JPH11141128A - Cracking prevention device of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely perform temperature control of concrete, facilitate management inspection working of operation and the like and eliminate fear of interfering with construction working of a structure. SOLUTION: A cracking prevention device 11 is provided with a first water circulation part 16 disposed on a preceding element 13 and a second water circulation part 17 disposed on a subsequent element 14. Furthermore, a plurality of cooling pipes 22, 22 are provided in the first and second water circulation parts 16, 17, and an adjustment part capable of adjusting a water flow rate flowing in the inside is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a configuration in which a preceding concrete structure and a following concrete structure are disposed adjacent to each other via a joint surface, such as an underground continuous wall. The present invention relates to a concrete structure crack preventing device which is applied to a concrete structure and prevents the occurrence of cracks inside the concrete structure.

[0002]

2. Description of the Related Art In mass concrete structures, such as underground continuous walls and dams, in which concrete is cast as a large mass at one time, the internal temperature tends to rise due to accumulation of heat of hydration of cement. Then, a large tensile stress is generated by the subsequent cooling, which may cause a temperature crack.

[0003] As means for preventing such temperature cracks, for example, a pipe is previously arranged at a position where concrete is to be poured, and water is passed through the pipe after the concrete is poured. Pipe cooling for removing water is known.

In the above-mentioned mass concrete structure, a concrete placement site is divided into a plurality of blocks, and construction is sequentially performed for each of the blocks to construct a concrete structure. Is often adopted.

[0005] When such a construction method is adopted, when a block formed earlier (previous block) and a block formed later (subsequent block) are connected, the entire preceding block becomes While it has already been cooled to some extent, the subsequent block is accumulating heat of hydration of concrete, so that a large temperature difference occurs at the joint surface. Therefore, the portion near the joint surface and the entirety of the succeeding block contract and deform, and this contraction deformation itself is constrained by the preceding block via the joint surface, and tensile stress is generated inside the succeeding block. Occurs. Thus, there is a concern that cracks may occur in the subsequent block.

Therefore, by applying the above-described pipe cooling technique, pipes are arranged in both the preceding and succeeding blocks, and these pipes are connected to each other to form a continuous pipe, and water is circulated in the pipe. Thus, a method has been proposed in which the subsequent block is cooled and the preceding block is heated. That is, the heat of hydration of the succeeding block is moved relative to the preceding block via the water circulating in the pipe, thereby reducing the temperature difference between the two and preventing the occurrence of cracks.

[0007] As an apparatus for transferring the heat of hydration of concrete from the succeeding block to the preceding block, for example, the one shown in Fig. 10 filed by the present applicant is known. The crack preventing device 1 for a concrete structure shown in FIG. 10 is described in Japanese Patent Application Laid-Open No. Hei 7-217211, and is disposed inside each of a preceding element 2 and a succeeding element 3 arranged adjacent to each other. And cooling pipes 4 and 5
A connecting pipe 7 for connecting the cooling pipes 4 and 5 to each other;
A circulation pump 8 is provided in the middle of the connection pipe 7.

[0008] Because of the above-described configuration, in the crack preventing device 1, water and the like are circulated through the cooling pipes 4, 5 and the connecting pipe 7, and the leading and following elements 2
3 can be reduced.

[0009]

However, the above-described crack prevention device 1 has room for improvement in the following points. First, in order to prevent temperature cracks in a concrete structure, it is necessary to reduce the temperature gradient in each part of the concrete structure as much as possible. However, in the crack prevention generating device 1, it is difficult to control the flow rate of water flowing in each pipe, so that it is difficult to make the insides of the preceding and succeeding elements 2 and 3 uniform.

Further, in the crack generating apparatus 1, there is a problem that it is difficult to feed water by the circulation pump 8 when air is present in the piping. Further, in the crack generation device 1, the preceding and following elements 2, 3
Cooling pipes 4 and 5
However, there is a problem in that the work becomes a hindrance when assembling and connecting the reinforcing bars.

[0011] The present invention has been made in view of the above circumstances, and it is possible to reliably control the temperature of concrete, to easily perform management and inspection work such as operation, and to hinder the construction work of a structure. It is an object of the present invention to provide a device for preventing cracks in a concrete structure, which does not cause a problem.

[0012]

In order to solve the above problems, the present invention employs the following means. That is, the concrete structure crack preventing device according to the first aspect includes a preceding concrete structure (preceding block) and a succeeding concrete structure (posting block) arranged adjacent to each other via a joint surface. A crack preventing device for a concrete structure, which is applied to a concrete structure to be structured and prevents the occurrence of cracks inside the concrete structure, wherein the first water circulating unit disposed in the preceding concrete structure And a second water circulating unit arranged in the following concrete structure, and the first and second water circulating units are both configured to include a plurality of pipes, and these pipes include: An adjusting unit capable of adjusting a flow rate of water flowing in the pipe is provided.

[0013] With this configuration, the flow rate of water flowing through each pipe can be adjusted, and the temperature gradient inside the concrete structure can be controlled.

According to a second aspect of the present invention, there is provided an apparatus for preventing cracks in a concrete structure according to the first aspect, wherein the first and second water circulating portions include water in the pipe. And a water supply unit for discharging air in the pipe.

[0015] Because of the above-mentioned configuration, in this apparatus, it is possible to easily supply water into the pipe and pressure-feed water in the pipe.

According to a third aspect of the present invention, there is provided a crack preventing device for a concrete structure, wherein the preceding concrete structure and the following concrete structure are both reinforced concrete. And the pipe is temporarily fixed to a reinforcing steel or a steel plate constituting the reinforced concrete structure.

With the above configuration, the piping does not hinder the work when assembling and connecting the reinforcing bars.

According to a fourth aspect of the present invention, there is provided an apparatus for preventing cracks in a concrete structure according to any one of the first to third aspects, wherein the first and second water circulators are provided. The water circulated through the second water circulation unit is connected to each other so as to be supplied to the first water circulation unit.

Due to the above-mentioned structure, in this apparatus, it is possible to supply the heat of hydration accumulated in the subsequent concrete structure to the preceding concrete structure. Thus, the temperature difference between the two can be reduced.

According to a fifth aspect of the present invention, there is provided an apparatus for preventing cracks in a concrete structure according to any one of the first to fourth aspects, wherein the pipes are arranged at an interval from each other. In addition, the inside diameter, the arrangement interval, and the flow rate of the water flowing inside are set in the following ranges. Inner diameter: 25 mm to 150 mm Arrangement interval: 50 to 120 cm Flow rate: 1.0 to 5.0 m ³ / hr

Due to the above-mentioned structure, this device is easy to control the operation and, when applied to a general concrete structure, hinders work such as concrete casting. Therefore, it is possible to effectively control the temperature inside the concrete structure.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram illustrating an example in which a crack prevention device 11 according to an embodiment of the present invention is applied to an underground continuous wall (concrete structure) 12.

The underground continuous wall 12 includes a preceding element (preceding concrete structure) 13 and a following element (following concrete structure) both having a reinforced concrete structure.
14 are alternately connected to each other. The construction of the underground continuous wall 12 is performed in the following procedure. That is, first, a plurality of preceding elements 13 are constructed at intervals in the ground. Next, the ground between these preceding elements 13 is excavated, and the succeeding element 14 is constructed there, and the preceding element 13 and the following element 14 are integrated. Since the above-described construction method is adopted, a joint surface 15 is formed between the preceding element 13 and the following element 14.

On the other hand, as shown in the figure, the crack preventing device 11 includes first and second water circulating portions 16, 17 and first connecting pipes 19, 19 connecting between them, and a second connecting portion. It is roughly composed of a pipe 20 and a pump P provided between the first connection pipes 19, 19.

The first connecting pipe 19 has a structure in which water flows in the direction from the following element 14 to the preceding element 13 (the direction s in the drawing), and the second connecting pipe 20 has It is configured such that water flows in the direction from the preceding element 13 to the following element 14 (the direction t in the drawing).

On the other hand, the first and second water circulation sections 16, 1
7 is embedded in each of the preceding and following elements 13 and 14, and includes a plurality of cooling pipes (pipes) 22,
,... Are provided.

The cooling pipes 22, 22,... Are provided with rebar cages 23, 23 constituting the preceding and following elements 13, 14, respectively.
Are fixed to the first or second connection pipes 19, 20 via flexible hoses 26, 26,. Are arranged at intervals of about 60 cm in the direction in which the underground continuous wall 12 extends.

FIG. 2 is a view showing the situation when the underground continuous wall 12 is viewed from a vertical section perpendicular to the extending direction (p direction in FIG. 1). As shown in the figure, the cooling pipe 22 is composed of a pair of vertical pipes 2 arranged vertically inside the underground continuous wall 12.
8, 28 and lower end portions 28 of these vertical pipes 28, 28.
a, and a U-shaped tube 29 connected to 28a. Therefore, the cooling pipe 22 is connected to the underground continuous wall 12.
From the upper end 12a to the lower end 12b, and again the upper end 1
2a.

As a result, in the first water circulation section 16, the water supplied from the first connection pipe 19 is supplied to the cooling pipe 22.
Circulates through the inside of the underground continuous wall 12 and flows to the second connecting pipe 20.
In the above, the water supplied from the second connection pipe 20 flows through the cooling pipe 22 and flows to the first connection pipe 19.

The vertical pipe 28 is made of L-shaped steel 25,2.
Are fastened to the reinforcing bar cage 23 through the members 5,.
Further, as shown in the drawing, the vertical pipe 28 is formed by connecting a plurality of pipes 30, 30,... Vertically through connecting pipes 31, 31,.

The tube 30 and the U-shaped tube 29 have a nominal diameter of 25A, and the first and second connecting tubes have a nominal diameter of about 80A.

FIG. 3 is an enlarged view showing the vicinity of the first and second connection pipes 19 and 20 in FIG. As shown in the drawing, a first connection pipe 32 extends from the first connection pipe 19 in the horizontal direction. The first connection pipe 32 has a distal end portion 32 a connected to the flexible hose 26, and the flexible hose 2.
6 and connected to one end of a cooling pipe 22 (see FIGS. 1 and 2).

On the other hand, from the second connection pipe 20, a second connection pipe 33 extends in the horizontal direction, and the flexible hose 26 is connected to the tip 33a of the second connection pipe 33 in the same manner. Have been. The flexible hose 26 connected to the second connection pipe 33 is connected to the cooling pipe 2.
2 (see FIGS. 1 and 2).

As shown in the figure, the second connecting pipe 33 is provided with an adjusting section 35 for adjusting the flow rate of water flowing inside the second connecting pipe 33. The adjusting unit 35 is specifically composed of a valve 36 and a flow meter 37. By adjusting the opening and closing of the valve 36 while watching the flow meter 37, the flow rate of water flowing through the second connection pipe 33 is adjusted. Can be adjusted.

FIG. 4 is an enlarged view of the second connection pipe 33 and shown from above. As shown in the figure,
The second connecting pipe 20 is provided with a reduced-diameter cheese 39, and the base end 33 b of the second connecting pipe 33 is connected to the branch portion 39 a of the reduced-diameter cheese 39. . Further, the tip portion 33a of the second connection pipe 33
Against the flexible hose 26 by the band 40.
Is fixed. In addition, the reduced-diameter cheese 39 shown in FIG. 4 is similarly used for a connection portion between the first connection pipe 19 and the first connection pipe 32.

FIG. 5 shows the first and second connecting pipes 19,1.
It is the figure which showed the detail of 9 and 20. As shown in the figure, the first connecting pipes 19, 19 are both arranged so as to be inclined downward toward the pump P,
The second connecting pipe 20 is arranged so as to be inclined upward in the direction from the preceding element 13 to the following element 14 (direction t in the drawing).

The pump P in the first connection pipes 19, 19
A water supply container 42 serving as a water supply port is provided at each of the ends 19a, 19a on the side opposite to the above and the end 20a of the second connection pipe 20 on the side of the succeeding element 14.

FIG. 6 is a diagram showing the details of the water supply container 42. As shown in the figure, the water supply container 42 has an opening 42a at its upper part, and is configured to be able to supply water to the opening 42a from the outside. Further, an adjustment valve 43 is provided at the lower end portion 42b of the water supply container 42. By operating the adjustment valve 43, the supply of water to the first and second connection pipes 19 and 20 can be adjusted. It is possible.

FIG. 7 is a view showing details of the joint structure between the tube 30 and the reinforcing cage 23 shown in FIG. As shown in the figure, the pipe 30 is made of L-shaped steel 2 fixed to the reinforcing steel basket 23.
The upper part 30a and the lower part 30b are fastened to 5 and 25. As shown in FIG. 8, the fastening is temporarily performed using a U-shaped bolt 44 and a nut 45, and the position of the tube 30 can be changed by loosening the nut 45.

As shown in FIG. 7, a connecting pipe 31 is provided at the upper end and lower ends 30c and 30d of the pipe 30. The connecting pipe 31 is provided to prevent the pipe 30 from dropping. Is provided.

The main structure of the crack prevention device 11 has been described above. Next, a method of installing the crack prevention device 11 on the underground continuous wall 12 will be described. First, at the time of installing the crack prevention device 11, before assembling the rebar cage 23 of the preceding and following elements 13 and 14,
In advance, the L-shaped steel 25 is fixed to the rebar constituting the rebar cage 23, and the U-shaped steel 25 is fixed to the L-shaped steel 25.
The tubular bodies 30 and 3 are formed by the
0,... Are fixed at predetermined intervals. At this time, connecting pipes 31, 31,... Are provided at upper ends 30c, 30c,.

Next, the reinforcing bar to which the tube 30 is fixed is assembled to form the reinforcing bar cage 23. Reinforcing basket 2
When assembling 3, when it is necessary to connect the pipes 30 vertically, by fitting the end of another pipe 30 into the connecting pipe 31 previously provided for the pipe 30, The tubes 30, 30 are connected to each other.

When connecting the tubes 30, the nut 45 is loosened to adjust the position of the tube 30,
The pipes 30 can be reliably connected to each other. However,
At least one of the joints between the tube 30 and the L-shaped steel 25 in the vertical direction is made to have a strong connection, thereby preventing the tube 30 from dropping. The lowermost tube 30 has a U-shaped tube 2.
9 so that the cooling pipe 22 is formed.

After the rebar basket 23 has been assembled,
The reinforcing cage 23 is buried in the excavation groove formed at the installation position of the preceding element 13 in the ground. At the time of building the reinforced basket 23, the water stopping property of the continuous pipe 31 is also checked. This check is performed by placing the continuous pipe 31 in muddy water and forcing air from a compressor (not shown) to the end of the cooling pipe 22. At this time, the degree of fastening of the tube 30 by the continuous tube 31 is confirmed by torque. Further, after the installation of the reinforcing cage 23 is completed, the leading element 13 is constructed by placing concrete in the excavation trench.

After the construction of the preceding element 13, the succeeding element 14 is constructed adjacent to the preceding element 13 in exactly the same procedure. Trailing element 14
After construction, the preceding element 13 and the following element 14
Are connected to the first and second connection pipes 19, via flexible hoses 26, 26,.
20, the pump P, the adjusting unit 35,
A water supply container 42 and the like are provided. Thereby, the installation of the crack prevention device 11 is completed.

Next, a method for preventing the occurrence of cracks in the underground continuous wall 12 using the crack prevention device 11 will be described. Subsequent element 1 immediately after placing concrete
In No. 4, since the heat of hydration of concrete is accumulating, the temperature inside the concrete rises. On the other hand, the preceding element 13 at this time has already elapsed since the concrete was cast, and has therefore been cooled to some extent. As a result, a temperature gradient occurs inside the succeeding element 14 in the vicinity of the joining surface 15. If this temperature gradient is left untreated, the concrete constituting the following element 14 shrinks and causes temperature cracks. Therefore, the operation of the crack prevention device 11 is started as follows.

First, water is supplied to the inside of the crack prevention device 11 from the openings 42a, 42a, 42a of the water supply containers 42, 42, 42. Next, when the first and second water circulation sections 16 and 17 and the first and second connection pipes 19 and 20 are filled with water, the operation of the pump P is started, and the injected water is cooled by the cooling pipes 22 and 22. , ... Circulate inside.

At this time, the pump P is controlled so that the flow rate of the water flowing inside each cooling pipe 22 is about 1.0 m ³ per hour.
And the opening and closing of the valve 36 is adjusted. Pump P
In the operation of the cooling pipe 22 and the first and second connection pipes 1
If air is present in the pumps 9 and 20, the pumping of water becomes difficult, so that the pump P is continuously operated to open the regulating valve 43 to discharge the air in the pipes and the water supply container 42. Replenish the water from the water. This supply of water is continued until the operation of the crack prevention device 11 is completed.

As described above, the water circulated through the cooling pipes 22, 22,...
While being heated by the heat of hydration of the concrete accumulated inside the following element 14, the first connecting pipes 19 and 1 are heated.
9 through the cooling pipes 22, 2 inside the preceding element 13.
, And thereby the temperature inside the preceding element 13 is increased. On the other hand, the water that has been deprived of heat in the preceding element 13 and has dropped in temperature is supplied again to the succeeding element 14 through the second connecting pipe 20.

By continuously performing such water circulation, the temperature difference between the preceding and succeeding elements 13 and 14 decreases, and the temperature gradient inside the succeeding element 14 decreases. Thereby, the occurrence of temperature cracks in the succeeding element 14 is prevented.

The preceding and succeeding elements 13, 1
When the temperatures of the pumps 4 become the same, the operation of the pump P is stopped. After this, the preceding and following elements 13, 14
Is naturally cooled at the same temperature. Thus, the preceding and following elements 13 and 14
Concrete shrinks at the same rate,
Generation of tensile stress in the vicinity of the joint surface 15 is prevented. Further, after the operation of the crack prevention device 11 is completed,
Drain the water inside the device and grout.

In the crack preventing device 11 described above,
The cooling pipes 22 are provided for the first and second water circulation sections 16 and 17.
Since the adjusting unit 35 for adjusting the flow rate of the water in the inside is provided, by operating the adjusting unit 35, the optimal temperature control for equalizing the temperature distribution in the preceding and following elements 13 and 14 is performed. It is possible to do. This makes it possible to reliably prevent temperature cracks in the succeeding element 14.

In the crack preventing device 11, a water supply container 42 and a regulating valve 43 are provided for the first and second water circulating portions 16 and 17, and the cooling pipes 22, 22, and , And by opening the regulating valve 43 during the operation of the pump P, the cooling pipes 22, 22,. The air in the first and second connection pipes 19 and 20 can be discharged. Thereby, the cooling pipes 22, 22,.
The supply of water into the second connection pipes 19 and 20 can be easily performed, and the pumping of water in these pipes can be easily performed. Therefore, the motor and the like constituting the pump P are not adversely affected.

Further, in the crack preventing device 11, the pipes 30, 30,... Constituting the cooling pipe 22 are composed of the rebar cages 23 constituting the preceding and following elements 13, 14.
, The positions of these tubes 30 can be adjusted so as not to hinder the work when assembling the rebar cage 23. Therefore, the construction work of the preceding and succeeding elements 13 and 14 can be easily performed.

Further, in the crack preventing device 11, the first and second water circulating portions 16 and 17 are connected by the first and second connecting pipes 19 and 20, and circulated through the second water circulating portion 16. Since the water is configured to be supplied to the first water circulation unit 17, it is possible to supply the heat of hydration accumulated inside the subsequent element 14 to the preceding element 13, This makes it possible to quickly reduce the temperature difference between the two. Therefore, it is possible to reliably prevent the occurrence of temperature cracks in the succeeding element 14.

In the crack preventing device 11,
The nominal diameter of the pipe 30 and the U-shaped pipe 29 used for the cooling pipe 22 is 25 A, and the cooling pipes 22
m and are adjusted so that the flow rate of water flowing therethrough is 1.0 m ³ per hour.

Thus, the preceding and succeeding element 1
Since the temperature gradient inside the cooling pipes 3 and 14 can be easily reduced, and the pipe diameter of the cooling pipe 22 and the flow rate inside the cooling pipe 22 are set as described above, the load on the pump P can be appropriately reduced. Things. Further, the cooling pipe 22
Are arranged as described above, the cooling pipe 2
2 does not hinder concrete placement when the preceding and following elements 13 and 14 are constructed.

Therefore, according to the crack preventing device 11, it is possible to effectively control the temperature inside the concrete structure, and also to easily perform the operation control and the management inspection. Further, the crack preventing device 11 can be suitably used when the underground continuous wall 12 is constructed.

In the above embodiment, other structures are adopted for the structure of each part of the crack prevention device 11 and the structure to which the crack prevention device 11 is applied, without departing from the scope of the present invention. You may do it.

For example, instead of the reduced-diameter cheese 39 used in the above embodiment, holes are formed in the first or second connection pipes 19 and 20 as shown in FIG. The second connection pipes 32, 33 may be welded.

The cooling pipe 22 is not limited to the above-described embodiment, but may have a nominal diameter of 25A.
Ａ150A (inner diameter of about 25 mm to 150 mm) can be suitably used.

Further, the arrangement interval of the cooling pipes 22 and the flow rate of water in the cooling pipe 22 are not limited to those in the above-described embodiment.
cm and the flow rate may be in the range of 1.0 to 5.0 m ³ / hr.

The first and second connection pipes 19, 20
The pipe diameter is not limited to the pipe diameter as in the above embodiment. In addition, the nominal diameter is 80A to 15A.
Those having a range of 0A (80 mm to 150 mm) can be suitably used. Further, the structure to which the crack prevention device 11 is applied does not need to be an underground continuous wall, and may be another concrete structure such as a dam.

[0064]

As described above, in the apparatus for preventing cracks in a concrete structure according to the first aspect, the flow rate of water flowing through the pipes constituting the first and second water circulating portions is controlled. An adjustment section is provided to adjust the temperature, making it possible to perform optimal temperature control to equalize the temperature distribution in the preceding and following concrete structures, and reliably prevent temperature cracks in the concrete structure It is possible to

In the apparatus for preventing cracking of a concrete structure according to the second aspect, a water supply section is provided for the first and second water circulation sections, and water can be supplied into the pipe via these. It is possible, and it is possible to discharge the air in the piping. This makes it possible to easily supply water into the pipes, and to facilitate water pumping in these pipes,
There is no adverse effect on the pump motor and the like.

In the apparatus for preventing cracks in a concrete structure according to the third aspect, since the pipe is temporarily fixed to a reinforcing steel or a steel plate constituting the concrete structure, the concrete structure can be prevented from being damaged. The positions of these pipes can be adjusted so as not to hinder the work. Thereby, this crack prevention device is suitably used at the time of construction work of a concrete structure.

In the apparatus for preventing cracking of a concrete structure according to the fourth aspect, the water circulated through the second water circulating section is supplied to the first water circulating section. The heat of hydration accumulated inside the body can be supplied to the preceding concrete structure, whereby the temperature difference between the two can be rapidly reduced. Thus, the occurrence of temperature cracks in the concrete structure can be reliably prevented.

According to the apparatus for preventing cracks in a concrete structure according to the fifth aspect, the inner diameter of the pipe, the interval between the pipes, and the flow rate flowing inside the pipe are as follows: inner diameter: 25 mm to 150 mm, arrangement interval: 50 to 120 cm, flow rate: 1 0.0-5.0m ³ / hr
It is possible to effectively control the temperature inside the concrete structure because it is set in the range of
It is possible to easily perform the operation control, management check, and the like. Further, this crack preventing device can be suitably used when constructing a reinforced concrete structure.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an embodiment of the present invention, and is a plan view showing a schematic configuration of a crack preventing device and an underground continuous wall (concrete structure) to which the device is applied. .

FIG. 2 is an elevational sectional view showing a situation when the crack prevention device and the underground continuous wall (concrete structure) shown in FIG. 1 are viewed in a section orthogonal to an extending direction of the underground continuous wall.

FIG. 3 is an enlarged sectional view showing first and second connection pipes in the crack preventing device shown in FIG. 2;

FIG. 4 is a plan view showing a situation when the second connection pipe shown in FIG. 3 is shown in an enlarged manner.

FIG. 5 is a front view showing details of a configuration of first and second connection pipes shown in FIG. 3;

6 is an enlarged front view showing a water supply container and a regulating valve provided between the first and second connections shown in FIG. 5;

FIG. 7 is an enlarged sectional view showing a part of the cooling pipe (piping) shown in FIG. 2;

FIG. 8 is a plan sectional view showing a joint structure between a pipe constituting the cooling pipe shown in FIG. 7 and an L-shaped steel fixed to a reinforcing cage.

FIG. 9 is a plan view showing another embodiment of the joint between the first or second connection pipe and the first or second connection pipe shown in FIG. 4;

FIG. 10 is a perspective view of an apparatus for preventing cracking of a concrete structure according to the prior art of the present invention.

[Explanation of symbols]

 Reference Signs List 11 crack prevention device 12 underground continuous wall (concrete structure) 13 preceding element (preceding concrete structure) 14 following element (following concrete structure) 15 joining surface 16 first water circulation section 17 second water circulation section 19 first connection pipe 20 second connection pipe 22 cooling pipe (pipe) 35 adjustment unit 42 water supply container 43 adjustment valve

Claims (5)

[Claims] The present invention is applied to a concrete structure including a preceding concrete structure (preceding block) and a succeeding concrete structure (postponing block) arranged adjacent to each other via a joint surface. A crack preventing device for a concrete structure, which prevents cracks from occurring inside the concrete structure, wherein the first water circulating unit is arranged in the preceding concrete structure, and is arranged in the succeeding concrete structure. The first and second water circulators are each provided with a plurality of pipes, and the pipes can adjust the flow rate of water flowing through the pipes. An apparatus for preventing cracks in a concrete structure, characterized in that it is provided with a simple adjusting section. 2. The crack prevention device for a concrete structure according to claim 1, wherein the first and second water circulating units supply water into the pipe and discharge air from the pipe. An apparatus for preventing cracks in a concrete structure, comprising a water supply unit. 3. The apparatus for preventing cracking of a concrete structure according to claim 1, wherein the preceding concrete structure and the following concrete structure are both reinforced concrete structures, and the pipes constitute the reinforced concrete structure. A crack preventing device for a concrete structure, which is temporarily fixed to a reinforcing steel or a steel plate. 4. The apparatus for preventing cracks in a concrete structure according to claim 1, wherein the first and second water circulating units are configured such that water circulated through the second water circulating unit is: A device for preventing cracks in a concrete structure, wherein the devices are connected to each other so as to be supplied to the first water circulation unit. 5. The crack preventing device for a concrete structure according to claim 1, wherein the pipes are arranged at an interval from each other, and
An apparatus for preventing cracks in a concrete structure, wherein the inner diameter, the arrangement interval, and the flow rate are set in the following ranges. Inner diameter: 25 to 150 mm Arrangement interval: 50 to 120 cm Flow rate: 1.0 to 5.0 m ³ / hr