JP7254386B2 - Tip head of pile cage and pile cage using the same - Google Patents

Description

The present invention relates to foundation work for building structures, and more particularly to improvements in cast-in-place piles.

Construction of cast-in-place piles involves, for example, excavating the ground at a predetermined location with an excavator, filling the hole with muddy water (stabilizing liquid) that prevents landslides on the wall surface, and excavating to a support layer where the ground is stable. to form A reinforcing bar cage having a predetermined design length is erected in this hole, and concrete is poured into the reinforcing bar cage to construct a concrete pile. A plurality of reinforcing bar cages (joints) manufactured in advance based on the design length, for example, are lowered into the hole while being connected sequentially at the mouth of the hole.

For example, when connecting reinforcing bar cages to each other, temporarily place the reinforcing bar cage (first joint) inserted into the hole first with a temporary placing jig such as a temporary placing bar, and then insert the upper reinforcing bar cage (first joint). second section) is lowered onto the lower reinforcing bar cage by hanging with a crane. The descent is stopped when the lower ends of the main bars of the upper reinforcing bar cage are dropped to the extent that they come in contact with the upper ends of the main bars of the lower reinforcing bar cage. While the upper reinforcing bar cage is temporarily suspended by a crane, the main bars of the upper and lower reinforcing bar cages are connected via a coupler or the like.

Subsequently, the temporary placement jig is pulled out, and the connected reinforcing bar cage is gently lowered into the hole. By repeating this process, a reinforcing bar cage of a predetermined length formed by connecting each joint of the reinforcing bar cage is erected in the hole, and the reinforcing bar cage is fixed so that the tops of the main bars are aligned with a reference level such as the ground. Concrete is then poured into the cage using tremie pipes. The crown of the concrete being placed is measured, and the tremie pipe is pulled up step by step so that the tremie pipe does not come out of the concrete. Form.

For example, Patent Literature 1 introduces an example of a cast-in-place pile construction method.

JP-A-6-158653

However, in the cast-in-place pile construction method described above, slime (excavated soil) is generated during the excavation process. Slime floats in the circulated muddy water and is collected at the mouth of the hole or the tip of the bit. If a long time elapses before pouring ready-mixed concrete (due to work flow, trouble, etc.), slime in the muddy water settles and deposits on the bottom of the hole. When concrete is placed on top of the accumulated slime, a concrete pile whose tip is separated from the bottom of the hole (supporting layer) is shorter than the design length. Slime treatment is necessary to remove the slime in order to secure the original design length and strength of the pile.

However, once the slime builds up on the bottom, it is difficult to remove. For example, slime treatment requires work such as removing a reinforcing bar cage from a borehole, which takes a long time. Especially in the summer, if the slime treatment takes a long time, problems with the quality and strength of the concrete may occur, and the concrete in ready-mixed concrete trucks waiting for casting may become unusable. Losses are also great.

In addition, when the reinforcing bar cage is erected, the conventional construction method tends to lack stability at the 1st and 2nd joints when inserting the hole of the reinforcing bar cage, and there is also a problem that it may come into contact with the pile hole wall.

The present invention has been made to solve the above problems, and aims to shorten the slime processing time and improve the pile quality.

In order to achieve the above objects, the tip head of the pile cage of the present invention is:
A tip head of the pile cage provided at the lower end of the pile cage arranged in the excavation hole, the body acting to pull down the pile cage, and a body for connecting the body and the pile cage. A connecting means and an agitating portion for agitating water in the borehole are provided, and the agitating portion includes a strip-shaped protrusion formed vertically on the outer periphery of the body.
With such a configuration, it is easier to keep the center axis of the pile cage vertical in the excavation hole, so the pile cage is rotated (repeated forward and reverse rotation) to move the tip head and move the bottom of the excavation hole. It becomes possible to agitate and float the slime that has precipitated. As a result, the slime on the bottom and the like is removed, and the bottom of the pile cage is more securely attached to the bottom of the hole.

Also, the tip head of the pile cage in the reference example is
A tip head of the pile cage provided at the lower end of the pile cage arranged in the excavation hole, the body acting to pull down the pile cage, and a body for connecting the body and the pile cage. and a connecting member.
With such a configuration, it becomes easier to keep the center axis of the pile cage vertical in the borehole.

In addition, the tip head of the pile cage of the present invention is
A tip head of the pile cage provided at the lower end of the pile cage arranged in the excavation hole, the body acting to pull down the pile cage, and a body for connecting the body and the pile cage. A connection means and an agitating portion for agitating water in the borehole are provided, the agitating portion including inclined protrusions or inclined grooves formed on the outer circumference of the body.
With such a configuration, when the pile cage is moved up and down in the borehole, the tip head is rotated by the mechanical action of the slanted protrusion or the slanted groove and the fluid in the borehole, and the water in the borehole is removed. It becomes possible to float the slime that has settled to the bottom or the like by stirring. As a result, the slime on the bottom and the like is removed, and the bottom of the pile cage is more securely attached to the bottom of the hole.

Preferably, the body is formed with an introduction hole for guiding concrete to the bottom side of the excavation hole. As a result, even if a head is provided at the tip of the reinforcing bar cage, it becomes easy to lead out the cement to the bottom of the borehole.
Preferably, the agitating part includes at least a protrusion or a groove inclined with respect to the axial direction of the pile cage formed on the outer periphery of the body.
Preferably, one wall surface of the groove is tapered.
As a result, when the tip head is moved up and down, the tip head rotates due to the resistance of the fluid in the borehole, making it possible to float the slime.

Preferably, the pile cage is provided with a tip head as described above at the tip. Thereby, it becomes possible to obtain a pile cage capable of producing cast-in-place concrete piles which are less affected by slime.

According to the present invention, the weight of the tip head helps keep the center axis of the pile cage vertical within the borehole. In addition, since the slime settled on the bottom of the excavation hole is stirred by the rotation of the tip head, it is possible to remove the slime from the bottom of the excavation hole, etc., so that the pile cage can more reliably reach the bottom.

FIG. 3 is an explanatory diagram for explaining the tip head of Example 1; FIG. 4 is an explanatory diagram illustrating an example of connection between the tip head and the reinforcing bar cage of Example 1; FIG. 4 is an explanatory diagram illustrating an example of connection between the tip head and the reinforcing bar cage of Example 1; It is explanatory drawing explaining the construction example of a cast-in-place pile. It is explanatory drawing explaining the construction example of a cast-in-place pile. FIG. 4 is an explanatory diagram for explaining the action of the introduction hole of the tip head; It is explanatory drawing explaining the example of the inclination of a pile cage. FIG. 10 is an explanatory diagram for explaining the tip head of Example 2; FIG. 11 is an explanatory diagram for explaining an example of connection between the tip head and the reinforcing bar cage of Example 2; FIG. 11 is an explanatory diagram for explaining an example of connection between the tip head and the reinforcing bar cage of Example 2; FIG. 11 is an explanatory diagram illustrating a tip head of Example 3; FIG. 11 is an explanatory diagram illustrating a tip head of Example 4; FIG. 12 is an explanatory diagram illustrating an example of connection between the tip head and the reinforcing bar cage of Example 4; FIG. 11 is an explanatory diagram illustrating a tip head of Example 5; FIG. 11 is an explanatory diagram for explaining a tip head of Example 6; FIG. 11 is an explanatory diagram illustrating an example of connection between the tip head and the telescopic pile cage of Example 6; It is explanatory drawing explaining the example of the erection of a telescopic pile cage. FIG. 10 is an explanatory diagram for explaining an example of erection of the telescopic pile cage to which the tip head is connected; FIG. 10 is an explanatory diagram for explaining the action of the distal head and the tremie tube;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1A and 1B illustrate an example of the tip head of a pile cage according to Example 1 of the present invention, in which FIG. 1A is a plan view of the tip head, FIG. FIG. (C) is a bottom view of the tip head. In addition, in each of the following examples, a reinforced cage is used as a cage of piles, but the cage is not limited to an iron material.

As shown in FIG. 1 , the tip head 10 includes a body 11 , a connection reinforcing bar 12 , an introduction hole 13 , an agitating section 14 , a center of gravity 15 and a seat surface 16 . The body 11 serves as the base of the tip head 10, and has an appropriate weight to vertically pull down a reinforcing bar cage 20, which will be described later, which is connected to the tip head 10. For example, it is made of metal such as iron or concrete. . The weight of the body 11 is, for example, approximately 20% to 70% of the weight of the first joint of the reinforcing bar cage 20 . More preferably, it is about 50%. For example, when the length of the reinforcing bar cage 20 is about 3 m and the weight is 500 kgw, the weight of the tip head 10 is set to about 250 kgw. If the weight is small (20% or less), the attraction force acting in the vertical direction is weak, and if the weight is large (70% or more), the strength burden of the reinforcing bars and the hanging load of the crane increase. The body 11 is generally formed in a hemispherical shape, a bowl shape, or the like, and a plurality of connecting rebars 12 projecting upward are annularly arranged on the upper surface of the body 11 . Note that the shape of the body 11 is not limited to a hemispherical shape or the like. As shown in FIG. 1A, it may be polygonal in plan view. The connecting reinforcing bars 12 are members as connection means for connecting the tip head 10 and the reinforcing bar cage 20 , and are arranged at positions corresponding to the lower ends of the plurality of main bars of the reinforcing bar cage 20 .

In the illustrated example, the outer periphery of the upper surface of the body 11 is formed in an octagonal shape, and stirring portions 14 protruding outward are provided at the apexes of the octagonal shape (see FIG. 1(A)). The outer surface of the body 11 is provided with a plurality of stirring portions 14 projecting outward from the outer surface. The stirring part 14 is formed of a band-shaped projection composed of a projection formed radially on the bottom of the body 11 and a projection formed vertically on the outer periphery of the body 11 . The amount of protrusion of the stirring portion 14 is, for example, about 30 mm to 250 mm, but is not limited to this. For example, the protrusion amount e of the stirring part 14 at the bottom of the body 11 can be set to about 50 mm to 200 mm, and the protrusion amount f of the stirring part 14 formed on the side can be set to about 30 mm to 100 mm. See FIG. 3(A)). The amount of protrusion of the stirring part 14 is appropriately set according to the diameter of the reinforcing bar basket 20, the hole diameter of the excavation hole 1, and the like.

As will be described later, when the builder attaches the tip head 10 to the reinforcing bar cage 20 and alternately rotates the suspended reinforcing bar cage 20 in the forward or reverse direction, the tip head 10 also rotates, and the stirring part 14 rotates. The pore water 115 is agitated by . The slime 4, which is sediment and sediment deposited on the bottom 3 of the hole, is fluidized and floats. In addition, it becomes possible to scrape off the earth and sand 5 left uncut on the hole wall surface 2 (see FIG. 4).

A circular seat surface 16 is formed on the bottom of the body 11 (annular seat surface 16 when the introduction hole 13 is provided). A circular or annular bearing surface 16 provides the most stable placement of the rebar cage 20 at the bottom of the borehole.

Desirably, an introduction hole 13 that penetrates the upper surface side and the lower surface side (bottom portion) of the body 11 is provided at a portion corresponding to the central axis of the body 11 . As will be described later, the introduction hole 13 facilitates driving concrete into the hole bottom 3 of the excavated hole by means of a tremie pipe. More desirably, the hole diameter on the upper surface side is set larger than the hole diameter on the lower surface side. This makes it easier for the tip of the tremie tube to enter the insertion hole. In addition, the concrete is led out to the introduction hole 13 and easily gathers at the hole bottom 3 of the excavated hole.

The center of gravity 15 of the body 11 is designed and manufactured so as to exist on the central axis of the hemispherical body 11 . Even if the introduction hole 13 is not provided, the tip head 10 functions to pull down the reinforcing bar cage 20 in the vertical direction (downward) by its weight.

2 and 3 are diagrams for explaining an example of connection between the tip head 10 and the reinforcing bar cage 20 of the first embodiment.

The cylindrical reinforcing-bar cage 20 includes a plurality of main reinforcing bars 21 arranged in a ring and extending in the central axis direction, and a plurality of ring-shaped ties 22 orthogonally connected to the plurality of main reinforcing bars 21 .

In the example shown in FIG. 2A, the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 is narrower than the diameter of the reinforcing bar cage 20 . For this reason, the lower end portion side of the main reinforcement 21 is formed in a crank shape to adjust the radial deviation from the connecting reinforcement 12 . The connection between the reinforcing bar cage 20 and the tip head 10 is performed, for example, by suspending the reinforcing bar cage 20 of the first section with a crane, and connecting the lower ends of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10. are connected by sleeves 30, respectively. In this example, the connecting reinforcing bar 12 and the sleeve 30 are connecting means.

In the example shown in FIG. 2(B), the tip head 10 is directly provided on each lower end of the plurality of main bars 21 of the reinforcing bar cage 20 of the first section without using the sleeve 30 . In this example, the lower ends of the main bars 21 are used as connecting reinforcing bars. In this example, the lower ends of the main reinforcements 21 also serve as connecting means. Incidentally, the connection means is not limited to those of the embodiments, and any means having the same function may be used.

In the example shown in FIG. 2C, the diameter of the annular arrangement of the main bars 21 of the reinforcing bar cage 20 and the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 are formed to be the same. The lower ends of the main bars 21 of the reinforcing bar cage 20 do not have a crank-like portion and are formed straight. The reinforcing bar cage 20 and the tip head 10 are connected by connecting the lower ends of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10 with sleeves 30 . In this example, the connecting reinforcing bar 12 and the sleeve 30 are connecting members.

In the example shown in FIG. 3A, the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 is narrower than the diameter of the reinforcing bar cage 20 . Therefore, the radial deviation from the connecting reinforcing bars 12 is adjusted by inclining the lower ends of the main bars 21 inward (in the direction of the central axis). The reinforcing bar cage 20 and the tip head 10 are connected by connecting the lower ends of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10 with sleeves 30 . In this example, the connecting reinforcing bar 12 and the sleeve 30 are connecting members. Incidentally, the projection amounts e and f of the stirring portion 14 are explained in the explanation of FIG.

In the example shown in FIG. 3(B), the tip head 10 is provided at each lower end of the plurality of main bars 21 of the reinforcing bar cage 20 of the first section without using the sleeve 30 in the example shown in FIG. 3(A). In this example, the lower ends of the main bars 21 are used as the connecting reinforcing bars 12 . A lower end portion of the main reinforcement 21 also serves as a connecting member.

In the examples of FIGS. 2A, 2C, and 3B described above, the tip head 10 and the reinforcing bar cage 20 are made separately, so that they are easy to manufacture. In the example of FIGS. 2B and 3B, the reinforcing bars (not shown) in the tip head 10 are assembled when manufacturing the first section of the reinforcing bar cage 20, and the tip head 10 is attached to the first section by the concrete formwork. formed in

In order to scrape off unshavings 5 on the hole wall surface 2 by (the agitating portion 14 of) the tip head 10 (see FIG. 4), as shown in FIG. It is desirable that d be greater than the diameter D of the reinforcing bar cage 20 . On the other hand, if the diameter d of the tip head 10 is too large, a part of the tip head 10 tends to come into contact with the hole wall surface 2 when the reinforcing bar cage 20 is erected, and the dirt and slime 4 on the hole bottom 3 increase. there is a possibility. Therefore, the diameter d of the tip head 10 including the protrusions of the stirring part 14 or the amount of protrusion of the stirring part 14 from the body 11 in the radial direction is appropriately determined according to the excavation hole diameter, hole depth, reinforcing bar cage diameter, erection accuracy, etc. are set to the appropriate dimensions. For example, the amount of protrusion of the stirring part 14 from the body 11 is set to about 10% to 60% of the cover (the distance from the reinforcing bar cage to the wall surface of the hole), but it is not limited to this. For example, if the drill hole diameter (diameter) is 1000 mm, the diameter D of the reinforcing bar basket is 800 mm, and the cover is 100 mm, the diameter d of the tip head 10 including the stirring part 14 is set to about 860 mm (protrusion from the reinforcing bar basket is 30 mm on one side). . However, there are various drill hole diameters and reinforcing bar cages, and the values are not limited to these values.

FIG.4 and FIG.5 is explanatory drawing explaining the construction example of the cast-in-place pile using the tip head of an Example.
FIG. 4(A) shows a state in which the bore 1 has reached the bearing layer after centering of the pile core based on the construction design and the start of excavation, and the excavation is completed. A standpipe 110 is provided to prevent collapse near the mouth of the hole, and the drilling hole 1 is formed by a bit 113 of an excavator (not shown). The inside of the excavation hole 1 is filled with water. As filling water, it is desirable to use a stabilizing liquid 114, such as a bentonite solution, which suppresses wall collapse.

For example, the stabilizing liquid 114 is supplied into the borehole 1 from the tip of the bit 113 via the rod 112 during excavation. The bentonite solution has the property of adsorbing particles of earth and sand, and the excavated earth and sand rise from the hole bottom 3 together with the stabilizing liquid 114 . Bore water (mud water) 115 containing a stabilizing liquid 114 and cutting earth and sand is stored in the borehole 1, and the borewater 115 is discharged to the outside from the mouth of the borehole by a sand pump (not shown). The specific gravity of the pore water 115 is appropriately adjusted. The discharged hole water 115 is reused after removing earth and sand with a mud screen or the like.

FIG. 4B shows pore wall inspection. After the drilling is completed, the condition of the borehole 1 is checked using the sonic borehole wall measuring device 117 . In the illustrated example, a part of the hole wall surface 2 of the excavation hole 1 is left uncut 5 . A slime 4 remains on the hole bottom 3 of the excavation hole 1. - 特許庁The sonic hole wall measuring device 117 continuously measures the hole diameter in the depth direction of the borehole 1 and records the state of the wall surface. The builder can determine the location of the uncut portion 5 from this record. Also, the location (depth) of the slime 4 can be determined.

FIG. 4(C) shows an example in which the tip head 10 is used to remove the unshavings 5 during erection of the reinforcing bar cage 20 . The installer connects the tip head 10 to the first segment of the rebar cage 20 . Furthermore, connecting the second joint to the first joint is repeated to connect a plurality of joints to assemble a reinforcing bar cage 20 of a required length, and the reinforced cage 20 is erected into the excavation hole 1 . An example of the assembly of the reinforcing bar cage 20 is illustrated in FIG. 7 below. The reinforcing bar cage 20 is suspended by a crane (not shown), adjusted so that the central axis of the boring hole 1 and the central axis of the reinforcing bar cage are aligned, and introduced into the boring hole. When the lowering position of the tip head 10 of the reinforcing bar cage 20 reaches the place of the unshaving portion 5, the worker rotates the reinforcing bar cage 20 slowly. As a result, the agitating portion 14 and the like of the tip head 10 causes the water 115 in the hole to flow and the unshavings 5 to drop. In addition, the stirring part 14 and the like come into contact with the unshavings 5 to drop and remove the unshavings 5 . A slime 4 of excavated earth and sand is deposited on the hole bottom 3 of the excavation hole 1 .

FIG. 4(D) shows an example of stirring the slime 4 using the tip head 10 of the reinforced cage 20 . The construction worker lowers the reinforcing bar cage 20, and when the tip head 10 reaches the position where the slime 4 exists, the reinforcing bar cage 20 is slowly rotated. As a result, the agitating portion 14 of the tip head 10 and the like agitate the deposited slime 4 and the water 115 in the pores. Agitated slime floats to the top. Further, by adjusting the descending amount of the reinforcing bar cage 20, the tip head 10 is repeatedly stirred and lowered to directly above the hole bottom 3 to float the slime on the hole bottom 3. - 特許庁

FIG. 5A shows the supply of stabilizing liquid 114 into the pores by tremie tube 130 . After stirring, the reinforcing bar cage 20 is lowered to seat the bottom of the tip head 10 on the hole bottom 3, and the reinforcing bar cage 20 is fixed on the standpipe 110 side. Next, the tremie tube 130 is suspended by a crane and introduced into the reinforcing bar cage 20 . Further, the amount of descent is adjusted to insert the tip of the tremie tube 130 into the introduction hole 13 of the tip head 10 . Stabilizing liquid 114 is supplied to hole bottom 3 via tremie tube 130 . As a result, most of the agitated slime 4 floats toward the pore opening together with the stabilizing liquid 114 .
Alternatively, a rubber hose may be inserted into the tremie tube 130 to supply the stabilizing liquid 114 to the hole bottom portion 3 through the rubber hose. In some cases, the stabilizing liquid 114 is supplied from the hole opening by the excavation method, a rubber hose is inserted into the tremie tube 130, and the stabilizing liquid 114 is sucked from the tip of the tremie tube 130 through the rubber hose.

FIG. 5B shows supply of concrete 140 into the hole by tremie pipe 130 . The supply to the tremie tube 130 is switched from the stabilizer 114 to the concrete 140 . The tip of the tremie tube 130 is inserted into the introduction hole 13 of the tip head 10 , and the concrete 140 is supplied to the hole bottom 3 via the tremie tube 130 .

As shown in FIG. 6, the concrete 140 supplied from the tremie pipe 130 passes through the introduction hole 13 of the tip head 10, reaches the hole bottom 3, and rises along the hole wall surface 2. As shown in FIG. The hole bottom 3 , the tip head 10 and the tip of the reinforcing bar cage 10 are embedded with concrete 140 . Residues and slime 4 remaining at the bottom 3 of the hole are pushed up by the concrete 140, float together with the stabilizing liquid 115, and carried to the mouth of the hole. Pushed up towards the mouth. The slime 4 floating at the mouth of the hole is led out of the hole and collected by a sand pump or the like (not shown).

FIG. 5(C) shows filling of holes of concrete 140 with tremie tubes 130 . The builder measures the crown of the cast concrete, removes the tremie pipes 130 connected in such a manner that the tremie pipes 130 do not come off from the concrete in which the tremie pipes 130 are cast, and raises them step by step. Concrete 140 is poured. Concrete 140 rises toward the hole mouth with slime 4 placed on the top.

FIG. 5(D) shows a state in which the concrete 140 has been placed. When the filling of the concrete 140 reaches the mouth of the hole, the placing of concrete is completed. The slime 4 pushed up by the concrete 140 and reaching the hole mouth is removed by a pump, a construction worker, or the like, and the tremie tube 130 is pulled out. A concrete pile is formed in the borehole 1 by hardening the concrete 140 .

FIG. 7 is a diagram for explaining the problem caused by the inclination of the reinforcing bar cage 20 and the improvement caused by the load of the tip head 10 (weight action).
FIG. 7A shows an example in which the tip head 10 is not connected to the first joint of the reinforcing bar cage 20. FIG. A standpipe (or mouth pipe) 110 is provided at a predetermined position on the ground, and an excavation hole 1 is formed. In this example, the reinforcing bar cage 20 is configured by connecting two joints.

A connection example of each node of the reinforcing bar cage 20 will be described. Each section of the rebar cage 20 is prepared near the borehole 1, fabricated near the site or elsewhere. The builder shall
(1) The first joint 20a of the reinforcing bar cage 20 is lifted by a crane (not shown), introduced into the excavation hole 1, and supported and fixed using the temporary placement jig 120. FIG. The temporary placement jig 120 is, for example, hairpins. The temporary placement jig 120 fixes the reinforcing bar cage 20 to the standpipe 110, a workbench (not shown), or the like. In some cases, it is fixed to the mouth of the excavation hole 1 or the like.

(2) The second joint 20b of the reinforcing bar cage 20 is lifted by a crane and connected (coupled) to the fixed first joint 20a via a sleeve.
(3) The second joint of the reinforcing bar cage 20 is hung by a crane, the temporary placement jig 120 is released, and the first joint 20a and the second joint 20b of the reinforcing bar cage 20 are slowly lowered into the excavation hole 1. do.
(4) The temporary placement jig 120 supports and fixes the second joint 20b of the reinforcing bar cage 20 . FIG. 7A shows this state.
This procedure is repeated to connect each node of the reinforcing bar cage 20 to assemble a pile cage of a desired length in the hole.

In the example of FIG. 7A, the center of the drilling hole 1 and the center of the cylindrical reinforcing bar cage 20 are aligned at the reference position (for example, the temporary placement jig 120), but the center axis of the reinforcing bar cage 20 is Slightly tilted from vertical. Such problems may occur due to inaccurate work, insufficient support of the reinforcing bar cage 20, poor assembly accuracy of the reinforcing bar cage 20, bending of the reinforcing bar cage 20, or the like. For example, if the length (depth) of the drilled hole 1 is 30 m and the deflection (eccentricity) is 500 mm, and the cover is 100 mm, the reinforcing bar cage 20 contacts the hole wall surface 2 at a distance of 6 m from the hole mouth. When the cover is 100 mm, the reinforcing bar cage 20 contacts the hole wall surface 2 at a distance of 10 m from the hole mouth. The reinforcing bar cage 20 descends while scraping off the earth and sand on the wall surface of the hole from the contact position. Since the reinforcing bar cage 20 is as long as, for example, 10 m to 35 m, there is a possibility that the tip of the reinforcing bar cage 20 may come into contact with the hole wall surface 2 and drop earth and sand on the wall surface even with a slight inclination. It is important that the reinforcing bar cage 20 is accurately manufactured and introduced vertically at the center position of the borehole 1 .

FIG. 7(B) shows an example in which the tip head 10 is provided on the first node 20a of the reinforcing bar cage 20, and corresponds to the procedure (3) in the example of FIG. 7(A). The center of gravity of the tip head 10 , the first joint 20 a and the second joint 20 b of the reinforcing bar cage 20 is accurately assembled so that it is substantially on the central axis of the reinforcing bar cage 20 . This reinforcing bar cage 20 is hung by a crane and slowly descended into the excavation hole 1 .

In this state, the load of the tip head 10 acts on the tip of the reinforcing bar cage 20 as a vertical attractive force. When the builder aligns the center of the reinforcing bar cage 20 with the center of the drilling hole 1 by a crane, the tip head 10 acts so that the central axis of the boring hole 1 and the central axis of the reinforcing bar cage 20 are coaxial. Further, the load of the tip head 10 acts to suppress the shaking of the rotating shaft when the builder slowly rotates the reinforcing bar cage 20 . This makes it possible to avoid directly scraping the wall surface of the hole when stirring the water 115 in the hole with the tip head 10 .

FIG. 7(C) shows an example in which the second joint 20b of the reinforcing bar cage 20 is supported and fixed while the tip head 10 is connected to the lower end of the first joint 20a of the reinforcing bar cage 20. FIG. ) corresponds to the procedure (4) in the example. The temporary placement jig 120 supports and fixes the second joint 20 b of the reinforcing bar cage 20 .

In this example as well, the load of the tip head 10 acts on the reinforcing bar cage 20 in the vertical direction. As a result, the central axis of the borehole 1 and the central axis of the reinforcing bar cage 20 are aligned with each other, and the inclination of the reinforcing bar cage 20 is corrected. By aligning the center of the reinforcing bar basket 20 with the center of the excavation hole 1 in the temporary placement jig 120, the spacing between the reinforcing bar basket 20 and the hole wall surface 2 is kept substantially constant. When concrete is poured in this state, the reinforcing bars of the concrete pile are prevented from being exposed and a uniform cover thickness is obtained.
In this way, the tip head 10 functions as a weight for correcting the central axis of the reinforcing bar cage 20 in the vertical direction, which is convenient.

FIG. 8 is a diagram illustrating an example of the tip head of the cage pile according to the second embodiment of the present invention.
(A) is a plan view of the pile cage of Example 2, (B) is a side view, and (C) is a bottom view. In this embodiment, in addition to the stirring protrusion 14, a stirring plate 14a is provided as a means for stirring slime or the like.

In the first embodiment, the body 11 and the stirring projection 14 are integrally molded, or the stirring projection 14 is shaped as a part of the body 11. A stirring plate 14a made of a metal plate different in material is provided. Therefore, it is possible to construct a stirring means with a higher degree of freedom in shape than when it is manufactured from a part of the body 11 . The metal plate is preferably an iron plate, but may be a stainless steel plate, a copper plate, an aluminum plate, a resin plate, or the like, and is not limited to a specific material. The agitating plate 14a may have a shape called fins or blades as long as it can agitate the slime or the like.

The tip head 10 is manufactured by embedding a part of the stirring plate 14a in the body 11 of concrete, for example. Also, after the stirring plate 14a is connected to the reinforcing bars for the body 11 by welding or the like, it is manufactured by concrete molding using the reinforcing bars as internal reinforcing bars. The agitating projections 14 provided at the top of the polygonal body 11 protrude in the radial direction and can be used to scrape off unshavings on the hole wall surface (see FIG. 8(A)).

As shown in FIGS. 8B and 8C, the stirring plate 14a protrudes outward from the bottom and side surfaces of the hemispherical body 11. As shown in FIG. For example, the amount of protrusion of the stirring plate 14a is, for example, about 30 mm to 250 mm, but is not limited to this. For example, the protrusion amount a of the stirring plate 14a at the bottom of the body 11 can be set to about 50 mm to 200 mm, and the protrusion amount b of the stirring plate 14a formed on the side can be set to about 50 mm to 250 mm. See FIG. 9B). The amount of protrusion of the stirring portion 14a is appropriately set according to the diameter of the reinforcing bar cage 20, the hole diameter of the excavation hole 1, and the like, and may be larger than the above dimensions.
Incidentally, the stirring plate 14a at the bottom of the body 11 can be extended radially outward as appropriate, and in addition to stirring the slime, the stirring protrusions 14 at the polygonal apex can play a role of removing unshavings from the wall surface. It is possible. Other configurations are the same as those of the first embodiment.

9 and 10 show examples of connection between the tip head 10 and the reinforcing bar cage 20 of the second embodiment.
In the example shown in FIG. 9A, the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 is narrower than the diameter of the reinforcing bar cage 20 . For this reason, the lower end portion side of the main reinforcement 21 is formed in a crank shape to adjust the radial deviation from the connecting reinforcement 12 . This is done by connecting the respective lower end portions of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10 with sleeves 30 .

In the example shown in FIG. 9B, the tip head 10 is provided at each lower end of the plurality of main bars 21 of the reinforcing bar cage 20 of the first section without using the sleeve 30 . In this example, the lower ends of the main bars 21 are used as connecting reinforcing bars. The projection amounts a and b of the stirring plate 14a are explained in the explanation of FIG.

In the example shown in FIG. 9C, the diameter of the annular arrangement of the main bars 21 of the reinforcing bar cage 20 and the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 are formed to be the same. The lower ends of the main bars 21 of the reinforcing bar cage 20 do not have a crank-like portion and are formed straight. The reinforcing bar cage 20 and the tip head 10 are connected by connecting the lower ends of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10 with sleeves 30 .

In the example shown in FIG. 10A, the diameter of the annular arrangement of the connecting reinforcing bars 12 of the tip head 10 is narrower than the diameter of the reinforcing bar cage 20 . Therefore, the radial deviation from the connecting reinforcing bars 12 is adjusted by inclining the lower ends of the main bars 21 inward (in the direction of the central axis). The reinforcing bar cage 20 and the tip head 10 are connected by connecting the lower ends of the plurality of main bars 21 of the reinforcing bar cage 20 and the plurality of connecting reinforcing bars 12 of the tip head 10 with sleeves 30 .

In the example shown in FIG. 10(B), the tip head 10 is provided at each lower end of the plurality of main bars 21 of the reinforcing bar cage 20 of the first section without using the sleeve 30 in the example shown in FIG. 10(A). In this example, the lower ends of the main bars 21 are used as the connecting reinforcing bars 12 .

As shown in FIG. 9(B), it is desirable that the diameter d of the tip head 10 is larger than the diameter D of the reinforcing bar cage 20 in this embodiment as well. It is convenient for scraping off unshavings 5 on the hole wall surface 2 by (the agitating portion 14 of) the tip head 10 described above.

FIG. 11 illustrates an example of the tip head of the pile cage of Example 3 of the present invention. FIG. 11(A) is a plan view of the tip head, FIG. 11(B) is a side view, and FIG. 11(C) is a bottom view. Compared to the tip heads of Examples 1 and 2, the tip head 10 of this embodiment has a smaller amount of projection of the agitating protrusion 14 as the agitating means, and is assumed to be used mainly as a weight for the first joint of the reinforcing bar cage. are doing.

There are various methods for constructing cast-in-place piles, but in some cases it is not necessary to agitate the water in the hole after the completion of the drilling hole. Even in such a case, it is still important to hang the reinforcing bar cage vertically and install it at the bottom of the hole while aligning the central axis of the reinforcing bar cage with the central axis of the hole. Thus, the tip head 10 is used as a first node weight with the required weight corresponding to the first node. A bottom bearing surface 16 of the tip head 10 is formed in an annular shape. As shown in FIG. 4A, the hole bottom 3 formed in the supporting layer by the bit 113 has an inverted conical shape. The ring-shaped seat surface 16 of the tip head 10 stably seats (bottoms) the reinforcing bar cage on the hole bottom portion 3 of the shape. The tip head of Example 3 can be connected to the reinforcing bar cage 20 in various forms similar to the examples shown in FIGS.

FIG. 12 illustrates an example of the tip head of the pile cage of Example 4 of the present invention. FIG. 12(A) is a plan view of the tip head, FIG. 12(B) is a side view, and FIG. 12(C) is a bottom view. The tip head of the pile cage is composed of one iron ring (metal ring) 17, a plurality of connecting reinforcing bars 12, and a plurality of stirring plates (stirring portions) 14a. Each connecting reinforcing bar 12 is connected to the annular upper surface of the iron ring 17 at regular intervals, for example, by welding. The stirring plates 14a are connected to the annular lower surface of the iron ring 17 at regular intervals, for example, by welding. An iron plate is preferable for each stirring plate 14a, but a stainless steel plate, a copper plate, an aluminum plate, a resin plate, or the like may be used, and the material is not limited to a specific one. The agitating plate 14a may have a shape called fins or blades as long as it can agitate the slime or the like. The dimensions of the stirring part 14a are appropriately set according to the diameter of the reinforcing bar cage 20, the hole diameter of the excavation hole 1, and the like. In order to scrape off the unshavings 5 on the hole wall surface 2, it is desirable that the outer edge of each radially extending agitating plate 14a exceeds the outer circumference of the reinforcing bar cage 20 in plan view by an appropriate amount.

The tip head 10 of this embodiment does not have the heavy body 11 as compared to the tip heads of the first and second embodiments. For example, when the weight of the first joint of the reinforcing bar cage 20 is considerably large and the first joint of the reinforcing bar cage 20 is oriented vertically due to its own weight, the tip head is mainly provided in the reinforcing bar cage 20. It is intended to be used as
Note that the iron ring 17 may be embedded in the body 11 as shown in FIG. In this case, each stirring plate 14a is exposed from the bottom and side surfaces of the body 11 in an appropriate size. It is convenient that the central axis portion of the body 11 is formed as a cavity (introduction hole) so that the concrete supplied from the top can be led out to the bottom of the hole. The iron ring 17 may be a reinforcing bar, a tie bar, or the like formed in an annular shape.

FIG. 13 shows an example of connection between the tip head and the reinforcing bar cage of the fourth embodiment. In this example, the tip head 10 and the reinforcing bar cage 20 are connected via the sleeve 30, but the connection can be made according to need, similar to the various connection examples shown in FIGS. It is possible. 4(C) and 4(D), by rotating the reinforcing bar cage 20, the water 115 in the hole and the slime 4 deposited on the hole bottom 3 are agitated to float the slime at the hole bottom. to make the bottoming of the reinforcing bar cage 20 on the support layer more reliable. In addition, by floating the slime on the bottom, it becomes easier to pour concrete using a tremie pipe.

14A and 14B are explanatory diagrams for explaining an example of the tip head of the pile cage according to the fifth embodiment of the present invention. FIG. FIG. 14(A) is a plan view of the tip head, FIG. 14(B) is a side view, and FIG. 14(C) is a bottom view. It is convenient to use the tip head of this embodiment as a weight for extending a telescoping pile cage, which will be described later. The tip head has concave grooves 18 on the outer circumference and bottom of the body 11 as means for stirring slime or the like. Further, when the tip head moves up and down in the excavation hole 1, the groove 18 having a predetermined shape receives a mechanical action (fluid resistance) by a fluid such as muddy water to generate a rotational force in the tip head.

As shown in FIG. 14, tip head 10 generally has a top-shaped body 11 including an upper inverted frusto-conical portion and a lower inverted conical portion. A connecting reinforcing bar 12 exposed in a semicircular shape is annularly arranged on the upper surface of the body 11, and a concrete introduction hole 13 penetrating from the upper surface to the lower surface is provided in the central part of the body 11. - 特許庁At the introduction hole 13 portion, a hanging part 19 having a shape such as an inverted V shape or an inverted U shape that can be hooked is provided so as to straddle the introduction hole 13 . A hook 121 provided at the lower end of a lowering wire 122 of a crane (not shown) is detachably engaged with the suspending portion 19, as shown in FIG. 16, which will be described later.

A plurality of moderately deep grooves 18 are formed in the outer peripheral surface of the body 11 obliquely from the upper surface to the lower surface of the body. The groove 18 on the lower surface (seat surface) extends from the outer peripheral surface to the introduction hole 13 in the center. The grooves 18 on the outer peripheral surface and the lower surface of the body 11 form unevenness on the surface of the body 11, and have a shape suitable for stirring slime or the like. Also, the inclined groove 18 (see FIG. 14B) on the outer peripheral surface of the body 11 allows muddy water or the like to pass through when the tip head 10 is moved up and down within the borehole 1 . At this time, muddy water or the like collides with the groove wall of the inclined groove 18 and acts to rotate the tip head 10 in the circumferential direction.

It should be noted that instead of the inclined groove 18, an inclined linear or spiral projection may be used. For example, the agitating protrusion 14 (see FIG. 1) shown in the first embodiment may be obliquely formed on the outer circumference of the body 11 . Further, a stirring plate 14a (see FIGS. 8B and 8C) may be provided on the bottom surface (seat surface) of the body 11 as in the second embodiment.

FIG. 15 is an explanatory diagram illustrating an example of the tip head of the cage pile according to the sixth embodiment of the present invention. FIG. 15(A) is a plan view of the tip head, FIG. 15(B) is a side view, and FIG. 15(C) is a bottom view. In the tip head of this embodiment, the groove 18 in the body of the tip head of the fifth embodiment is formed by groove walls 18a and tapered surfaces 18b. As a result, when the tip head 10 is moved up and down in the borehole 1, a fluid such as muddy water exerts a strong mechanical action on the inclined groove wall 18a, making it easier for the tip head to rotate in one direction with greater force. ing. Other configurations are the same as those of the fifth embodiment.

FIG. 16 is a diagram illustrating an example of connection between the tip head and the telescoping pile cage of the sixth embodiment. The telescoping pile cage 20 is, but not limited to, an extensible reinforcing bar cage using main bars having appropriate flexibility, for example. For example, Japanese Unexamined Patent Application Publication No. 2020-186538 describes an example of erecting a telescoping reinforced cage.
The telescoping pile cage (reinforcing bar cage) 20 in the extended state has a cylindrical shape, and a plurality of flexible main reinforcements 21, which are arranged in an annular shape and extend in the longitudinal direction, are made of, for example, PC steel stranded wires, It includes a plurality of annular ties 22 connected to a plurality of main reinforcements 21 via a rotatable jig (not shown). The lower end of each main rebar 21 is connected to the corresponding connecting rebar 12 of the tip head 10 via a sleeve 30 . A hook 121 is engaged with the suspending portion 19 of the tip head 10, and the tip head 10 is suspended by a lowering wire 122 of a crane (not shown). Since a plurality of groove walls 18a inclined with respect to the vertical direction are provided on the outer circumference of the body of the tip head 10, the tip in the fluid can be lifted by moving the lowering wire 122 or the main reinforcement 21 (or the entire reinforcing bar cage 20) up and down. By rotating the head 10, it is possible to agitate muddy water and slime by means of the recesses and protrusions on the outer periphery of the body and the bottom.

FIG. 17 is an explanatory diagram illustrating an example of erection of a telescoping reinforced cage that does not use the tip head of the present application. As shown in FIG. 17(A), the entire reinforcing bar cage is twisted to deform the flexible main reinforcing bars into a helical shape, and the reinforcing bar cage 20 contracted into a coil shape is placed in the standpipe 110 at the entrance of the excavation hole 1. . The reinforcing bar cage 20 is kept in a contracted state by the binding member 124 . Reinforcement ring members (not shown) are provided at the upper end and lower end of the reinforcing bar cage 20, respectively, and a hanging wire 123 of a crane (not shown) is connected to the ring member at the upper end to position the upper end of the reinforcing bar cage 20. be done. A lowering wire 122 of a crane is connected to an annular member at the lower end of the reinforcing bar cage 20 to position the lower end of the reinforcing bar cage 20 .

Next, as shown in FIG. 17(B), a temporary placement jig 120 is used to align the central axis of the reinforcing bar cage 20 with the center of the excavation hole 1 and fix the upper end. The binding member 124 of the reinforcing bar cage 20 is removed, and the lowering wire 122 is slowly lowered to gradually extend the reinforcing bar cage 20 downward. The reinforcing bar cage 20 descends while rotating by linearly extending the spiral main reinforcing bars.

As shown in FIG. 17(C), the lower end of the reinforcing bar cage 20 is extended toward the bottom of the hole by letting out the lowering wire 122 . For example, when it is detected that the lower end of the reinforcing bar cage 20 has reached the bottom 3 of the excavation hole 1 by the amount of feed of the lowering wire 122 or the measure connected to the lower end of the reinforcing bar cage 20 at one end, the lowering wire 122 is stopped, the hook is removed, and the lowering wire 122 is recovered. In this manner, the reinforcing bar basket 20 is arranged inside the borehole 1 . After that, the cast-in-place pile is completed by pouring concrete using a tremie tube and compressing the concrete by tightening the flexible main reinforcing bars in the same manner as in Example 1.

FIG. 18 is an explanatory diagram illustrating an example of erection of a telescoping reinforced cage using the tip head of the present application. In the construction method using the telescoping reinforced cage described above, a cylindrical reinforced cage with flexible wires such as PC steel strands as the main reinforcement is spirally wound to be reduced, bound in a coil state, and transported. However, when the bundle is removed, the stress of the coiled main reinforcement is released, and it is possible that the coiled state will become uneven. In addition, the telescoping reinforced cage expands from the coiled state to the original cylindrical shape by its own weight, but if the coiled portion decreases, the weight of that portion decreases and the downward expansion may be insufficient. In addition, there is a possibility that the reinforcing bar cage is distorted due to deformation of the flexible main bars due to winding (see FIG. 17(C)).

As shown in FIG. 18(A), in this embodiment, the telescopic reinforcing bar cage 20 is placed in the standpipe 110 at the entrance of the excavation hole 1 with the tip head 10 connected to the bottom of the telescopic reinforcing bar cage 20 . The weight (weight) of the tip head 10 pulls down the reinforcing bar cage 20 and the hoisting wire 122 in the vertical direction, thereby stabilizing the posture of the reinforcing bar cage 20 .

As shown in FIG. 18(B), when the binding member 124 is removed, the elastic stress of the flexible main reinforcement 21 is released. The flexible reinforcing bar 20 is fixed at its upper end by a temporary placement jig 120, and slowly rotates and extends downward from the coiled state due to its own weight and elastic stress, returning to its original cylindrical shape. In this embodiment, since the tip head 10 is provided below the reinforcing bar cage 20, the weight and rotation of the tip head 10 absorb the elastic stress associated with the opening of the flexible main bars while pulling the reinforcing bar cage 20 downward. Further, the tip head 10 rotates together with the reinforcing bar cage 20 and descends while agitating the muddy water in the borehole 1 . It is desirable to set the inclination direction of the stirring grooves 18 of the tip head 10 so that the resistance increases (the amount of stirring increases) in the rotating direction of the reinforcing bar cage 20 . Moreover, it is desirable that the groove or the groove wall is inclined at an angle of about 45 degrees with respect to the axial direction of the tip head 10, while generating an appropriate rotational force in the tip head 10 and not causing radial deflection. However, it is not limited to this. The descent amount and descent speed of the tip head 10 can be adjusted by feeding the lowering wire 122 connected to the tip head 10 .

As shown in FIG. 18(C), the tip head 10 extends the entire telescopic reinforcing bar cage 20 downward by its weight, so that the contracted coiled state can be returned to the original cylindrical reinforcing bar cage 20. It is convenient because it is possible to avoid (correct) deformation due to winding of the lower end of the telescoping cage 20 .

FIG. 19 illustrates a usage example of the tip heads 10 of Examples 5 and 6. FIG. In this example, the inverted V-shaped shape of the hanging portion 19 of the tip head 10 functions as an introduction guide to the position of the introduction hole 13 of the tremie tube 130 . 6, the inner diameter of the tremie tube 130 is set larger than the inner diameter of the introduction hole 13, and the lower end of the tremie tube 130 abuts the upper surface of the tip head 10. As shown in FIG. By pushing down the tip head 10 toward the hole bottom 3 with the tremie tube 130, the telescopic reinforcing bar cage 20 connected to the tip head 10 is extended downward, and the tip head 10 (or the reinforcing bar cage) is pressed against the hole bottom 3. It works like this.

In the embodiment, a ferrous material is used for the reinforcing bar cage as the pile cage, and a PC steel stranded wire is used for the flexible main reinforcing bars of the telescopic reinforcing bar cage. not something. For example, rust-resistant metal material, piano wire, highly rigid resin material, carbon fiber, or the like may be appropriately used.
Also, the technical elements described in each embodiment can be appropriately combined. For example, the stirring protrusion 14 of the tip head 10 shown in FIG. 1 may be formed obliquely. A stirring plate 14a shown in FIG. 8 may be added to this tip head. Furthermore, the stirring plate 14a may be extended from the bottom to the outer periphery.
The product may also be configured as a pile basket with the various tip heads described above.

As described above, in the embodiment of the present invention, a moderately heavy tip head is connected to the lower part of the reinforcing bar cage of the cast-in-place pile so that the central axis of the reinforcing bar cage is oriented in the vertical direction as much as possible. Therefore, by aligning the center of the drilled hole with the center of the reinforcing bar cage, contact between the reinforcing bar cage and the wall surface of the hole can be avoided, and the construction worker can easily erect the reinforcing bar cage. In addition, since the tip head is provided with a stirring means, when the tip head is moved by rotating the reinforcing bar cage (repeating forward and reverse rotation), the water and slime inside the drill hole are stirred and settled at the bottom. Since the slime is floated, the pile cage can be more reliably attached to the bottom of the hole (supporting layer), and concrete piles of the design length can be obtained. In addition, since it is possible to start pouring concrete with the tip of the tremie pipe positioned at the bottom of the hole (excluding the slime), the slime in the concrete pile is removed and the quality of the concrete pile is improved. In addition, when the reinforcing bar cage is erected, the tip head can be rotated to scrape off the unshavings remaining on the peripheral wall of the excavation hole, and it is possible to reduce the unshavings that will be included in the concrete pile. . Also, the tip head is good for use with telescoping pile cages.

REFERENCE SIGNS LIST 1 drilling hole 2 hole wall surface 3 hole bottom 4 slime, residue 5 unshavings on wall surface 10 tip head 11 body 12 connecting reinforcing bar (connecting means)
13 introduction hole 14 stirring protrusion (stirring part)
14a stirring plate (stirring part)
15 Center of gravity of tip head 16 Bearing surface 17 Iron ring 18 Groove 18a Groove wall 18b Taper surface 19 Suspension part 20 Rebar basket (pile basket)
20a Reinforcing bar cage of the first section 20b Reinforcing bar cage of the second section 21 Main bar 22 Tie bar 30 Sleeve (joint, connection means)
110 stand pipe 112 rod 113 bit 114 stabilizing liquid (bentonite solution)
115 muddy water (bore water)
117 Ultrasonic sensor 120 Temporary placement jig (hairpin steel)
121 hook 122 lowering wire 123 lifting wire 124 binding member 130 tremie pipe 140 concrete

Claims (5)

A tip head of the pile cage provided at the lower end of the pile cage arranged in the borehole,
a body acting as a weight to pull down the pile cage;
connection means for connecting the body and the pile cage;
a stirring unit for stirring the water in the borehole ,
The tip head of the pile cage, wherein the agitating part includes a band-shaped protrusion formed vertically on the outer circumference of the body. A tip head of the pile cage provided at the lower end of the pile cage arranged in the borehole,
a body acting as a weight to pull down the pile cage;
connection means for connecting the body and the pile cage;
a stirring unit for stirring the water in the borehole,
The tip head of the pile cage, wherein the agitating part comprises a slanted protrusion or a slanted groove formed on the outer circumference of the body. 3. The pile cage tip head according to claim 2 , wherein one wall surface of said groove is tapered. 4. The tip head of the pile cage according to any one of claims 1 to 3, wherein the body is formed with an introduction hole for guiding concrete to the bottom side of the excavation hole. A pile cage provided with a pile cage tip head according to any one of claims 1 to 3 .

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