JP2004011312A - Fiber-mixed concrete segment and method of manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of composing and manufacturing a matrix to avoid cracking of a precast segment as a tunnel lining, while enhancing its fireproof function. <P>SOLUTION: Plastic fiber-mixed concrete 4 and/or 5 and normal concrete 6 are stacked as the matrix of a segment 2 to avoid a neutralization degradation resulting from microcracks caused by drying shrinkage force during fabrication and by changes in temperature and external load (earth pressure/water pressure) after use. While temperature is elevated in the event of a tunnel fire, the plastic melts at low temperatures at the early stage of the fire, creating penetrating voids, and avoiding the explosion of trapped water as steam and blasting due to the expansion of reinforcements. A method of forming different kinds of ready-mixed concrete such as plastic fiber-mixed concrete into a uniform thickness employs easy and economical manufacturing techniques based on such methods as centrifugal forming, using stationary forms, embedding curved plates, or setting plastic cages. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a configuration of a concrete material for improving the function of a segment as a lining material of a shield tunnel and a method of manufacturing the same.
[0002]
[Prior art]
Groundwater penetrates and leaks from cracks on the surface of the segment caused by drying shrinkage of concrete during the manufacturing process.
In addition, corners may be lost when the segments are carried in and assembled. The edge of the concave portion of the tenoned segment and the periphery of the seal groove may be broken due to the fastening force at the time of assembly.
Furthermore, in terms of long-term durability, it is known that when a microcrack occurs due to a change in temperature or load, air and moisture easily enter the interior of the concrete from the microcrack and neutralization proceeds.
[0003]
On the other hand, when a tunnel fire occurs, the water vapor in the concrete explodes, and in high temperatures, the concrete explodes due to the expansion of the reinforcing steel. This can lead to a situation in which the concrete comes off and the lining is destroyed.
As a fire countermeasure, secondary lining concrete is poured in and its thickness is increased to suppress temperature rise.
However, recently, secondary linings are often omitted due to cost reduction requirements.
As a countermeasure for preventing cracking, a wire mesh is provided in the corner portion. However, if the cover is reduced, rust is generated, and if the cover is increased, the occurrence of chipping or cracking cannot be stopped.
[0004]
[Problems to be solved by the invention]
As a countermeasure, it is necessary to suppress the occurrence of cracks in the segments themselves and to improve the fire resistance performance. In suppressing the occurrence of cracks and microcracks, and in improving fire resistance, plastic fiber mixed concrete improves its function, and improves compressive strength, tensile strength, bending toughness, alkali resistance, adhesion, It solves the problem by using properties such as no generation of toxic gas during a fire. Above all, in the event of a fire, polypropylene fibers and vinylon fibers dissolve at a low temperature, forming microscopic voids, and the water contained in the concrete has the effect of suppressing steam explosion caused by a rise in temperature. I know.
[0005]
An object of the present invention is to provide a configuration of concrete as a matrix of segments and a method of manufacturing the segments as a method for solving the above-mentioned problems.
[0006]
[Means for Solving the Problems]
To achieve the above objectives,
According to the first aspect of the present invention, the material of the concrete which is the matrix of the segments is fiber-mixed concrete.
As a result, cracks generated on the rear side during manufacturing are suppressed, and the fire resistance on the inner side is improved. In the long-term durability, the generation of microcracks is suppressed, and the deterioration of neutralization due to intrusion of air or groundwater is suppressed.
The invention described in claim 2 aims at improving fire resistance by using fiber-mixed concrete on the inner surface side and ordinary concrete as the remainder. In addition, fiber-mixed concrete is arranged on the inner side and the back side, and the central part is made of ordinary concrete to prevent cracking and improve fire resistance.
According to the third aspect of the present invention, the fiber-mixed concrete is formed in the whole area or in two or three layers for the segment having a tenon.
According to a fourth aspect of the present invention, the plastic fiber is made of polypropylene fiber, aramid fiber or vinylon fiber.
According to a fifth aspect of the present invention, when the segments are manufactured by a centrifugal force forming method, the material supply sequence is as follows: first, a reinforcing cage is set, and then fiber-mixed concrete and / or ordinary concrete, ordinary concrete, fiber-mixed. This is a manufacturing method in which concrete is supplied in order, and the mold is rotated and compacted by centrifugal force.
According to the invention described in claim 6, when the segment is manufactured with a stationary formwork or a movable formwork, first, a reinforcing bar and a needle fence are set, and then the fiber-mixed concrete on the inner surface side has a curved shape. When a predetermined thickness is secured in the center of the area, normal concrete is added on both sides to make a counterweight, compacted by vibration, and the remaining material such as normal concrete is supplied on it to form a segment It is a manufacturing method. Alternatively, a method may be used in which a material up to a horizontal plane having a predetermined thickness secured in the center of the curved shape is formed of fiber-mixed concrete, and a material such as ordinary concrete is supplied thereon. In the case of the three-layer type, the method is a method of manufacturing a segment in which a holding lid is set, ordinary concrete is supplied up to the surface, and fiber-mixed concrete is supplied thereon and molded.
According to the invention described in claim 7, a curved plate made of fiber-mixed concrete on the inner surface side is manufactured by another mold, the finished product of the curved plate is set in the mold, and a reinforcing cage is placed on the curved plate. This is a manufacturing method in which segments are stored in a fixed position, and the remaining material such as ordinary concrete is supplied to compact the members by vibration compaction.
The invention described in claim 8 is a segment manufacturing method in which a groove is formed in the vertical and horizontal directions on the upper surface of the curved plate in order to stably store the reinforcing cage, and a dowel is buried in the surface and projected.
According to a ninth aspect of the present invention, a lattice-like or net-like basket is manufactured from a fiber wire, and the basket is sewn under a reinforcing cage to form a double basket, and the double basket is set in a mold. Then, the concrete is put in, and the compaction is performed by vibration to produce the segments. The basket made of fiber wire is set so as to exist over the entire area of the required thickness.
[0007]
Regarding the shape and performance of the material of the fiber-mixed concrete, the polypropylene fiber and the vinylon fiber among the plastic fibers will be described below. Description of the shape and performance of other fiber materials will be omitted.
A typical shape of the fiber is a rectangle of 0.5 mm × 1.5 mm or an ellipse with an average diameter of 0.7 mm and a length of 25 to 30 mm. The volume mixing ratio is 0.5 to 1.0%. The above fibers can enhance the flexural toughness of concrete due to the high interfacial adhesion of the matrix.
[0008]
Due to the tunnel fire, the internal temperature of the concrete of the segment gradually rises from the inner surface side, but begins to melt at 160 to 240 ° C., and a myriad of voids are connected to form an escape route for water vapor.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fiber-mixed concrete and ordinary concrete are superimposed on the whole area in two or three layers to form a segment. By covering the specified thickness of the surface layer with fiber-mixed concrete, the strength of the segment and the occurrence of cracks are suppressed. And a function of suppressing explosion in the event of a fire.
[0010]
FIG. 1 and FIG. 2 are drawings showing the usage status of the segments which are the precast lining material of the tunnel and the names of the respective parts.
FIGS. 3, 4, 7, 8, and 9 are diagrams showing the configuration of the matrix of the segments and the manufacturing procedure according to the present embodiment.
5 and 6 are views showing a manufacturing method.
[0011]
FIG. 1 is a cross section of a road shield tunnel. The lining structural material installed on the outer periphery of the tunnel is the segment 2. The segment 2 is connected to form the segment ring 1.
[0012]
FIG. 2 is a sectional view of each segment piece. (A) is a side view, (B) is an inner plan view, and (C) is a main sectional view. On the girder surface of the main section, there are a convex tenon 201 and a concave tenon 202, a seal groove 203, and a caulking groove 204. The convex tenon 201 and the concave tenon 202 between the rings are fitted with each other during assembly. A seal material (not shown) is attached to the seal groove 203.
[0013]
FIG. 3 shows the inside of the side surface of the segment 2 (a) shows a two-layer structure of different materials, a plastic fiber mixed concrete 4 for fire resistance on the bottom side, and ordinary concrete 6 on the top side. (B) shows a three-layer structure, and shows a plastic fiber-mixed concrete 5 for suppressing cracks on the uppermost side of a two-layer system.
[0014]
FIG. 4 shows the inside of the side surface of the matrix of the segment 2. (A) is a three-layer type, plastic fiber mixed concrete 5 for crack control on the upper surface side, plastic mixed concrete 4 for fire resistance on the bottom side, ordinary concrete 6 in the middle part, and needle-shaped on the lower surface of the reinforced cage 3. The mounting position of the fence 7 is shown. (B) shows a partial arrow view of the needle fence 7.
[0015]
FIG. 5 is an explanatory view of the centrifugal force forming method. A circumferential form 8 and a wife form 9 are mounted on the left and right rotors 10. The rotor is connected to and driven by a drive motor 11 via a chain. There is a concrete supply port 12 inside the cylindrical form. Two or three layers of segments are formed by successively feeding different types of raw material concrete from this supply port.
[0016]
FIG. 6 shows a stationary formwork 13.
[0017]
FIG. 7 shows a production process using a stationary formwork or a movable formwork. First, the reinforcing cage 3 is set, but a drawing showing the state is omitted. (A) -1 is a drawing showing the first step, in which the plastic fiber mixed concrete 4 (prepared concrete) is put and finished up to a horizontal plane that maintains a predetermined thickness at the center of the curve. (B) As shown in (b) -2, if the ordinary concrete 6 (prepared concrete) is piled up on the side wall form 14 side at the center of the curvature of the plastic fiber-mixed concrete 4 and poured over, the predetermined thickness is obtained at the center of the curve. Can be easily held. (B) is a drawing showing the second step, in which ordinary concrete 6 (prepared concrete) is put in and the holding lid 17 is attached. (C) shows a state in which the holding lid is removed and the upper lid is attached in the third step, and the plastic fiber mixed concrete 5 (prepared concrete) is put into the formwork surface to finish.
[0018]
FIG. 8 shows a method of manufacturing a curved plate by another means. (A) is a drawing in which a curved plate 16 made of a plastic fiber mixture is manufactured in another mold. The formwork of the curved plate 16 includes a normal formwork, a reverse formwork, and a vertical formwork, which are not shown. (B) shows a state in which the curved plate 16 and the reinforcing bar cage 3 are set on the formwork in the second step. Hereinafter, the production is sequentially performed according to the above-described procedure.
[0019]
FIG. 9 shows a manufacturing method of the fifth aspect. (A) Set a basket made of plastic fiber wire, supply ordinary concrete (prepared concrete) to the full formwork volume, and compact. (B) is an arrow view of the plastic fiber basket 18. According to this lattice basket method, there is no need to knead two or three layers of different materials, and a continuous void can be reliably formed. Further, as shown in (c), a plastic fiber can be used by braiding it in a net shape.
[0020]
【The invention's effect】
Since the present invention is configured as described above, it has the following effects.
{Circle around (1)} By reinforcing the matrix of the segments with plastic fibers, the occurrence of cracks and microcracks can be suppressed.
{Circle around (2)} By mixing plastic fibers with the matrix of the segment, at the time of a tunnel fire, it melts at a relatively low temperature and creates an infinite number of through-holes, thereby suppressing the explosion of the contained water vapor.
{Circle over (3)} Prevents chipping of the edges of corners and recesses that occur at the time of loading and assembling segments represented by tenoned segments.
(1) Regarding the production method of laminating plastic fiber reinforced concrete and ordinary concrete in two or three layers, centrifugal force molding method, material input method with stationary mold, method of separately producing curved plate, plastic grid By appropriately selecting the method of embedding depending on the diameter, thickness, etc. of the segment, a high quality segment can be easily and economically manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a shield tunnel (for road) according to an embodiment of the present invention.
FIG. 2 is a side view, a plan view, and a main cross-sectional view of a segment piece.
FIG. 3 is also a side view of a reinforcing bar cage of a segment and a perspective view of a needle fence.
FIG. 4 is also a sectional view of a segment, showing a configuration of two layers and three layers.
FIG. 5 is a schematic diagram showing a method for forming a segment by centrifugal force.
FIG. 6 is also a stationary or movable formwork diagram of a segment.
FIG. 7 is a view showing a procedure of manufacturing a segment in the stationary formwork.
FIG. 8 is a view showing the production of a curved plate by another means.
FIG. 9 is a view showing a manufacturing method for embedding a plastic grating.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Segment ring 2 ... Segment 3 ... Reinforcing cage 4 ... Plastic fiber mixed concrete (for fire resistance)
5 ・ ・ ・ Plastic fiber mixed concrete (for crack prevention)
6 ... Normal concrete 7 ... Needle fence 8 ... Circumferential form 9 ... Wife form 10 ... Rotor 11 ... Drive motor 12 ... Concrete supply port 13 ... Stationary mold 14 ... Side wall mold 15 ... Top lid 16 ... Curved plate 17 ... Holding lid 18 ... Plastic fiber basket 201 ... Convex tenon 202 ... Concave tenon 203 ...・ Seal groove 204 ・ ・ ・ Caulking groove

Claims (9)

In concrete which is matrix of segment which is lining material of tunnel,
Characterized by using concrete mixed with at least one of plastic fiber, inorganic fiber, organic fiber and metal fiber,
Fiber mixed concrete segment. In the configuration of the matrix of the segments,
A layer of a certain thickness on the inner side of the tunnel, or a part of the inner side with a certain thickness on the outer side is laminated with fiber-mixed concrete, and the remaining part is superimposed on two or three layers with ordinary concrete. Characterized by forming
The fiber-mixed concrete segment according to claim 1. The segment is a segment having a tenon on a joint surface,
The fiber-mixed concrete segment according to claim 1. The plastic fiber is
The fiber-mixed concrete segment according to any one of claims 1 to 3, wherein the fiber-mixed concrete segment is a polypropylene fiber, an aramid fiber or a vinylon fiber. After setting the reinforced basket in the formwork,
From the outer surface of the formwork, materials are supplied in the order of fiber-mixed concrete and / or ordinary concrete, ordinary concrete, fiber-mixed concrete, and different types of materials are superimposed,
Characterized by forming the segments by centrifugal force forming method,
How to make fiber mixed concrete segments. After setting the reinforced basket and the needle fence in the formwork,
At the center of the curved shape, the fiber-mixed concrete on the inner side
When the specified thickness is secured, normal concrete is put on both sides, vibration compaction is performed, and the remaining material such as normal concrete is supplied on top,
Characterized by molding the segment with a stationary formwork,
How to make fiber mixed concrete segments. The curved side of fiber-mixed concrete on the inner surface side is manufactured by another means,
Set the finished product of the curved plate in the mold,
Supply the remaining materials, such as reinforced cages and ordinary concrete, on the curved plate,
Characterized by forming a segment,
How to make fiber mixed concrete segments. On the upper surface of the curved plate,
Grooves are provided in the vertical and horizontal directions for storing reinforced baskets,
Characterized by burying and projecting a dowel on the surface,
A method for producing a fiber-mixed concrete segment according to claim 7. In advance, make a lattice or mesh basket of fiber wires,
The basket is sewn under the reinforced basket and set in the formwork,
Ordinary concrete is poured into the entire formwork, compacted by vibration,
Characterized by forming a segment,
How to make fiber mixed concrete segments.

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