JP2006161519A - Rotating embedding method for piles with concrete spiral projections - Google Patents

Abstract

An object of the present invention is to provide a method for burying concrete piles with less excavation and excavation, low rotational torque when piles are laid, and less likely to cause misalignment of piles.
When rotating and embedding a ready-made concrete pile having a small-diameter portion at the tip of the pile and having a concrete helical protrusion on the outer periphery of the small-diameter portion, the ground has a diameter smaller than the outer peripheral diameter of the concrete helical protrusion. After drilling, the expanded drilling hole is formed and the hardened body material is filled, and then a predetermined position reaching the ground surface or near the ground surface with a diameter larger than the outer peripheral diameter of the spiral projection is pulled up and drilled. A method of rotating and embedding a concrete pile, characterized in that the pile is rotationally embedded in an excavation hole and fixed in the enlarged excavation hole.
[Selection] Figure 2

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 a spiral protrusion on 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.
A conventional method for pre-boring rotary embedding of piles having spiral protrusions is to drill a vertical hole with a depth that reaches 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 a hollow tube pile having spiral blades is embedded in a drilling hole while rotating (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. In this case, since the overhanging wing contacts the hard ground, a large torque is required, and it is difficult to make the overhanging wing from concrete from the viewpoint of strength.
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 method for rotating and embedding prefabricated concrete piles having difficult concrete spiral projections.

To achieve the above object, the present invention is as follows.
(1) A small-diameter portion is provided at the tip of the pile, and there is at least one concrete spiral protrusion for approximately one to several turns on the outer periphery of the small-diameter portion, and the outer diameter of the concrete spiral protrusion is the maximum of the pile. When rotating and embedding a ready-made concrete pile having a diameter equal to or larger than the outer diameter, after excavating the ground with a diameter of 70% or more of the pile body diameter and smaller than the outer diameter of the concrete spiral protrusion, 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 then the surface of the expansion excavation hole is larger than the outer peripheral diameter of the concrete spiral projection or from the ground surface or A method for rotationally burying piles, wherein a predetermined position reaching the vicinity of the ground surface is pulled up and excavated, and the pile is rotationally embedded in the excavation hole and fixed in the enlarged excavation hole.
(2) The pile embedding method according to (1), wherein the ready-made concrete pile has at least one concrete spiral protrusion or concrete nodular protrusion on the pile main body.
(3) The rotational embedding method of a pile according to (1) or (2), in which the outer peripheral diameter of the small-diameter portion at the tip of the pile is 65% to 98% of the outer peripheral diameter of the pile main body.
(4) The method for rotationally embedding a pile according to any one of (1) to (3), wherein the shape of the concrete spiral protrusion near the tip of the ready-made concrete pile is a trapezoid.

Since the present invention is configured as described above, first, the rotational torque when the pile is rotated and buried by excavating the ground with a diameter of 70% or more of the pile main body diameter and smaller than the outer peripheral diameter of the concrete spiral projection. In addition, it is possible to leave an appropriate ground hardness on the outer periphery of the pile body so that the pile does not bend (escape) during rotation of the pile, and the preceding excavation diameter is preferably 90% of the pile body diameter. % Or more. 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, an enlarged excavation hole is formed at the tip of the excavation hole, and a hard material is filled in the enlarged excavation hole, so that a pile is rotationally embedded in the excavation hole and a concrete spiral projection or the like is enlarged. It can be placed and fixed in the excavation hole to form an enlarged rooted bulb portion, 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.

Next, by pulling up a predetermined position from the enlarged excavation hole to the ground surface or near the ground surface with a diameter larger than the outer peripheral diameter of the concrete spiral projection, for example, a predetermined position of a hard formation is expanded and excavated. Since the outer periphery of the spiral projection can be loosened over a wide range, the rotational torque during the rotary laying of the pile can be reduced, and the excavation hole is composed of a hollow part created by the previous excavation and a soft part produced by the expanded excavation. Since it has a layered structure, it is possible to create an ideal excavation hole that does not cause the tip of the pile to escape due to low resistance at the tip of the pile when it is rotated and buried due to the lead holes from the previous excavation.
The pulling excavation may be performed by enlarging the entire length of the pile from the enlarged excavation hole to the ground surface or the vicinity of the ground surface to loosen the outer peripheral ground of the spiral protrusion in a wide range.

  Since the present invention has the above-described configuration and action, it has less excavation and earth excavation, requires only a small rotational torque when rotating piles, and is difficult to cause pile misalignment and bending (escape). A rotation embedding method of a pile having a protrusion can be provided.

An embodiment of a method for rotary embedding piles according to the present invention will be specifically described with reference to the drawings. FIG. 1 and FIG. 2 are diagrams for explaining a method for rotationally embedding 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. 4 to 10 are diagrams showing the configuration of various protrusions provided on the pile.
In FIG. 1, reference numeral 1 denotes a drilling rod that is driven to rotate by an auger motor (not shown) and digs a drilling hole 4 in which a pile is buried. A spiral blade 1 a is attached to the peripheral surface of the drilling rod 1. An 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 (c), the enlarged excavation bit 2 is provided with a pair of enlarged excavation blades 6 that can be expanded by contact with the ground 3 as the excavation rod 1 is reversed. As shown in FIG. 1 (a), when the excavating rod 1 rotates forward, the enlarged excavating 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 a direction to dig down the ground 3 by the normal rotation of the spiral blade 1a.
Further, as shown in FIG. 1 (c), in a 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 FIG. 1A, the excavation rod 1 is configured such that air, water, excavation liquid, and the like are ejected from the nozzle at the tip of the excavation rod. 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.
FIGS. 1A to 1D are views showing a state in which the tip of the excavation hole 4 in which a pile having a spiral protrusion 5a is embedded in the outer periphery near the tip is enlarged and excavated by using the enlarged excavation bit 2. FIG. First, the shaft center 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 rotationally driven to rotate the excavation rod 1 forward as shown in FIG. Then, the ground 3 is dug down in a state where the expanded excavation blade 6 is accommodated, and a small-diameter excavation hole 4a corresponding to the outer diameter of the spiral blade 1a is formed.

The outer peripheral diameter of the spiral blade 1a of the excavating rod 1 is larger than the outer peripheral diameter of the ready-made pile main body 5 shown in FIG. 2 and smaller than the outer peripheral diameter of the spiral protrusion 5a provided at the tip small-diameter portion of the pile. The small-diameter excavation hole 4a excavated by the excavation rod 1 shown in FIG. 1 (a) is larger than the outer peripheral diameter of the pile main body 5 and smaller than the outer peripheral diameter of the spiral protrusion 5a. Drilled at.
Ready-made piles include concrete piles, steel pipe concrete piles, and steel pipe piles. The concrete spiral protrusion may be integrally formed with the ready-made concrete pile body using a mold.
At the time of excavation, air is supplied to a 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 nozzle at the end of the pipe, as shown in FIG. Thus, the ground 3 is dug down to a predetermined depth. If drilling air is used without using water, drilling fluid, etc. during advanced excavation, industrial waste can be reduced and the site can be constructed cleanly. 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 excavating the ground 3 to a predetermined depth, as shown in FIG. 1 (c), the excavating rod 1 is reversely rotated to expand the enlarged excavating blade 6, and the excavating rod 1 is pulled up by a predetermined section. A cement hardened body that is a solidified liquid as an example of a hardened body material is formed in a pipe provided inside the drilling rod 1 from a batcher plant installed on the ground while forming an enlarged drilling hole 4b at the tip of the drilling hole 4 The slurry for use is supplied, and the slurry for hardened cement body is injected into the enlarged excavation hole 4b from the nozzle at the end of the pipe.
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. 1B, 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 and excavate the ground 3 to excavate. An enlarged excavation hole 4b can also be formed at the tip end portion.
And if necessary, as shown in FIG.1 (d), while excavating the expansion rod 4b while repeating the excavation rod 1 up and down, it is provided in the inside of the excavation rod 1 from the batcher plant installed on the ground. As an example of the hardened body material, a cement hardened body slurry, which is a root hardening liquid, is supplied to 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.

Thereafter, as shown in FIG. 1 (e), the enlarged excavation bit 2 is pulled up to the surface of the ground 3 while maintaining the rotation of the auger motor in the reverse direction to form a large-diameter excavation hole 4c continuous with the enlarged excavation hole 4b. To do. (See FIG. 1 (f)).
The outer diameter of the enlarged excavation blade 6 is set to be larger than the outer diameter of the spiral protrusion 5a of the pile, whereby the large diameter excavation hole 4c excavated by the excavation rod 1 shown in FIG. Then, it is excavated with a diameter larger than the outer peripheral diameter of the spiral projection 5a of the pile from the enlarged excavation hole 4b to the surface of the ground 3.
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, you can reverse and expand to a predetermined depth near the ground surface, lift it up, then return to normal rotation and continue to lift it to loosen the ground in a predetermined section near the pile head extensively. It can be avoided. 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. 1, a small-diameter excavation hole 4a is preliminarily excavated in the ground 3 as shown in FIG. 1, and an enlarged excavation hole 4b is formed at the tip of the excavation hole 4b. After injecting the slurry, the large diameter drilling hole 4c is coaxially raised from the enlarged drilling hole 4b to the surface of the ground 3 on the outer periphery of the small diameter drilling hole 4a to form the drilling hole 4, and the drilling hole 4 is formed. Fig. 5 shows the case where piles are buried in rotation.
As shown in FIG. 2 (a), before the hardened cement slurry injected into the expanded excavation hole 4b is cured, a pile provided with a spiral projection 5a on the tip small diameter portion is set on an auger motor (not shown), The axis center of the pile tip is aligned with the pile core position, and the auger motor is driven to rotate, and the ground 3 is dug down and rotated and embedded in the excavation hole 4 while rotating the pile forward.
At this time, as shown in FIG. 2A, the excavated soil can be reduced by filling the hollow pile with the generated soil 11 excavated on the ground surface by the excavating rod 1 and backfilling it. .
Then, as shown in FIG. 2 (b), the pile is rotated and embedded until the spiral protrusion 5a of the pile is disposed in the enlarged excavation hole 4b, and the cement-curing body slurry injected into the enlarged excavation hole 4b is cured. By doing so, the pile-shaped protrusion 5a of a pile can be fixed in the enlarged excavation hole 4b, and the pile which formed the enlarged root consolidation bulb part can be embed | buried in the ground 3. FIG. 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 is rotationally embedded.
The ground surface near the outer periphery of the head of the pile can be filled with cement milk or the like to a predetermined depth to improve the surface ground.

According to the above-described method of rotating and embedding a pile, first, when excavating the ground 3 with a diameter larger than the outer peripheral diameter of the pile main body 5 and smaller than the outer peripheral diameter of the spiral protrusion 5a, While reducing a rotational torque, moderate hardness of the ground 3 can be left on the outer periphery of a pile main body so that a bending (escape) of a pile may not occur at the time of pile embedding.
Next, an enlarged excavation hole 4b is formed at the tip of the small-diameter excavation hole 4a, and a cement hardened body slurry, which is a hardened material, is injected into the enlarged excavation hole 4b. By rotating and embedding, the spiral protrusion 5a can be disposed 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.
Next, the outer periphery of the spiral projection 5a is expanded by excavating the entire length of the pile by pulling up from the expanded excavation hole 4b to the vicinity of the surface of the ground 3 with a diameter larger than the outer diameter of the spiral projection 5a. 3 can be loosened over a wide range, so that the rotational torque at the time of rotary burying of piles can be reduced. Since the large-diameter excavation hole 4c has a two-layer structure, an ideal excavation hole 4 in which the tip resistance when the pile is buried by rotation is small and the escape of the tip of the pile does not occur due to the guide hole by the preceding excavation.

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, since the excavation is performed by rotating the excavating rod 1 in the forward direction and the pulling is performed in the reverse direction from the excavation, the force for leaving the loose ground 3 in the excavation hole 4 works, so that the excavation soil can be further reduced. I can do it.
In the above embodiment, the excavation rod 1 is reversed and the enlarged excavation blade 6 is widened. However, the expansion excavation blade 6 is provided with a hydraulic mechanism by using an excavator with a separate hydraulic path in the excavation rod 1. It can be set as the structure expanded by etc. In this case, the excavation rod 1 can be excavated while rotating forward, 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 provided in the drilling rod 1, 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 shows a case where a predetermined position from the enlarged excavation hole 4b shown in FIG. 1 (d) to the ground surface or the vicinity of the ground surface is selectively partially enlarged, and the ground 3 measured in advance from the enlarged excavation hole 4b is shown. Until reaching the hard formation 3a, the excavation rod 1 is rotated forward while the expansion excavation blade 6 is housed and the ground 3 is pulled up and excavated. When the expansion excavation blade 6 reaches the lower part of the hard formation 3a, the excavation rod 1 is removed. In a state where the expanded excavation blade 6 is expanded in the reverse direction, the excavation is performed in the range of the hard formation 3 a of the ground 3, and a large diameter excavation hole 4 c discontinuous with the expanded excavation hole 4 b is formed in the middle portion of the excavation hole 4. Form.
Then, when the enlarged excavating blade 6 passes through the upper part of the hard formation 3a, the excavating rod 1 is rotated forward and the enlarged excavating blade 6 is housed and the excavated blade 6 is pulled up to the surface of the ground 3 for excavation. Others can be constructed in the same manner as described above with reference to FIGS.
FIG. 4 shows the configuration of the concrete spiral protrusion 5a provided on the small-diameter portion of the pile tip of the pile. Thus, it is preferable that the shape of the concrete spiral protrusion is a trapezoid because it is easy to manufacture and can be embedded in a rotating manner.

FIG. 5 shows a configuration in which a concrete spiral projection 5a and a concrete nodule projection 5b are provided on the small diameter portion of the pile tip.
FIG. 6 shows a configuration in which a concrete spiral protrusion 5a is provided on a pile tip small diameter portion and a pile main body portion.
FIG. 7 shows a configuration in which a concrete spiral projection 5a is provided on the pile tip small-diameter portion, and a concrete nodal projection 5b is provided on the pile body portion.
FIG. 8 shows a configuration in which a concrete spiral projection 5a and a concrete nodule projection 5b are provided at the small diameter portion of the pile tip, and a nodule projection 5b is provided on the pile main body.
FIG. 9 shows a configuration in which a concrete spiral protrusion 5a is provided at the small-diameter portion of the pile tip, and a node-like protrusion 5b is provided at the pile main body portion.
FIG. 10 shows a configuration in which a concrete spiral projection 5a and a concrete nodule projection 5b are provided at the small tip portion of the pile, and a nodule projection 5b is provided on the pile main body portion, and only the small diameter portion is disposed in the enlarged excavation hole. Is.
The location and number of the concrete spiral protrusions or the concrete nodular protrusions are not limited to the above. Further, only a small diameter portion may be used for rotating and embedding the pile and fixing it in the enlarged excavation hole.

  As an application example of the present invention, the present invention can be applied to a pre-boring method for concrete piles, in particular, a pre-boring rotary burying method for piles having spiral protrusions in the outer periphery near the tip.

It is a figure explaining the rotation embedding method of the pile concerning the present invention. It is a figure explaining the rotation embedding method of the pile concerning the present invention. It is a figure which shows a mode that the predetermined | prescribed position from the expansion excavation hole to the ground surface or the ground surface vicinity is selectively expanded partially. It is a figure which shows the structure of the concrete helical protrusion provided in the front-end | tip small diameter part of the pile. It is a figure which shows the structure of the concrete helical protrusion provided in the front-end | tip small diameter part of the pile, and the concrete nodal protrusion. It is a figure which shows the structure of the concrete helical protrusion provided in the pile tip small diameter part and the pile main-body part. It is a figure which shows the structure which provided the concrete helical protrusion in the pile front end small diameter part, and the concrete nodal protrusion in the pile main-body part. It is a figure which shows the structure which provided the concrete helical protrusion and the concrete nodular protrusion in the pile tip small diameter part, and provided the nodular protrusion in the pile main-body part. It is a figure which shows the structure which provided the concrete helical protrusion in the pile tip small diameter part, and provided the node-like protrusion in the pile main-body part. It is a figure which shows the structure which provided concrete spiral protrusion and concrete nodular protrusion in the pile tip small diameter part, provided the nodular protrusion in the pile main-body part, and has arrange | positioned only a small diameter part in the enlarged excavation hole.

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 excavation hole 5 ... Pile main body 5a ... Spiral projection 5b ... Nodal projection 5c ... Expanded portion 5d ... Pile small-diameter portion 6 ... Expanded excavation Blade 8 ... Excavating blade 9 ... Stirring blade 10 ... Co-rotation prevention device 11 ... Generated soil

Claims (4)

A small-diameter portion is provided at the tip of the pile, and there is at least one concrete spiral protrusion for approximately one to several rotations on the outer periphery of the small-diameter portion, and the outer peripheral diameter of the concrete spiral protrusion is the maximum outer peripheral diameter of the pile. When rotating and embedding a ready-made concrete pile having the same or larger diameter, after excavating the ground with a diameter of 70% or more of the pile main body diameter and smaller than the outer peripheral diameter of the concrete spiral projection, An enlarged excavation hole is formed at the tip, and the enlarged excavation hole is filled with a hardened material, and then the enlarged excavation hole has a diameter larger than the outer peripheral diameter of the concrete spiral projection, or the ground surface or the vicinity of the ground surface. A method for rotating and embedding piles, wherein the pile is excavated and excavated, and the pile is rotationally embedded in the excavation hole and fixed in the enlarged excavation hole. 2. The pile embedding method according to claim 1, wherein the ready-made concrete pile has at least one concrete spiral protrusion or concrete nodular protrusion on the pile main body. The rotation embedding method of the pile of Claim 1 or Claim 2 which made the outer periphery diameter of the small diameter part of a pile front-end | tip part 65% or more and 98% or less of the outer periphery diameter of a pile main-body part. The method for rotating and embedding piles according to claim 1, 2 or 3, wherein the shape of the concrete spiral protrusion near the tip of the ready-made concrete pile is a trapezoid.

Images