JP2005067146A - Segment production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a segment production method by which bubble traces in concrete curing can be prevented from occurring without using a sheet member for deaeration, unbiassed strength after curing can be obtained, and production efficiency is improved. <P>SOLUTION: A formwork body is held at a slant by a base 4. The bottom face 3a of the formwork body is nearly horizontal in a width direction, but is formed so as to incline, in a periphery, to one side of the left and right direction in view from the width direction from one inner face 3b in the periphery toward the other inner face 3c. Concrete is placed from one end part in the periphery at an uppermost position along the bottom face 3a of the formwork. The concrete is preferably a high-flow concrete. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a segment manufacturing method.

Conventionally, in a cylindrical underground structure such as a shield tunnel, a curved plate segment having a shape obtained by dividing such a covering body in the axial direction and the circumferential direction in order to form a cylindrical covering body, A construction method is adopted in which it is arranged on the excavation surface and joined in the extending direction and circumferential direction of the lining body. As such a segment, a concrete segment having a reinforced concrete structure, a synthetic segment for placing concrete on a steel frame, and the like are known. Also, when manufacturing these segments, in the case of hard-mixed concrete, it was necessary to vibrate and compact the segment formwork, so that high-fluidity concrete was cast to improve manufacturing efficiency. A method has been proposed.
For example, Patent Document 1 discloses a segment manufacturing formwork for placing concrete in a posture in which a bottom plate having an arcuate curved surface is convex upward and supports the left and right of the bending direction substantially horizontally. Has been described.
Patent Document 2 discloses a sheet having air permeability and water permeability on the inner surface of the outer peripheral mold surface in order to effectively eliminate excess air and excess water when placing high-fluidity concrete in a segment mold. A concrete segment manufacturing formwork in which members are provided and a number of holes are formed in the vicinity of the concrete input slit on the outer periphery formwork surface and a manufacturing method using the same are described.
In addition, Patent Document 3 discloses a segment manufacturing form in which a plurality of degassing sheets are provided on the inside of the cover form in order to escape air bubbles gathering on the bottom face of the cover form when placing high-fluidity concrete. Is described.
Japanese Patent Laid-Open No. 10-286813 (page 2-3, FIG. 1) JP 10-193310 A (page 2-3, FIG. 1-3) JP 2002-200610 A (page 2-3, FIG. 1-3)

However, the conventional segment manufacturing method as described above has the following problems.
In the technique described in Patent Document 1, there is a problem that bubbles are easily caught when high-fluidity concrete is placed.
Although the techniques described in Patent Documents 2 and 3 are improved to facilitate degassing even when such bubble entrainment occurs, since the sheet member for degassing is used, the cost of the segment mold is reduced. There was a problem of being expensive.
On the other hand, in recent years, demands for improving the crack strength and earthquake resistance of segments have increased, and it is conceivable to disperse reinforcing fibers in high-fluidity concrete. However, according to the experiments conducted by the inventors, in the conventional segment manufacturing method, when high-fluidity concrete containing reinforcing fibers is placed, the orientation of reinforcing fibers is biased and the strength becomes non-uniform. I found out that

  The present invention has been made in view of the above problems, and can prevent generation of bubble marks during curing of a concrete without using a deaeration sheet member, etc. An object of the present invention is to propose a segment manufacturing method capable of improving the manufacturing efficiency.

In order to solve the above-mentioned problems, the invention described in claim 1 has a curved bottom surface that is straight in the width direction and curved in the circumferential direction perpendicular to the width direction, and the periphery and upper side thereof are covered with a formwork surface. A segment manufacturing method including a step of placing concrete in a segment formwork forming a concrete placement space, wherein the curved bottom surface is substantially horizontal in the width direction and the circumferential direction is in the width direction. Inclined to the left and right direction when viewed from the side, held in a posture in which one end in the circumferential direction is positioned at the top, and put concrete from one end side of the segment formwork And a segment manufacturing method.
According to this invention, by placing concrete from one end side in the circumferential direction of the segment formwork, the concrete flows uniformly in the substantially horizontal width direction and inclines in one direction in the circumferential direction. It flows down along the inclination of the curved bottom surface and is filled in the segment mold. Therefore, the entrainment of bubbles is reduced, and even if the entrainment occurs, the bubbles can move to the upper surface side of the segment formwork along the inclination and can naturally escape from one end side of the segment formwork. Moreover, since the concrete flows down along the slope of the curved bottom surface, the flow direction is aligned in one direction.

According to a second aspect of the present invention, in the segment manufacturing method according to the first aspect, the concrete is a high fluidity concrete containing reinforcing fibers.
According to this invention, since the reinforcing fibers are aligned along the flow direction of the concrete, the longitudinal direction of the reinforcing fibers can be aligned with the curved direction of the segments.

According to a third aspect of the present invention, in the segment manufacturing method according to the second aspect, the reinforcing fiber has a length of 20 mm to 60 mm, a diameter of 0.3 mm to 0.9 mm, and a short aspect ratio of 30 to 100. It is a fibrous steel fiber, and the mixing rate with respect to the concrete is 0.4% by volume to 2.0% by volume.
According to this invention, by mixing such a shape and amount of steel fibers, the crack strength and shear strength after hardening can be improved, so that it is possible to omit the distribution bars, hoop bars, etc. It becomes. As a result, higher fluidity can be obtained in the segment formwork, and the production efficiency can be improved. Further, since the distribution bars, hoop lines, etc. can be omitted, it can be manufactured at low cost.

According to a fourth aspect of the present invention, in the segment manufacturing method according to any one of the first to third aspects, at least immediately before finishing the concrete placing, the periphery of the curved bottom surface at one end of the segment mold It arrange | positions so that the inclination of a direction may become substantially horizontal.
According to the present invention, one end of the segment mold that serves as an injection hole for placing concrete is disposed so that the circumferential inclination is substantially horizontal, so that it is formed at the end of the concrete placing process. The concrete surface to be formed can be formed substantially horizontally. Therefore, since the concrete flows naturally, an outer surface along the outer peripheral surface of the segment can be formed, so that post-finishing such as finishing can be unnecessary or simplified.

  According to the segment manufacturing method of the present invention, since concrete can be filled smoothly, it is possible to prevent the generation of bubble marks when the concrete is cured without using a deaeration sheet member or the like, and the flow state of the concrete is uniform. It is possible to obtain a uniform strength after curing and to improve the production efficiency.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.
A segment manufactured by the segment manufacturing method of the present embodiment can be formed into a cylindrical structure such as a shield tunnel by joining the plurality of segments in the annular direction and also in the axial direction of the annular structure. To do. For this reason, the segment is a curved plate-like member in which a predetermined curve is formed along the circumferential direction in the cross section orthogonal to the axial direction of the cylindrical structure. Therefore, hereinafter, unless there is a possibility of misunderstanding, the axial direction and the circumferential direction of the cylindrical structure are also used when referring to the directions related to the segment unit and the segment formwork.
Fig.1 (a) is a cross-sectional explanatory drawing of the circumferential direction for demonstrating an example of the segment manufactured by the segment manufacturing method which concerns on embodiment of this invention. FIG.1 (b) is AA sectional drawing of Fig.1 (a). FIG. 2 is a perspective explanatory view for explaining a schematic configuration of a segment mold used in the segment manufacturing method according to the embodiment of the present invention. FIG. 3 is a schematic explanatory diagram for explaining the outline of the segment manufacturing method according to the embodiment of the present invention. 4A to 4D are process explanatory diagrams for sequentially explaining the processes of the segment manufacturing method according to the embodiment of the present invention.

A segment manufacturing method according to an embodiment of the present invention will be described.
First, a schematic configuration of the segment 6 shown in FIG. 1 will be described as an example of a segment manufactured by the segment manufacturing method of the present embodiment.
The segment 6 extends in a predetermined axial direction and has an outer circumferential surface 6e and an inner circumferential surface 6a having a substantially concentric cylindrical curve, and an axial end surface for joining with other segments adjacent in the axial direction. A curved plate surrounded by joint surfaces 6d, 6d, and joint surfaces 6b, 6c for forming a circumferential end surface substantially perpendicular to the joint surfaces 6d, 6d and joining to other segments adjacent in the circumferential direction. It is a concrete segment hardened in a shape. That is, the segment 6 has a shape that is straight in the axial direction and curved in the circumferential direction.
Thus, since the joining surfaces 6c and 6c which oppose the axial direction in the segment 6 are made parallel by a predetermined distance, the axial direction is also referred to as the width direction below.
In the vicinity of the outer peripheral surface 6e and the inner peripheral surface 6a, main bars 8 extending substantially along the curves are arranged. Further, in the vicinity of the joint surfaces 6b and 6c, joint portions 13 for joining the other segments 6 in the circumferential direction are provided and joined to the main bars 8.

The detailed configuration of the joint portion 13 includes a joint fitting 12 arranged in alignment with the surfaces of the joint surfaces 6b and 6c, a connecting rod 10 that supports the joint fitting 12 on the inner side, and a load received by the connecting rod 10 inside the segment. The main frame base 11 for transmitting to the joint is coupled by welding, bolt fastening or the like.
Further, the detailed configuration of the main bar base 11 includes main bar receiving portions 11a and 11a that extend in the segment width direction and join the main bars 8 and a connecting plate 11b that connects them in the segment thickness direction.

In the present embodiment, fiber reinforced high fluidity concrete is used as the concrete 7. Fiber-reinforced high-fluidity concrete is a mixture of high-fluidity concrete with a predetermined amount of reinforcing fibers.
For example, short fiber steel fibers can be used as the reinforcing fibers. As the shape of the short fiber, for example, those having a length of 20 mm to 60 mm, a diameter of 0.3 mm to 0.9 mm, and an aspect ratio of 30 to 100 are preferable. Moreover, it is preferable that the mixing rate with respect to concrete shall be 0.4 volume%-2.0 volume%.
The high-fluidity concrete may have any configuration. For example, by mixing powder such as silica fume or adding a thickener, separation resistance is ensured and high fluidity is ensured. The structure which obtains can be adopted.

In order to manufacture such a segment 6, in this embodiment, the segment formwork 1 shown in FIG. 2 is used.
A schematic configuration of the segment mold 1 includes a lid mold 2, a mold body 3, and a base 4.
The lid mold frame 2 covers the upper side of the mold body 3 to form the outer peripheral surface 6e of the segment 6, and the outer mold surface 2a (mold surface) which is curved substantially along the outer peripheral surface 6e. A rectangular frame-shaped concrete injection portion 2b that opens up and down is provided on one end side in the circumferential direction of the lid main body 2d made of a substantially rectangular curved plate in plan view. Reference numeral 2c denotes an injection opening formed in the lid body 2d.

The mold body 3 has a circumferential side plate 3B, a width side plate 3D, a circumferential side plate 3C, and a width side plate 3D erected around a bottom plate 3A having an upwardly convex curved plate shape, and an upper end portion thereof is This is a member on which the side plate upper surface 3e is formed along the curve of the inner peripheral surface 6a of the segment 6.
Further, on the inner side surrounded by them, a mold bottom surface 3a (curved bottom surface) which is a mold surface for forming the inner peripheral surface 6a of the segment 6, and the joint surfaces 6b, 6d, 6c, 6d, a circumferential inner surface 3b (form frame surface), width direction inner side surface 3d (form frame surface), circumferential direction inner side surface 3c (form frame surface), and width direction inner side surface 3d (form frame surface) are provided.
When the lid mold frame 2 is disposed at a predetermined position on the side plate upper surface 3e of the mold body 3, the outer mold surface 2a, the mold bottom surface 3a, the circumferential inner surface 3b, the width inner surface 3d, and the circumferential direction A concrete placement space 5 surrounded by the inner side surface 3c and the width direction inner side surface 3d is formed.

The base 4 holds the mold body 3 at a high position on the circumferential side plate 3B side with respect to the circumferential side plate 3C, and the mold bottom surface 3a from the circumferential inner side surface 3b side when viewed from the width direction. The holding member is arranged so as to be inclined toward the left and right direction toward the circumferential inner surface 3c.
In the present embodiment, the mold body 3 is disposed so that the tangential direction between the side plate upper surface 3e and the mold bottom surface 3a on the inner side surface 3b side in the circumferential direction is substantially horizontal.

With the configuration described above, when viewed from the width direction side, as shown in FIG. 3A, when concrete is injected into the concrete injection portion 2b by the concrete injection means 14, the concrete is inclined to the bottom surface 3a of the formwork. It flows down smoothly as shown by the arrow in the left direction in the figure.
On the other hand, in the top view, as shown in FIG. 3 (b), since the width direction of the mold bottom surface 3a is arranged substantially horizontally, the concrete poured anywhere in the concrete pouring part 2b extending in the width direction It does not flow in one direction in the width direction, and a uniform and stable flow along the circumferential direction is formed.
Therefore, when high fluidity concrete is used, a vortex flow is generated and bubbles are less likely to be involved. Moreover, since the flow state is uniform, there is no bias in strength. In particular, when reinforcing fibers such as steel fibers are included, the reinforcing fibers are oriented along a uniform flow, so that the longitudinal direction of the fibers can be along the circumferential direction, which is more stable. There is an advantage that uniform strength can be exhibited.

Each process of the segment manufacturing method of this embodiment is demonstrated with reference to FIG.
As shown in FIG. 4A, the main frame 8, the joint portion 13 and the like are arranged on the mold body 3 (see FIG. 3), and the outer mold surface 2a is brought into close contact with the side plate upper surface 3e. 2 is placed. At this time, the concrete injection part 2b is arrange | positioned in the vicinity of the circumferential direction inner surface 3b, and the injection | pouring part opening 2c is formed in the position which follows a substantially horizontal surface.
Next, as shown in FIG. 4 (b), the concrete 7 is injected from the concrete injection portion 2 b by the concrete injection means 14. Then, the concrete 7 flows down in the direction of the arrow shown along the form bottom surface 3a.
When the circumferential inner side surface 3c side is filled, the concrete 7 is filled along the inclination of the outer peripheral mold surface 2a from the lower side to the outer peripheral mold surface 2a (see FIG. 4C). At this time, even if the orientation of the steel fiber or the like is not disturbed due to the influence of turbulent flow, or even if some bubbles are involved, the bubbles rise by buoyancy and gather on the outer mold surface 2a side. In order to obtain a sufficient amount of time that can be obtained, the injection amount of the concrete 7 is adjusted in order to obtain an appropriate flow rate.

In the case of the present embodiment, since there is no reinforcing bar that hinders flow, such as a distribution bar and a hoop line, a more excellent orientation can be obtained.
For this reason, the entrainment of bubbles is very small, and even if it is gathered somewhat on the outer peripheral mold surface 2a side, it is gradually moved upward by the concrete 7 that gradually rises from below and is returned to the concrete placement space 5. Accordingly, for example, it is not necessary to provide a deaeration sheet member or the like on the outer peripheral mold surface 2a, so that the manufacturing process is simplified.

In this way, finally, as shown in FIG. 4 (d), the steel fibers are oriented in the circumferential direction, and the air bubbles on the outer peripheral mold surface 2a side are naturally extracted upward, and then the concrete 7 The top surface of the lead reaches the injection opening 2c, and a smooth concrete surface 15 aligned with the side plate upper surface 3e is formed in a substantially horizontal direction. For this reason, finishing processes, such as wrinkle finishing, can be omitted.
In addition, since the concrete 7 smoothly flows and is filled, it is not necessary to compact the segment mold 1 to apply vibration, and it is not necessary to provide the segment mold 1 on the vibration table. There is no need to do. Therefore, there exists an advantage that it can be set as the cheap and highly durable segment formwork 1. FIG.
Then, the injection of the concrete 7 is stopped, and the segment 6 is manufactured by demolding from the mold body 3 after waiting for hardening.

  In the above description, the case where high-fluidity concrete is injected has been described. However, what is called high-fluidity concrete is concrete having fluidity enough to smoothly flow down along the bottom of the formwork? Concrete, which is not said to be highly fluid, may be used.

  In the above description, an example of a segment having a rectangular shape in plan view has been described. However, the segment is not limited to a rectangular shape in plan view as long as it is straight in the width direction and curved in the circumferential direction. For example, it may be a hexagon in plan view, and a configuration in which hexagonal chevron is arranged at the end in the circumferential direction can be adopted. In this case, it is possible to form a uniform flow in the width direction by forming the concrete injection hole along a mountain shape. Alternatively, it is also possible to provide a mountain-shaped top injection hole so that it spreads in the width direction along with the underflow of the concrete and reaches the side surface in the width direction, and then uniformly flows down along the circumferential direction.

  In the above description, the mold body 3 is fixed and the inclination of the curved bottom surface is fixed. However, the inclination may be changed during concrete placement. For example, at the time of initial filling, the inclination may be increased to increase the flow velocity, and the inclination may be gradually decreased after the concrete reaches the lower end side. At that time, it is preferable that the injection opening 2c be inclined so as to be substantially horizontal immediately before completion of the concrete placing.

  Further, in the above description, the case where the injection portion opening 2c is substantially horizontal has been described as a more preferable example. However, the injection portion opening 2c is not necessarily horizontal if it can be filled.

  In the above description, as a more preferable example, the curved bottom surface is convexly disposed on the upper side. However, a concave surface is disposed on the upper side so that the circumferential direction of the concave surface is inclined in one direction. Good. Even in this case, there is an effect similar to the above in which the bubbles are driven out along the inclination and the reinforcing fibers are oriented in the circumferential direction. Needless to say, the injection opening 2c is covered with another formwork at the final stage of placing the concrete so that the concrete is completely filled.

It is sectional drawing of the circumferential direction and axial direction for demonstrating an example of the segment manufactured by the segment manufacturing method which concerns on embodiment of this invention. It is an isometric view explanatory drawing for demonstrating schematic structure of the segment formwork used for the segment manufacturing method which concerns on embodiment of this invention. It is a schematic explanatory drawing for demonstrating the outline | summary of the segment manufacturing method which concerns on embodiment of this invention. It is process explanatory drawing for demonstrating sequentially the process of the segment manufacturing method which concerns on embodiment of this invention.

Explanation of symbols

1 Segment formwork 2a Peripheral formwork surface (formwork surface)
2b Concrete injection part 2c Injection part opening 3 Formwork body 3a Formwork bottom (curved bottom)
3b, 3c Circumferential inner surface (form surface)
3d Width direction inner side surface 3e Side plate top surface 4 Base 5 Concrete placement space 6 Segment 7 Concrete 8 Main reinforcement 15 Concrete surface

Claims (4)

Placing concrete in a segment formwork that is straight in the width direction and has a curved bottom surface that is curved in the circumferential direction perpendicular to the width direction and covers the periphery and upper side with a formwork surface to form a concrete placement space A segment manufacturing method including
The segment mold frame is configured such that the curved bottom surface is substantially horizontal in the width direction, the circumferential direction is inclined to the left and right directions when viewed from the width direction, and one end in the circumferential direction is positioned at the top. Hold on,
A method for producing a segment, comprising placing concrete from one end side of the segment formwork.   The segment manufacturing method according to claim 1, wherein the concrete is high-fluidity concrete containing reinforcing fibers.   The reinforcing fiber is a short fiber-like steel fiber having a length of 20 mm to 60 mm, a diameter of 0.3 mm to 0.9 mm, and an aspect ratio of 30 to 100, and a mixing ratio with respect to the concrete is 0.4 volume%. The segment manufacturing method according to claim 2, wherein the volume is set to ˜2.0% by volume.   At least immediately before completion of concrete placement, the circumferential direction inclination of the curved bottom surface at one end of the segment mold is arranged to be substantially horizontal. The segment manufacturing method described in 1.

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