JP3713678B2 - Cast-in-place pile, underground wall and its construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cast-in-place pile, an underground wall, and a construction method thereof.
[0002]
[Prior art]
The construction of piles or underground walls using cast-in-place concrete is done by assembling a reinforcing bar with a combination of reinforcing bars on the ground surface, hanging it in a hole or wall (hereinafter referred to as “groove”) drilled in the ground, and placing concrete Is building.
In this case, at the site where the upper space such as under the overhead is constrained, it is not possible to lift the long reinforcing bar rods.
Therefore, when the length of a pile or a wall becomes long, a joint location will increase and work efficiency will fall.
As a method to improve such points, flexible flexible reinforcing bars are continuously inserted vertically into the groove, and continuous reinforcing bar rods are manufactured by winding the reinforcing bars around the entire length of the flexible reinforcing bar group. However, a construction method for suspending it in the groove has also been developed.
[0003]
[Problems to be solved by the present invention]
Even in the above-described method, a step of winding a band reinforcing bar around the entire length of the flexible reinforcing bar group in the vertical direction is required. For this reason, it was necessary to work for a long time in a narrow space where the surroundings were restricted, which was an inefficient and uneconomic construction method.
[0004]
The present invention was made to solve the conventional problems as described above, and can be constructed efficiently in a narrow work space without using a reinforcing bar, a cast-in-place pile, an underground wall and a construction method thereof The purpose is to provide.
[0005]
In order to solve the above-described problems, the present invention provides a flexible reinforcing bar group including a PC steel material vertically arranged in a hole drilled in a field, a groove for a wall, and a horizontal ring attached to the lower end of the flexible reinforcing bar group. If, to form a support wire hanging the horizontal ring, the fiber reinforced concrete which is Da設to said groove,
It also features cast-in-place piles and underground walls, which are constructed without using rebars.
The present invention also provides a flexible reinforcing bar group including a PC steel material vertically arranged in a hole drilled in a field, a groove for a wall, a horizontal ring attached to a lower end of the flexible reinforcing bar group, and a support for suspending the horizontal ring. a wire, and fiber reinforced concrete which is Da設to said groove, constituted by hoop basket installed only on the head close to the surface, is obtained by cast-in-place piles, underground walls and features.
The present invention also provides a flexible reinforcing bar group including a PC steel material vertically arranged in a hole drilled in a field, a groove for a wall, a horizontal ring attached to a lower end of the flexible reinforcing bar group, and a support for suspending the horizontal ring. wire and, those where the usual concrete Da設the bottom of said groove, formed by the fibers concrete Da設the top, and was constructed without using the hoop, place pile, the basement walls, wherein It is.
[0006]
Further , the cast-in- place pile of the present invention, the underground wall is a hole excavated in the field, a flexible rebar group including a PC steel material arranged vertically in the groove for the wall, and ordinary concrete placed in the lower part of the groove , Formed by fiber concrete placed on top,
It also features cast-in-place piles and underground walls, which are constructed without using rebars .
[0007]
[Embodiments of the present invention]
Embodiments of a cast-in-place pile, an underground wall, and a construction method thereof according to the present invention will be described below with reference to the drawings.
[0008]
<I> Groove excavation.
At the site, holes for piles or grooves for walls (hereinafter referred to as “groove 1”) are excavated in the ground.
As this excavation method, a conventionally known method can be adopted.
The excavated groove 1 is filled with a stabilizing liquid such as bentonite as in the prior art to prevent the surrounding wall from collapsing.
[0009]
<B> Insert flexible rebar. (Elevator mount type)
The flexible rebar 2 group containing PC steel material is inserted in the inside of the stable liquid of the excavated groove 1 in the vertical direction. Insertion of the flexible rebar 2 including the PC steel material into the groove 1 is performed by the lifting rack 3. (Figure 1)
For this purpose, a take-up drum 4 is arranged around the lifting frame 3, and the flexible rebar 2 containing PC steel is wound around the drum 4 in a roll shape.
A plurality of guide pipes 5 are attached to the top of the gantry 3.
Each guide pipe 5 passes through one flexible rebar 2 including PC steel drawn from the drum 4 one by one.
And the lower end of the flexible rebar 2 containing each PC steel material is fixed to the circumference of the horizontal ring 6 at regular intervals. The horizontal ring is suspended by a support wire 7, and the support wire 7 is held and supported by a center hole jack 8 arranged on the lifting platform 3 in the vertical direction.
By extending and contracting the center hole jack 8, the horizontal ring 6 is gradually suspended in the groove 1 and reaches the bottom of the groove 1.
As a result, the flexible rebar 2 including the PC steel material whose one end is fixed to the horizontal ring 6 can be extended to the deepest portion of the groove 1 by gradually extending in the vertical direction.
[0010]
<C> Inserting flexible reinforcing bars. (Drum type)
When inserting the flexible rebar 2 group which contains PC steel material in the perpendicular direction inside the stable liquid of the excavated groove 1, it is performed by a built-in drum. (Figure 2)
For this purpose, a built-in drum 12 that rotates about a horizontal axis is disposed in the upper space of the groove 1. This built-in drum 12 is rotatably attached to a horizontal shaft 15 at the tip of the arm 14 of the driving device 13. Further, a winding drum 4 is installed in the vicinity of the groove 1, and the flexible reinforcing bar of the winding drum 4 is wound in a roll shape. The flexible rebar 2 group of the winding drum 4 is pulled out through the built-in drum 12, and the lower end thereof is fixed to the circumference of the horizontal ring 6 at regular intervals. The horizontal ring is then suspended in the groove 1 as a weight.
As a result, the flexible rebar 2 including the PC steel material whose one end is fixed to the horizontal ring 6 can be extended to the deepest portion of the groove 1 by gradually extending in the vertical direction.
Thereafter, the horizontal ring 16 is also installed on the upper part of the pile, and the flexible rebar 2 is suspended and gripped by the upper horizontal ring.
[0011]
<D> Configuration without band reinforcement.
In this way, when the flexible rebar 2 including the PC steel material is gradually extended in the vertical direction, it is not necessary to attach a band rebar around the periphery in the construction method of the present invention.
Since the work of attaching the rebar is unnecessary, the work that requires time in a narrow space can be omitted.
In addition, on the outer periphery of the flexible rebar 2 group containing PC steel, retaining rings for shape retention are attached to multiple locations, but this prevents the flexible rebar 2 from being separated or approached by the pressure when placing concrete. It is just something to do, and does not expect strength as a band reinforcement.
[0012]
<E> Placing fiber-reinforced concrete.
In this way, the tremy tube is inserted into the groove 1 in which the flexible reinforcing bars 2 including the PC steel material are vertically arranged. Then, the fiber reinforced concrete 9 is placed in a state of being raised from the bottom of the groove 1 through this tremy tube.
As the fiber reinforced concrete 9, it is possible to employ a concrete in which short fibers made of steel fiber or polypropylene fiber are put into a mixer and kneaded.
By adopting the concrete 9 in which the fibers are mixed, the shear strength can be improved, and as a result, the reinforcement by the belt reinforcing bars becomes unnecessary.
If the fiber reinforced concrete 9 is hardened, construction of piles, underground walls and the like is completed in the ground.
[0013]
<F> Partial placement of fiber reinforced concrete.
The above example is a method of placing the fiber reinforced concrete 9 over the entire length of the groove. However, the generated cross-sectional force is usually concentrated near the head in cast-in-place piles and underground walls. In consideration of this point, it is possible to employ a construction method in which the fiber reinforced concrete 9 is not placed over the entire range, and the fiber reinforced concrete 9 is placed in the upper portion and the ordinary concrete 10 is placed in the lower portion. (Figure 3)
The position of the boundary between the fiber reinforced concrete 9 and the ordinary concrete 10 is determined at the design stage. If such a structure is adopted, an economical underground structure can be constructed.
[0014]
<G> Use of rebar for the head only.
As described above, the generated cross-sectional force in the cast-in-place pile and the underground wall is normally concentrated near the head, so as another construction method considering that point, when the fiber mixing amount of fiber reinforced concrete is small, A method of inserting the reinforcing bar rod 11 only into the head can also be adopted. (Fig. 4)
This method is constructed by pressurizing and inserting the reinforcing bar rod 11 only into the head while the placed fiber reinforced concrete 9 is not yet solidified.
In the case of this embodiment, since the rebar does not have to be bound with the flexible rebar 2 including the PC steel material which is the main rebar, after the flexible rebar 2 including the PC steel material is set up, the rebar bar 11 is made of fiber. It can be constructed by being inserted into the reinforced concrete 9.
[0015]
[Effect of the present invention]
Since the cast-in-place pile, underground wall, and construction method thereof according to the present invention are as described above, the following effects can be obtained.
<I> Since fiber reinforced concrete has high shear strength, piles and underground walls can be constructed in the ground without the need for shear reinforcement.
For this reason, it is not necessary to use a rebar and inefficient work such as attaching the rebar to the rebar in a narrow space is no longer necessary.
<B> Therefore, it is possible to improve the workability and shorten the work time.
<C> Since concrete reinforced with fibers is used, it is possible to obtain a pile and an underground wall excellent in tensile strength, bending strength, resistance to cracking, toughness, shear strength, and impact resistance.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of a method for constructing a cast-in-place pile and an underground wall according to the present invention.
FIG. 2 is an explanatory diagram of another construction method.
FIG. 3 is an explanatory diagram of an example of a completed cast-in-place pile and underground wall.
FIG. 4 is an explanatory diagram of another embodiment.
FIG. 5 is an explanatory diagram of another embodiment.

Claims (3)

A flexible rebar group including PC steel materials arranged vertically in a hole drilled in the field, a groove for a wall,
A horizontal ring attached to the lower end of this flexible rebar ,
A support wire to suspend this horizontal ring ,
Formed by Da設the fiber reinforced concrete to said groove,
And it was configured without using the band reinforcement,
Cast-in-place piles, underground walls. A flexible rebar group including PC steel materials arranged vertically in a hole drilled in the field, a groove for a wall,
A horizontal ring attached to the lower end of the flexible reinforcing bar group ;
A support wire to suspend this horizontal ring ,
And fiber reinforced concrete which is Da設to said groove,
Constructed by belt reinforcement bars installed only on the head near the ground surface,
Cast-in-place piles, underground walls. A flexible rebar group including PC steel materials arranged vertically in a hole drilled in the field, a groove for a wall,
A horizontal ring attached to the lower end of the flexible reinforcing bar group ;
A support wire to suspend this horizontal ring ,
And ordinary Concrete Da設the bottom of said groove,
Formed by fiber concrete placed on top,
And it was configured without using the band reinforcement,
Cast-in-place piles, underground walls.

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