JP2881501B2 - Construction method for high strength cast-in-place concrete piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cast-in-place concrete.
High-strength cast-in-place concrete with enhanced tip support, which is implemented in the construction method for building piles, embedded piles, continuous underground wall foundations, etc. (hereinafter collectively referred to as cast-in-place concrete piles, etc.) -It is related to the construction method of piles.

[0002]

2. Description of the Related Art Conventionally, in the construction of cast-in-place concrete piles and the like, there has been a problem that the tip supporting force is reduced due to loosening of the tip ground due to excavation.
In the construction method described in JP-A No. 19, the skeleton concrete
A construction method has been proposed in which the compacted pile penetrates into the tip ground after the strength has developed and the tip ground is compacted to increase the bearing capacity.

[0003]

In the above-mentioned known construction method, the means for penetrating the compacted pile into the ground at the tip is as follows: 1) A driving method using Monken or the like. 2) Press-fitting method using an expanding material. 3) Press-fitting method by drilling. Are disclosed.

[0004] However, a cast-in-place concrete that extends over several meters below the ground even if it is shallow, and 30-50 meters below the ground when it is deep
Approximately 30cm in diameter, length 5
It is extremely difficult work to operate and penetrate a compacted pile of about 0 cm to 100 cm with a monken or a press machine installed on the ground, and it takes a lot of time and the construction period is prolonged. In addition, very large heavy machinery is required to secure the reaction force required for the penetration of the compacted pile on the ground, which is costly. Further, in the press-fitting method using an expanding material or the like, it is not possible to confirm whether the compacted pile has penetrated a predetermined depth into the ground at the tip end, and the reliability is lacking.

[0005]

As a means for solving the above-mentioned problems of the prior art, a construction method of a high-strength cast-in-place concrete pile according to the present invention is, as shown in the embodiment in the drawings, a method for constructing a concrete pile. Prior to construction of the skeleton 11, in the construction method of the driving concrete pile or the like, the front end opening is shielded by the cover plate 7 which can be knocked out, and the female screw portion 4 on the inner surface of the front end portion.
a, and screw the male screw portion 6b of the compaction pile 6 into the
The guide pipe 4 equipped with the shaft is landed on the ground at the tip end 5 and installed substantially vertically, and after the completion of the skeleton 11, the rotary shaft 12 is inserted into the guide pipe 4 from the ground and the compacted pile 6 is rotated. Then, the cover plate 7 is advanced by a screw motion to knock out the cover plate 7 so as to penetrate the tip ground 5 to a desired depth, and then the filling mortar 10 and the like are filled in the guide pipe 4 to fix the compaction pile 6. And a step.

[0006]

After the body 11 has developed strength, the compaction pile 6 previously mounted on the tip of the guide pipe 4 is moved to the rotating shaft 12.
, The compacted pile 6 advances (downs) by the screw motion, knocks out the cover plate 7 by the advancing force, and penetrates into the tip ground 5 as it is. The intrusion reaction force at this time is the guide pipe 4 and the skeleton concrete 1
1, the compaction pile 6 can sufficiently penetrate into the tip ground 5, and the tip ground can be compacted.

[0007] The compacted pile 6 penetrating into the tip ground 5 is filled with the filling mortar 10 filled in the guide pipe 4.
Therefore, the compaction pile 6 is prevented from loosening or falling out of the tip ground 5.

[0008]

【Example】

Next, the illustrated embodiment of the present invention will be described. First, FIG. 1A
-D show the essential process charts in the construction of the high strength cast-in-place concrete pile. FIG. 1A shows a stage in which a hole 2 for a pile is excavated in a ground 1 to a depth reaching a support layer (hereinafter referred to as a tip ground) 5, and FIG. 1B shows a reinforcing bar 3 and a guide pipe 4 in the hole 2. Shows the stage at which was installed. As shown in FIG. 2, three guide pipes 4 are arranged at three positions distributed based on the diameter (about 2 to 4 m) of the hole 2 for the cast-in-place concrete pile and the cross-sectional shape thereof ( However, the position and the number are not limited to this), each guide pipe 4 ...
Are integrally attached to the reinforcing bar 3 by a method such as bundling or welding, and the guide pipe 4 is also installed in the hole 2 to serve as the installation of the reinforcing bar cage 3.

The guide pipe 4 has an inner diameter (for example, inner diameter 3) slightly larger than the outer diameter (normally about 30 cm) of the compaction pile 6.
An iron tube having a length at least equal to the depth of the hole 2 at about 2 cm) is used. 3A to 3C, the distal end opening of the guide pipe 4 is watertightly shielded by a cover plate 7 made of an iron plate. A female screw portion 4 a is formed on the inner surface of the distal end portion of the guide pipe 4.
b is screwed in, and the compaction pile 6 is previously mounted on the distal end portion in the guide pipe 4 in such a position that the distal end is located directly above the cover plate 7 (FIGS. 4A to 4C). Between the inner surface of the cover plate 7 and the inner surface of the guide pipe 4, a reinforcing plate 8 having an inverted conical shape with a taper of approximately 45 ° is installed to reinforce the pressure resistance of the cover plate 7. The reinforcement is performed to such an extent that the cover plate 7 is not damaged when the lower end of the guide pipe 4 is landed on the tip ground 5. Therefore, the excavated muddy water and the casting concrete do not flow back into the guide pipe 4 installed in the hole 2 together with the reinforcing bar 3. A large number of cut grooves 9 are formed in the cover plate 7 in a radial arrangement from the center. As shown in FIG. 3C, details of the cut groove 9 are provided on the outer surface (lower surface) of the cover plate 7 with a thickness t (about 4 mm) of the cover plate 7.
Is formed as a V-cut groove having a depth a and an opening width b of about 2 × 2 mm. Therefore, the cover plate 7 is strong against the pressure on the outside surface, but relatively weak against the pressure from the inside surface.
Breaking (so-called knockout) by the compaction pile 6 is easy, and the cover plate 7 is broken in a tulip shape along each cut groove 9.

FIG. 1C shows a stage in which a concrete is poured into the hole 2 to construct the pile skeleton 11. FIG. 1D shows a compacted pile in the guide pipe 4 after the pile skeleton 11 has developed strength. 6 penetrates into the tip ground 5 and has a high strength cast-in-place concrete
This shows the stage at which the construction of the pile was completed. Compaction pile 6
As shown in FIG. 4A, the rotary shaft 12 is inserted from the upper end of each guide pipe 4 and the square hole at the tip of the rotary shaft is fitted to the square shaft 6a at the upper end of the compaction pile 6, and is rotated by a rotating machine not shown. By doing so, it is advanced by the screw motion, and the cover plate 7 is broken and penetrated into the tip ground 5. The inside of the guide pipe 4 is a space in which only air exists until the lid plate 7 is knocked out. The compacted pile 6 advances by a screw motion as it is rotated by the rotating shaft 12, penetrates the cover plate 7 at the lower end of the guide pipe, and penetrates deeply into the tip ground 5 (FIG. 4B). Therefore, the time required for the compaction pile 6 to penetrate is only several minutes. Each piece broken in the form of a tulip along the cut groove 9 by the compaction pile 6 forms a shape that adheres to the outer peripheral surface of the compaction pile 6 and exerts a shielding effect, so that groundwater or the like is removed. Backflow in the guide pipe 4 is suppressed well. Therefore, the quality of the filling mortar 10 filled in the guide pipe 4 immediately after the penetration is prevented, and the compaction pile 6 is firmly fixed by the filling mortar 10.

As described above, the compaction pile 6 penetrated into the tip ground 5 by the screw motion is sharply shaped like an arrow for the purpose of preventing its eccentricity, reducing the resistance at the time of penetration, and pushing the tip ground 5 apart. The basic shape is a sharply tapered conical shape, a male screw 6b is formed on the outer periphery of the uniform diameter portion, and the square shaft 6a is formed short on the upper end surface.

[0012]

Second Embodiment FIGS. 5A and 5B show construction drawings of a high-strength precast concrete pile. FIG. 5A shows the use of the hollow portion 14a of the precast concrete pile 14 as a guide pipe for the compacted pile 6, and a short guide pipe 4 'at the lower end in the hollow portion 14a of the precast concrete pile 14. The guide pipe 4 ′ is installed, and the end opening of the guide pipe 4 ′ is shielded by the cover plate 7. A female screw 4a is formed on the inner surface of the guide pipe 4 ', and a male screw 6b of the compaction pile 6 is screwed into the female screw 4a. The rotating shaft 12 is inserted into the hollow portion 14a of the existing concrete pile 14 from the ground.
Is inserted and the compaction pile 6 is rotated and advanced (downward) by a screw motion to break the cover plate 7, and the compaction pile 6 penetrating into the tip ground 5 is filled in the hollow portion 14a. Filling and fixing the mortar is the same as in the case of the cast-in-place concrete pile of the first embodiment.

[0013]

Third Embodiment FIG. 6 shows a construction drawing of a high-strength underground continuous wall foundation 16. In this case, the guide pipe 4 is attached to the wall reinforcing bar 15 and is installed together with the wall reinforcing bar 15 in the excavation hole. The rotation of the compaction pile 6 in each guide pipe 4 after developing the strength and the advancement by the screw motion to penetrate the tip ground 5 are the same as those in the first and second embodiments, respectively.

[0014]

[Effects of the present invention]

According to the construction method of the high-strength cast-in-place concrete pile or the like according to the present invention, the time required for penetrating the compacted pile 6 can be considerably shortened, and work can be performed efficiently in a short time. In addition, the operation from the ground can be easily and reliably performed based on the screw motion without requiring much skill. Since the compacted pile 6 is securely penetrated into the tip ground 5 and the compaction effect of the tip ground 5 is large, it is possible to provide a high-strength cast-in-place concrete pile having a large tip supporting force, and to provide workability, quality, and reliability. It contributes to the construction of highly efficient structures.

[Brief description of the drawings]

FIGS. 1A to 1D are essential process diagrams of the construction method of the present invention.

FIG. 2 is a perspective view showing a guide pipe laid in a reinforcing cage.

FIGS. 3A, 3B and 3C are an enlarged sectional view and a bottom view of a lower end portion of a guide pipe, and an enlarged view of a cut groove.

FIGS. 4A to 4C are cross-sectional views of a step of penetrating a compaction pile in a guide pipe into the tip ground.

5A and 5B are construction diagrams of a high-strength precast concrete pile.

FIG. 6 is a construction drawing of a high strength underground continuous wall foundation.

[Explanation of symbols]

 Reference Signs List 11 frame 7 cover plate 4 guide pipe 5 tip ground (support layer) 6 compaction pile 10 filling mortar

Continued on the front page (72) Inventor Tomio Tsuchiya 2-5-14 Minamisuna, Koto-ku, Tokyo Inside the Technical Research Institute, Takenaka Corporation (72) Inventor Yoshihiko Kurita 2-14-14 Minamisuna, Koto-ku, Tokyo Stock Company Takenaka Corporation Technical Research Institute (72) Inventor Takuhei Fukuhara 8-21-1, Ginza, Chuo-ku, Tokyo Co., Ltd. Takenaka Civil Engineering Co., Ltd. (56) References JP-A-63-312419 (JP, A) JP-A-5 −209409 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 5/34 E02D 5/20 102 E02D 27/12

Claims (1)

(57) [Claims] In a method of constructing a cast-in-place concrete pile or the like, prior to construction of a skeleton, an opening at a tip is shielded by a cover plate which can be knocked out, and a male screw of a pile is compacted to a female screw portion on an inner surface of the tip. The guide pipe with the compaction pile attached to it by screwing the part to the bottom of the tip ground and installing it almost vertically, and after the completion of the skeleton, insert the rotating shaft from the ground into the guide pipe and insert the compaction pile. A step of rotating and moving forward by screw motion to knock out the lid plate to penetrate a desired depth into the tip ground, and then filling a guide pipe with a filling mortar or the like and fixing a compacted pile, A method for constructing a high-strength cast-in-place concrete pile or the like, characterized by being formed.