JP4287640B2 - Inner mold and method for producing hollow concrete body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inner mold and a method for producing a hollow concrete body.
[0002]
[Prior art]
As an internal mold in the production of a conventional hollow concrete body, there are many cases using foamed polystyrene b, wood, steel material and the like.
The hollow concrete body is a hollow concrete body provided with a cavity inside the concrete body.
When the inner mold is left as a part of the concrete body and used as a discarded mold, the cavity may be filled with the inner mold (see FIG. 6).
In such a case, when the cavity is used for passing wiring or piping, it is necessary to remove the inner mold in the cavity.
[0003]
[Problems to be solved by the invention]
The above-described conventional inner mold of a hollow concrete body has the following problems.
<I> Since the discarded mold is used once, there is no diversion, and the total of the material cost and production cost of the inner mold is directly used as the mold cost.
<B> When using a wooden or steel material as the inner mold of the hollow concrete body, because of the high rigidity as the material, for example, the mixing material during curing after placing a fiber-reinforced cement-based mixed material For self-shrinking, the inner model restrains this.
Due to this constraint, when the strength of the mixed material is developed, a tensile stress is generated inside the material, and a predetermined tensile resistance may not be expected in the hollow concrete body by design.
<C> When a relatively flexible material such as expanded polystyrene is used as the inner mold, the problem of restraint against the self-shrinkage of the mixed material hardly occurs.
However, polystyrene has a high material price and makes it difficult to produce a hollow concrete body economically.
<D> Since the styrofoam has a small rigidity, when the length of the inner mold is increased with the production of a long hollow concrete body, a large buoyancy is generated when the mixed material is placed. In order to resist this buoyancy, it becomes necessary to tightly connect the expanded polystyrene and the outer mold frame with a tie bar or the like. These tie bars cause the fibers to close in the vicinity of the tie bars in order to inhibit the flow of the fibers when placing the mixed material, and it is difficult to produce a hollow concrete body whose material is uniformly controlled. Become.
In the case of a wooden formwork, it is necessary to closely set a tie bar for preventing buoyancy and preventing deformation of the inner formwork, which may cause the same problem as described above.
<E> When a divertable wooden formwork is used as the inner formwork, it is difficult to demold the actual inner formwork.
When the cross section of the inner mold is circular, it takes time to manufacture the mold, and the manufacturing cost is expensive. Also, it is difficult to remove the mold without destroying the mold itself, and the second reuse is almost impossible.
[0004]
OBJECT OF THE INVENTION
The present invention has been made to solve the conventional problems as described above, and an object of the present invention is to provide a method for producing the following inner mold frame and hollow concrete body.
<I> An economical form of hollow concrete body that can be diverted.
<B> An inner mold of a hollow concrete body that does not give excessive restraint to self-shrinkage that occurs during curing after placing cement-based mixed material.
<C> When the length of the inner mold is increased, it is necessary to connect the inner mold and the outer mold with a tie bar or the like that obstructs the flow of fibers when a fiber-reinforced cement-based mixed material is used. Do not hollow concrete body form.
<D> A method for producing an inner mold frame and a hollow concrete body, which makes it possible to easily remove the inner mold frame of the hollow concrete body.
<E> A manufacturing apparatus used in a method for manufacturing a hollow concrete body, which makes it possible to easily remove the inner mold of the hollow concrete body.
The present invention achieves at least one of these objects.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an inner mold of a hollow concrete body according to the present invention includes a core material for forming a basic shape of a cavity, a flexible outer cylinder provided on an outer periphery of the core material, A filling port for injecting a liquid having a specific gravity greater than water or water as a fluid is provided between the core material and the outer cylinder.
[0006]
Between the core material and the outer cylinder, a flexible annular gap holding material is provided over the entire circumference of the outer circumference of the core material in a direction substantially perpendicular to the drawing direction of the core material, and the gap holding material is provided as the core material. In some cases, a plurality of them are provided at intervals in the drawing direction.
[0007]
Between the core material and the outer cylinder, a flexible cylindrical gap retaining material is provided over the entire outer periphery of the core material, and the core material is pulled out on the outer surface of the cylindrical gap retaining material. There may be a case where a convex portion substantially parallel to is provided.
[0008]
In some cases, the outer cylinder may be an outer cylinder that is provided with a convex portion substantially parallel to the drawing direction of the core material.
[0009]
In the method for manufacturing the hollow concrete body according to the present invention, a mold is formed by the outer mold and the inner mold, and the fluid is press-fitted between the core material and the outer cylinder via the filling port. In a state where the inner mold is embedded, a cement-based mixed material is placed in the outer mold, and after the cement-based mixed material reaches a predetermined strength, the press-fitted fluid is discharged from the filling port. By doing so, the inner mold is removed.
[0010]
In the manufacturing method in the case of using the annular gap retaining material, a mold is formed by the outer mold and the inner mold, and the fluid is supplied between the core and the outer cylinder via the filling port. Press-fit, press-fit a fluid into the annular gap retaining material, and in a state where the inner mold is embedded, the cement-based mixed material is placed in the outer mold, and the cement-based mixed material has a predetermined strength. After reaching, the fluid is discharged from the annular gap retaining member, and the fluid between the core member and the outer cylinder is discharged from the filling port, thereby releasing the inner mold.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
<I> Hollow concrete body The hollow concrete body is a concrete body in which a cavity is formed, and the volume of the concrete can be suppressed by providing the cavity portion.
The hollow concrete body is non-stretched by propelling the hollow concrete body into the ground in parallel when constructing a hollow slab prestressed via the tension steel material 92 or a subbase crossing structure while using the upper roadbed. It is used when building underground structures by excavation.
[0013]
<B> Internal formwork (Figure 1)
The inner mold 1 is a mold used for forming a hollow of a hollow concrete body. The inner mold 1 injects a fluid 21 between the core material 10 and the outer cylinder 11, and a flexible outer cylinder 11 provided on the outer periphery of the core material 10 for forming a hollow basic shape. It is formed by the filling port 12 provided for this purpose. In order to discharge the air remaining between the core material 10 and the outer cylinder 11 when the fluid 21 is injected, an exhaust port 13 may be provided in the upper part of the core material 10.
The outer cylinder 11 is attached to the core member 10 with an attachment band 14 at the end thereof, and the fluid 21 is prevented from leaking from between the outer cylinder 11 and the core member 10 to the outside.
A filling pipe 31 for press-fitting the fluid 21 or discharging the fluid 21 is installed in the filling port 12, and an exhaust pipe 32 for removing air is installed in the exhaust port 13.
[0014]
<C> Core material The core material 10 is a constituent member of the inner mold 1 and forms the basic shape of the hollow concrete body. Therefore, the core material 10 is predetermined with respect to the hydraulic pressure 8 of the cement-based mixed material to be placed. It is made of a material having a certain degree of rigidity so as to secure an internal space with high accuracy.
As the core material, for example, a steel tube, a wood tube, a vinyl chloride tube formed in a cylinder or a rectangular tube is used.
Further, the core material 10 is not limited to the one having the same cross-sectional shape over the entire length, and a core material whose cross-sectional shape gradually changes such as a divergent pipe can also be used.
[0015]
<D> Outer cylinder The outer cylinder 11 is a structural member of the inner mold 1 and is a flexible film. The outer cylinder 11 is provided over the entire outer periphery of the core member 10. It attaches to the core material 10 with the attachment band 14.
Since the fluid 21 is press-fitted between the core material 10 and the outer cylinder 11 to form a predetermined cavity size, the outer cylinder 11 needs to be flexible.
Further, the outer surface of the outer cylinder 11 may be formed in an uneven shape in the drawing direction. The convex part 112 is a convex part at the time of shape | molding the outer surface of the outer cylinder 11 in uneven | corrugated shape in the extraction direction (refer FIG. 3).
After the cement-based mixed material 6 reaches a required strength, the outer cylinder 11 is molded so that it can be easily peeled from the surrounding hardened cement-based mixed material when the inner mold 1 is pulled out.
In order to more effectively peel the outer cylinder 11 from the hardened cementitious mixed material, for example, a peeling paste may be applied to the outer surface of the outer cylinder 11.
As a material constituting the outer cylinder 11, for example, rubber, rubber reinforced with fiber, a synthetic resin sheet, a synthetic fiber sheet, or the like is used.
[0016]
<E> Fluid The fluid 21 is press-fitted between the core material 10 and the outer cylinder 11 via a filling port 12 to be described later, and is used to ensure a predetermined cavity size of the hollow concrete body. .
After the fluid 21 is press-fitted until a predetermined cavity size is secured and the cement-based mixed material 6 is placed, the pressure of the fluid 21 may be adjusted in order to adjust the variation of the cavity size due to the hydraulic pressure 8.
As the material of the fluid 21, a liquid or water having a specific gravity higher than that of water is used.
[0017]
<F> Filling port The filling port 12 is an opening provided in the core member 10, and a filling pipe that allows the fluid 21 to pass through the filling port 12 is installed to press-fit the fluid 21 from the outside.
After the cement-based mixed material 6 reaches the required strength, the fluid 21 is discharged to the outside through the filling port 12 and the filling pipe 31.
[0018]
<G> Annular gap retainer The annular gap retainer 41 has an annular shape having flexibility. The annular gap retaining member 41 is provided over the entire circumference of the outer periphery of the core member in a direction substantially orthogonal to the drawing direction of the core member 10, and a plurality of the annular gap retaining members 41 are arranged at intervals in the drawing direction of the core member 10.
Here, different types of structures can be used for the annular gap retaining member 41.
The first structure has a tubular shape, and adjusts the eccentricity of the outer cylinder 11 by press-fitting the fluid 4a into the tubular annular gap retaining member 41 (FIG. 4 (a)). ) And (b)).
That is, when the cement-based mixed material 6 is placed in the outer mold 5 with the inner mold 1 embedded, the cement-based mixed material 6 is still fresh at the beginning of the placement, and the cement-based mixed material 6 The pressure exerted on the mold acts in a state close to the hydrostatic pressure distribution. In this case, a pressure from below to above acts on the inner mold 1. In particular, when the specific gravity of the fluid 21 is smaller than the specific gravity of the cement-based mixed material 6, the outer cylinder 11 surrounding the fluid 21 is upward. (See FIG. 4B). By expanding the annular gap retaining member 41 with the fluid 4a injected, the eccentricity of the outer cylinder 11 can be adjusted during the production of the hollow concrete body.
For example, rubber, a synthetic resin sheet, a synthetic fiber sheet, or the like is used as a material constituting the annular gap retaining member 41.
In order to effectively exhibit the function of the annular gap retaining member 41, the annular gap retaining member 41 is filled with a fluid 4 a having a larger specific gravity than the fluid 21 that is press-fitted between the core member 10 and the outer cylinder 11. In some cases.
[0019]
The second structure is a solid annular gap retaining member 41. The annular gap retaining member 41 is made of a soft and easily deformable material.
For example, sponge, urethane foam or the like is used as a material constituting the annular gap retaining member 41.
[0020]
<H> Cylindrical gap retaining material The cylindrical gap retaining material 42 is provided over the entire circumference of the outer periphery of the core member 10, and the outer surface thereof is formed into an uneven shape substantially parallel to the drawing direction of the core member 10.
The convex portion 421 is a convex portion when the outer surface of the cylindrical gap retaining member 42 is formed in an uneven shape in the drawing direction (see FIG. 5).
The concave portion 422 is provided so that when the fluid 21 is press-fitted, the fluid 21 passes through the concave portion 422 and easily spreads.
The gap between the convex portion 421 and the inner surface of the outer cylinder 11 is kept small.
As the material of the cylindrical gap retaining member 42, for example, a rubber sheet or the like is used.
[0021]
<Re> Cement-based mixed material The cement-based mixed material 6 is a general term for materials used for concrete structures, and includes concrete, high-strength concrete, fiber-reinforced cement-based mixed material, and the like. Among them, when the fiber reinforced cementitious mixed material that has high material strength and required dimensional accuracy is used as the cementitious mixed material 6, it is preferable to use the inner mold 1 of the present invention.
Examples of the fiber-reinforced cement-based mixed material include a compressive strength of 200 to 220 MPa, a bending strength of 40 to 45 MPa, an adhesion strength of 15 to 90 MPa, an air permeability coefficient of 2.5 × 10 ⁻¹⁸ m ² , and a water absorption of 0.05 kg / m ^3. A material having the characteristics of a salt diffusion coefficient of 0.02 × 10 ⁻¹² m ² / sec and an elastic modulus of 55 GPa can be used.
[0022]
Hereinafter, the manufacturing apparatus of the present invention will be described with reference to FIG.
[0023]
An inner mold frame fixing frame 71 and an inner mold frame moving frame 72 for fixing the inner mold frame 1 are provided outside the outer mold frame 5, and one end of the core material 10 constituting the inner mold frame 1 is connected to the inner mold frame fixing frame 72. And the other end of the core material 10 is fixed to the inner formwork moving frame 71. The inner formwork moving stand 71 has wheels 711 so that it can be easily moved on the inner formwork receiving rail 712.
Such a set of the inner formwork fixing base 72 and the inner formwork moving base 71 is installed according to a desired hollow number.
The outer mold 5 is fixed by, for example, an outer mold mount 51 installed on the ground.
With the above configuration, the manufacturing apparatus 7 of the present invention is constructed (see FIG. 2).
When creating a hollow concrete body as a pre-tension material, for example, a tension jack 91 is installed on the inner formwork moving base 71, and a tension fixing end 93 as a fixing jig is provided on the inner formwork fixing base 72. Install (see FIG. 2).
[0024]
Hereinafter, the manufacturing method of the present invention will be described with reference to FIGS.
[0025]
First, the manufacturing apparatus 7 described above is constructed.
Next, a fluid 21 is press-fitted through the filling port 12 between the core material 10 and the outer cylinder 11 of the inner mold 1 to mold the outer dimension of the inner mold 1 to a predetermined size.
When prestress is introduced into the hollow concrete body, a predetermined prestress is applied to the tension steel 92 by the tension jack 91. At that time, an axial compression force acts on the core material 10, and the core material 10 becomes a reaction force device without fixing the manufacturing device 7 to the ground, which is economical.
Thereafter, the cement-based mixed material 6 is placed in the outer mold 5 while the inner mold 1 is embedded. When the gap retaining material 4 is used for the inner mold 1, the fluid 4 a is pressed into the gap retaining material 4 before the cement-based mixed material 6 is placed. When the hydraulic pressure 8 acts immediately after the cement-based mixed material 6 is placed and the outer cylinder 11 is lifted upward, the eccentricity of the outer cylinder 11 is adjusted by press-fitting the fluid 4a again.
After the cement-based mixed material 6 reaches a predetermined strength, the fluid 21 is discharged through the filling port 12 so that atmospheric pressure acts on the outer cylinder 11. The space 23 forms a zero space, and the outer cylinder 11 is forcibly separated from the hardened cement-based mixed material 6 (see FIGS. 6A and 6B).
When the tubular annular gap retaining member 41 is used, the fluid 4 a inside the annular gap retaining member 41 is discharged before or after the fluid 21 is discharged, and the fluid 21 is discharged through the filling port 12.
After discharging the fluid 21, the inner mold frame 1 is removed by moving the inner mold frame moving stand 71 along the inner mold frame receiving rail 712.
When the tension steel material 92 is used, the prestress is introduced into the cement-based mixed material 6 by releasing the prestress from the tension steel material 92.
[0026]
【The invention's effect】
Since the inner formwork and the hollow concrete body manufacturing apparatus of the present invention are as described above, the following effects can be obtained.
<I> Demolding work can be facilitated and work efficiency can be improved.
<B> The removed inner mold can be diverted and is economical.
<C> By providing the outer surface of the outer cylinder with a convex portion that is substantially parallel to the drawing direction of the core material, the outer cylinder can be easily separated from the hardened cementitious mixed material.
<D> When a gap retaining material is provided, when fluid pressure is applied and the outer cylinder is lifted up immediately after placing the cement-based mixed material, the fluid is pressed into the gap retaining material. The eccentricity of the outer cylinder can be adjusted.
<E> When prestress is introduced into a hollow concrete body, the core material can be used as a reaction body, so that a large-scale reaction device is not required.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating the configuration of an inner mold according to the present invention. FIG. 2 is a side view illustrating a hollow concrete body manufacturing apparatus according to the present invention. FIG. 4 is a cross-sectional view of the inner mold frame when a flexible annular gap retainer is used, and the flexible outer cylinder is moved upward when the hydraulic pressure after placing the cement-based mixed material is applied. FIG. 5 is a perspective view of a cylindrical gap retaining member provided with a convex portion on the outer surface. FIG. 6 is a diagram showing a space after discharging the fluid filled between the core and the outer cylinder. Side view and cross-sectional view explaining that it is formed. [Fig. 7] Perspective view of a conventional hollow concrete body using polystyrene foam as an inner mold. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inner form frame 10 ... Core material 11 ... Outer cylinder 12 ... Filling port 21 ... Fluid 41 ... Annular gap retaining material 42 ... Cylindrical gap retaining material 4a ... Fluid 5 ... Outside Form 6 ... Cement-based mixed material 7 ... Production equipment 71 .... Inner formwork moving stand 72 ... Inner formwork fixed stand

Claims (5)

An internal formwork used to form a hollow of a hollow concrete body, with a cavity formed inside the concrete body,
A core for forming the basic shape of the cavity;
A flexible outer cylinder provided on the outer periphery of the core;
Between the core material and the outer cylinder, a flexible tube shape,
While provided over the entire circumference of the outer periphery of the core material in a direction substantially orthogonal to the drawing direction of the core material,
A plurality of annular gap retaining materials provided at intervals in the drawing direction of the core material;
Between the core material and the outer cylinder, a fluid having a specific gravity higher than water as a fluid or a filling port opened in the peripheral surface of the core material for press-fitting water ,
Inner formwork. An internal formwork used to form a hollow of a hollow concrete body, with a cavity formed inside the concrete body,
A core for forming the basic shape of the cavity;
A flexible outer cylinder provided on the outer periphery of the core;
Between the core material and the outer cylinder, it is flexible and provided over the entire circumference of the outer periphery of the core material,
A cylindrical gap retainer provided on the outer surface with a convex portion substantially parallel to the drawing direction of the core;
It consists of a filling port opened in the peripheral surface of the core material into which a liquid having a specific gravity higher than water or water is injected as a fluid between the core material and the outer cylinder,
Inner formwork. 3. The fluid between the outer cylinder and the core material is prevented from leaking by an attachment band provided at an end of the outer cylinder.
  Inner formwork. The inner mold according to any one of claims 1 to 3,
The outer surface of the outer cylinder is provided with a convex portion substantially parallel to the drawing direction of the core material,
Inner formwork. In the method for producing a hollow concrete body, in which a cavity is opened inside the concrete body,
A mold is formed by the outer mold and the inner mold according to claim 1.
While pressing a liquid or water having a specific gravity higher than water into the annular gap retaining material between the core material of the inner mold and the outer cylinder as a fluid,
A liquid having a specific gravity greater than water or water is injected as a fluid through the filling port between the core and the outer cylinder,
In a state where the inner mold is embedded, a cement-based mixed material is placed in the outer mold,
After the cementitious mixed material reaches the predetermined strength,
The inner mold frame of the hollow concrete body is demolded by discharging the fluid press-fitted into the outer cylinder and the annular gap retainer ,
A method for producing a hollow concrete body.

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