d _{3 of} the cutting edge is several cm smaller than the diameter d ₁ of the upper end portion of the compaction pile. ing. The usefulness of this side cutter 4 is described in FIG.
As is clear from the comparison between the results shown in FIG. 6 and FIG. The model No. in FIG. No. 1B + c.
Compared with 1B + c ′, the installation position of the side cutter 4 is more excellent when it is provided above the tip cutter 3 at a distance from the tip cutter 3 to some extent. Therefore, in consideration of this point, the embodiment of the compaction pile is, as shown in FIG.
With the configuration provided with, the penetrability is further improved.

Next, in the case of the compacted pile shown in FIGS. 1 and 10, a spiral ridge 5 is provided in a range of about 1/5 of the entire length of the tapered portion 1 from the tip. As apparent from the contrast between FIGS. 6 and 7, the effect of the spiral ridges 5 is markedly improved in the penetration performance. The reason why the range in which the spiral ridge 5 is provided is limited to a range that does not exceed 全長 of the entire length L of the tapered portion 1 is that as shown in FIGS. It depends on the result of studying the limit. This is because, when the spiral ridge 5 causes upward soil discharge at the time of intrusion, the compaction efficiency is reduced and the compaction pile is used for filling the guide pipe from the ground to the tip ground. The above-mentioned earth removal deteriorates the quality of the cement milk that has been deteriorated, and before the supporting force of the constructed cast-in-place concrete pile or the like approaches the allowable limit, the deterioration of the quality of the filled cement milk causes a decrease in the supporting force. It is because it causes.

Reference numeral 6 in FIG. 1 denotes an injection hole penetrated along the center line of the pile to discharge the cement-based hardening material from the tip during the penetration of the compacted pile. The hardened material discharged through the injection hole 6 realizes a firm compacted ground. In addition, as compaction pile of driving or pushing method,
The above-described configuration is performed by removing the tip cutter 3, the side cutter 4, and the spiral ridge 5, and omitting the connection part 2 in some cases.

[0017]

[Effects of the present invention] The compacted pile such as the cast-in-place concrete pile according to the present invention is excellent in the penetration property to the tip ground, is excellent in compaction performance of the tip ground, and is harmful when penetrating the tip ground. Since no earth removal occurs, it exerts a remarkable power in strengthening the bearing capacity by compacting the tip ground.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a compaction pile according to the present invention.

FIG. 2 is a characteristic diagram comparing compaction performance according to a gradient of a pile.

FIG. 3 is a characteristic diagram showing the penetration performance of a parallel pile.

FIG. 4 is a characteristic diagram showing the penetration performance of the tapered pile.

FIG. 5 is a characteristic diagram showing penetration performance depending on the shape and structure of the tip cutter.

FIG. 6 is a characteristic diagram showing penetration performance by a side cutter.

FIG. 7 is a characteristic diagram showing penetration performance by a spiral ridge.

FIG. 8 is a characteristic diagram showing the presence / absence of earth removal depending on the difference in the range in which the spiral ridge is provided.

FIG. 9 is a characteristic diagram showing the presence or absence of earth removal depending on the difference in the range in which the spiral ridge is provided.

FIG. 10 is a front view showing another embodiment of the compaction pile according to the present invention.

[Explanation of symbols]

L length d ₂ tip diameter d ₁ the upper end diameter θ Slope 3 Tip cutter 1 Taper d ₃ Maximum cutting edge diameter 4 Side cutter 5 Spiral ridge

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tomio Tsuchiya 2-5-1 Minamisuna, Koto-ku, Tokyo Inside the Technical Research Institute, Takenaka Corporation (72) Yoshihiko Kurita 2-5-1-14 Minamisuna, Koto-ku, Tokyo No. Takenaka Corporation Technical Research Institute (72) Inventor Yuyasu Ikuta 4-1-1-13 Honcho, Chuo-ku, Osaka-shi Inside Takenaka Corporation, Osaka Main Store (72) Inventor Takuhei Fukuhara Ginza, Chuo-ku, Tokyo No. 21-1, Takenaka Civil Engineering Co., Ltd. (56) References JP-A-63-31419 (JP, A) JP-A-50-132710 (JP, A) JP-A-33-10418 (JP, B1) (58 ) Surveyed field (Int.Cl. ⁶ , DB name) E02D 5/72 E02D 5/34 E02D 5/56

Claims (2)

(57) [Claims] The diameter of the tip is about 5 to 30 cm and the diameter of the upper end is about 10 to 60 cm.
A compacted pile such as a cast-in-place concrete pile, which is formed in a tapered shape with a slope of about 20. 2. The diameter of the tip of a cast-in-place concrete pile or the like is approximately the same, the tip diameter is about 5 to 30 cm, and the upper end diameter is about 10 to 60 cm.
The tip is formed in a tapered shape with a gradient of about 20, and a plurality of tip cutters are attached to the tip of the pile to protrude forward from the tip of the pile along the outer peripheral surface thereof. The side cutter is provided with a dimension specification and arrangement in which the maximum diameter of the cutting edge is smaller than the upper end diameter of the pile, and a spiral ridge is provided above the tip of the pile in a range not exceeding 1/2 of the total taper length. Compacted piles such as cast-in-place concrete piles.