JP2007069367A - Manufacturing method of segment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the manufacturing time up to a surface finishing process without causing a water route or cracking in a manufacturing method of a segment. <P>SOLUTION: Highly flowable concrete is cast in a form and subsequently heated internally to be brought to a self-supporting and surface finishable state. A lid form is detached to perform the surface finish and steam curing before a concrete segment is demolded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a segment.

Conventionally, when manufacturing a segment using concrete, it is manufactured by placing the concrete on a mold, performing vibration compaction, taking the lid mold and finishing the surface, and then curing after steam curing. Yes.
On the other hand, a method for manufacturing a segment using high-fluidity concrete has been proposed in order to shorten the time for placing on the mold and simplify the manufacturing process by eliminating the need for vibration compaction.
However, in this case, although the concrete placing process is speeded up, it takes time until the concrete becomes self-supporting. If the concrete cannot be self-supported, the surface of the concrete cannot be finished and surface finishing cannot be performed. There was a problem that it could not be shortened so much.
In order to solve this problem, Patent Document 1 discloses that surface treatment is performed by heating and curing at a temperature higher than normal temperature for a predetermined time after high-fluidity concrete is cast, A method for producing a concrete segment using high-fluidity concrete that is finished and then cured and demolded is described.
Japanese Patent Laid-Open No. 11-58348 (FIG. 2)

However, the conventional segment manufacturing method as described above has the following problems.
In the technique described in Patent Document 1, heat curing from the outside of the mold can shorten the time until the concrete can stand on its own, but it heats from the outside of the mold, so from the side close to the mold surface. Curing proceeds. For this reason, even if the curing progresses until the surface finish is possible, the hydration reaction within the segment does not progress so much. Therefore, the steam curing process is entered in a state where the internal hydration reaction has not sufficiently progressed. As a result, bleeding occurs inside the segment, and bubbles are confined inside the segment.
In addition, after the heat curing, the finishing work cannot be performed unless the temperature is lowered, so that there is a problem in that there is a limit in the amount of time reduction because it is necessary to wait for the temperature to drop.

  The present invention has been made in view of the above problems, and a segment manufacturing method that can reduce the manufacturing time until entering the surface finishing process without causing a water groove or a crack. The purpose is to provide.

In order to solve the above-mentioned problems, in the invention described in claim 1, the high-fluidity concrete is driven into a mold and cured until the high-fluidity concrete is self-supporting and surface finish is possible, and then the lid mold is removed. A segment manufacturing method for finishing the surface of the high-fluidity concrete, after the high-fluidity concrete is driven into the mold, and then curing the high-fluidity concrete in the mold until the surface can be finished by internal heating. .
According to the present invention, since high-fluidity concrete is driven and then internally heated, the hydration reaction of the concrete is promoted, and the time required for hardening until the surface can be finished can be shortened.
In addition, for example, heat curing does not cause rapid curing from the surface and non-uniform curing does not occur, and curing progresses substantially evenly, so that water spots and cracks do not occur. it can.

According to a second aspect of the present invention, in the method for producing a segment according to the first aspect, the internal heating is performed by irradiating the high-fluidity concrete with microwaves.
According to this invention, by irradiating the microwave adjusted to an appropriate frequency, for example, only water in high-fluidity concrete can be heated to perform internal heating. Therefore, hardening can be uniformly promoted with respect to the inside of the high fluidity concrete.

  According to the method for manufacturing a segment of the present invention, since substantially uniform curing can be promoted as a whole by performing internal heating in the mold after the high-fluidity concrete is placed, it is manufactured until the surface finishing process is started. There is an effect that it is possible to shorten the time and to provide a method for manufacturing a segment that does not cause water pits or cracks.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, the segment manufactured by the segment manufacturing method according to the embodiment of the present invention will be briefly described.
FIG. 1 is a perspective explanatory view for explaining a segment according to an embodiment of the present invention.

As shown in FIG. 1, the concrete segment 1 (segment) of the present embodiment is a plate-like member having a substantially constant thickness (t ₀ ) and curved in an arc shape in one direction, and joining a plurality of them. As a result, the inside of the excavation tunnel is used for lining.
In general, as the shape of the concrete segment that covers the excavation tunnel, various plan view shapes such as a hexagonal shape in plan view and a K-shaped segment having a trapezoidal view in plan view are known. There are various shapes depending on the joint structure.
The present invention can be easily applied to segments having such various planar shapes and joint structures, but in the following, for the sake of simplicity, two planes including the tunnel central axis and the tunnel central axis are orthogonal. An example of a rectangular shape in plan view taken along two planes will be described.
That is, on the side of the concrete segment 1, substantially rectangular joint surfaces 2a and 2a included in a plane including the center axis of the tunnel, and a fan-shaped joint surface 2b included in a plane orthogonal to the center axis of the tunnel, 2b is formed. The concave side of the curve is the inner peripheral surface 4, and the convex side is the outer peripheral surface 5.
Joint portions 3 are provided at appropriate intervals at positions where the inner peripheral surface 4 and the joint surfaces 2a, 2a, 2b, and 2b intersect.
The joint portion 3 is provided with, for example, a joint plate 3a for bolt joining along the joint surface 2a (2b), and a hole space for performing the joining work is formed on the inner peripheral surface 4 side. is there.

  Hereinafter, when referring to the direction, the extending direction of the central axis of the concrete segment 1 that coincides with the central axis of the tunnel is the axial direction, the direction along the curved surface in the plane orthogonal to the axial direction is the circumferential direction, and the radial direction of the bending The direction along the direction is sometimes referred to as the plate thickness direction (see FIG. 1).

A segment manufacturing method according to an embodiment of the present invention will be described.
FIG. 2 is a flowchart for explaining each step of the segment manufacturing method according to the embodiment of the present invention. 3, 4, and 5 are schematic cross-sectional views in a direction perpendicular to the segment axial direction, for explaining each step of the segment manufacturing method according to the embodiment of the present invention.

  The segment manufacturing method of the present embodiment is a method for manufacturing a segment using high-fluidity concrete. As shown in FIG. 2, the outline process is a formwork preparation process (step S1), concrete pouring. It consists of a process (step S2), an internal heating process (step S3), a surface finishing process (step S4), a curing process (step S5), and a demolding process (step S6).

  In the mold preparation step, as shown in FIG. 3 (a), a joint forming projection 13, a hole forming projection 14 and the like are provided inside the mold formed of the lower mold 10 and the lid mold 16. In this step, the reinforcing bars 9 are arranged so that high-fluidity concrete can be placed.

The lower mold 10 is for forming the shapes of the inner peripheral surface 4 and the joint surfaces 2a, 2a, 2b, and 2b of the concrete segment 1, and the inner peripheral mold frame surface 10a and the joint mold corresponding to each of them. The frame surfaces 10b and 10b, and the unillustrated joint portion mold surface are provided on the back side and the near side of the paper surface, the upper side is opened, and the upper end portions of the mold frame end surfaces 10d are formed along the curve of the outer peripheral surface 5. It is a thing.
And the inner periphery part form surface 10a, the joint part form surfaces 10b, 10b, and the joint part form surface (not shown) provided on the back side and the front side of the paper are made of a metal that reflects microwaves. .
On the inner peripheral mold surface 10a, a joint forming projection 13, a hole forming projection 14 and the like are appropriately provided according to the required shape such as the joint 3 and the hole 6.

The cover mold 16 covers the lower mold 10 from above, and the outer peripheral mold surface 16b is installed on the mold end surface 10d, thereby forming a mold space for placing high-fluidity concrete. Is. An injection hole 16a for injecting high-fluidity concrete is provided at the top of the lid mold 16 at the curve.
In this embodiment, it is comprised with the nonmetal which permeate | transmits a microwave, for example, synthetic resin, wood, etc.

  The concrete placement step is a step of placing the high fluidity concrete 17 in the formwork space. In this step, as shown in FIG. 3B, high-fluidity concrete 17 is poured through the concrete injection pipe 15 into the injection hole 16a and placed.

  The high fluidity concrete 17 is a concrete having both high fluidity and material separation resistance, and is obtained by adding an admixture to cement, water and aggregate and kneading them.

Portland cement can be used as the cement. For example, ordinary Portland cement, early-strength Portland cement, blast furnace cement, low heat Portland cement, medium heat heat Portland cement and the like can be used.
Tap water can be used as the water.
As the aggregate, fine aggregate and coarse aggregate can be used as necessary. As the fine aggregate, land sand, river sand, crushed sand, sea sand, slag fine aggregate, lightweight fine aggregate, heavy fine aggregate, recycled fine aggregate, or a mixed fine aggregate thereof can be used. Further, as the coarse aggregate, river gravel, mountain gravel, sea gravel, crushed stone, slag coarse aggregate, lightweight coarse aggregate, heavy coarse aggregate, recycled coarse aggregate, or a mixed coarse aggregate thereof can be used.

  Examples of the admixture include admixtures such as blast furnace slag fine powder, fly ash, silica fume, limestone fine powder, early-strength expansion material, and high-performance water reducing agent. In addition, an air entraining agent, a foam suppressor, an antifoaming agent, a foaming agent, a thickening agent, a rust preventive agent, a pigment, and the like may be used as an admixture as long as the strength and workability are not impaired.

Table 1 shows an example of a combination of these materials used.

Table 2 shows examples of these suitable formulations as examples. The comparative example in Table 2 is an example of conventional concrete.

  Since the high fluidity concrete 17 is rich in fluidity and excellent in filling property, it flows along the cylindrical shaft die surface 10a and the like from the injection hole 16a according to gravity, and is quickly filled in the mold space. Therefore, there is no need to perform vibration compaction. FIG. 3C shows a state at the end of placement.

  In the internal heating process, the surface of the high-fluidity concrete 17 is not removed even when the high-fluidity concrete 17 is internally heated and the lid mold 16 is removed in a state where the placement of the high-fluidity concrete 17 on the mold is completed (see FIG. In this step, the concrete is in a self-supporting state, and after the cover mold 16 is removed, the hardening is advanced to such a degree that the outer peripheral surface 5 of the surface is kept soft enough to be flat finished. Such a degree of curing may be approximately the same as the degree of curing when the surface finishing process is started in the conventional segment manufacturing method. Although the criteria for determining the hardness that can be finished differ slightly depending on the know-how of each company, for example, in general concrete, finishing starts with the time when bleeding stops, so the time to reach the hardness of the state can be The curing time until finishing is possible.

In the present embodiment, internal heating is performed using the heating device 20.
As shown in FIG. 4 (d), the schematic configuration of the heating device 20 includes a frame 21 that covers the lower mold 10 on which the high-fluidity concrete 17 is placed, and a space between the frame 21 and the lid mold 16. The microwave heater 23 is provided so as to be movable along a curve corresponding to the outer peripheral surface 5 formed by the lid mold 16.
The mechanism for moving the microwave heater 23 includes a guide member 22 provided on the lower surface side of the frame 21 and a moving mechanism 23 a including a self-propelled mechanism that moves along the guide member 22.

The microwave heater 23 is for irradiating the high-fluidity concrete 17 in the lower mold 10 with a microwave having a frequency of 2450 MHz that matches the natural frequency of water. It is arranged along the segment axis direction toward the back side.
Then, while irradiating the microwave from the microwave heater 23 toward the high-fluidity concrete 17, the microwave heater 23 is reciprocated along the guide member 22 at an appropriate speed, and the high-fluidity concrete 17 in the formwork is moved. The microwaves are evenly irradiated. Thereby, the molecular vibration of the water in the high fluidity concrete 17 becomes active and the water temperature rises. And the hydration reaction of concrete is promoted.

  In addition, although the microwave is reflected in the metal in the high fluidity concrete 17, such as the reinforcing bar 9, the area is small, so that a blind spot area not irradiated with the microwave is not formed. The reflected microwave propagates to the surroundings due to scattering, and the microwave that is reflected and propagates from the reflecting surface such as the inner peripheral mold surface 10a reaches the back side as well, so that the microwave is evenly distributed throughout. Is irradiated.

Since the heating temperature by the microwave heater 23 is determined by the intensity of the microwave and the irradiation time, the temperature is determined by, for example, experiments according to the composition and amount of the high-fluidity concrete 17.
In general, the higher the temperature, the more preferable the concrete hydration reaction is promoted, but the temperature is such that water boils and bubbles are not generated more than necessary in the high-fluidity concrete 17.
Also, it is preferable to grasp the relationship between the internal heating temperature and the curing time by appropriately experimenting. In consideration of the heat storage effect, it is preferable to reduce the output of the microwave heater 23 in the second half of the internal heating process. Furthermore, in order to smoothly shift to the surface finishing process, control may be performed to reduce the heating amount so that the set temperature is gradually lowered. These operations for reducing the output may change the output of the microwave, but can also be adjusted by intermittently changing the irradiation time.

  Since microwaves are used in the internal heating process, at least during the internal heating process, the heating device 20 is surrounded by a metal plate so that the operator is not exposed to microwaves.

In the surface finishing process, after the internal heating process is completed, the lid mold 16 is removed, and the surface of the high-fluidity concrete 17 exposed on the surface is aligned with the upper surface of the mold including the mold end surface 10d on which the lid mold 16 is disposed. This is a process (see FIG. 4E) for finishing the surface as a smoothly curved curved surface and forming the outer peripheral surface 5.
In this step, as shown in FIG. 4 (e), for example, the finishing square bar 18 is handed over to the unillustrated joint form surface on the back side and the near side of the paper, and as shown in the double arrow in the figure, the circumferential direction , The unevenness on the surface of the high fluidity concrete 17 is leveled. Then, the outer peripheral surface 5 is formed by shaping into a smooth curved surface.
This process starts after a certain period of time until the working temperature is reached after completion of the internal heating process.

As shown in FIG. 5 (f), the curing process is performed by steam curing that is left in a heated steam atmosphere while the high-fluidity concrete 17 whose surface finishing process is finished is held in the lower mold 10. This is a step of promoting the hardening of the high fluidity concrete 17.
The curing process can basically employ the same curing method as in the conventional segment manufacturing method.

FIG. 6 is a schematic graph showing an example of segment temperature setting in the segment manufacturing method according to the embodiment of the present invention. The horizontal axis represents the elapsed time from the end of the concrete placing process, and the vertical axis represents the set temperature.
In FIG. 6, the broken line 40 shows the outline of the change of preset temperature between step S4 to S7 in FIG.
The change represented by the polygonal line 40 is constant at the temperature T ₁ (where T ₁ > T ₀ ) from the elapsed time 0 to t ₁ (line 40a), and the temperature T between the elapsed time t ₁ and t ₂ is constant. _The temperature is lowered to ₀ (straight line 40b) and is maintained at the temperature T ₀ from the elapsed time t ₂ to t ₃ (straight line 40c), and the temperature is raised from the elapsed time t ₄ to the temperature T ₁ and between the elapsed time t ₃ and t ₄ , Temperature T ₁ (straight line 40d). Then, the temperature T ₀ is lowered from the elapsed time t ₄ to t ₅ (straight line 40e), and the temperature T ₀ is maintained until the elapsed time t ₆ (straight line 40f).
Here, 0 <t ₁ <t ₂ <t ₃ <t ₄ <t ₅ <t ₆ . Then, indicating the elapsed time 0 to t ₂ represents the process of step S4, the elapsed time _t 2 ~t ₃ steps S5, the elapsed time _t 3 ~t ₅ is a process in step S6, respectively. Demolding step described below is carried out on the elapsed time _t 5 ~t _6.

The temperature T ₀ is the temperature at the place where the lower mold 10 is installed, and is set to room temperature. For example, T ₀ = 15 ° C. to 30 ° C.
Temperatures T ₁ may be the curing temperature equal to or slightly lower temperatures employed in the conventional method of manufacturing a segment. For example, T ₁ = 45 ° C. can be employed. A preferred range of temperatures _{T 1} is thirty-three to fifty-five ° C..
In the internal heating process, the time t ₁ during which the temperature T ₁ is maintained is a time obtained by experiments in advance. Since the heating by the microwave can be performed entirely from the inside of the segment, it can reach the temperature T ₁ more uniformly and at a higher speed than the case of heating from the outside. The time t ₂ for lowering the temperature T ₁ to the temperature T ₀ depends on the cooling time determined by the shape and size of the segment. Moreover, the curing time (t ₅ -t ₅ ) of the curing process can be about 3.5 h.
However, the conditions of these curing processes vary depending on the amount of the hardening accelerator, the blending ratio of the high fluidity concrete 17, and the like, and are not limited to such conditions. For example, when changing the temperatures T ₀ and T ₁ , it is preferable to appropriately change the time for keeping them constant and the time required for cooling.

As shown in FIG. 5 (f), the demolding step is a step of demolding the high-fluidity concrete 17 exhibiting a predetermined strength from the lower mold 10 after completing the curing step.
In this way, the concrete segment 1 is manufactured from the high fluidity concrete 17.

Next, the operation of the segment manufacturing method according to the embodiment of the present invention will be described.
In the present embodiment, since the internal heating process is performed after the concrete placing process, the hydration reaction in the high-fluidity concrete 17 is promoted, and the curing is promoted substantially uniformly from the inside. Therefore, for example, when it is heated from the outside to promote the hydration reaction, it does not harden rapidly from the outer surface side, so the uncured concrete is trapped inside and bleeding occurs as the hardening proceeds. Thus, there is no risk of water or cracks.

  Moreover, since the heating apparatus 20 heats only water by microwaves, the part where the hydration reaction proceeds is maintained at a necessary temperature, and the lower mold 10 and the like are only heated by the residual heat. Therefore, efficient heating can be performed as a whole. In other words, as in the case of external heating, the internal temperature is raised to an appropriate temperature, so there is no need to set the external temperature high, and there is no waste of heat energy, and cooling is allowed to enter the surface finishing process. There is an advantage that the time required for the process can be shortened.

Next, a modification of this embodiment will be described.
FIG. 7 is a schematic cross-sectional view in a direction orthogonal to the segment axis direction for explaining a modification of the segment manufacturing method according to the embodiment of the present invention.

In this modification, as shown in FIG. 7, a lid mold 36 and a heating device 30 are used in the internal heating process instead of the lid mold 16 and the heating device 20.
The lid mold frame 36 has substantially the same shape as the lid mold frame 16, and only the material is replaced with a metal that reflects microwaves. The lid mold frame 36 includes an injection hole 16 a similar to the lid mold frame 16 at the top of the curve.
The heating device 30 includes a frame 31 that covers the lower mold 10 on which the high-fluidity concrete 17 is placed, and microwave heating that is fixed at a position above the injection hole 16a when the frame 31 is disposed on the lower mold 10. And a container 33.
The microwave heater 33 is provided with magnetrons 34... So as to emit microwaves obliquely with respect to the injection hole 16a.

  According to such a configuration, the microwave 35 emitted from the magnetron 34 is reflected between the lid mold 36 and the inner surface of the lower mold 10 such as the inner peripheral mold surface 10a, so that the high fluid concrete 17 Propagate inside. Therefore, the high fluidity concrete 17 can be uniformly heated without moving the microwave heater 33. As a result, there is an advantage that the heating device 30 can be manufactured at low cost. Further, since microwave leakage hardly occurs, there is an advantage that microwave shielding can be easily performed.

  In the above description, the demolding process is described as being performed after the temperature is lowered to room temperature. However, if there is no problem with the strength of the segment and the demolding operation, the demolding process may be performed before the temperature completely returns to room temperature. Good.

Further, in the above description, the set temperature of the temperature setting and curing process of the internal heating process are both described in the example of a temperature T _1, which is an example, it may be set to different temperatures.

  In the above description, the example of the RC segment is described as the segment. However, the segment is not limited to the RC segment as long as it is a concrete segment that requires surface finishing. For example, the synthetic | combination segment by which the outer peripheral surface or the inner peripheral surface was exposed as a concrete surface may be sufficient.

It is a perspective explanatory view for explaining a segment concerning an embodiment of the present invention. It is a flowchart for demonstrating each process of the manufacturing method of the segment which concerns on embodiment of this invention. It is a schematic cross section of the direction orthogonal to the segment axial direction for demonstrating each process of the manufacturing method of the segment which concerns on embodiment of this invention. FIG. 4 is a schematic cross-sectional view in the direction orthogonal to the segment axis direction for explaining each step following FIG. 3. FIG. 5 is a schematic cross-sectional view in a direction perpendicular to the segment axis direction for explaining each step following FIG. 4. It is a typical graph which shows an example of the temperature setting of the segment in the manufacturing method of the segment which concerns on embodiment of this invention. It is a schematic cross section of the direction orthogonal to the segment axial direction for demonstrating the modification of the manufacturing method of the segment of embodiment of this invention.

Explanation of symbols

1 Concrete segment (segment)
4 inner peripheral surface 5 outer peripheral surface 10 lower mold frame 16, 36 lid mold frame 17 high fluidity concrete 20, 30 heating device 23, 33 microwave heater 34 magnetron

Claims (2)

A segment manufacturing method in which high-fluidity concrete is driven into a mold, and after the high-fluidity concrete is hardened until it becomes self-supporting and surface finish is possible, the lid mold is removed to finish the surface,
A method for producing a segment, characterized in that, after the high-fluidity concrete is driven into the mold, the high-fluidity concrete in the mold is internally heated until it can be surface-finished.   The method for producing a segment according to claim 1, wherein the internal heating is performed by irradiating the high-fluidity concrete with microwaves.

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