JP2005240395A - Rotary embedding method for pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary embedding method for a pile by which the quantity of excavated waste soil is small, running torque generated in the rotary embedding of the pile is small, and the misalignment of the pile and a bend (clearance) are hardly generated. <P>SOLUTION: By the rotary embedding method for the pile, the primary excavation of the ground 3 is carried out so as to form a hole having a diameter equal to or larger than the outer diameter of a pile 5 body and smaller than the outer diameter of a spiral blade 5a, and thereafter a secondary excavation step is repeatedly carried out at a predetermined location of the primarily drilled hole 4a so as to have a diameter larger than the outer diameter of the spiral blade 5a until the secondary excavation reaches a predetermined depth. Thereafter an expansively drilled hole 4b is formed at the front end of the drilled hole 4, and a hardening material is filled into the expansively drilled hole 4b. Further when the pile 5 is rotatively embedded in the drilled hole 4, the spiral blade 5a is settled in the expansively drilled hole 4b while soil discharged to the ground is back-filled into a pile hollow portion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a pre-boring method for ready-made piles, and more particularly to a pre-boring rotary burying method for piles having spiral blades at the outer periphery of the tip.

Conventionally, various construction methods for ready-made piles have been developed, but low-pollution construction methods are required in urban areas.

The conventional method of pre-boring rotary embedding of piles with spiral blades is to drill a vertical hole deep enough to reach the support layer in advance, and inject cement milk for consolidation into the tip of the vertical hole. Before the milk solidifies, the pile with the overhanging wings is inserted while rotating, and when the tip reaches the lower end of the vertical hole, the cement milk is stirred downward while pushing the cement milk downward with the overhanging wings. Some are pressed against the inner wall surface and bulge into a bulb shape (see, for example, Patent Document 1).

In addition, there is a type in which a solidified material such as cement milk is injected while excavating the ground in advance, and the hollow pipe pile having spiral wings is rotated and embedded in the drilling hole (for example, see Patent Document 2).

Also, after rotating the hollow shaft of the open / close excavating blade in a forward direction and injecting and stirring cement milk while excavating the ground in advance with the open / close excavating blade having a reduced diameter, the hollow shaft is rotated in the reverse direction to enlarge the open / close excavating blade After forming an enlarged hole at the tip of the excavation hole, and then rotating the hollow shaft forward again and pulling up the open / close excavation blade in a reduced diameter state, the pile provided with the spiral blades is pushed in while drilling to excavate Some are embedded in a fistula filled with cement milk mixed with soil (for example, see Patent Document 3).

Japanese Patent No. 2668384 (FIG. 3) JP-A-4-185813 (FIGS. 1 to 2) Japanese Patent Application Laid-Open No. 60-238515 (FIGS. 6 to 9)

However, in the above-described conventional example, in the technique of Patent Document 1, since the pre-boring is excavating the vertical hole with a diameter smaller than the outer diameter of the overhanging blade provided on the outer peripheral portion of the tip of the pile, the pile is rotated and inserted. When projecting, the overhanging wings come into contact with the hard ground, so a large torque is required, and the pile insertion work takes time.

In the techniques of Patent Documents 2 and 3, pre-boring is excavated with a diameter larger than the outer diameter of the spiral blade provided at the outer periphery of the tip of the hollow tube pile, so a large amount of excavated soil is generated during pre-boring. Since the pre-boring is excavated with a diameter larger than the outer diameter of the spiral blade, there has been a problem that the center misalignment or bending (escape) of the pile tends to occur when the hollow pipe pile is rotationally embedded.

The present invention solves the above-mentioned problems, and the object of the invention is that there is little excavation and excavation, rotational torque at the time of rotary laying of the pile is small, and misalignment and bending (escape) of the pile occur. It is intended to provide a difficult method of rotating piles.

In order to achieve the above object, the method of rotating and embedding a pile according to the present invention, when embedding a pile having a spiral blade at the outer periphery of the tip, is 70% or more of the pile main body diameter and the outer diameter of the spiral blade. After excavating to a predetermined depth while repeatedly excavating a predetermined position of the primary excavation hole with a diameter larger than the outer peripheral diameter of the spiral blade, An enlarged excavation hole is formed at the tip of the excavation hole, and the expanded excavation hole is filled with a hardened material, and the pile is rotated and embedded in the excavation hole, and the spiral blade is placed in the enlarged excavation hole. It is characterized in that piles are installed while soil discharged to the ground when settling is backfilled in the pile hollow part.

Since the present invention is configured as described above, first, the ground torque is first excavated with a diameter of 70% or more of the pile main body diameter and smaller than the outer peripheral diameter of the spiral blade, so that the rotational torque when the pile is rotationally buried is obtained. In addition to reducing the pile pile, it is possible to leave an appropriate ground hardness on the outer periphery of the pile body so that the pile will not be bent (run away), and the diameter of the preceding excavation (primary excavation hole) is preferably 90% or more of the main body diameter. In particular, it is more preferable that the diameter is equal to or larger than the pile main body diameter, because the rotational torque at the time of rotational embedding is reduced most, and the bending (escape) of the pile does not occur at the time of rotational embedding of the pile.

Next, by selectively excavating a predetermined position of the primary excavation hole with a diameter larger than the outer peripheral diameter of the spiral blade, an arbitrary range such as a hard formation portion as the predetermined position is selectively expanded and excavated. Since the outer periphery of the spiral blade can be loosened over a wide range, it is possible to reduce the rotational torque at the time of rotary laying of the pile, and the excavation hole is a hollow part created by preceding excavation (primary excavation) and expanded excavation (secondary excavation) ), It is possible to create an ideal excavation hole that does not cause the tip of the pile to escape due to the small resistance of the tip of the pile when it is buried by rotation.

In the secondary excavation (expanded excavation), the outer peripheral ground of the spiral blade may be loosened over a wide range by enlarging the entire length of the primary excavation (preceding excavation) hole.

Next, an enlarged excavation hole is formed at the tip of the excavation hole, and a hardened material is filled in the enlarged excavation hole, so that a pile is rotated and embedded in the excavation hole, and the spiral blade is placed in the enlarged excavation hole. It is possible to form an enlarged root-fixing bulb by arranging and fixing to a large pile, and a large pile tip support force can be obtained.
As an example of the hardened material, a cement hardened material slurry may be injected or cement powder or the like may be filled. The cement powder can be mixed with water used during excavation or the like and water contained in the ground to form a slurry.
In the pile embedding process, the pile is rotated and buried while the soil discharged on the ground in the excavation process or the like is backfilled in the hollow portion of the pile, so that the final total amount of soil can be reduced.

Since the present invention has the above-described configuration and action, the excavation soil is small, the rotational torque is small when the pile is buried, and the pile is buried less likely to be misaligned or bent (escape). A method can be provided.

An embodiment of a rotary embedding method for piles according to the present invention will be specifically described with reference to the drawings. 1 and 2 are diagrams for explaining a rotary burying method for piles according to the present invention, and FIG. 3 is a diagram showing a state in which a predetermined position from an enlarged excavation hole to the ground surface or near the ground surface is selectively partially expanded. FIG. 4 is a diagram showing the configuration of various spiral blades provided on the outer periphery of the tip of the pile.

In FIG. 1, reference numeral 1 denotes a drilling rod that is driven to rotate by an auger motor (not shown) to dig a drilling hole 4 in which a pile 5 is embedded. A spiral blade 1 a is attached to the peripheral surface of the drilling rod 1. The enlarged excavation bit 2 is provided at the tip.

Further, between the spiral blade 1 a and the enlarged excavation bit 2, a stirring blade 9 that rotates integrally with the excavation rod 1 and a co-rotation prevention device 10 that is provided so as to be rotatable with respect to the excavation rod 1 are attached. ing.

As shown in FIG. 1 (b), the enlarged excavation bit 2 includes a ground 3 as the excavation rod 1 is reversed.
A pair of enlarged excavating blades 6 that can be expanded by contact with are provided. And FIG. 1 (a),
As shown in (c), when the excavation rod 1 rotates forward, the enlarged excavation blade 6 is locked in a state of being housed inside the outer diameter of the spiral blade 1a. Further, when the excavation rod 1 rotates in the forward direction, the excavation rod 1 advances in the direction of digging the ground 3 by the normal rotation of the spiral blade 1a.

Further, as shown in FIG. 1 (b), in the state where the excavation rod 1 is reversed, the enlarged excavating blade 6 bites into contact with the wall surface of the ground 3, and the enlarged excavating blade 6 is expanded by its resistance force, The enlarged excavation blade 6 is locked in a state of protruding outward from the outer diameter of the spiral blade 1a. Further, when the excavation rod 1 reverses, the excavation rod 1 advances in the direction of pulling up from the ground 3 by the reverse rotation of the spiral blade 1a.

The excavation rod 1 is hollow inside and also serves as a pipe. As shown in FIGS. 1 (a) and 1 (c), air, water, drilling fluid, etc. are ejected from the nozzle at the tip of the excavation rod (primary cutting). Is configured to do. In FIG. 1, reference numeral 8 denotes an excavation blade provided at the tip of the enlarged excavation bit 2 rather than the outer diameter of the spiral blade 1 a.

1 (a) to 1 (f), using the above-described expanded excavation bit 2, excavating the excavation hole 4 in which the pile 5 having the spiral blade 5a on the outer peripheral portion of the tip is buried while repeating primary cutting and secondary cutting. First, the axis of the enlarged excavation bit 2 provided at the tip of the excavation rod 1 is aligned with the pile core position, and an auger motor (not shown) is rotated to rotate the excavation rod 1 in a normal direction. (A
), The ground 3 is dug down in a state where the enlarged excavating blade 6 is housed to form a small-diameter excavation hole (primary cutting hole) 4a corresponding to the outer diameter of the spiral blade 1a.

The outer diameter of the spiral blade 1a of the excavating rod 1 is larger than the outer diameter of the main body of the existing pile 5 shown in FIG. 2 and smaller than the outer diameter of the spiral blade 5a provided at the outer periphery of the tip of the pile 5. It is set by the diameter. As a result, the small diameter drilling hole (primary cutting hole) 4a primarily excavated by the excavating rod 1 shown in FIG. 1A is excavated with a diameter larger than the outer diameter of the pile 5 body and smaller than the outer diameter of the spiral blade 5a. Is done.

Examples of the prefabricated pile 5 include a concrete pile, a steel pipe concrete pile, and a steel pipe pile. In addition, when the spiral blade 5a provided at the tip is made of steel, the pile at the tip is made of a steel pipe concrete pile or a steel pipe pile, or even in the case of a concrete pile, a bellows is wrapped with a steel pipe and welded to this, etc. May be provided. In the case of a concrete pile, a concrete spiral blade may be integrally formed with the pile body using a mold.

At the time of primary excavation, air is supplied to the pipe provided inside the excavation rod 1 from a compressor or the like installed on the ground, and excavation is performed while injecting air from the pipe tip nozzle.
The ground 3 is dug down to a predetermined depth. Do not use water, drilling fluid, etc. during pre-drilling (primary cutting)
When drilling air is used, industrial waste can be reduced and the construction site can be cleanly constructed. Of course, water, drilling fluid or the like may be used. When an appropriate amount of bentonite drilling fluid is used when excavating sandy collapsible ground, not only excavation torque and pile burying torque are reduced, but the final total amount of soil removal may be reduced.

After the above-mentioned primary cutting, as shown in FIG. 1B, the small-diameter drilling hole (primary drilling hole) 4a is drilled over almost the entire length while switching the rotation of the auger motor and pulling up the enlarged drilling bit 2 (secondary drilling). Drilling). That is, the small-diameter cutting hole (primary excavation hole) 4a in a state where the excavation rod 1 is switched from normal rotation to reverse rotation and the expanded excavation blade 6 protrudes outside the outer diameter of the spiral blade 1a.
Is expanded (secondary excavation) over almost the entire length to form a large diameter excavation hole 4c. Enlarged drilling blade 6
The outer peripheral diameter is set to be larger than the outer peripheral diameter of the spiral blade 5 a of the pile 5. Thereby, the large-diameter drilling hole 4c secondary drilled by the drilling rod 1 shown in FIG. 1 (b) has a diameter larger than the outer peripheral diameter of the spiral blade 5a of the pile 5 over almost the entire length of the primary drilling hole 4a. Expanded excavation.

And again, as shown in FIG.1 (c), the ground 3 in the state which accommodated the expansion excavation blade 6 inside the outer periphery of the spiral blade | wing 5a, switching rotation of an auger motor and rotating the excavation rod 1 forward.
The primary excavation. Thus, after performing the primary excavation which excavates the ground 3 in the state which accommodated the expansion excavation blade 6 in the inside rather than the outer periphery of the spiral blade 5a, the expansion excavation blade 6 is outside the outer diameter of the spiral blade 1a. Excavating to a predetermined depth while repeating the step of performing secondary excavation in which the primary excavation hole 4a is extended and excavated over substantially the entire length in a state of protruding to the right.

After excavating the ground 3 to a predetermined depth, as shown in FIG. 1 (e), the excavating rod 1 is reversely rotated to expand the enlarged excavating blade 6 and excavated. As an example, the drilling hole 4c is pulled up to the bottom of the large-diameter drilling hole 4c to form an enlarged drilling hole 4b continuous with the large-diameter drilling hole 4c at the tip of the drilling hole 4 and provided from the batcher plant installed on the ground to the inside of the drilling rod 1 For example, a cement hardened body slurry, which is a root hardening liquid, is supplied to the pipe as an example of a hardened body material, and the cement hardened body slurry is injected into the enlarged excavation hole 4b from the pipe tip nozzle.

The hardened material filled in the expanded excavation hole 4b may be filled with cement powder or the like. The cement powder can be mixed with water used during excavation or the like or water contained in the ground 3 to form a slurry.

In FIG. 1 (d), during the primary excavation after the secondary excavation, before the excavation blade 8 reaches the target depth, the excavation rod 1 is switched from normal rotation to reverse rotation to expand the expansion excavation blade 6. The ground 3 can also be dug down to form an enlarged excavation hole 4 b at the tip of the excavation hole 4.

And if necessary, as shown in FIG.1 (f), while excavating the expansion excavation hole 4b, repeating the excavation rod 1 up and down, the excavation rod 1 is taken from the batcher plant installed on the ground.
As an example of a hardened material, a cement hardened body slurry, which is a root hardening liquid, is supplied to a pipe provided inside the pipe, and the cement hardened body slurry is injected into the enlarged excavation hole 4b from the pipe tip nozzle. Cement milk or the like can be applied as the slurry for the cement cured body to be injected.

Note that the large-diameter excavation hole 4c is not necessarily provided in a predetermined section near the ground surface. If you want to expect a large horizontal resistance to the pile 5, at the time of the secondary excavation after the first primary excavation, reverse excavation and pulling up to a predetermined depth near the ground surface, and then pulling forward again (primary excavation) It is also possible to avoid loosening the ground in a predetermined section near the pile head extensively by repeating the extended excavation (secondary excavation) by reverse rotation. Further, if necessary, it is possible to give a larger horizontal resistance by injecting slurry for cement hardened body into a predetermined section near the head of the pile or all sections to harden the periphery of the pile firmly.

As shown in FIG. 2, after the primary drilling of the small-diameter drill hole 4a in the ground 3 as shown in FIG. After excavating to a predetermined depth while repeating the step of secondary excavation of the excavation hole 4c, an enlarged excavation hole 4b is formed at the tip thereof, and a slurry for a hardened cement body as an example of a hardened material in the enlarged excavation hole 4b It is a figure which shows a mode that the hole 5 is inject | poured and the excavation hole 4 is formed, and the pile 5 is rotationally embedded in the excavation hole 4. FIG.

As shown in FIG. 2A, before the cement cement slurry injected into the enlarged excavation hole 4b is cured, the pile 5 provided with the spiral blade 5a on the outer periphery of the tip is set on an auger motor (not shown). The shaft center of the pile 5 is aligned with the pile core position, and the auger motor is rotationally driven to dig down the ground 3 while rotating the pile 5 in a normal direction, and rotationally embedded in the excavation hole 4.

  At this time, as shown in FIG. 2 (a), the amount of soil discharged is reduced by filling the hollow pile 5 with the soil 11 discharged to the ground surface by the excavation process so far and filling it back. I can do it. When two or more piles are connected, the reduction efficiency may be improved if the discharged soil is backfilled in the lower pile hollow portion for each connection of the piles.

And as shown in FIG.2 (b), the pile 5 is rotationally embedded until the spiral blade | wing 5a of the pile 5 is arrange | positioned in the enlarged excavation hole 4b, The slurry for cement hardening bodies injected into the enlarged excavation hole 4b Is hardened, the spiral blade 5a of the pile 5 is fixed in the enlarged excavation hole 4b, and the pile 5 in which the enlarged rooted bulb portion is formed can be embedded in the ground 3. The earth and sand in the excavation hole 4 is compressed and compacted and fixed to the side wall surface side of the excavation hole 4 when the pile 5 is rotationally embedded.

The vicinity of the ground surface on the outer periphery of the head of the pile 5 can be filled with cement milk or the like to a predetermined depth to improve the surface ground.

According to the above-described rotational embedding method of the pile 5, first, when the pile 5 is rotationally embedded by excavating the ground 3 with a diameter larger than the outer peripheral diameter of the pile 5 main body and smaller than the outer peripheral diameter of the spiral blade 5a. In addition to reducing the rotational torque of the pile 5, it is possible to leave an appropriate hardness of the ground 3 on the outer periphery of the pile 5 main body so that the pile 5 does not bend (escape) when the pile 5 is rotationally embedded.

Next, the spiral blade 5a is enlarged and drilled over substantially the entire length of the pile 5 by pulling up and drilling over the entire length of the small-diameter drill hole 4a, which is a primary drill hole, with a diameter larger than the outer peripheral diameter of the spiral blade 5a. Since the outer peripheral ground 3 of 5a can be loosened in a wide range, the rotational torque when the pile 5 is rotated and buried can be reduced, and the excavation hole 4 is a small-diameter excavation hole 4a composed of a hollow portion generated by the preceding excavation as the primary excavation. And because of the two-layer structure of the large-diameter drilling hole 4c formed by the soft excavation that is the secondary excavation, the tip resistance when rotating the pile 5 by the leading drilling hole is small, and the pile tip escapes. An ideal excavation hole 4 that does not occur can be created.

Next, an enlarged excavation hole 4b is formed at the tip of the small-diameter excavation hole 4a and the large-diameter excavation hole 4c, and slurry for cement hardened body, which is a hardened material, is injected into the enlarged excavation hole 4b. The pile 5 can be rotationally embedded in the hole 4 and the spiral blade 5a can be placed and fixed in the enlarged excavation hole 4b to form an enlarged root-clamping bulb portion, and a large pile tip support force can be obtained. .

In this embodiment, excavation fluid such as water is not used, and excavation is performed mainly for the purpose of loosening the ground 3, so there is almost no soil removal during excavation.

Further, the preceding excavation, which is the primary excavation, rotates the excavating rod 1 in the forward direction, and the lifting excavation, which is the secondary excavation, is performed in the reverse rotation to that during the primary excavation, so the force that leaves the loose ground 3 in the excavation hole 4 Can work to further reduce excavation and soil removal.

In the above-described embodiment, the excavation rod 1 is reversed and the enlarged excavation blade 6 is expanded. However, the enlargement excavation blade 6 is provided with a hydraulic mechanism or the like by using an excavation apparatus having a separate hydraulic path in the excavation rod. It can be set as the structure expanded by. In this case, the enlarged excavation can be performed regardless of the rotation direction of the excavation rod 1, and the outer diameter of the enlarged excavation hole 4b and the outer diameter of the large-diameter excavation hole 4c can be easily adjusted to different outer diameters. Further, by using a drilling device in which a high-pressure water pipe is separately built in the drilling rod, it is possible to perform an extended drilling with high-pressure jet water. In this case as well, excavation rod 1 can be excavated while rotating normally.

FIG. 3 is a diagram showing a state where the predetermined position of the primary excavation hole is selectively partially expanded at the time of the secondary excavation, that is, the process leading to FIG. Until the hard ground layer 3a of the ground 3 is reached, the ground 3 is pulled up and excavated while the expanded excavating blade 6 is housed while the excavating rod 1 is rotated forward, and the expanded excavating blade 6 reaches the lower part of the hard ground layer 3a. Drilling rod 1
And the expanded excavating blade 6 is expanded and the excavated drilling blade 6 is lifted and excavated in the range of the hard formation 3 a of the ground 3, and the large excavated hole 4 c discontinuous with the expanded excavated hole 4 b is formed in the middle portion of the excavated hole 4. To form.

Then, when the enlarged excavating blade 6 passes through the upper portion of the hard formation 3a, the excavating rod 1 is switched from reverse rotation to normal rotation, and the ground 3 is dug down again while the enlarged excavating blade 6 is stored. Others can be constructed in the same manner as described above with reference to FIGS.

FIG. 4 is a diagram showing the configuration of various spiral blades 5 a provided on the outer periphery of the tip of the pile 5. The spiral blade 5a provided on the outer periphery of the tip of the pile 5 shown in FIG. 2 is an example in which three spiral blades 5a having the same outer diameter are provided on the outer periphery of the tip of the pile 5. However, as shown in FIG.
Of the three spiral blades, the outer peripheral diameter of the spiral blade 5a at the most advanced part can be made large, and the outer peripheral diameter of the spiral blade 5b at the middle part and the upper part can be made small.

Since the supporting force of the pile 5 increases according to the cross-sectional area of the tip portion of the pile 5, the supporting force of the pile 5 is ensured by increasing the outer peripheral diameter of the spiral blade 5a at the most advanced portion. The cost can be reduced by reducing the outer peripheral diameters of the remaining intermediate and upper spiral blades 5b.

The pile 5 shown in FIG.4 (b) is an example of a ready-made concrete pile, and has the enlarged diameter part 5c by which the front-end | tip part of the pile 5 was expanded. Thereby, the outer peripheral diameter of the spiral blade 5a at the most advanced portion provided on the outer peripheral portion of the enlarged diameter portion 5c can be made large, and the outer periphery diameter of the spiral blade 5b at the intermediate portion and the upper portion can be made small. The cost can be reduced by reducing the width of the spiral blade 5a.

The spiral blade 5d shown in FIG. 4 (c) has a structure divided into two in a semi-ring shape, and is inclined with respect to the axial direction of the pile 5 and arranged in a direction crossing each other so as to have a phase shift. 5 is provided at the outer periphery of the tip.

Further, the spiral blade 5e shown in FIG. 4 (d) has a structure that is divided into four crescents, and is arranged sequentially in a direction inclined with respect to the axial direction of the pile 5 so as to have a phase shift. It is provided at the outer periphery of the tip.

Further, the spiral blade 5f shown in FIG. 4 (e) arranges a plurality of flat bars in a direction slightly inclined with respect to the axial direction of the pile 5, and the tip of the pile 5 so that the whole is arranged in a spiral shape. It is the structure which provided in the outer peripheral part and divided into multiple.

As shown in FIGS. 4C to 4E, the cost can be reduced by dividing the spiral blade provided on the outer peripheral portion of the tip of the pile 5 into a plurality of pieces.

FIG. 4 (f) shows an example in which the outer peripheral diameter of the spiral blade 5a at the foremost part is large, and a plurality of ridge rings 12 having a small outer diameter are provided in place of the spiral blades at the middle part and the upper part. In addition, FIG.
Is a spiral blade 5d similar to that shown in FIG. 4C, in which the spiral blade at the foremost part has a large outer diameter and is divided into a half ring shape, and the height is substituted for the spiral blades at the middle part and the upper part. A plurality of small protrusions 13 are provided. As shown in FIGS. 4 (f) and 4 (g), instead of the spiral blades provided on the outer periphery of the tip of the pile 5, the cost is reduced by using a ridge ring 12 having a small outer diameter or a protrusion 13 having a small height. You can go down.

As an application example of the present invention, the present invention can be applied to a pre-boring method for ready-made piles such as concrete piles, steel pipe concrete piles, steel pipe piles, etc., in particular, a pre-boring rotary burying method for piles having spiral blades at the outer periphery of the tip.

It is a figure explaining the rotation embedding construction method of the pile concerning the present invention. It is a figure explaining the rotation embedding construction method of the pile concerning the present invention. It is a figure which shows a mode that the predetermined position of a primary excavation hole is selectively expanded partially. It is a figure which shows the structure of the various spiral blade | wing provided in the front-end | tip outer peripheral part of a pile.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drilling rod 1a ... Spiral blade 2 ... Expansion drill bit 3 ... Ground 3a ... Hard formation 4 ... Drilling hole 4a ... Small diameter drilling hole 4b ... Expansion drilling hole 4c ... Large diameter drilling hole 5 ... Pile 5a, 5b, 5d, 5e ... Spiral blade 5c ... Diameter expansion part 6 ... Expansion excavation blade 8 ... Excavation blade 9 ... Stirring blade
10 ... Spinning prevention device
11 ... Soil generated
12 ... Spring ring
13 ... Protrusions

Claims (1)

  In burying a pile having spiral blades at the outer periphery of the tip, after the primary excavation of the ground with a diameter of 70% or more of the pile body diameter and smaller than the outer periphery diameter of the spiral blades, the outer diameter of the spiral blades After excavating to a predetermined depth while repeating the step of secondary excavation at a predetermined position of the primary excavation hole with a larger diameter, an enlarged excavation hole is formed at the tip of the excavation hole, and the enlarged excavation hole Filling the inside with a hardened body material, burying the pile in the excavation hole, and refilling the pile hollow portion with the soil discharged to the ground when fixing the spiral blade in the enlarged excavation hole A pile laying method characterized by installing piles.

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