JP2001131966A - Construction method for tip-closed hollow pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method for a tip-closed hollow pile capable of solving a problem of height stop of the pile generated when a preboring construction method is executed, and smoothly constructing the tip-closed hollow pile which is easy to have effects of buoyancy in an excavation hole. SOLUTION: In constructing the tip-closed hollow pile in a prebored excavation hole, the tip-closed hollow pile is rotated around its axial line to be constructed in the excavation hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for laying a foundation pile such as a concrete pile, a steel pipe pile and the like, and more particularly to a method for laying a hollow pile having a closed end in a prebored borehole.

[0002]

2. Description of the Related Art In the method of laying a foundation pile such as a concrete pile or a steel pipe pile, it is required to reduce noise and vibration. Therefore, a so-called pre-boring method is often used. In this method, a drill hole having a diameter larger than the pile diameter is excavated by a spiral auger or the like attached to an excavator until a predetermined depth is reached, and a foundation pile is built in the drill hole formed thereby.

[0003] In the case of using a closed-end pile as a foundation pile in carrying out this pre-boring method, the pile is piled up against buoyancy caused by water in the borehole, muddy water or pile fixation fluid flowing out into the borehole. It is necessary to sink the pile, and the pile is pushed in using auxiliary means such as yatco and weight in addition to the weight of the pile.In such pushing, the center of the pile is displaced from the center of the drill hole, However, there was a tendency for the side of the borehole to be shaved, and the shaved soil accumulated on the bottom of the borehole, causing the pile to stop at a high height. In particular, when the pile length is long, the above tendency is remarkably a problem in construction.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in construction, and particularly to piles and steel pipe piles which are susceptible to buoyancy in an excavation hole due to a long pile length. It is an object of the present invention to propose a method of mounting a closed-end hollow pile which can be buried in a drilled hole without causing the above-mentioned problems without causing the above-mentioned problems. I do.

[0005]

Means for Solving the Problems The inventors of the present invention have carried out various experiments in order to solve the above-mentioned problems that occur when the closed-end hollow pile is built, and as a result, the closed-end hollow pile was prebored. When the hollow pile is installed in the borehole while rotating the hollow pile around the axis when the hollow pile is installed in the borehole, it has been found that the above problem is unlikely to occur, and the present invention has been completed. is there.

That is, according to the present invention, when the closed-end hollow pile is built into a pre-bored borehole, the closed-end hollow pile is built into the borehole while rotating about the axis thereof. Yes, this allows the embedding of the hollow tip closure pile into the borehole while substantially aligning the axis of the pile with the axis of the borehole.

Further, according to the present invention, in carrying out the invention, the diameter of the borehole and the diameter of the hollow pile with the tip closed are determined.
D (D + 50mm) or less, which makes it possible to create a frictional force between the excavated pile wall and the pile to counter the buoyancy generated in the pile, and to make the building smooth Things.

Further, in carrying out the present invention, the present invention uses a steel pipe pile as the hollow pile closed at the tip, and can easily solve the problem caused by buoyancy generated when piles are built in a conventional steel pipe pile. It is to be.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be specifically described with reference to an example in which the present invention is applied to a so-called pile pushing method. As shown in FIG. 1, in the pile driving method,
First, set the pile driver and stagger 1 at the specified pile installation point,
The drill hole 4 is excavated by rotating the spiral auger 2 and the tip bit 3 attached to the tip of the spiral auger 2 (a).
Then, the pushing pile 11 with the tip cap 13 set at the tip thereof is drooped into the excavation hole 4 by the stakeout strut 1 (b). Then, hitting hammer 2 on pile driver 1
1 and the upper hammer 22, and the tip impact hammer 21 is passed through the through hole 14 of the pile body 12 so that the tip cap 1
3 reach the bottom plate 15 (c), the tip impact hammer 21
Thereby, the bottom plate 15 of the tip cap 13 is hit with the upper hitting hammer 22 on the head of the pile body so that the tip of the pile reaches the support layer 5 (d). Further, as shown in FIG. 1 (e), the bottom plate 15 of the tip cap 13 is hit by the tip hitting hammer 21 and the head of the pile body is hit by the upper hitting hammer 22 to set the tip of the pile at a predetermined depth in the support layer. Driving to obtain the specified support force.

In the present invention, the above steps (b) to (b)
In (c), the pile body 12 is rotated along its axis 31. Taking the case where the pile body 12 is a concrete pile 32 as an example, an end plate 33 provided at the head of the concrete pile 32
By using a bolt, a metal member 35 provided with a claw 34 is attached to the pile rotating cap 37 shown in FIG. 3, and the pile rotating cap 37 is provided on the pile inner tower 1 (shown in FIG. 3). No). Here, the pile rotating cap 37 is formed by cutting an engagement groove 39 into a cylindrical metal piece 38 whose upper end is closed, and by connecting the rotating shaft 40 to a rotating mechanism (not shown) provided in the peg 1 of the pile. The concrete pile 34 is configured to be rotatable.

When the pile body 12 is a steel pipe pile 41, as shown in FIG. 4, a nail 42 is attached to the steel pipe pile 41 itself by welding or the like, and this is engaged with a pile rotation cap 43 and rotated. What should I do? The structure of the pile rotation cap 43 is similar to that of the pile rotation cap 37 used for the concrete pile 32, and the steel pipe pile head engaging groove 45 may be cut into the cylindrical hardware 44 and connected to the rotation shaft 46.

Using the rotation mechanism configured as described above, the pile (in this case, the pushing pile 11 configured as a closed-end hollow pile) is suspended in the excavation hole 4 and furthermore, the pile main body 12 is suspended in the process of being built. Is rotated together with the tip cap 13. As a result, the pushing pile 11 is suspended substantially vertically, and the tip of the pushing pile 11 can reach the bottom of the drill hole while being positioned at the center of the drill hole 4. Further, even if the tip of the pushing pile 11 hits the side surface of the excavation hole 4, since the pushing pile 11 is rotating, the pile 11 can be laid relatively without resistance. It should be noted that the rotation speed is not particularly limited, and may be set to such an extent that the frictional force between the outer periphery of the pile and the periphery of the excavation hole is reduced when the pile is laid. The rotation does not need to be in one direction, but can be reversed as appropriate.

In the above case, it is effective to set the diameter of the excavation hole to +50 mm or less with respect to the diameter of the hollow pile with the tip closed as described below. First, the clearance between the borehole and the closed-end hollow pile became smaller,
With the rotation, friction occurs between the pushing pile 11 and the excavation hole 4 via, for example, muddy water, a pile circumference fixing liquid, or the like,
The pile works as if it were pushed by a screw, and even if buoyancy is exerted on the pushing pile 11 by muddy water, pile surrounding fixing liquid, or the like, the pile can be pushed efficiently against this.

Such an operation is effective for a concrete pile having a long pile length, which is likely to be lifted by buoyancy, but is particularly effective for a steel pipe pile having a hollow portion having a large volume. For example, nominal diameter 600mm, pile length 20m
When a pile of steel pipe is set in a drill hole, the pile cannot be set to a predetermined position by its own weight due to buoyancy due to water in the hole if the pile is not rotated as in the past. When the pile was excavated with a diameter of +20 mm and rotated by applying the method of the present invention, the pile could be laid down to a predetermined position only by its own weight. As a result, there was no need to perform any additional work, such as installing weights to prevent the lifting of piles, which was necessary in the past, and the time required for building piles was reduced by an average of 40%.

When the present invention is applied to a concrete pile, care must be taken so that the rotation torque applied to the pile when rotating the pile does not exceed the torsional resistance moment of the pile. For example, in PHC piles, the resistance moment required according to the pile diameter (nominal diameter), thickness, and type of pile must be lower.

Although the specific embodiment of the present invention has been described above as being applied to a pile pushing method, the scope of the present invention is not limited to this, and is widely applied to a method of laying a hollow pile with a closed tip. You can do it. For example,
It can be suitably used for a cement milk method and the like. Also, the type of pile is not limited to concrete piles or steel pipe piles, but can be applied to these composite piles and further to these node piles.

[0017]

According to the present invention, it is possible to effectively prevent piles from being stopped at a high height, which tends to occur when a closed-end hollow pile is conventionally installed in a pre-bored borehole.
In addition, it is now possible to settle the closed-end hollow pile, which had been difficult to settle smoothly due to buoyancy, mainly by its own weight, shortening the time required for building the pile.
The cost of incidental equipment such as weights was reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the entire process in the case where the present invention is applied to a pile driving method, which is an example of an embodiment of the present invention.

FIG. 2 is a plan view (a) and a side sectional view (b) of an example of a pile head structure for rotating a concrete pile.

FIG. 3 is a side view of a rotating cap for rotating a concrete pile.

FIG. 4 is a plan view (a) and a side sectional view (b) of an example of a pile head structure for rotating a steel pipe pile.

FIG. 5 is a side view of a rotating cap for rotating a steel pipe pile.

[Explanation of symbols]

 1: Pile driving tower 2: Spiral auger 3: Tip bit 4: Drilling hole 5: Support layer 11: Pushing pile 12: Pile body 13: Tip cap 14: Through hole 15: Bottom plate 21: Pile tip hammer 22: Top Hammer 31: Axis line 32: Concrete pile 33: End plate 34: Claw 35: Hardware 36: Bolt 37: Pile rotation cap 38: Cylindrical hardware 39: Engagement groove 40: Rotating shaft 41: Steel pipe pile 42: Claw 43: Pile Rotating cap 44: Tubular hardware 45: Steel pipe pile head engaging groove 46: Rotating shaft

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masanobu Okubo 2-17-4 Kuramae, Taito-ku, Tokyo F-term in Kawatetsu Techno Construction Co., Ltd. 2D050 AA03 AA06 CA01 CB05 CB13 EE03 EE06

Claims (3)

[Claims] 2. The method according to claim 1, further comprising the step of: mounting the closed-end hollow pile in the pre-bored borehole while rotating the closed-end hollow pile around the axis thereof. How to build a closed hollow pile. 2. The diameter of the borehole and the diameter of the closed-end hollow pile
2. The method according to claim 1, wherein when it is D, it is not more than (D + 50 mm). 3. The method according to claim 1, wherein the hollow pile having a closed tip is a steel pipe pile.