JP2024017251A - Method for erecting reinforcing bar cage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for erecting a reinforcing bar cage that can be suitably applied even if there are restrictions such as overhead clearance.

SOLUTION: Reinforcing bar cages 1a and 1b are telescopic ones each having a cage body 2 in which tie hoops and flexible strands are connected such that the intersection angle is variable. When erecting these reinforcing bar cages 1a and 1b into an excavation hole 100, above the reinforcing bar cage 1a inserted into the excavation hole 100 with the axial direction of the cage body 2 being the vertical direction, the reinforcing bar cage 1b in which at least a portion including an upper end portion of the cage body 2 is contracted is arranged with the axial direction of the cage body 2 being the vertical direction. After that, the lower end of the strand of the upper reinforcing bar cage 1b and the upper end of the strand of the lower reinforcing bar cage 1a are connected. Two reinforcing bar cages 1a and 1b whose strands are connected to each other are suspended into the excavation hole 100. At this time, at least the cage body 2 of the upper reinforcing bar cage 1b is expanded.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a method for erecting a reinforcing bar cage, etc.

When constructing cast-in-place concrete piles or circular deep foundations under low clearance conditions, there is a construction method that uses a retractable reinforcing bar cage. Patent Documents 1 to 3 describe examples of such telescoping reinforcing cages.

FIG. 17 is a diagram illustrating the telescoping reinforcing bar cage 1. As shown in FIG. 17(a), the telescoping reinforcing bar cage 1 uses flexible PC steel strands (hereinafter referred to as strands) instead of ordinary deformed reinforcing bars in the axial steel material constituting the cage body 2. )21 was used.

In the cage body 2, the strands 21 and the ties 22 are connected by a connecting member at their intersections so that the intersection angle in the vertical plane between the strands 21 and the ties 22 is variable, as shown by arrow A. By twisting the upper end of the cage 2, the cage 2 contracts as shown in FIGS. 17(b) and 17(c). On the other hand, as shown by arrow B in FIG. 17(c), when the upper end of the cage body 2 is rotated in the direction opposite to the arrow A, the cage body 2 is expanded. The above-mentioned coupling members are described in Patent Documents 1 to 3, and their explanation will be omitted here.

Japanese Patent Application Publication No. 2005-048519 Japanese Patent Application Publication No. 2006-132190 Japanese Patent Application Publication No. 2008-214990

When constructing long cast-in-place concrete piles underground using telescopic reinforcing bar cages, it is necessary to connect the reinforcing bar cages together and build them into the excavated hole. One way to do this is, for example, to lift the upper end of the cage with a crane on the ground near the borehole, extend the entire length of the cage, and then insert the reinforcing bar cage into the borehole or join the reinforcing bar cages together. It will be done.

However, the above method of extending the cage on the ground only requires that there is an air head or a lift above the ground of the crane that can fully extend the cage on the ground, but if these are limited, the above method cannot be used. Sometimes it is difficult to do.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a method for erecting a reinforcing bar cage that can be suitably applied even when there are restrictions such as empty heads.

In order to solve the above-mentioned problems, the present invention is directed to the construction of a retractable reinforcing bar cage in an excavation hole, which has a cage body in which tie bars and flexible strands are combined so that the intersection angle is variable. In this method, a reinforcing bar cage, in which at least a portion including the upper end of the cage body is contracted, is placed above the reinforcing bar cage inserted into a borehole with the axial direction of the cage body in the vertical direction. A step (a) of arranging the axial direction as the vertical direction, a step (b) of connecting the lower ends of the strands of the upper reinforcing bar cage and the upper ends of the strands of the lower reinforcing bar cage, and two reinforcing bars that connect the strands to each other. A method for erecting a reinforcing bar cage, comprising a step (c) of lowering the cage into an excavated hole, and in the step (c), at least the cage body of the upper reinforcing bar cage is extended. be.

In this embodiment, when the telescopic reinforcing bar cages are connected vertically and erected, the upper reinforcing bar cage is transported and placed in a contracted state using a crane, etc., and the lower reinforcing bar cage located in the excavation hole is connected to the lower reinforcing bar cage. Join directly above the excavation hole, etc. Therefore, even when construction conditions are low and there is a limit to the crane's above-ground lifting height, reinforcing bar cages can be joined to make them longer, making it possible to construct structures such as cast-in-place concrete piles deep underground. I can do it.

Before the strands are connected to each other in step (b), at least a portion of the lower reinforcing bar cage including the lower end of the cage body is contracted, and in step (c), the cage body of the lower reinforcing bar cage is contracted. It is desirable to lower the lower end of the cage into the excavation hole and extend the cage bodies of the upper and lower reinforcing bar cages.
In this case, the reinforcing bar cage can be stretched in one go, and the work can be done in a short time.

Before connecting the strands to each other in step (b), the entire length of the cage body of the lower reinforcing bar cage and the lower end of the cage body of the upper reinforcing bar cage are in an extended state, and the strands of the upper reinforcing bar cage are stretched. It is also desirable that the lower ends of the strands and the upper ends of the strands of the lower rebar cage are arranged vertically.
Thereby, the work of connecting the strands can be easily performed.

In the cage body of the upper reinforcing bar cage, reinforcing rings along the circumferential direction of the cage body are provided in three or more stages spaced apart vertically, and vertically adjacent reinforcing rings are connected to each other by a connecting material, Before connecting the strands in step (b), it is also desirable to remove the lowest connecting member and stretch the cage in the section between the reinforcing rings connected by the connecting member.
Thereby, the lower end of the cage body of the upper reinforcing bar cage can be partially extended, and the work of connecting the reinforcing bar cages can be easily performed even under low head construction conditions.

In step (c), the connecting material located at the bottom of the upper reinforcing bar cage is removed, the cage body in the section between the reinforcing rings connected by the connecting material is expanded, and the two reinforcing bars with the strands connected to each other are removed. It is also desirable to repeat the process of lifting and lowering the basket.
By repeating the above procedure and repeating the partial extension of the cage body of the upper reinforcing bar cage and the insertion of the reinforcing bar cage into the excavated hole, the reinforcing bar cage can be erected even under construction conditions of low head height. can.

In step (c), when removing the connecting member located at the bottom of the upper reinforcing bar cage and extending the cage body in the section between the reinforcing rings located on the ground, which were connected by the connecting member, the relevant It is desirable to restrain the rotation of the rebar cage in the excavation hole located below the section, stretch the cage body in the section, and then vertically drop the two rebar cages with their strands connected without rotating.
This prevents the reinforcing bar cage from rotating within the excavated hole and scraping off the hole wall, and has the advantage that the spacer for the upper reinforcing bar cage can be made simple.

According to the present invention, it is possible to provide a method for erecting a reinforcing bar cage that can be suitably applied even if there are restrictions such as empty heads.

A diagram showing reinforcing bar cages 1a and 1b. FIG. 4 is a diagram showing a reinforcing ring 4b and a centering mechanism 43. The figure which shows the erection method of reinforcing bar cages 1a and 1b. The figure which shows the erection method of reinforcing bar cages 1a and 1b. FIG. 3 is a diagram illustrating connection of strands 21 to each other. The figure which shows the erection method of reinforcing bar cages 1a and 1b. A diagram showing reinforcing bar cages 1c and 1d. A diagram showing how to erect reinforcing bar cages 1c and 1d. A diagram showing how to erect reinforcing bar cages 1c and 1d. A diagram showing how to erect reinforcing bar cages 1c and 1d. A diagram showing how to erect reinforcing bar cages 1c and 1d. A diagram showing a reinforcing bar cage 1e. A diagram showing how to erect reinforcing bar cages 1d and 1e. A diagram showing how to erect reinforcing bar cages 1d and 1e. A diagram showing how to erect reinforcing bar cages 1d and 1e. A diagram showing how to erect reinforcing bar cages 1d and 1e. FIG. 3 is a diagram illustrating expansion and contraction of the reinforcing bar cage 1.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

[First embodiment]
(1. Rebar cages 1a, 1b)
FIGS. 1(a) and 1(b) are diagrams showing reinforcing bar cages 1a and 1b used in this embodiment, and respectively show the inside and outside of the cage body 2 in a contracted state. Similar to the above-mentioned reinforcing bar cage 1, the reinforcing bar cages 1a and 1b have a cage body 2 in which strands 21, which are flexible axial steel materials, and tie bars 22 are connected so that the intersection angle is variable. In addition, reinforcing rings 4 (4a, 4b) are provided on the inside and outside of the cage body 2, respectively.

The reinforcing rings 4 (4a, 4b) are provided in multiple stages at intervals in the axial direction of the cage body 2 at both ends of the cage body 2 in the axial direction and at an intermediate portion between both ends. The vertically adjacent reinforcing rings 4 (4a, 4b) can be removed by twisting the cage bodies 2 of the reinforcing bar cages 1a, 1b as shown by arrows A and B in FIGS. 17(a) and (c). Relative rotation according to expansion and contraction.

FIG. 2(a) is a diagram showing a reinforcing ring 4b arranged inside the cage body 2. As shown in FIG. The reinforcing ring 4b is a ring-shaped steel material having an L-shaped cross section with a vertical portion 41 and a horizontal portion 42. The reinforcing ring 4b can be formed, for example, by processing an angle material into a ring shape.

The reinforcing ring 4b inside the cage 2 is arranged along the circumferential direction of the cage 2 with the vertical portion 41 facing outside (on the cage 2 side), and a hole 411 is formed in the vertical portion 41. The hole 411 is used to attach a rotational coupling member (not shown) that rotatably couples the reinforcing ring 4b and the strand 21 in a vertical plane. A number of holes 411 corresponding to the number of strands 21 are provided in the vertical portion 41 at equal intervals in the circumferential direction.

An example of a rotation coupling member is described in Patent Document 3, but to briefly explain, a shaft member such as a stud bolt is provided on the outer surface of a sleeve through which the strand 21 is inserted. The rotary coupling member can be attached to the reinforcing ring 4b by passing it through the hole 411 and tightening a nut on its tip.

The reinforcing ring 4a on the outside of the cage 2 has a configuration in which the vertical portion 41 and the horizontal portion 42 of the reinforcing ring 4b on the inside of the cage 2 are swapped inside and out, with the vertical portion being on the inside (on the cage 2 side). will be placed in The rest of the structure is substantially the same as that of the reinforcing ring 4b.

The reinforcing bar cage 1a in FIG. 1(a) is a reinforcing bar cage joined to the lower part of the reinforcing bar cage 1b, and the reinforcing rings 4a and 4b of the second stage (the number of stages when counting from the top; the same applies hereinafter) are They are arranged at the same height near the upper end of the cage body 2. The upper end of the strand 21 of the cage body 2 is made to protrude upward by a certain length from the uppermost strap 22.

Further, a hanging material L1 having a length that extends from above the cage body 2 is attached to the lowermost reinforcing ring 4b. For example, a wire or a chain is used for the hanging material L1, and is attached to the reinforcing ring 4b via a hanging jig h such as a column lock (registered trademark).

The uppermost reinforcing ring 4b is provided with a centering mechanism 43 for the hanging material L1, whereby the planar position of the hanging material L1 is fixed to the planar center of the reinforcing bar cage 1a.

FIG. 2(b) is a diagram showing an example of the centering mechanism 43. The centering mechanism 43 supports a cylindrical body 432 arranged at the planar center of the reinforcing bar cage 1a by, for example, an arm 431 extending inward from the reinforcing ring 4b. By passing the hanging material L1 through this cylindrical body 432, the planar position of the hanging material L1 can be fixed to the planar center of the reinforcing bar cage 1a.

The reinforcing bar cage 1b in FIG. 1(b) is a reinforcing bar cage that is joined above the reinforcing bar cage 1a, and the second-stage reinforcing ring 4a and the third-stage reinforcing ring 4b are at the same height near the lower end of the cage body 2. It is placed in The lower end of the strand 21 of the cage body 2 is made to protrude downward by a certain length from the lowermost strap 22.

Further, hanging materials L2 such as wires having a length that extends from the top and bottom of the cage body 2 are arranged inside the cage body 2. The uppermost reinforcing ring 4b is provided with a centering mechanism 43 similar to that described above, whereby the planar position of the hanging material L2 is fixed to the planar center of the reinforcing bar cage 1b.

(2. How to erect reinforcing bars 1a and 1b)
The reinforcing bar cages 1a and 1b are manufactured in advance in a factory or the like with the cage body 2 in a contracted state. In this embodiment, the reinforcing bar cages 1a and 1b manufactured in a factory or the like are transported by land transport means such as trucks to a construction site or an unloading point in the vicinity, and then the reinforcing bar cages 1a and 1b are suspended by a crane or the like. , transport to the borehole where the cast-in-place concrete pile will be constructed.

In this embodiment, first, the reinforcing bar cage 1a is first built into the excavated hole 100 as shown in FIG. 3(a). The reinforcing bar cage 1a is suspended from the crane by attaching the upper end of the hanging member L1 to the crane with the cage body 2 contracted, and is suspended inside the excavated hole 100 until the second stage reinforcing rings 4a and 4b reach the hole opening level. inserted.

The reinforcing bar cage 1a is transported and erected by a crane with the axial direction of the cage body 2 being the vertical direction, and the reinforcing rings 4a at the second and lowest stages being secured with lashing material La such as a lever hoist. be exposed. The planar position of the hanging material L1 is fixed to the planar center of the reinforcing bar cage 1a by a centering mechanism 43, thereby preventing the cage body 2 from falling over.

Next, as shown in FIG. 3(b), the uppermost reinforcing rings 4a and 4b are pulled up manually, and a steel material used as a hairpin 200 is inserted over the second reinforcing rings 4a and 4b and inserted into the hole. The second stage reinforcing rings 4a, 4b and the hairpin 200 are connected using a joining means (not shown) such as a bolt.

Here, since the second and bottom reinforcing rings 4a are secured by the lashing material La, by lifting the topmost reinforcing rings 4a and 4b, the top and second reinforcing rings 4a are secured together. Only the cage body 2 in the section between (the upper end of the cage body 2) extends slightly upward, and the cage body 2 in the section between the second stage and the lowest reinforcing ring 4a (including the lower end of the cage body 2) some) remain in a contracted state.

Thereafter, as shown in FIG. 3(c), the upper end of the hanging material L1 is removed from the crane, the centering mechanism 43 is removed, and the entire weight of the reinforcing bar cage 1a is supported from the hairpin 200.

Then, as shown in FIG. 4(a), the reinforcing bar cage 1b is suspended and transported from the main hoist of the crane by the hanging material L3 attached to the uppermost reinforcing ring 4a, and is placed above the reinforcing bar cage 1a. , attach the lower end of the hanging material L2 to the upper end of the hanging material L1.

The reinforcing bar cage 1b is transported with the axial direction of the cage body 2 being the vertical direction, and the reinforcing rings 4a at the top and second stages are tied down with a lashing material La such as a lever hoist. The cage body 2 in the section (a part including the upper end of the cage body 2) is in a contracted state. On the other hand, since the reinforcing ring 4a at the lowest stage is not secured with the lashing material La, the cage body 2 in the section below the second stage reinforcing ring 4a (the lower end of the cage body 2) is slightly tilted downward due to its own weight. It is expanding.

Next, the reinforcing bar cage 1b is suspended, and the reinforcing bar cages 1a and 1b are joined together. In this embodiment, as shown in FIG. 5(a), apartments (external threads) 221 are formed at the ends of the strands 21 of the reinforcing bar cages 1a and 1b, and by connecting the apartments 211 of both strands 21, The reinforcing bar cages 1a and 1b are joined together. A coupler 212 having a female thread is used to connect the strands 21 (apartments 211). The coupler 212 is screwed and attached in advance to the apartment 211 at the lower end of the strand 21 of the reinforcing bar cage 1b.

The condominiums 211 at the ends of the strands 21 of both reinforcing bar cages 1a and 1b are butted against each other, and a special condominium gripping jig (not shown) is used to pull the condominiums 211 together to align their axes, correct the twist in the condominiums 211, and then connect the coupler 212. By rotating and moving it forward, the apartment 211 at the upper end of the strand 21 of the reinforcing bar cage 1a is screwed into the inside of the coupler 212, as shown in FIG. 5(b). After the condominiums 211 are screwed into the coupler 212 by an appropriate length, both condominiums 211 are fixed to the coupler 212 using a fixing means such as a set screw (not shown). Thereby, the reinforcing bar cages 1a and 1b are joined together as shown in FIG. 4(b).

After that, the upper end of the hanging material L2 is attached to the auxiliary hoist of the crane, and as shown in FIG. The lashing material La is removed to release the lashing of the cage body 2. Note that the planar position of the hanging material L2 is fixed to the planar center of the reinforcing bar cage 1b by the centering mechanism 43 of the reinforcing bar cage 1b, thereby preventing the cage bodies 2 of the reinforcing bar cages 1a and 1b from falling over.

Next, the lashing material La of the reinforcing bar cage 1b is removed to release the lashing of the cage body 2, and the hanging materials L2 and L3 are simultaneously lowered, as shown in FIG. 6(a), to secure the reinforcing bar cages 1a and 1b. It is suspended into the excavation hole 100. In this embodiment, when the reinforcing bar cages 1a and 1b are lowered to a predetermined depth in the excavation hole 100, the hairpin 200 is spanned over the hole opening, and the reinforcing ring 4b at the top of the reinforcing bar cage 1b and the hairpin 200 are suspended. Connect with reinforcing bars 201.

Thereafter, the hanging material L3 is removed from the reinforcing ring 4a at the top of the reinforcing bar cage 1b, the hanging material L2 is lowered to lower the lower end of the reinforcing bar cage 1a, and the cage bodies 2 of the reinforcing bar cages 1a and 1b begin to extend. . These cage bodies 2 begin to extend in order from top to bottom and descend while rotating. As shown in FIG. 6(b), when the lower ends of the reinforcing bar cages 1a and 1b are lowered until the entire length of the cage bodies 2 of the reinforcing bar cages 1a and 1b are extended, these reinforcing bar cages 1a and 1b are supported by the hairpin 200.

When the hanging materials L1 and L2 are collected as shown in FIG. 6(c), the erection of the reinforcing bar cages 1a and 1b is completed. Thereafter, the centering mechanism 43 of the reinforcing bar cage 1b is removed and concrete is poured into the excavated hole 100, thereby constructing a cast-in-place concrete pile. Note that the structure constructed using the reinforcing bar cages 1a and 1b is not limited to this, and may be, for example, a circular deep foundation. The purpose of removing the centering mechanism 43 is to ensure smooth concrete placement, and the removed centering mechanism 43 can be reused.

If necessary, the hanging material L3 is attached to the reinforcing ring 4a at the top of the reinforcing bar cage 1b, and after hoisting the hanging material L3 up from the crane and tensioning it, the hanging reinforcing bar 201 is removed from the hairpin 200, and the hanging material L3 is By lowering the reinforcing bar cages 1a and 1b, it is also possible to lower the reinforcing bar cages 1a and 1b again to adjust the height of the construction. After adjusting the height, the hanging reinforcing bars 201 are connected to the hairpins 200 again, and the hanging material L3 is removed.

As described above, in this embodiment, when the telescopic reinforcing bar cages 1a and 1b are joined vertically and erected, the upper reinforcing bar cage 1b is transported and placed in a contracted state using a crane, and is placed inside the excavation hole 100. It is connected to the lower reinforcing bar cage 1a located directly above the excavated hole 100. Therefore, even when construction conditions are low, or there is a limit to the crane's lifting height above the ground, the reinforcing bar cages 1a and 1b can be joined to make them longer, and structures such as cast-in-place concrete piles can be built deep underground. Can be built.

In addition, in this embodiment, the lower reinforcing bar cage 1a is also transported and placed in a contracted state, which is effective when there is a restriction such as an empty head. 6(b)) can be performed at once by lowering the hanging material L2 once, and it takes an extremely short time.

Note that the reinforcing bar cages 1a and 1b are provided with spacers (not shown) for maintaining the distance from the hole wall of the drilled hole 100, but the reinforcing bar cages 1a and 1b rotate within the drilled hole 100 during the above-mentioned extension. do. Therefore, in order to prevent the spacers of the reinforcing bar cages 1a and 1b from scraping off the earth and sand on the hole walls, the spacers require skids in the rotational direction.

A skid is an inclined shape of a spacer, and in order to prevent the spacer from scraping off earth and sand from the hole wall during rotation, the skid is only tilted in the vertical direction, as shown in Figure 4 of JP-A No. 2006-274726. It is also necessary to form the skid in the rotational direction (horizontal direction) by giving it roundness in the horizontal direction or by bending the plate material.

In addition, when assembling the reinforcing bar cages 1a and 1b at a factory, for the purpose of ensuring the protruding length of the tips of the strands 21, the ties 22 near the upper end of the cage body 2 of the reinforcing bar cage 1a are set a predetermined length from the upper end of the strands 21. (For example, by about several tens of centimeters) is shifted downward, and the tie bars 22 near the lower end of the cage body 2 of the reinforcing bar cage 1b are also shifted upward by a predetermined length from the lower end of the strands 21. These ties 22 are returned to appropriate positions after the strands 21 are connected to each other. Alternatively, these straps 22 may be half-split ties 22 that are attached after the strands 21 are connected to each other. In addition, in order to adjust the direction of the tips of the strands 21 when connecting the strands 21, the reinforcing rings 4a and 4b at the top of the reinforcing bar cage 1a and the reinforcing rings 4a and 4b at the bottom of the reinforcing bar cage 1b are disassembled and removed. You can. The above also applies to the examples described later.

Hereinafter, other examples of the present invention will be described as second and third embodiments. In each embodiment, the points different from the first embodiment will be mainly explained, and the same points will be denoted by the same reference numerals in the figures and the like, and the explanation will be omitted. Furthermore, the configurations described in each embodiment, including the first embodiment, can be combined as necessary.

[Second embodiment]
(1. Rebar cages 1c, 1d)
FIGS. 7(a) and 7(b) are diagrams showing reinforcing bar cages 1c and 1d used in the second embodiment, and are views of the inside and outside of the cage body 2 in a contracted state, respectively.

The reinforcing bar cage 1c in FIG. 7(a) differs from the reinforcing bar cage 1a used in the first embodiment mainly in that outer reinforcing rings 4a are provided in upper and lower two stages at both ends of the cage body 2.

On the other hand, in the reinforcing bar cage 1d in FIG. 7(b), the reinforcing rings 4a and 4b are spaced apart in the axial direction of the cage body 2 at both ends of the cage body 2 in the axial direction and at an intermediate portion between both ends. The reinforcing rings 4a are provided in three or more stages (four stages in the illustrated example), and vertically adjacent reinforcing rings 4a are connected to each other by a connecting member 5.

(2. How to build reinforcing bar cages 1c and 1d)
The reinforcing bar cages 1c and 1d are also prefabricated in a factory etc. with the cage body 2 in a contracted state, and after being transported to an unloading point and unloaded, they are suspended by a crane etc. and cast-in-place concrete piles are constructed. transport to the drilling hole.

In this embodiment, first, the reinforcing bar cage 1c is first built into the excavated hole 100 as shown in FIG. 8(a). The reinforcing bar cage 1c is suspended from the crane by attaching the upper end of the hanging material L1 to the crane, with the cage body 2 contracted, and inserted into the excavated hole 100 until the reinforcing ring 4 at the top level reaches the hole opening level. .

The reinforcing bar cage 1c is in a state in which the axial direction of the cage body 2 is the vertical direction, and the reinforcing rings 4a at the top and bottom stages are tied down with lashing material La such as a lever hoist. After suspending and lowering the basket 1c, remove it. Further, as in the first embodiment, the planar position of the hanging material L1 is fixed to the planar center of the reinforcing bar cage 1c by the centering mechanism 43, so that the reinforcing bar cage 1c will not fall.

Next, as shown in FIG. 8(b), the uppermost reinforcing rings 4a and 4b are pulled up manually, and the steel material used as the hairpin 200 is inserted under the uppermost reinforcing rings 4a and 4b, and is placed over the hole. . Then, the reinforcing rings 4a, 4b and the hairpin 200 are joined using a joining means (not shown) such as a bolt.

Thereafter, as shown in FIG. 8(c), the hanging material L1 is lowered, and the cage body 2 of the reinforcing bar cage 1c is extended downward within the excavated hole 100. The cage body 2 extends while rotating, and when the entire length of the cage body 2 is extended, the upper end of the strand 21 is arranged along the vertical direction, and the reinforcing bar cage 1c is supported from the hairpin 200. After that, the hanging material L1 is collected. Note that the centering mechanism 43 may be removed at this point.

In this embodiment, a reinforcing bar cage 1d is joined onto this reinforcing bar cage 1c. At this time, as shown in FIG. 9(a), a gate-shaped frame 8 was assembled in advance at the mouth of the excavation hole 100, and the axial direction of the cage body 2 was made vertical, and the entire length of the cage body 2 was shrunk. The reinforcing bar cage 1d in this state is suspended and transported by a crane, and placed above the reinforcing bar cage 1c. Then, a hanging material L3 such as a lever hoist hanging from the topmost beam of the frame 8 is attached to the reinforcing ring 4a at the top of the reinforcing bar cage 1d, thereby suspending and supporting the reinforcing bar cage 1d.

After that, the connecting member 5 (lowest connecting member) connecting the third stage and the lowest reinforcing ring 4a of the reinforcing bar cage 1d is removed, and these reinforcing rings are removed as shown in FIG. 9(b). The cage body 2 in the section between 4a is expanded. At this time, the lower end of the strand 21 of the reinforcing bar cage 1d is arranged in the vertical direction.

As a method for extending the cage body 2, for example, a lid (not shown) is provided at the mouth of the excavation hole 100, and the hanging material L3 is lowered and the reinforcing bar cage 1d is temporarily placed on the lid. Since the load will not be borne, the reinforcing bar cage 1d may be lifted up by the hanging material L3 after the connecting member 5 is removed. Alternatively, the reinforcing bar cage 1d is transported from the uppermost reinforcing ring 4a with the lowermost reinforcing ring 4a secured using a securing material (not shown) such as a lever hoist, and arranged as shown in FIG. 9(a). After that, by hoisting up the lashing material, the above-mentioned connecting material 5 will be in a state where it does not bear the load, so after removing the lashing material 5, by loosening the lashing material, the third and bottom tier can be reinforced. It is also possible to extend the cage body 2 in the section between the rings 4a downward.

After that, as shown in FIG. 9(c), the reinforcing bar cage 1d is suspended, and as in the example of FIG. are connected by a coupler 212. Thereby, the reinforcing bar cages 1c and 1d are joined together. In this embodiment, since the tips of these strands 21 are vertical, the work of connecting the condominiums 211 to each other is easier than in the first embodiment, and no special tools are required.

After joining the reinforcing bar cages 1c and 1d, the hanging material L3 is rolled up slightly and the hairpin 200 is removed. Then, as shown in FIG. 10(a), the hanging material L3 is lowered, and the cage body 2 in the extended section of the reinforcing bar cage 1d in FIG. 9(b) is inserted into the excavation hole 100.

In addition, a hanging material L4 such as a lever hoist hanging from the topmost beam of the frame 8 is attached to the third-stage reinforcing ring 4a of the reinforcing bar cage 1d located above the above section, and the third-stage reinforcing ring 4a is suspended and supported by the hanging material L4. In this state, remove the connecting member 5 (at this point, the lowest connecting member 5) between the second and third reinforcing rings 4a located on the ground, as shown in FIG. 10(b). When the hanging material L3 is rolled up, the cage body 2 in the section between the second and third reinforcing rings 4a from which the connecting material 5 has been removed rotates and extends upward.

Here, if the third stage reinforcing ring 4a of the reinforcing bar cage 1d is fixed so as not to rotate on a plane, the reinforcing bar cages 1c and 1d in the excavation hole 100 located below the above-mentioned section of the reinforcing bar cage 1d will be fixed. Rotation is restricted and the hole wall will not be scraped. The third-stage reinforcing ring 4a can be fixed, for example, by temporarily joining the reinforcing ring 4a to a hairpin (not shown) that spans the opening of the excavation hole 100 with bolts or the like. The fixing means is not limited to this. Further, the fixing means such as a hairpin is removed after the cage body 2 in the above-mentioned section of the reinforcing bar cage 1d is completely extended as shown in FIG. 10(b).

When the extension of the cage body 2 in the above section of the reinforcing bar cage 1d is completed, the hanging material L4 is removed from the third stage reinforcing ring 4a, and as shown in FIG. 10(c), the hanging material L3 is lowered to complete the reinforcing bar cage 1c. , 1d are vertically lowered without rotating, and the cage body 2 in the extended section is inserted into the excavation hole 100. Thereafter, by repeating the operations shown in FIGS. 10(a) to 10(c), the entire length of the cage body 2 of the reinforcing bar cage 1d is extended. When the hanging material L3 is further lowered, the reinforcing bar cages 1c and 1d with the entire length of the cage body 2 extended are suspended into the excavated hole 100 as shown in FIG. 11.

In this embodiment, a hanging reinforcing bar 201 is attached to the reinforcing ring 4b at the top of the reinforcing bar cage 1d while the reinforcing bar cages 1c and 1d are being lowered, and when the reinforcing bar cages 1c and 1d are lifted down to a predetermined depth of the excavation hole 100. Then, the hairpin 200 is installed at the hole opening, and the hairpin 200 and the hanging reinforcing bar 201 are connected. Thereafter, the hanging material L3 is removed from the reinforcing ring 4a at the top of the reinforcing bar cage 1d and removed, thereby completing the erection. It is also possible to adjust the built-in height using the same method as in the first embodiment.

As described above, in the present embodiment, after the entire length of the cage body 2 of the reinforcing bar cage 1c is expanded in advance in the excavation hole 100, the reinforcing bar cages 1c and 1d are joined together, and the reinforcing bar cages 1c and 1d are connected to each other and placed in a contracted state directly above the excavation hole 100. The reinforcing bar cage 1d is erected by extending it section by section. This also provides the same effects as the first embodiment.

In addition, not only the upper reinforcing bar cage 1d but also the lower reinforcing bar cage 1c are transported and placed in a contracted state, which is effective when there is a restriction such as an empty head. Since the tips of these strands 21 are in a vertical state before being connected, the work of connecting the strands 21 is facilitated. Therefore, it is possible to easily accommodate a structure in which the connecting portions of the strands 21 are not aligned at the same height but are arranged in a staggered manner.

Regarding the upper reinforcing bar cages 1d, the cage body 2 can be partially extended before connecting the strands 21 (see Fig. 9(b), etc.), and even under construction conditions with low head height, the reinforcing bar cages 1c and 1d can be extended. Connection work can be easily performed. However, compared to the first embodiment, a slight empty head is required, and the workable empty head is determined depending on the length of the reinforcing bar cage 1d. Therefore, it is also desirable that the reinforcing bar cage 1d be shorter than the reinforcing bar cage 1c.

In addition, when erecting the reinforcing bar cages 1c and 1d, by repeating the partial extension of the cage body 2 of the upper reinforcing bar cage 1d and the insertion of the stretched section of the cage body 2 into the excavated hole 100, the reinforcing bar cage Construction of 1c and 1d can be carried out even under construction conditions of low head height. Further, in this embodiment, the frame 8 at the mouth of the excavation hole 100 is used to suspend and lower the reinforcing bar cages 1c and 1d, thereby making it possible to perform the erection work easily. Furthermore, by using the frame 8 as an auxiliary aid, the lifting capacity of the crane can be relatively low.

Further, in this embodiment, the reinforcing bar cage 1d does not rotate within the excavated hole 100. Therefore, the spacer of the reinforcing bar cage 1d does not require the above-mentioned skid in the rotational direction, and can be simple and inexpensive. It is also possible to attach the spacers on the ground while extending the cage body 2 section by section. Note that since the reinforcing bar cage 1c extends while rotating within the excavated hole 100 in the step shown in FIG. 8(c), the spacer requires a skid in the rotational direction.

In addition, in the first and second embodiments, an example was explained in which two upper and lower reinforcing bar cages are joined, but the same method can be implemented when three or more upper and lower reinforcing bar cages are joined.

For example, in the first embodiment, after joining the reinforcing bar cages 1a and 1b as shown in FIG. After re-lashing the reinforcing ring 4a of the tier and the reinforcing ring 4a of the lowest tier of the reinforcing bar cage 1a with the lashing material La, the second tier reinforcing rings 4a and 4b of the reinforcing bar cage 1b are secured to the hole opening level using a hairpin 200. , and then a new reinforcing bar cage 1b may be joined on top of the reinforcing bar cage 1b. On the other hand, in the second embodiment, in the process shown in FIG. 11, the uppermost reinforcing rings 4a and 4b of the reinforcing bar cage 1d are supported at the hole opening level by hairpins 200, and a new reinforcing bar cage 1d is joined thereon. Bye.

Further, in this embodiment, the frame 8 is assembled during construction and the hanging material L3 such as a lever hoist is hung down, but the frame 8 is assembled from the beginning and the hanging material L3 such as the lever hoist is hung from the frame 8. The reinforcing bar cage 1c may be connected to the hanging material L1 to suspend and support the reinforcing bar cage 1c in the steps shown in FIGS. 8(a) to 8(c). Further, although the connecting member 5 connects the reinforcing rings 4a on the outside of the cage body 2, it may connect the reinforcing rings 4b on the inside of the cage body 2. However, in this case, it takes some effort to remove the connecting member 5.

[Third embodiment]
(1. Rebar cage 1e)
FIG. 12 is a diagram showing a reinforcing bar cage 1e used in the third embodiment, and shows the inside of the cage body 2 in a contracted state. In this embodiment, this reinforcing bar cage 1e and the above-mentioned reinforcing bar cage 1d (see FIG. 7(b)) are joined together and built into the excavated hole 100.

The reinforcing bar cage 1e is different from the reinforcing bar cage 1a used in the first embodiment in that a hanging reinforcing bar 44 that protrudes upward from the cage body 2 is attached to the uppermost reinforcing ring 4b, and a temporary reinforcing bar is attached to the upper end of the hanging reinforcing bar 44. The difference is that a receiving steel ring (hereinafter referred to as a temporary receiving ring) 6 is attached.

(2. How to build reinforcing bar cages 1e and 1d)
The reinforcing bar cages 1e and 1d are prefabricated in a factory or the like with the cage body 2 in a contracted state, and after being transported to an unloading point and unloaded, they are suspended by a crane, etc., and cast-in-place concrete piles are constructed. transport to the drilling hole.

In this embodiment, first, the reinforcing bar cage 1e is first built into the excavated hole 100 as shown in FIG. 13(a). The reinforcing bar cage 1e is suspended and supported from the crane with the upper end of the hanging material L1 attached to the crane, the axial direction of the cage body 2 is the vertical direction, and the cage body 2 is contracted. It is inserted into the borehole 100 until it is located above.

Then, the hairpin 200 is inserted under the temporary support ring 6 and spanned over the opening of the excavated hole 100, and the hairpin 200 and the temporary support ring 6 are joined by a joining means (not shown) such as a bolt. Similar to the second embodiment, the reinforcing bar cage 1e is in a state in which the reinforcing rings 4a at the top and bottom stages are tied down with lashing material La such as a lever hoist, and the lashing material La is used to suspend the reinforcing bar cage 1e. After unloading, remove it.

Thereafter, as shown in FIG. 13(b), the hanging material L1 is lowered, and the cage body 2 of the reinforcing bar cage 1e is extended downward within the excavated hole 100. The cage body 2 extends while rotating, and when the entire length of the cage body 2 is extended, the upper ends of the strands 21 are arranged along the vertical direction, as in the second embodiment. The spacing between the temporary support ring 6 and the reinforcing rings 4a and 4b at the top of the reinforcing bar basket 1e is such that the apartment 211 at the upper end of the strand 21 does not interfere with the temporary support ring 6 or the hairpin 200 at this time.

After that, the hanging material L1 is replaced with the temporary support ring 6, the hairpin 200 is removed, and the reinforcing bar cage 1e is lifted up by the hanging material L1 as shown in FIG. Insert it again. Thereafter, the hanging material L1 is collected, and the temporary support ring 6, centering mechanism 43, hanging reinforcing bar 44, etc. are also removed.

In this embodiment, a reinforcing bar cage 1d is joined onto this reinforcing bar cage 1e. At this time, as shown in FIG. 14(a), a gate-shaped frame 8 is assembled in advance at the mouth of the excavation hole 100, and the axial direction of the cage body 2 is made vertical, and the entire length of the cage body 2 is contracted. The reinforced reinforcing bar cage 1d is lifted and transported by a crane, and placed above the reinforcing bar cage 1e. Then, a hanging material L3 such as a lever hoist hanging from the topmost beam of the frame 8 is attached to the reinforcing ring 4a at the top of the reinforcing bar cage 1d, thereby suspending and supporting the reinforcing bar cage 1d.

Thereafter, as shown in FIG. 14(b), the connecting member 5 between the third and lowest reinforcing rings 4a (the lowest connecting member 5) is connected in the same manner as in the second embodiment. Then, the cage body 2 in the section between these reinforcing rings 4a is expanded. Thereby, the lower end of the strand 21 of the reinforcing bar cage 1d is arranged in the vertical direction.

Thereafter, the reinforcing bar cage 1d is suspended, the reinforcing bar cages 1d and 1e are joined together as in the second embodiment, and then the hanging material L3 is rolled up as shown in FIG. 14(c). When the upper end of the reinforcing bar cage 1d approaches the topmost beam of the frame 8, the beam and the reinforcing ring 4a at the top of the reinforcing bar cage 1d are connected with the hanging reinforcing bars 44. In this embodiment as well, the reinforcing bar cages 1d and 1e are connected to each other by connecting the apartment 211 at the lower end of the strand 21 of the reinforcing bar cage 1d and the apartment 211 at the upper end of the strand 21 of the reinforcing bar cage 1e using the coupler 212. Since the vertically standing condominiums 211 are connected to each other, the work is easy and no special tools are required.

Thereafter, as shown in FIG. 15(a), the hanging material L3 is replaced with the reinforcing ring 4b at the top of the reinforcing bar cage 1e. Further, a hanging material L4 such as a lever hoist suspended from the topmost beam of the frame 8 is attached to the third reinforcing ring 4a of the reinforcing bar cage 1d.

Next, as shown in FIG. 15(b), the reinforcing bar basket 1e was suspended and supported by the hanging material L3, the hairpin 200 was removed, and the third stage reinforcement ring 4 of the reinforcing bar cage 1d was suspended and supported by the hanging material L4. In this state, the connecting member 5 (the connecting member 5 located at the lowest position at this point) between the second and third reinforcing rings 4a of the reinforcing bar cage 1d is removed.

Thereafter, as shown in FIG. 15(c), when the hanging material L4 is loosened and the hanging material L3 is lowered at the same time, the reinforcing rings 4a of the second and third stages of the reinforcing bar cage 1d from which the connecting members 5 have been removed are removed. The cage body 2 in the section between rotates and extends downward, and the reinforcing bar cages 1d and 1e are suspended into the excavated hole 100. At this time, the portion of the reinforcing bar cage 1d to which the hanging material L4 is attached below the third reinforcing ring 4a is suspended into the excavated hole 100 while rotating. After suspending and lowering the reinforcing bar cages 1d and 1e, the hanging material L4 is removed from the third reinforcing ring 4a of the reinforcing bar cage 1d.

After that, as shown in FIG. 16(a), a hanging material L4 is attached to the second-stage reinforcing ring 4a of the reinforcing bar cage 1d located above the extended section, and the reinforcing ring 4a is attached to the reinforcing ring 4a by the hanging material L4. In the suspended and supported state, the connecting member 5 between the reinforcing rings 4a on the uppermost stage and the second stage is removed. Furthermore, the hanging material L3 is replaced with the third reinforcing ring 4b of the reinforcing bar cage 1d.

Then, as shown in FIG. 16(b), when the hanging material L4 is loosened and the hanging material L3 is lowered at the same time, as in FIG. 15(c), the uppermost stage of the reinforcing bar cage 1d and the two The cage body 2 in the section between the reinforcing rings 4a of the tiers rotates and expands, and the reinforcing bar cages 1d and 1e are suspended into the excavated hole 100. At this time, the portion of the reinforcing bar cage 1d to which the hanging material L4 is attached, below the second stage reinforcing ring 4a, is suspended into the excavated hole 100 while rotating. After suspending and lowering the reinforcing bar cages 1d and 1e, the hanging material L4 is removed from the second stage reinforcing ring 4a of the reinforcing bar cage 1d.

In this embodiment, the entire length of the cage body 2 of the reinforcing bar cage 1d is extended through the above steps. If the number of reinforcing rings 4a of the reinforcing bar cage 1d is large, the steps shown in FIGS. 16(a) and 16(b) may be repeated according to the number of reinforcing rings 4a. After extending the entire length of the cage body 2 of the reinforcing bar cage 1d in this way, the hanging material L3 is replaced with the reinforcing ring 4a at the top of the reinforcing bar cage 1d, and with the reinforcing bar cages 1d and 1e suspended and supported by the hanging material L3, 44 will be removed.

Thereafter, the hanging material L3 is lowered, and the reinforcing bar cages 1d and 1e are suspended into the excavated hole 100, as shown in FIG. 16(c). In this embodiment, the hanging reinforcing bars 44 are attached to the reinforcing ring 4b at the top of the reinforcing bar cages 1d while the reinforcing bar cages 1d and 1e are being lowered, and when the reinforcing bar cages 1d and 1e are lifted down to a predetermined depth of the excavation hole 100. Then, the hairpin 200 is installed at the opening of the hole, and the hairpin 200 and the hanging reinforcing bar 44 are connected. Thereafter, the hanging material L3 is removed and removed to complete the erection.

In this manner, also in this embodiment, after the entire length of the cage body 2 of the reinforcing bar cage 1e is expanded in advance in the excavation hole 100, the reinforcing bar cages 1e and 1d are joined, and the reinforcing bars in the contracted state are placed directly above the excavation hole 100. The cage body 2 of the cage 1d is extended section by section, and the reinforcing steel cages 1d and 1e are erected. As a result, the same effects as in the second embodiment can be obtained.

Furthermore, in this embodiment, in the steps shown in FIG. 16(b) etc., the extension of the cage body 2 of the reinforcing bar cage 1d and the insertion into the excavation hole 100 are performed at the same time. Construction time can also be shortened. However, since the cage body 2 of the reinforcing bar cage 1d is inserted into the excavated hole 100 while rotating, the skid described above is required as a spacer.

In this embodiment, the reinforcing bar cage 1e is once lifted in FIG. This is because the work described in the first embodiment of returning the muscle 22 to an appropriate position is performed on the ground. Although it is possible to join the reinforcing bar cages 1e and 1d with the upper end of the cage body 2 located inside the excavation hole 100 as shown in FIG. takes some time.

Further, in the second and third embodiments, the reinforcing bar cage is suspended and supported from the frame 8, but instead of the frame 8, it is also possible to suspend and support the reinforcing bar cage using another lifting device such as a crane. Further, at least two hanging members L4 such as lever hoists are required, but preferably three or more are required so that the suspended reinforcing ring 4a can be kept horizontal. Furthermore, in the third embodiment, when the hanging material L4 is loosened and the hanging material L3 is lowered at the same time, the cage body 2 rotates, so depending on the specifications, the hanging material L4 and the cage body 2 come into contact. In such a case, it is preferable to use four or more hanging materials L4 and change the circumferential attachment position of two hanging materials L4 on the same reinforcing ring 4a to avoid contact. Also, at least two hanging reinforcing bars 44 are required, but preferably three or more, and threaded reinforcing bars are preferred so that the suspended reinforcing ring 4a can be maintained horizontally.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that those skilled in the art can come up with various changes or modifications within the scope of the technical idea disclosed in this application, and these naturally fall within the technical scope of the present invention. Understood.

1, 1a, 1b, 1c, 1d, 1e: Rebar cage 2: Cage body 4, 4a, 4b: Reinforcement ring 5: Connecting material 8: Frame 21: Strand 22: Strap 100: Excavation hole

Claims (6)

A method for building a retractable reinforcing bar cage into an excavation hole, the cage having a cage body in which tie bars and flexible strands are combined so that the intersection angle is variable, the method comprising:
A reinforcing bar cage with at least a portion including the upper end of the cage in a contracted state is placed above the reinforcing bar cage inserted into the excavation hole with the axial direction of the cage body as the vertical direction. arranging step (a);
(b) connecting the lower ends of the strands of the upper reinforcing bar cage and the upper ends of the strands of the lower reinforcing bar cage;
a step (c) of lowering two reinforcing bar cages in which the strands are connected into the excavation hole;
A method for erecting a reinforcing bar cage, characterized in that in the step (c), at least the cage body of the upper reinforcing bar cage is stretched. Before connecting the strands to each other in step (b), at least a portion of the lower reinforcing bar cage, including the lower end of the cage body, is in a contracted state;
The method for erecting a reinforcing bar cage according to claim 1, wherein in step (c), the lower end of the cage body of the lower reinforcing bar cage is lowered within the excavation hole, and the cage bodies of the upper and lower reinforcing bar cages are extended. . Before connecting the strands to each other in step (b), the entire length of the cage body of the lower reinforcing bar cage and the lower end of the cage body of the upper reinforcing bar cage are in an extended state, and the strands of the upper reinforcing bar cage are stretched. 2. The method of erecting a reinforcing bar cage according to claim 1, wherein the lower end of the strand and the upper end of the strand of the lower reinforcing bar cage are arranged in a vertical direction. In the cage body of the upper reinforcing bar cage, reinforcing rings along the circumferential direction of the cage body are provided in three or more stages spaced apart vertically, and vertically adjacent reinforcing rings are connected to each other by a connecting material,
A claim characterized in that, before connecting the strands to each other in step (b), the lowest connecting member is removed and the cage body in the section between the reinforcing rings connected by the connecting member is expanded. The method for erecting a reinforcing bar cage as described in Section 3. In step (c), the connecting material located at the bottom of the upper reinforcing bar cage is removed, the cage body in the section between the reinforcing rings connected by the connecting material is expanded, and the two reinforcing bars with the strands connected to each other are removed. 5. The method for erecting a reinforcing bar cage according to claim 4, characterized in that the work of lifting and lowering the cage is repeated. In step (c),
When removing the connecting member located at the bottom of the upper reinforcing bar cage and extending the cage body in the section between the reinforcing rings located on the ground, which were connected by the connecting member, Restricts the rotation of the reinforcing bar cage in the borehole,
6. The method for erecting a reinforcing bar cage according to claim 5, characterized in that, after the cage body in the section is extended, the two reinforcing bar cages having their strands connected to each other are vertically lowered without being rotated.

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