Bearing platform mass concrete curing method

Abstract

The invention relates to the technical field of concrete curing, in particular to a bearing platform mass concrete curing method which comprises the following steps: S1, reasonably selecting raw materials, and optimizing the concrete mixing proportion; s2, a cooling water pipe is pre-buried; s3, the thickness of a pouring layer is reduced, and the heat dissipation speed of concrete is increased; the mass concrete is poured in a layered mode, the thickness of a pouring layer is reduced as much as possible, and the pouring layer is of a V-shaped structure. S4, the temperature of concrete entering the mold is reduced; s5, reinforcing concrete curing; covering and preserving heat after the concrete surface is finally set, keeping the surface moist, and covering a curing pad; s6, reinforcing the measurement and monitoring of the internal temperature of the concrete; a thermistor element is embedded in member concrete; according to the invention, the aspects of material preparation, curing method, temperature measurement control, curing time and the like are comprehensively considered, and the curing is carefully organized and systematically managed, so that the quality of the concrete is ensured, cracks are avoided, and the safety and reliability of a project are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of concrete curing, and in particular to a method for curing large-volume concrete of a foundation. Background Art

[0002] The maintenance of large-volume caps is an important part of ensuring the quality and durability of cap concrete. The purpose of maintenance is to maintain the appropriate temperature and humidity conditions of concrete during the hardening process to promote the hydration of cement and prevent the concrete from losing water too quickly and causing shrinkage cracks and other quality problems.

[0003] During the hardening process, large-volume concrete will generate a large amount of hydration heat, which will cause the internal temperature to rise rapidly. If it is not properly maintained, it is very easy to produce temperature cracks, which will affect the safety and durability of the structure. Therefore, it is very important to formulate a scientific and reasonable maintenance plan.

[0004] The length of concrete curing time depends on many factors, such as cement type, concrete strength grade, environmental conditions, etc. Generally speaking, the curing time of ordinary Portland cement concrete is not less than 7 days; for high-strength concrete or concrete with special requirements, the curing time may be longer. The specific curing time should be determined based on the actual project situation and test results.

[0005] In the existing technology, large-volume concrete curing is difficult, but most of them are based on the experience of the construction team and are cooled and sprayed through simple water supply pipelines. The maintenance plan is not systematic and cannot be systematically managed and monitored, and the construction reliability and safety cannot be guaranteed. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for curing large-volume concrete of a foundation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A method for curing large-volume concrete of a cap, comprising the following steps: Step S1, rationally select raw materials and optimize concrete mix ratio; according to the design principle of large-volume concrete mix ratio, use slag silicate cement with low hydration heat to reduce the hydration heat generated by concrete during the setting process; improve aggregate gradation, add fly ash and admixtures, and reduce cement dosage and hydration heat as much as possible while ensuring concrete strength; Step S2, pre-buried cooling water pipes; during the process of burying and pouring the cooling water pipes, the joints are wrapped with tape to prevent water leakage or blockage. After the cooling work is completed, the cooling water pipes can be grouted and sealed as needed, and the exposed part of the foundation can be removed; Step S3, reducing the thickness of the casting layer to speed up the heat dissipation of the concrete; the large volume of concrete is cast in layers, the thickness of the casting layer is reduced as much as possible, and thin layers are cast to speed up the heat dissipation of the concrete, and the casting layer has a V-shaped structure; Step S4, lowering the temperature of concrete entering the mold; the concrete material should be covered to avoid exposure to sunlight, and cooling water should be used when mixing the concrete to lower the temperature; Step S5, strengthening concrete curing; after the concrete surface is finally set, cover it with insulation and keep the surface moist, cover it with a curing mat, control the temperature and humidity of the concrete surface, and take insulation measures in case of sudden temperature changes; Step S6, strengthen the measurement and monitoring of the internal temperature of the concrete; bury thermistor elements in the concrete of the component to observe the changes in the temperature difference between the inside and the outside at any time; determine the water inlet temperature, water flow rate, water flow time and water storage and curing time of the cooling water pipe and the curing pad based on the observation results to reduce the temperature difference between the inside and outside of the concrete.

[0008] Preferably, in step S1, the mass concrete mix design principle is: ① Large volume concrete should be mixed with retarders, water reducers and admixtures that reduce the heat of cement hydration; ② For large-volume concrete, the content of admixtures and aggregates should be increased to reduce the amount of cement per cubic meter of concrete while ensuring the strength and slump requirements of the concrete; ③ The coarse aggregate of large-volume concrete should be continuously graded, and the fine aggregate should be medium sand; ④After the mix ratio of large volume concrete is determined, the hydration heat should be verified or measured.

[0009] Preferably, in step S1, well-graded 5-40 mm crushed stone is used to reduce the content of needle-shaped, flaky and stone powder; high-quality medium sand is used, with a fineness modulus of 2.50-2.70 and a mud content of less than 1%; and Grade II fly ash is added to the concrete to replace part of the cement to reduce the amount of cement and reduce the hydration heat; Add high-efficiency water-reducing agent to concrete to prolong the initial setting time of concrete, meet the design strength of concrete, and delay the time when the peak heat of cement hydration occurs; the slump of concrete is controlled at 14 to 16 cm.

[0010] Preferably, in step S2, the cooling water pipe adopts a standard cast iron water pipe with a diameter of 30MM, the pipes are connected with matching joints, the cooling water pipes are arranged in layers, the spacing between the cooling water pipes is 20 to 80cm, and both ends of the cooling water pipes extend 40cm from the base surface.

[0011] Preferably, in step S3, the middle of the casting layer sinks and the two sides are piled up, the middle part is cast first and then the two sides are cast, so as to increase the surface area, improve the heat dissipation effect, ensure the reliability of the bonding between the concrete, and the cooling water pipes are evenly arranged in the casting layer.

[0012] Preferably, in step S5, the maintenance pad includes a waterproof membrane, a main water pipe, a water distribution pipe and a sponge pad, the water distribution pipe is arranged in an S shape and is provided in multiple groups, the water distribution pipe is embedded in the sponge pad, the waterproof membrane is arranged on the lower side of the water distribution pipe, and a suspended gap is provided between the water distribution pipe and the waterproof membrane.

[0013] Preferably, the main water pipes are provided with two groups, and the two groups of the main water pipes are respectively arranged at both ends of the water branch pipe, the diameter of the main water pipe is larger than that of the water branch pipe, and a water seepage port is opened on the upper side of the water branch pipe.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention comprehensively considers and carefully organizes aspects such as material preparation, curing methods, temperature measurement control, and curing time, and systematically manages and maintains the concrete to ensure the quality of the concrete, avoid the generation of cracks, and ensure the safety and reliability of the project; 2. The present invention provides a curing mat, which is combined with a spray pipe and a thermal insulation film cover mat. By adjusting the front and back of the curing mat, the thermal insulation and moisture retention or wetting curing function is achieved. It is more convenient to use. When necessary, hot water or steam can be supplied for thermal insulation or steam humidification, which is more convenient for concrete curing in winter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flowchart of a method for curing large-volume concrete of a cap proposed by the present invention; Figure 2 A schematic diagram of the three-dimensional structure of the pouring layer of a cap mass concrete curing method proposed by the present invention; Figure 3 A schematic diagram of the three-dimensional structure of a curing pad for a cap mass concrete curing method proposed by the present invention; Figure 4 The present invention is a schematic diagram of the right-side structural view of a curing pad for a method for curing large-volume concrete of a foundation.

[0016] In the figure: 1. casting layer; 2. cooling water pipe; 3. waterproof membrane; 4. main water pipe; 5. water distribution pipe; 51. seepage port; 6. sponge pad. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Reference Figure 1-4 A method for curing large-volume concrete of a cap comprises the following steps: Step S1: Rationally select raw materials and optimize concrete mix ratio; Generally, cement with low hydration heat is selected, and the cement and water consumption is controlled to reduce the temperature stress inside the concrete; according to the design principle of large-volume concrete mix ratio, slag silicate cement with low hydration heat is used to reduce the hydration heat generated by concrete during the setting process; aggregate grading is improved, fly ash and admixtures are added, and the cement consumption and hydration heat are reduced as much as possible while ensuring the strength of the concrete; Principles of mass concrete mix design: ① Large volume concrete should be mixed with retarders, water reducers and admixtures that reduce the heat of cement hydration; high-efficiency water reducers should be added to concrete to extend the initial setting time of concrete, meet the design strength of concrete, and delay the time when the peak heat of cement hydration occurs; ② For large-volume concrete, the content of admixtures and aggregates should be increased to reduce the amount of cement per cubic meter of concrete while ensuring the strength and slump requirements of the concrete. The slump of the concrete should be controlled at 14-16cm, generally 15cm, with good workability, no water seepage, and easy pumping; Adding Class II fly ash to concrete to replace part of the cement can reduce the amount of cement and lower the hydration heat; ③ The coarse aggregate of large-volume concrete should be continuously graded, and the fine aggregate should be medium sand; use well-graded 5-40mm crushed stone to reduce the content of needle-shaped, flaky and stone powder; use high-quality medium sand with a fineness modulus of 2.50-2.70, generally 2.60, and a mud content of less than 1%; ④After the mix ratio of large volume concrete is determined, the hydration heat should be verified or measured.

[0019] Step S2, pre-burying cooling water pipe 2; During the process of burying and pouring the cooling water pipe 2, the joint part is wrapped with tape to prevent water leakage or blockage. After the cooling work is completed, the cooling water pipe 2 can be grouted and sealed as needed, and the exposed part of the foundation can be removed; There are multiple groups of cooling water pipes 2, which are evenly arranged to improve the heat dissipation efficiency. The cooling water pipes 2 adopt standard cast iron water pipes with a diameter of 30MM. The connection between the pipes adopts matching joints. The cooling water pipes 2 are arranged in layers. The spacing between the cooling water pipes 2 is 20 to 80cm, generally 60cm. Both ends of the cooling water pipes 2 extend 40cm from the base surface. According to the needs of cooling intensity, the cooling water pipes 2 can be connected in series or in parallel. When the weather temperature is high and rapid cooling is required, the cooling water pipes 2 are connected to the water supply pump alone, or in parallel with the main water supply pipe to shorten the length of the cooling water pipe 2 circulation pipeline. The short pipe quickly changes water to achieve efficient cooling. When the weather temperature is low and high-efficiency cooling is not required, the cooling water pipes 2 are connected in series to complete the water circulation through a limited water supply pump. The water supply pipeline is extended, and the temperature difference between the water inlet and the water outlet increases, but the demand for water supply equipment is reduced.

[0020] Step S3, reducing the thickness of the pouring layer to speed up the heat dissipation of the concrete; Large volume concrete is poured in layers. The thickness of pouring layer 1 is as thin as possible. Thin layers are used to speed up the heat dissipation of concrete. The thickness of each layer is controlled at about 30cm to 50cm, generally 45cm. Vibration is performed while pouring. In the process of pouring layer by layer, the second layer of concrete should be poured before the first layer of concrete begins to set to ensure the overall strength. The pouring layer 1 is in a V-shaped structure. The middle of the pouring layer 1 is sunken and the two sides are piled high. In this way, during a single construction, the middle part is poured first, and then the two sides are poured, which increases the surface area, improves the heat dissipation effect, and ensures the reliability of the bonding between the concrete. The cooling water pipes 2 are evenly arranged in the pouring layer 1. The number and arrangement of the cooling water pipes 2 are determined according to the heat dissipation requirements; During the pouring process, the free fall height of the concrete should be controlled to avoid segregation. At the same time, the concrete should be vibrated with a vibrator to ensure that the concrete is dense and free of bubbles. During the vibration process, attention should be paid to controlling the vibration time and intensity to avoid over-vibration or missed vibration. Reasonably control the pouring speed according to the size of the pedestal and the initial setting time of the concrete; ensure that the pouring and vibration of this layer are completed before the initial setting of the concrete, and also ensure the heat dissipation efficiency.

[0021] Step S4, lowering the temperature of concrete entering the mold; The internal temperature of concrete is the superposition of various temperatures such as the adiabatic temperature rise of cement hydration heat, the pouring temperature and the heat dissipation temperature drop of the structure. Therefore, lowering the temperature of concrete entering the mold can effectively lower the internal temperature of concrete. The specific method is: the concrete material should be covered to avoid exposure to sunlight, and cooling water should be used when mixing concrete to lower the temperature.

[0022] Step S5, strengthening concrete curing; After the concrete surface has finally set, cover it with insulation and keep the surface moist. Choose to cover it with a special curing mat to control the temperature and humidity of the concrete surface. If there is a sudden change in temperature, insulation measures should be taken; The maintenance pad includes a waterproof membrane 3, a main water pipe 4, a water distribution pipe 5 and a sponge pad 6. The water distribution pipe 5 is arranged in an S shape and is provided with multiple groups. The water distribution pipe 5 is embedded in the sponge pad 6. The waterproof membrane 3 is arranged on the lower side of the water distribution pipe 5. It is convenient to roll up and there is no need to arrange the pipeline. There is a suspended gap between the water distribution pipe 5 and the waterproof membrane 3; the main water pipe 4 is provided with two groups, and the two groups of main water pipes 4 are respectively arranged at both ends of the water distribution pipe 5. The diameter of the main water pipe 4 is larger than that of the water distribution pipe 5. When placed normally, because of the suspended gap The main water pipe 4 is supported, the water distribution pipe 5 is suspended, and the middle part is bent downward. A water seepage port 51 is opened on the upper side of the water distribution pipe 5. When the water distribution pipe 5 is on the upper side of the waterproof membrane 3, the water distribution pipe 5 is bent to squeeze the water seepage port 51 to reduce water seepage. At the same time, the waterproof membranes 3 can be connected and sealed with tape to prevent water seepage from being discharged onto the concrete. The water distribution pipe 5 is on the lower side of the waterproof membrane 3, the water seepage port 51 faces downward, the water distribution pipe 5 is bent, and the water seepage port 51 is opened to seep water and wet the concrete for maintenance; In winter, if heat preservation is needed, the water distribution pipe 5 can be set upward, and the waterproof membrane 3 can be sealed to keep the temperature and moisture. When the temperature drops suddenly, hot water can be supplied to the main water pipe 4 to avoid excessive temperature difference between the inside and outside of the concrete, which may cause concrete cracking; Or when steam curing is required in winter, the water distribution pipe 5 is arranged downward, steam is introduced into the main water pipe 4, and is sprayed out through the water seepage port 51 to humidify and heat the concrete surface for curing, thereby ensuring that the concrete hardens normally.

[0023] Step S6, strengthening the measurement and monitoring of the internal temperature of the concrete; In order to measure the internal temperature of the concrete structure, thermistor elements are buried in the concrete of the component to observe the changes in the temperature difference between the inside and outside at any time; the peak temperature rise of the concrete and the time required to reach it are measured, the inlet and outlet temperatures of the cooling water pipe 2 are regularly recorded, and the temperature change curve inside the concrete is drawn; the inlet temperature, water flow rate, water flow time and water storage curing time of the cooling water pipe 2 and the curing pad are determined according to the observation results, the relevant water pumps or heating devices are controlled, the curing method is changed, and cooling or thermal insulation and moisture retention measures are added to reduce the temperature difference between the inside and outside of the concrete; a dedicated person can also be appointed to be responsible for temperature measurement, and the data can be collected with the help of a computer for analysis and organization, so as to facilitate the determination of a management plan, conduct systematic and efficient control of concrete curing, and analyze the changes in the internal temperature of the concrete based on the temperature data; when the measured temperature difference between the inside and outside of the concrete exceeds the specified value (generally 25°C), the flow rate of the cooling water pipe 2 should be accelerated to improve the heat transfer efficiency.

[0024] After the concrete is poured, it is cured. To prevent the concrete surface from drying out and cracking, curing should be continued until the concrete reaches more than 70% of the design strength to ensure the durability of the concrete. The curing time should be determined according to the growth of concrete strength, and generally lasts from 14 to 28 days. When curing in high temperature weather, care should be taken to avoid thermal damage to the concrete caused by excessive water temperature. In low temperature environments, water spraying curing is not suitable, and steam curing is generally used.

[0025] Steam curing is divided into four stages: static, heating, constant temperature, and cooling. The time and temperature of each stage must be strictly controlled. The ambient temperature and concrete temperature should be measured at any time during the curing process to ensure that the curing temperature is within the control range.

[0026] Concrete maintenance mainly includes the following aspects: Initial maintenance (0-3 days): After cement and water are mixed, a chemical reaction begins to occur between them, releasing a large amount of heat, which raises the temperature of the concrete. After the concrete is poured, the cooling water pipe 2 is controlled to cool down according to the data measured by the thermistor element to avoid excessive temperature that affects the hardening of the concrete. At the same time, initial maintenance should be carried out in time to avoid cracking of the concrete surface.

[0027] The initial setting time of concrete is generally 2 to 3 hours after pouring, and the final setting time is usually no more than 10 hours; therefore, it is more appropriate to carry out spray curing in this period after initial setting and before final setting; Generally speaking, it is more appropriate to start watering and curing the concrete 8 hours after pouring. If the temperature is high, in order to avoid excessive water loss after concrete pouring, spraying and curing can be started 4 hours after concrete pouring. When the concrete gradually hardens, the hydration reaction is completely controlled by diffusion, the heat release is very small, and the strength of the concrete is basically stable, then the curing mat is laid; Turn over the curing pad, the water distribution pipe 5 is on the lower side of the waterproof membrane 3, the water seepage port 51 faces downward, the water distribution pipe 5 is bent, the water seepage port 51 opens, and water is supplied to the main water pipe 4. The water distribution pipe 5 seeps water to wet the concrete for curing. Water is supplied 2 to 3 times a day to keep the concrete surface moist.

[0028] At the same time, external forces should be avoided from impacting and rolling the concrete surface.

[0029] Mid-term maintenance (4-7 days): After initial curing, the concrete usually reaches a certain strength and requires mid-term curing.

[0030] Continue to take moisturizing measures, the sponge pad 6 on the curing pad stores water for moisture, and supplies water 2 to 3 times every other day; pay attention to controlling the evaporation rate of the concrete surface to prevent cracks caused by excessive drying.

[0031] Post-maintenance (8-28 days): After the box girder concrete reaches the late curing period, moisturizing measures need to be further strengthened.

[0032] The curing pad is sprayed with water twice a day to control the temperature inside and outside the concrete. The temperature difference should not be too large to avoid cracking and ensure that the concrete can be fully cured during the curing period to achieve the designed strength.

[0033] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

Claims

1. A method for curing large-volume concrete of a cap, characterized in that: The following steps are involved: Step S1, rationally select raw materials and optimize concrete mix ratio; according to the design principle of large-volume concrete mix ratio, use slag silicate cement with low hydration heat to reduce the hydration heat generated by concrete during the setting process; Improve aggregate gradation, add fly ash and admixtures, and reduce cement dosage and hydration heat as much as possible while ensuring concrete strength; Step S2, pre-buried cooling water pipes (2); during the process of burying and pouring the cooling water pipes (2), the joints are wrapped with tape to prevent water leakage or blockage. After the cooling work is completed, the cooling water pipes (2) can be grouted and sealed as needed, and the exposed part of the foundation can be removed; Step S3, reducing the thickness of the casting layer to speed up the heat dissipation of the concrete; the large volume of concrete is cast in layers, the thickness of the casting layer (1) is reduced as much as possible, and a thin layer is cast to speed up the heat dissipation of the concrete, and the casting layer (1) is in a V-shaped structure; Step S4, lowering the temperature of concrete entering the mold; the concrete material should be covered to avoid exposure to sunlight, and cooling water should be used when mixing the concrete to lower the temperature; Step S5, strengthening concrete curing; after the concrete surface is finally set, cover it with insulation and keep the surface moist, cover it with a curing mat, control the temperature and humidity of the concrete surface, and take insulation measures in case of sudden temperature changes; Step S6, strengthening the measurement and monitoring of the internal temperature of the concrete; burying thermistor elements in the concrete of the component to observe the change of the temperature difference between the inside and the outside at any time; determining the water inlet temperature, water flow rate, water flow time and water storage curing time of the cooling water pipe (2) and the curing pad according to the observation results, so as to reduce the temperature difference between the inside and the outside of the concrete.

2. A method for curing large-volume concrete of a cap according to claim 1, characterized in that: In step S1, the design principle of mass concrete mix ratio is: ① Large volume concrete should be mixed with retarders, water reducers and admixtures that reduce the heat of cement hydration; ② For large-volume concrete, the content of admixtures and aggregates should be increased to reduce the amount of cement per cubic meter of concrete while ensuring the strength and slump requirements of the concrete; ③ The coarse aggregate of large-volume concrete should be continuously graded, and the fine aggregate should be medium sand; ④After the mix ratio of large volume concrete is determined, the hydration heat should be verified or measured.

3. A method for curing large-volume concrete of a cap according to claim 2, characterized in that: In the step S1, well-graded 5-40 mm crushed stone is used to reduce the content of needle-shaped, flaky and stone powder; high-quality medium sand is used, with a fineness modulus of 2.50-2.70 and a mud content of less than 1%; and Grade II fly ash is added to the concrete to replace part of the cement to reduce the amount of cement and reduce the hydration heat; Add high-efficiency water reducing agent to concrete to extend the initial setting time of concrete, meet the design strength of concrete, and delay the time when the peak of cement hydration heat occurs; The slump of concrete is controlled between 14 and 16 cm.

4. A method for curing large-volume concrete of a cap according to claim 1, characterized in that: In step S2, the cooling water pipe (2) adopts a standard cast iron water pipe with a diameter of 30 mm, and the pipes are connected with joints matching therewith. The cooling water pipes (2) are arranged in layers, and the spacing between the cooling water pipes (2) is 20 to 80 cm. Both ends of the cooling water pipes (2) extend 40 cm above the base surface.

5. The method for curing large-volume concrete of a cap according to claim 1, characterized in that: In step S3, the middle of the pouring layer (1) is sunken and the two sides are piled up. The middle part is poured first and the two sides are poured later, so as to increase the surface area, improve the heat dissipation effect and ensure the reliability of the bonding between the concrete. The cooling water pipes (2) are evenly arranged in the pouring layer (1).

6. The method for curing large-volume concrete of a cap according to claim 1, characterized in that: In step S5, the maintenance pad comprises a waterproof membrane (3), a main water pipe (4), a water distribution pipe (5) and a sponge pad (6); the water distribution pipe (5) is arranged in an S shape and is provided in multiple groups; the water distribution pipe (5) is embedded in the sponge pad (6); the waterproof membrane (3) is arranged on the lower side of the water distribution pipe (5); and a suspended gap is provided between the water distribution pipe (5) and the waterproof membrane (3).

7. A method for curing large-volume concrete of a cap according to claim 6, characterized in that: The main water pipes (4) are provided with two groups, and the two groups of the main water pipes (4) are respectively arranged at both ends of the water branch pipe (5). The diameter of the main water pipe (4) is larger than that of the water branch pipe (5), and a water seepage port (51) is provided on the upper side of the water branch pipe (5).

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