JP2011111849A - Method of constructing mass concrete structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of constructing a mass concrete structure capable of restraining stress/strain generated on the surface layer thereof so as to restrain the occurrence of cracks on its surface. <P>SOLUTION: In the construction method of the mass concrete structure 1 wherein concrete is sequentially cast one lift by one lift from below so as to construct a plurality of concrete layers 2 in a vertical direction, the concrete layer 2 located at least in the uppermost part out of a plurality of the old cast concrete layers 2 is heated during the down period of its casting thereby alleviating a difference in temperature between the surface layer 4 and the inner layers 5 of an old cast concrete structure 3 consisting of a plurality of the old cast concrete layers 2, and further alleviating a difference in temperature between the surface layer 4 of the old cast concrete structure 3 and the inner layers of a new concrete structure which is newly cast on the top thereof. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for constructing a mass concrete structure.

  Mass concrete structure used for dam dam bodies and bridge piers is a method of forming multiple concrete layers in the vertical direction by placing concrete sequentially from the bottom for each lift of about 1 to 2 meters in height, for example. Is built by.

  By the way, in recent years, redevelopment construction is sometimes carried out to raise the bulk of the existing dam body (old bank body) with new levee body concrete, but this new dam body concrete is also a mass concrete structure with a large volume. For this reason, a construction method in which concrete is sequentially placed for each lift of a predetermined height is employed.

  When constructing a mass concrete structure as described above in a cold region with a large amount of snow, it may be necessary to provide a concrete placement stoppage period due to wintering. In this placing suspension period, as shown in FIG. 13, the temperature of the inner layer portion 101 of the new leve body concrete 100 rises due to the hydration reaction of the concrete, whereas the surface layer portion 102 is cooled by the outside air. The temperature difference between 101 and the surface layer portion 102 becomes large, and stress strain occurs. This stress strain is concentrated at the joint 103 between the upper end of the new dam body concrete 100 and the old dam body 110, and the joint 103 may be cracked. If these cracks extend along the joint surface, there is a possibility that the integration of the old and new levee bodies may be hindered.

  Therefore, in order to reduce the temperature difference between the inner layer portion 101 and the surface layer portion 102 of the new levee body concrete 100, conventionally, a measure to suppress the temperature drop of the surface layer portion by laying a heat insulating curing mat on the surface of the new dam body concrete 100 In addition, countermeasures have been taken such as precooling (for example, see Patent Document 1) for lowering the temperature of concrete to be placed in advance.

JP 2007-130971 A

  However, the above-described measures for laying the heat-insulating curing mat can suppress the temperature drop of the surface portion to some extent, but there is a possibility that the joint portion 103 is cracked and extended. In addition, the above-mentioned measures for precooling concrete can reduce the concrete temperature in summer by about 5 ° C, but there is almost no change in the temperature difference between the wintering surface (surface part) and the inside in winter. It is considered that the effect on suppressing the occurrence of stress strain at the time is small.

  Accordingly, the present invention has been devised to solve the above-described problem, and is capable of suppressing the occurrence of surface cracks by suppressing the stress strain generated in the surface layer portion of the mass concrete structure. It is an object to provide a method for constructing a structure.

  In order to solve the above-mentioned problem, the invention according to claim 1 is in a construction method of a mass concrete structure in which concrete is sequentially placed from the lower portion for each lift to construct a plurality of concrete layers in the vertical direction. Of the plurality of concrete layers, the surface layer portion of the placed concrete structure composed of the plurality of concrete layers already placed by heating the concrete layer located at least at the uppermost part during the placement suspension period This is a method for constructing a mass concrete structure characterized in that the temperature difference between the inner layer and the inner layer is reduced.

  According to such a method, the temperature difference between the surface layer portion and the inner layer portion of the placed concrete structure is efficiently reduced by heating at least the concrete layer positioned at the uppermost part during the placing suspension period. Therefore, the stress strain generated in the surface layer portion of the mass concrete structure can be suppressed, and the occurrence of surface cracks can be suppressed.

  The invention according to claim 2 is a construction method of a mass concrete structure in which concrete is sequentially placed from the lower portion for each lift to construct a plurality of concrete layers in the vertical direction. Among them, at least the concrete layer positioned at the uppermost portion is used to alleviate the temperature difference between the surface layer portion and the inner layer portion of the cast concrete structure composed of the plurality of cast concrete layers, and the cast concrete structure. The mass concrete structure is heated during the suspension period so as to alleviate the temperature difference between the surface layer part of the body and the inner layer part of the new concrete structure newly added to the upper part thereof. It is a construction method.

  According to such a method, the temperature difference between the surface layer portion and the inner layer portion of the cast concrete structure is efficiently reduced by heating at least the concrete layer located at the uppermost part during the casting pause period. Therefore, the stress strain generated in the surface layer portion of the mass concrete structure can be suppressed, and the occurrence of surface cracks can be suppressed. Furthermore, since the temperature difference between the surface layer portion of the cast concrete structure and the inner layer portion of the new concrete structure can be effectively reduced by the heating, the cast concrete structure and the new concrete structure can be reduced. It is also possible to suppress the stress strain generated at the joint portion and to prevent the occurrence of cracks at that portion.

  The invention according to claim 3 is characterized in that the heating of the concrete layer is performed by forming a heat medium flow path in the concrete layer and flowing the heat medium in the heat medium flow path. It is the construction method of the mass concrete structure of Claim 1 or Claim 2.

  According to such a method, the inside of the concrete layer can be efficiently heated easily with a simple configuration.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding effect that the stress distortion generate | occur | produced in the surface layer part of a mass concrete structure can be suppressed, and generation | occurrence | production of the crack of a surface can be suppressed is exhibited.

It is sectional drawing which showed the construction state of the 1st year of the construction method of the mass concrete structure which concerns on embodiment of this invention. It is sectional drawing which showed the construction state of the 2nd year of the construction method of the mass concrete structure which concerns on embodiment of this invention. It is sectional drawing which showed the construction state of the 3rd year of the construction method of the mass concrete structure which concerns on embodiment of this invention. (A) is a sectional view showing a structure for heating a concrete layer for one lift, (b) is a sectional view for showing a structure for heating a concrete layer for two lifts, and (c) is for three lifts. It is sectional drawing which showed the structure which heats the concrete layer of. It is the graph which showed the relationship between the number of lifts to heat, and the minimum temperature of a new dam body concrete structure. It is the graph which showed the relationship between the number of lifts to heat and the maximum distortion of a new dam body concrete structure. (A) is sectional drawing which showed the state which heated the concrete layer of the lower part by 1 lift from the surface, (b) is sectional drawing which showed the state which heated the concrete layer of the half lift part from the surface. It is the graph which showed the relationship between the flowing temperature of the warm water to heat, and the minimum temperature of a new dam body concrete structure. It is the graph which showed the relationship between the flow temperature of the warm water to heat, and the maximum distortion of a new dam body concrete structure. It is sectional drawing which showed the state at the time of the wintering of the 1st year of the dam dam body constructed | assembled by the construction method of the mass concrete structure which concerns on embodiment of this invention, (a) is a temperature distribution figure, (b) Is a strain distribution diagram. It is sectional drawing which showed the state at the time of the wintering of the 2nd year of the dam dam body constructed | assembled by the construction method of the mass concrete structure which concerns on embodiment of this invention, Comprising: (a) is a temperature distribution figure, (b) Is a strain distribution diagram. It is sectional drawing which showed the state at the time of the wintering of the 3rd year of the dam dam body constructed | assembled by the construction method of the mass concrete structure which concerns on embodiment of this invention, Comprising: (a) is a temperature distribution figure, (b) Is a strain distribution diagram. It is sectional drawing which showed the state at the time of wintering of the dam dam body constructed | assembled by the construction method of the conventional mass concrete structure.

  The form for implementing the construction method of the mass concrete structure which concerns on this invention is demonstrated in detail, referring an accompanying drawing. In this embodiment, the new dam body concrete structure in the redevelopment work that raises the dam dam body by adding the new dam body concrete to the existing dam body (old dam body) in a cold region with a lot of snow. The construction direction will be described as an example of a mass concrete structure.

  As shown in FIGS. 1 to 3, the new levee concrete structure (mass concrete structure) 1 formed along the inclined surface 51 of the old levee body 50 is sequentially cast from the lower portion for each lift. Thus, it is formed by constructing a plurality of concrete layers 2 in the vertical direction. One lift indicates the placement height (thickness) of one layer of the concrete layer 2, and is set to 1.5 m, for example. In cold regions where there is a lot of snow, concrete is suspended during wintering (for example, from November to March of the following year).

  By the way, as shown in FIGS. 1 and 2, the present invention is at the top of the plurality of concrete layers 2 that have been placed at least during the placement suspension period (hereinafter sometimes referred to as “over wintering”). The temperature of the surface layer part 4 and the inner layer part 5 of the cast-in concrete structure 3 composed of a plurality of cast-in concrete layers 2, 2... By heating the positioned concrete layer 2 during the placing pause period. It is characterized by alleviating the difference.

  The heating of the concrete layer 2 is performed by forming the heat medium flow path 10 in the concrete layer 2 and flowing the heat medium in the heat medium flow path 10 as shown in FIG. The heat medium flow path 10 is constituted by a pipe laid between the concrete layer 2 located at the uppermost part and the concrete layer 2 located below the concrete layer 2. For example, the heat medium flow path 10 is arranged meandering at a pitch of 1.5 m, and hot water heated to a predetermined temperature as a heat medium is passed through the heat medium flow path 10. When forming the heat medium flow path 10, after the concrete layer 2 located on the lower side of the uppermost part is constructed, a pipe is laid on the surface, and concrete is placed so as to cover the pipe, and the uppermost part is placed. The concrete layer 2 is constructed. As a result, the heat medium flow path 10 is built in and disposed in the surface layer portion 4 of the placed concrete structure 3. The heating of the concrete layer 2 is not limited to the method of flowing the heat medium in the heat medium flow path 10 as described above, and other methods such as heating with a heating wire or a catalyst without using a fluid. You may make it carry out by the method.

  In addition, the laying position of the heat medium flow path 10 is not limited only between the concrete layer 2 positioned at the uppermost portion and the concrete layer 2 positioned below the uppermost concrete layer 2. For example, in addition to the above position, a heat medium flow path 10 may be provided between the second concrete layer 2 and the third concrete layer 2 from above (see FIG. 4B). Further, the heat medium flow path 10 may be further provided below (see FIG. 4C).

  Further, as shown in FIG. 7B, the heat medium flow path 10 may be provided at a height position of half of one lift (half lift) inside the uppermost concrete layer 2. In this case, once the concrete is cast to the height of the half lift and the half of the concrete layer 2 is constructed, the heat medium flow path 10 is laid thereon, and then the upper concrete is cast, The heat medium flow path 10 is arranged in the middle part of the concrete layer 2.

  During the first year of wintering of the new dyke concrete structure 1 having the heat medium flow path 10 as described above, as shown in FIG. The surface layer portion 4 of the concrete structure 3 is heated.

  In this way, by heating the surface layer portion 4 of the placed concrete structure 3, it is possible to suppress the temperature drop of the surface layer portion 4 due to the outside air temperature during wintering. Thereby, the temperature difference between the surface layer portion 4 of the cast concrete structure 3 and the inner layer portion 5 that rises in temperature due to the hydration reaction of the concrete can be effectively reduced. Therefore, since the stress distortion which generate | occur | produces in the surface layer part 4 of the new bank body concrete structure 1 can be suppressed, generation | occurrence | production of the crack of a surface can be suppressed. In particular, the occurrence of cracks in the joint 6 between the new dam body concrete structure 1 and the old dam body 50 where stress strain is concentrated can also be suppressed. In addition, the result of having examined the concrete temperature change and stress distortion according to the installation position of the heat-medium flow path 10, the number of installation, and water flow temperature is mentioned later.

  When the 1st year placement suspension period ends, as shown in FIG. 2, a new dam body is constructed by sequentially constructing a new concrete structure 7 for the 2nd year on top of the concrete structure 3 for the 1st year. The concrete structure 1 is constructed.

  As described above, by placing the surface layer portion 4 of the cast concrete structure 3 during the potting suspension period (overwintering period), the cast concrete structure is also constructed during the construction period of the new concrete structure 7. The temperature difference between the surface layer portion 4 of the body 3 and the inner layer portion 8 that rises in temperature due to the hydration reaction of the concrete of the new concrete structure 7 can be effectively mitigated. It is possible to suppress the stress strain generated at the joint portion 9 between the body 3 and the new concrete structure 7 in the second year, and to suppress the occurrence of cracks at that portion.

  Then, the heat medium flow path 10 is formed in the concrete layer 2 located in the uppermost part of the concrete structure 3 in the 2nd year, which becomes a wintering surface in the 2nd year. The heat medium flow path 10 has the same configuration as that of the heat medium flow path 10 formed near the wintering surface in the first year, and is formed by the same process. During the second year of wintering of the new dam body concrete structure 1, the surface layer 4 of the concrete structure 3 placed in the second year is heated by flowing a heat medium in the heat medium flow path 10. .

  Thus, even during the wintering of the second year, by heating the surface layer part 4 of the cast concrete structure 3, the temperature difference between the surface layer part 4 and the inner layer part 5 of the cast concrete structure 3 is reduced. Since it can relieve | moderate efficiently, the stress distortion generate | occur | produced in the surface layer part 4 of the mass concrete structure 1 can be suppressed, and generation | occurrence | production of the crack of a surface can be suppressed.

  When the second-year placement suspension period ends, as shown in FIG. 3, a new dam body is constructed by sequentially constructing a new concrete structure 7 for the third year on top of the concrete structure 3 for the second year. The concrete structure 1 is constructed.

  As described above, by heating the surface layer portion 4 of the cast concrete structure 3 during the potting suspension period (overwintering period), the second-year driving is also performed during the construction period of the new concrete structure 7. Since the temperature difference between the surface layer portion 4 of the installed concrete structure 3 and the inner layer portion 8 of the new concrete structure 7 in the third year can be effectively mitigated, the placed concrete structure 3 and the new concrete It is possible to suppress the stress strain generated at the joint portion 9 with the structure 7 and to suppress the occurrence of cracks at that portion.

  In this embodiment, the new dyke body concrete structure 1 is completed by the construction in the third year, but the construction year is not limited to three years, except for the size of the dam dam body and the laying suspension period. The number of years of construction is determined according to the available construction period.

  Next, the result of examining the minimum temperature inside the new dam body concrete structure 1 and the generated stress strain using the number of installed heat medium flow paths 10 as a parameter will be described.

  First, as shown in FIG. 4A, when the heat medium flow path 10 is provided only in the lower part of the uppermost concrete layer 2 (1 lift heating), as shown in FIG. When the heat medium flow path 10 is provided in two steps at the lower part of the uppermost concrete layer 2 and the lower part of the concrete layer 2 below (2 lift heating), as shown in FIG. When the heat medium flow path 10 is provided in three stages in the lower part of the uppermost concrete layer 2, the lower part of the lower concrete layer 2, and the lower part of the lower concrete layer 2 (three lift heating). About the form, the minimum temperature of the new levee body concrete structure 1 at the time of wintering in the first year and the second year and the maximum strain generated in the new dam body concrete structure 1 were calculated by FEM analysis. Here, it is assumed that the height of one lift is 1.5 m, the arrangement pitch of the heat medium flow path 10 is 1.5 m, and the temperature of hot water flowing through the heat medium flow path 10 is 20 ° C. Further, a curing mat for wintering (not shown) is installed not only on the surface of the new dam body concrete structure 1 but also on the old dam body 50 from the wintering surface to the height of 2 lifts.

  As shown in FIG. 5, the minimum temperature inside the new dyke concrete structure 1 (surface layer part 4) is “4.11 ° C.” for 1 lift heating and “4. “18 ° C.” and “4.19 ° C.” after 3 lift heating. In the case of no heating, the minimum temperature is “3.47 ° C.” (see the black triangle in FIG. 5). Also, during wintering in the second year, it is “4.38 ° C.” with 1 lift heating, “4.43 ° C.” with 2 lift heating, and “4.42 ° C.” with 3 lift heating. 3.73 ° C. ”(see white triangle in FIG. 5).

  As shown in FIG. 6, the maximum strain generated in the new dam concrete structure 1 is “131.1 μ” for 1 lift heating and “134.8 μ” for 2 lift heating, It becomes “135.4μ” by heating. In the case of no heating, the maximum strain is “148.4 μ” (see the black triangle in FIG. 6). In addition, during the winter of the second year, “100.0 μ” is obtained by 1 lift heating, “101.5 μ” is obtained by 2 lift heating, “99.7 μ” is obtained by 3 lift heating, and “109.9 μ” is obtained without heating. (See white triangle in FIG. 6).

  From the above results, by heating the surface layer portion 4 of the new dam body concrete structure 1, the minimum temperature of the surface layer portion 4 becomes higher than that without heating, and the maximum strain generated in the new dam body concrete structure 1 It was found that can be reduced. In addition, it was found that it is effective to heat the portion close to the surface since the minimum temperature and the maximum strain are almost the same in each case from 1 lift heating to 3 lift heating. And it turned out that it is preferable to set it as 1 lift heating in consideration of the cost by heating and the reduction efficiency of maximum distortion.

  Next, as shown in FIG. 7A, in the case where the heat medium flow path 10 is provided below the uppermost concrete layer 2 (one lift heating), the hot water flow temperature is set to 20 ° C. and 30 ° C. The minimum temperature of the new dam body concrete structure 1 during the wintering in the first year and the second year and the maximum strain generated in the new dam body concrete structure 1 were calculated by FEM analysis while changing the temperature to 40 ° C. Moreover, as shown in (b) of FIG. 7, in the case where the heat medium flow path 10 is provided in the middle part of the uppermost concrete layer 2 (half lift heating), the water flow temperature of hot water is set to 30 ° C. The minimum temperature of the new dam body concrete structure 1 during the wintering in the first year and the second year and the maximum strain generated in the new dam body concrete structure 1 were calculated by FEM analysis.

  As shown in FIG. 8, the minimum temperature inside the new dyke concrete structure 1 (surface layer part 4) is “4.11 ° C.” at a water flow temperature of 20 ° C. in 1 lift heating during the wintering of the first year. It becomes “5.28 ° C.” at a water temperature of 30 ° C. and “6.45 ° C.” at a water passing temperature of 40 ° C. In the half lift heating (water flow temperature 30 ° C.), the minimum temperature becomes “6.18 ° C.” (see the black circle in FIG. 8). In the case of no heating, the minimum temperature is “3.47 ° C.” (see the black triangle in FIG. 8). In winter of the second year, “4.38 ° C.” at a water flow temperature of 20 ° C., “5.60 ° C.” at a water flow temperature of 30 ° C., and “6.82” at a water flow temperature of 40 ° C. ° C ". In the half lift heating (water flow temperature 30 ° C.), the minimum temperature is “6.54 ° C.” (see white circles in FIG. 8). In the case of no heating, the minimum temperature is “3.73 ° C.” (see the white triangle in FIG. 8).

  As shown in FIG. 9, the maximum strain generated in the new dam body concrete structure 1 is “131.1μ” at a water flow temperature of 20 ° C. and 1 ° C. at a water flow temperature of 30 ° C. “102.6μ” and “74.8μ” at a water flow temperature of 40 ° C. In half lift heating (water flow temperature 30 ° C.), the maximum strain is “69.8 μ” (see the black circle in FIG. 9). In the case of no heating, the maximum strain is “148.4 μ” (see the black triangle in FIG. 9). In winter of the second year, “100.0μ” at a water flow temperature of 20 ° C., “83.6μ” at a water flow temperature of 30 ° C., and “67.5μ” at a water flow temperature of 40 ° C. Become. In half lift heating (water flow temperature 30 ° C.), the maximum strain is “72.1 μ” (see white circles in FIG. 9). In the case of no heating, the maximum strain is “109.9 μ” (see white triangles in FIG. 9).

  From the above results, when heating the surface layer portion 4 of the new dam body concrete structure 1, the lowest temperature of the surface layer portion 4 is highest when the water flow temperature is 40 ° C. That is, it was found that the higher the water flow temperature, the lower the temperature drop, so that the temperature difference with the inner layer portion 5 can be reduced and the maximum strain generated in the new dam body concrete structure 1 can be reduced.

  Further, when comparing 1 lift heating and half lift heating, in the case of the same condition, the half lift heating increases the minimum temperature of the surface layer portion 4 of the new dam body concrete structure 1 and can suppress the temperature drop. It was found that the temperature difference with the part 5 can be reduced and the maximum strain generated in the new dam concrete structure 1 can be reduced. In particular, during wintering in the first year, the maximum strain is smaller in the case of half lift heating and a water flow temperature of 30 ° C. than in the case of water flow temperature of 40 ° C. in one lift heating.

  Next, the temperature distribution and strain in the old levee body 50 and the new dam body concrete structure 1 during the first year, the second year, and the third year overwintering when the water flow temperature is 30 ° C. by one-stage half lift heating. Distribution is calculated by FEM analysis. 10A to 12A, the temperature distribution inside the new dyke concrete structure 1 is shown in shades, and the correspondence between the temperature distribution and the shades is shown on the right side. Moreover, in FIG. 10 thru | or FIG.12 (b), the strain distribution inside the new dyke body concrete structure 1 is shown with the shading, and the correspondence of the strain distribution and the shading is shown on the right side.

  As shown in FIG. 10A, the temperature distribution during wintering in the first year is the highest in the inner layer 5 of the new dyke concrete structure 1 (29.2 ° C.) and is separated from the inner layer 5. As it goes on, the temperature gradually decreases. In addition, the temperature around the heat medium flow path 10 is also slightly higher, and the joint portion 6 of the upper end surface of the new dam body concrete structure 1 with the old dam body 50 is “6.5 ° C.”. As shown in FIG. 10B, the strain distribution generated by such a temperature distribution is a joint 6 with the old dam body 50 at the upper end surface of the new dam body concrete structure 1 where cracks are most likely to occur. Then, it becomes a very small value of “20 μ” on the tension side, and the occurrence of cracks can be prevented. In addition, the strain at the joint surface 12 between the old levee body 50 and the new dam body concrete structure 1 is, for example, “43 μ”. And the integration of the new dam body concrete structure 1 is not hindered. In FIG. 10, the darker shaded portion shown in the levee body shows the lower value side.

  As shown in FIG. 11A, the temperature distribution during wintering in the second year is the highest (27.0 ° C.) in the inner layer 5 of the new dyke concrete structure 1 constructed in the second year. ), The temperature gradually decreases as the distance from the inner layer portion 5 increases. Further, the temperature around the heat medium flow path 10 formed in the second year is also slightly higher, and the joint portion 6 of the upper end surface of the new dam body concrete structure 1 with the old dam body 50 is “7.0. It is “℃”. As shown in FIG. 11 (b), the strain distribution generated by such temperature distribution is as follows at the junction with the old dam body 50 on the upper end surface of the new dam body concrete structure 1 where cracks are most likely to occur. , Which is a very small value of “53 μ” on the tension side, and the occurrence of cracks can be prevented. At this time, the joint 6 with the old dyke body 50 on the first year wintering surface becomes “−15 μ” on the compression side, and the occurrence of cracks can be prevented. Further, even in the second year, the strain at the joint surface 12 between the old levee body 50 and the new dam body concrete structure 1 is less than “50 μ” even when viewed as a whole from the shading of the figure. There is no such thing as hindering integration with the body concrete structure 1. In addition, in FIG. 11, the dark part shown in the levee body has a low numerical value side.

  As shown in FIG. 12 (a), the temperature distribution during wintering in the third year is the highest in the inner layer portion 5 of the new dyke concrete structure 1 constructed in the third year. Since the thickness is thin, it is cooled to the outside air temperature and becomes “20.6 ° C.”, and the temperature difference between the surface layer portion 4 and the inner layer portion 5 is small. As shown in FIG. 12B, the strain distribution generated by such temperature distribution is compressed at the junction 6 between the old levee body 50 and the new levee body concrete structure 1 on the first year wintering surface. It becomes “−13μ” on the side, and the joint 6 between the old levee body 50 and the new dam body concrete structure 1 in the wintering surface in the second year becomes “−9μ” on the compression side, so that cracking occurs. Can be prevented. Even during the wintering of the third year, the strain at the joint surface 12 between the old levee body 50 and the new levee body concrete structure 1 is not more than “50 μ” when viewed as a whole. There is no such thing as inhibiting the integration with the concrete structure 1. In FIG. 12, the darker portion shown in the levee body shows the lower value side.

  As described above, according to the present embodiment, the stress strain generated in the surface layer portion 4 of the new dam body concrete structure 1 can be suppressed, and the occurrence of cracks on the surface can be suppressed. Moreover, since generation | occurrence | production of the crack between the old bank body 50 and the new bank body concrete structure 1 can also be suppressed, the old bank body 50 and the new bank body concrete structure 1 can be integrated reliably.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, a design change is possible suitably. For example, in the said embodiment, although the new levee body concrete structure 1 constructed | assembled along the slope part of the old levee body 50 was made into an example of a mass concrete structure, a mass concrete structure is not limited to this. For example, the present invention can also be applied to a mass concrete structure such as a newly installed dam body and a bridge pier.

1 New dyke body concrete structure (mass concrete structure)
2 Concrete layer 3 Placed concrete structure 4 Surface layer 5 Inner layer part (of cast concrete structure) 7 New concrete structure 8 Inner layer part (of new concrete structure) 10 Heat medium flow path

Claims (3)

In the construction method of a mass concrete structure in which concrete is sequentially placed from the bottom for each lift and a plurality of concrete layers are constructed in the vertical direction,
Of the plurality of cast concrete layers, at least the concrete layer located at the uppermost part is heated during the casting pause period, thereby forming a cast concrete structure composed of the plurality of cast concrete layers. A method for constructing a mass concrete structure, characterized in that a temperature difference between a surface layer portion and an inner layer portion of the material is alleviated. In the construction method of a mass concrete structure in which concrete is sequentially placed from the bottom for each lift and a plurality of concrete layers are constructed in the vertical direction,
The temperature difference between the surface layer portion and the inner layer portion of the cast concrete structure composed of the plurality of cast concrete layers, at least the concrete layer positioned at the top of the plurality of cast concrete layers. And heating during the placing pause period so as to reduce the temperature difference between the surface layer portion of the placed concrete structure and the inner layer portion of the new concrete structure newly added to the upper portion thereof. A method for constructing a mass concrete structure. The heating of the concrete layer is performed by forming a heat medium flow path in the concrete layer and flowing a heat medium in the heat medium flow path. Construction method of mass concrete structure.