JP2014095190A - Pile construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which easily and surely removes a tip bit from a casing auger when a drain pipe construction method is performed.SOLUTION: A lid member 7 is engaged with a tip of a casing auger 1, provided with projections 5 at the tip, so as to be locked to the casing auger 1 by the projections 5. A hollow 10 columnar drainage material 9 is inserted in an axial direction from the rear end side of the casing auger 1. While the casing auger 1 is normally rotated, it is embedded into the ground. After completion of embedding the casing auger 1, a weight 11 is made to collide with the lid member 7 through a hollow 10 part of the columnar drainage material 9 to remove the lid member 7 from the casing auger 1. Subsequently, the weight 11 is pulled out and removed from the columnar drainage material 9. The casing auger 1 is reversely rotated to draw the casing auger 1 from the ground while keeping the columnar drainage material 9 in the ground.

Description

  The present invention relates to an improvement of a drain pipe method.

A drain pipe construction method is known as a method for preventing liquefaction of the ground (Patent Document 1).
In this drain pipe method, a casing auger with a detachable tip is prepared, and a porous pipe is accommodated in the casing auger. Then, the ground is excavated by the casing auger and is embedded in the ground. Thereafter, the casing auger is rotated in the reverse direction to remove the tip portion from it, and the porous pipe is left in the ground.
As a result, the porous pipe becomes a pile and is buried in the ground. Since this pile is porous, it becomes a kind of well and prevents the liquefaction phenomenon by letting the groundwater pressure that rises at the time of the earthquake escape from the well to the ground surface.

  In the drain pipe method disclosed in Patent Document 1, a conical tip bit having a helical fin is attached to the tip of a casing auger. The coupling mode between the casing auger and the tip bit is that the engaging means provided on the tip bit is fitted inside the tip of the casing auger. In order to make the tip bit follow the rotation (in the embedding direction) of the casing auger, the tip bit is provided with a locking portion composed of an inclined portion and a precipice, and this locking portion is connected to the engaging portion on the inner periphery of the casing auger. Engaged. When the casing auger is rotated in the pulling direction, the locking portion of the tip bit is disengaged from the engaging portion of the casing auger. This leaves the tip bit in the ground.

Japanese Patent No. 2642577

In order to reliably prevent the liquefaction phenomenon, it is necessary to apply many drain pipe methods to the ground.
Considering the above-described conventional drain pipe construction method from this point of view, the shape of the tip bit is complicated and its production is expensive.
When the casing auger is embedded in the ground, a large force is applied to the tip bit, so the tip bit adheres to the casing auger, and when the casing auger is rotated in the reverse direction, the tip bit may follow the casing auger and not come off from it. is there.
In particular, when hetimalon (trade name, hereinafter the same), which is also introduced in the example of Patent Document 1 as a porous pipe, is used, it has elasticity (because of its low rigidity), so that it has an axial direction. Even if the power of is applied, the power is absorbed. Therefore, sufficient force cannot be applied to the tip bit, and it cannot be removed from the casing auger.
Therefore, the present invention provides a method of simplifying the structure of the tip bit as much as possible and providing it at a low cost, and a method for easily and reliably removing the tip bit from the casing auger.
Thereby, the drain pipe construction method can be executed at low cost.

The first aspect of the present invention that achieves the above object is defined as follows.
With respect to the casing auger provided with a protrusion at the front end, a lid member is fitted to the front end of the casing auger so as to be locked by the protrusion, and the columnar drainage material is hollow in the axial direction from the rear end side of the casing auger Insert
This is embedded in the ground while rotating the casing auger forward,
After completion of the insertion of the casing auger, a weight is caused to collide with the lid member through the hollow of the columnar drainage material, the lid member is removed from the casing auger, and then the weight is pulled up from the columnar drainage material. Remove
Reversing the casing auger, leaving the columnar drainage material on the ground, pulling out the casing auger from the ground,
Pile construction method characterized by that.

According to the pile construction method of the first aspect defined in this way, the structure for attaching the lid member attached to the tip of the casing auger to the casing auger only locks the protrusion at the tip of the casing auger. , Greatly simplified.
Furthermore, the lid member can be easily and reliably removed from the tip of the casing auger by adopting a method in which a weight is made to collide with the lid member and the lid member is removed from the tip of the casing auger by the impact force.

In the above description, the shape, structure, and the like of the protrusion attached to the tip of the casing auger can be arbitrarily selected as long as it has a strength capable of supporting the resistance force that the lid member receives from the ground when the casing auger is embedded in the ground. In the embodiment, in order to simplify the structure, three cubic steel materials (caramel) are equally distributed and fixed by welding in the same circumferential direction in the casing auger.
The outer diameter of the lid member is the same as the inner diameter of the tip of the casing auger so that the ground does not enter the casing auger when the casing auger is embedded in the ground. Accordingly, it is only necessary to provide rigidity that does not deform due to the resistance force received from the ground when the casing auger is embedded in the ground. In order to finally leave the lid member on the ground, it is preferable that the lid member and the casing auger tip are loosely fitted and the lid member easily falls from the casing auger tip.
If the casing auger is embedded in the ground in a state where the lid member is locked to the projection at the tip of the casing auger, a large resistance is applied from the ground to the lid member, and the lid member and the projection may adhere to each other. Moreover, the outer periphery of a cover member and the inner peripheral surface of a casing auger front end may adhere. Here, adhesion means that the soil component sandwiched between the lid member and the protrusion and / or the outer circumference of the lid member and the tip of the casing auger acts like an adhesive due to the resistance applied to the lid member, The state where both are fixed. If the two are not adhered, the lid member can be easily removed from the casing auger when the casing auger is rotated backward and removed from the ground.

However, according to the study of the present inventor, when the adhesion occurs and the casing auger rotates in the reverse direction, the lid member also rises following it. As the lid member rises, the columnar drainage material also rises. Therefore, by restraining the upper end of the lid member, an attempt was made to suppress the lid member from rising, that is, to separate the lid member from the casing auger. However, it is difficult to suppress the upper end of the columnar drainage material while rotating the casing auger in a reverse direction, and when using a columnar drainage material (so-called hetimalon) made by stacking curled synthetic fibers, the upper end of the columnar drainage material is suppressed. Even if it is possible, the force is absorbed by the columnar drainage material itself, and sufficient force is not transmitted to the lower end thereof, and the lid member cannot be separated from the front end of the casing auger.
Therefore, in the present invention, before the casing auger is reversely rotated, or after being slightly reversely rotated (about 1 to 10 rotations), the weight is caused to collide with the lid member through the hollow of the columnar drainage material, and the impact force Thus, the lid member was removed from the tip of the casing auger.
For the weight, it is preferable to use a steel pipe (or a steel ball) having a diameter smaller than that of the hollow columnar drainage material from the viewpoint of workability. A string or a rope is connected to the upper end of the steel pipe, and the steel pipe is fitted into the hollow portion of the columnar drainage material and dropped to collide with the lid member. Then, pull the steel pipe by pulling the string. This collision work can be repeated until the lid member is removed from the casing auger.
The weight of the weight can be appropriately selected in consideration of the ground condition, the depth of insertion of the casing auger, and the workability, etc. When the depth is about 5 m, the weight of the weight is preferably 5 to 10 kg or more in order to reliably separate the lid member from the tip of the casing auger.

FIG. 1 is a sectional view showing the relationship among a casing auger 1, a lid member 7, a columnar drainage material 9 and a weight 11 used in the construction method of the embodiment of the present invention. FIG. 2 is a bottom view of the state in FIG. 1 with the lid member 7 removed. FIG. 3 is a front view showing another embodiment of the lid member 17. 4 shows a configuration of a casing auger 31 suitable for the lid member 17 of FIG. 3, FIG. 4A is a front view, and FIG. 4B is a cross-sectional view of the small diameter portion 33. FIG. 5 is a front view showing another embodiment of the lid member 27. FIG. 6 is an exploded perspective view showing elements used in a pile construction method according to another embodiment. FIG. 7 is an exploded perspective view showing a coupling mode of the shaft member 118 and the lid member 117 in FIG. FIG. 8 is an exploded perspective view showing elements used in a pile construction method according to another embodiment. FIG. 9 is an exploded perspective view showing elements used in a pile construction method according to another embodiment. FIG. 10 is an exploded perspective view showing elements used in a pile construction method according to another embodiment. FIG. 11 is an exploded perspective view showing elements used in a pile construction method according to another embodiment.

Hereinafter, the construction method (drain pipe construction method) of the pile reinforcement structure of this embodiment will be described.
In this construction method, as shown in FIG. 1, a columnar drainage material 9 made of hetimalon is inserted into the casing auger 1. A blade 3 is formed on the outer peripheral surface of the casing auger 1. Three locking members (caramel) 5 are evenly distributed and fixed to the tip of the casing auger 1.
This locking member may be formed on the outer peripheral surface at the tip of the casing auger 1.
In this embodiment, a disc-shaped member is used as the lid member 7, but of course the shape is not particularly limited, and a conical member can be adopted as shown in FIGS. 3 and 4.
Although it should be avoided that a gap is formed between the lid member 7 and the casing auger 1, the lid member 7 is finally separated from the casing auger 1. It is preferable to be in a fitted state.
In order to prevent the lid member 7 from falling off, it is preferable to temporarily fix the casing auger 1 and the lid member 7 from the outside with a tape or the like before the casing auger 1 is embedded in the ground. This tape disappears during work.

After embedding the casing auger 1 to a predetermined depth (for example, 5 m), the casing auger 1 is slightly reversed and pulled up. Thereafter, a steel pipe 11 serving as a weight is inserted into the central hollow portion 10 of the columnar drainage material 9 and dropped. The steel pipe 11 collides with the lid member 7 and gives an impact force thereto. Thereby, the lid member 7 is separated from the casing auger 1. The dropping of the steel pipe 11 can be repeated a plurality of times so that the lid member 7 is reliably separated from the casing auger 1.
A rope 13 is connected to the upper end of the steel pipe 11, and the rope 13 is pulled up to remove the steel pipe 11 from the columnar drainage material 9.
Thereafter, when the casing auger 1 is reversely rotated and removed, since the lid member 7 is separated, there is no member supporting the columnar drainage material 9, and only the casing auger 1 is extracted from the ground. Even if the columnar drainage member 9 follows the casing auger 1, if the upper end portion of the columnar drainage material 9 is held down, the columnar drainage material 9 can be easily left in the ground by preventing the tracking.

In order to avoid interference between the locking member 5 and the columnar drainage member 9, the locking member 5 is preferably formed as thin as possible. Further, a vertical groove for avoiding interference with the locking member 5 may be formed on the outer periphery of the columnar drainage member 9.
FIG. 3 shows a conical lid member 17. A hook 18 is formed on the upper surface of the lid member 17, and the upper piece of the hook 18 engages with the upper surface of the locking member 5. That is, the lid member 17 is inserted into the casing auger 1 without the hook 18 interfering with the locking member 5, and the casing auger 1 is rotated relative to the lid member 17 so that the hook 18 becomes the locking member 5. Engage. The rotation direction at this time is the normal rotation direction of the casing auger 1.
On the other hand, when the casing auger 1 is reversed after the casing auger 1 is buried in the ground, the hook 18 and the locking member 5 are disengaged. If an impact force is applied to the lid member 17 downward by the steel pipe 11 in advance, the engagement between the hook 18 and the locking member 5 is reliably performed.

FIG. 4 shows a casing auger 31 suitable when the lid member 17 shown in FIG. 3 is used. 4A is a front view, and FIG. 4B is a cross-sectional view of the small diameter portion. In addition, the same code | symbol is attached | subjected to the element same as FIG. 3, and the description is abbreviate | omitted.
The casing auger 31 includes a small-diameter portion 33 in the vicinity of the tip thereof. A blade 35 is loosely inserted into the small diameter portion 33 so as to be movable in the axial direction.
As shown in FIG. 4B, keys 37, 37 project from the small diameter portion 33 in the axial direction, and key grooves 38, 38 are formed in the blades 35 so as to face the keys 37, 37.
As a result, the blade 35 rotates following the rotation of the casing auger 31. On the other hand, when the casing auger 31 is moved in the axial direction without rotating, the blade 35 does not follow the movement and moves relative to the casing auger 31 in the axial direction.
Therefore, after the casing auger 31 is buried to a predetermined depth and then reversely rotated, when the engagement between the hook 18 and the locking member 5 is released, the casing auger 31 is lifted by the reverse rotation, the casing When the auger 31 is moved up and down without rotating at all, since there is no resistance of the blades 35, a large impact force can be applied to the lid member 17. Therefore, the lid member 17 can be removed more reliably.

FIG. 5 shows a lid member 27 of another embodiment. A guide 28 is formed on the upper surface of the lid member 27. The lid member 27 is inserted into the casing auger 1 with the guide 28 not interfering with the locking member 5.
When the casing auger 1 is reversed after the casing auger 1 is embedded in the ground, the locking member 5 rides on the guide 28, so that the lid member 27 and the casing auger 1 are separated from each other. If an impact force is applied to the lid member 27 downward by the steel pipe 11 in advance, the riding of the locking member 5 on the guide 28 is promoted.

Next, a pile construction method according to another embodiment will be described.
The pile construction method includes a step of embedding a casing auger with a lid member locked to a tip thereof in the ground, and a step of leaving the lid member in the ground and removing the casing auger from the ground. In the method
A shaft construction method characterized in that a shaft material thinner than the casing auger is erected on the lid member, and when the casing auger is extracted, the shaft material is also left in the ground.
Hereinafter, this embodiment will be described in detail with reference to the drawings.
In the example shown in FIG. 6, a lid is formed at the tip of the casing auger 111, and rectangular holes 113, 113 and a round hole 115 are formed in the lid.
On the other hand, keys 119 and 119 are provided on the upper surface of the lid member 117 with the shaft member 118 as the center. The cover member 117 and the casing auger 111 are assembled by inserting the shaft member 118 into the round hole 115 and inserting the keys 119 and 119 into the rectangular holes 113 and 113, respectively.
When the excavation work by the casing auger 111 is completed, an impact force is applied to the shaft head of the shaft member 118, and the lid member 117 is separated from the casing auger 111. The shaft member 118 has the same length as that of the casing auger 111, that is, the depth of the drilled hole, and serves as a core material of the pile.
The cement material can be injected while the casing auger 111 is reversed and pulled out. The cement material can be injected through the rectangular hole 113. A hole dedicated for cement material injection may be provided.
The cement material may be injected into the hole (that is, around the shaft member 118) after the casing auger 111 is pulled out.
This cement material is solidified to complete a pile incorporating the shaft 118.

In the embodiment of FIG. 6, the lid member 117 can be rotated with a large torque by the relatively large diameter casing auger 111. Thereby, the efficiency of excavation work improves.
On the other hand, it is conceivable to rotate the lid member 117 by the shaft member 118 without using the casing auger 111. However, since the shaft member 118 has a small diameter, it is difficult to obtain a sufficient torque.
By providing the lid member 117 with a blade, the blade can be omitted from the outer peripheral surface of the casing auger 111.
As shown in FIG. 7, the shaft 118 and the lid member 117 can also be coupled by fitting the keys 121 and 131 and the key holes 123 and 133 together.

In the example of FIG. 8, keys 129 and 129 are provided on the casing auger 111 side, and key holes 133 and 133 are provided on the lid member 117 side.
In the example of FIG. 9, keys 139 and 139 and a shaft member 118 are continuously provided in the lid member 117, and the shape of the hole 145 on the casing auger 111 side is adjusted accordingly.
In the example of FIG. 10, the shaft member 118 is erected on the lid member 117 so as to overlap the thin rectangular key 149. On the other hand, a hole 155 corresponding to the key 149 is formed on the casing auger 111 side. The shaft member 118 is also passed through the hole 155.
When the key 149 is removed from the hole 155, a gap is formed between the shaft member 118 and the periphery of the hole 155, so that the cement material can be easily injected from there.
In the example of FIG. 11, the lid member 117 is provided with a round hole-shaped key hole 153. The key holes 153 are provided at the same distance and the same angle (90 degrees in this example) with the axis of the lid member 117 as the center.
On the other hand, four cylindrical keys 156 are arranged on the front end side of the casing auger 111 at positions facing the key holes 153.
The key 156 at the tip of the casing auger 111 is inserted into and removed from the key hole 153 of the lid member 117. Here, since the four key holes 153 are evenly distributed around the axis of the lid member 117, when the keys 156 are inserted into the respective key holes, it is easy to align them.

  The present invention is not limited to the description of the embodiments of the invention. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

DESCRIPTION OF SYMBOLS 1, 31 Casing auger 5 Locking member 7 Lid member 9 Columnar drainage material 11 Steel pipe 13 String

Claims (3)

With respect to the casing auger provided with a protrusion at the front end, a lid member is fitted to the front end of the casing auger so as to be locked by the protrusion, and the columnar drainage material is hollow in the axial direction from the rear end side of the casing auger Insert
This is embedded in the ground while rotating the casing auger forward,
After completion of the insertion of the casing auger, a weight is caused to collide with the lid member through the hollow of the columnar drainage material, the lid member is removed from the casing auger, and then the weight is pulled up from the columnar drainage material. Remove
Reversing the casing auger, leaving the columnar drainage material on the ground, pulling out the casing auger from the ground,
Pile construction method characterized by that.   The construction method according to claim 1, wherein the lid member has a plate shape.   The construction method according to claim 1, wherein the columnar drainage material is formed by stacking curled synthetic fibers.

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