Method for accurately monitoring multi-layer collaborative temperature change in mass concrete structure in construction

Abstract

The invention relates to the technical field of constructional engineering, and discloses a method for accurately monitoring multi-layer cooperative temperature change in a mass concrete structure in construction, and the method comprises the steps: uniformly arranging temperature and strain sensors in a layered manner during the pouring of bottom mass concrete, and arranging a heating water pipe near the upper surface of the bottom mass concrete; when upper-layer concrete is poured, the heating water pipe is started to control the temperature of the surface of the bottom-layer mass concrete, it is ensured that temperature deformation between the upper-layer concrete and the bottom-layer concrete is consistent, and meanwhile the temperature and stress uniformity of the upper-layer concrete is regulated and controlled in real time according to the internal temperature of the upper-layer concrete and a strain sensor; and a thin film and felt are laid on the surface of the concrete to avoid structural temperature loss. According to the method, the temperature difference between layers of the mass concrete is effectively reduced and temperature cracks are prevented through measures such as temperature monitoring and cooling water circulation, and the overall quality and durability of the mass concrete can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of construction engineering technology, in particular to a technology for monitoring temperature deformation inside a large-volume concrete structure, and more particularly to a method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction. Background Art

[0002] In the field of construction engineering technology, especially in the construction of large-volume concrete structures that require layered pouring, the hydration heat reaction within the concrete structure makes it prone to temperature deformation. Traditional methods usually use internal buried water pipes or split joints in the large-volume concrete. This method reduces the internal temperature level of the large-volume concrete during pouring and curing to a certain extent, but its use has certain limitations. When some large-volume concrete must be poured in layers from top to bottom, the lower concrete structure often exerts a strong restraining force on the bottom of the upper concrete structure. Especially when the upper concrete layer is a thin-walled structure or a structure prone to stress concentration, its bottom restraining force is very likely to cause the upper concrete structure to crack, thereby affecting its service performance. Traditional temperature control methods cannot solve this problem, let alone achieve accurate monitoring of the internal temperature deformation of the structure during the layered construction of large-volume concrete, thus creating a safety hazard in the construction and operation of large-volume concrete structures.

[0003] To address the above issues, the present invention proposes a method for precisely monitoring multi-layered, coordinated temperature changes within large-volume concrete structures during construction. When pouring the bottom layer of large-volume concrete, temperature and strain sensors are evenly arranged in layers within the structure, and heating pipes are placed near its upper surface. When pouring the upper layer of concrete, the heating pipes are activated to temperature-control the surface of the bottom layer of large-volume concrete, ensuring consistent temperature deformation between the upper and lower layers. Simultaneously, the temperature and stress uniformity of the upper layer of concrete are regulated in real time based on the internal temperature and strain sensors. Furthermore, a film and felt are laid on the concrete surface to prevent structural heat loss. Through temperature monitoring and cooling water circulation, this method effectively reduces temperature differences between layers of large-volume concrete and prevents temperature cracks, thereby effectively improving its overall quality and durability.

[0004] After review, some of the published patents related to the technology of monitoring the internal temperature deformation of large-volume concrete structures are as follows:

[0005] CN119163234A discloses a radiation-proof large-volume concrete anti-cracking construction method, which uses metal pipes as cooling pipes; CN105133615B discloses a large-volume concrete cooling circulating water temperature control construction method in a large temperature difference environment in the Qinghai-Tibet Plateau, which uses metal pipes as cooling pipes; compared with the plastic heating pipes used in the present invention, it has the disadvantages of high cost, heavy weight and difficult installation.

[0006] CN118034406A discloses an intelligent temperature control system and construction method for large-volume concrete, which uses multi-layer distributed cooling pipes to control the temperature inside the layered concrete. However, compared with the technology involved in the present invention, it does not take into account the differences in the upper and lower concrete structures and cannot be applied to situations where the upper structure is thin and cannot be equipped with built-in cooling pipes.

[0007] CN117306872A discloses a method for constructing large-volume concrete, which uses a method of heating aggregates and water to maintain the initial setting temperature of the concrete structure during concrete pouring; CN113402233A discloses a method for constructing large-volume concrete, a preparation method, and a construction process thereof, which controls the temperatures of water, cement, fly ash, fine aggregate, coarse aggregate, etc. entering the mold separately; however, compared with the technology involved in the present invention, it cannot be used to control the internal temperature of the concrete structure during the curing period.

[0008] CN116122159A discloses a concrete bridge maintenance and inspection system that uses a distributed cooling water pipe system to control the internal temperature of the concrete. CN113668928B discloses a method for controlling cracks during the construction of an ultra-long concrete pool, using a thermal storage method to mitigate the problem of rapid temperature drop in the concrete. However, compared to the technology involved in the present invention, this invention does not involve a staged method for controlling the temperature change within the layered structure throughout the entire process, and cannot solve the problem of the lower structure exerting a restraining force on the upper concrete during the layered pouring process.

[0009] CN115897651A discloses a method for manufacturing and controlling cracks in the foundation of a large-volume concrete equipment of a heating furnace. The method adopts a "jump bin method" for temperature crack control. This method can be applied to crack control of adjacent large-volume concrete, but cannot meet the requirements of temperature crack control inside concrete structures constructed on upper and lower layers. Summary of the Invention

[0010] In view of the problem that the existing methods proposed above cannot accurately monitor the internal temperature deformation of the structure during the layered construction of large-volume concrete, a method for accurately monitoring the multi-layer coordinated temperature changes inside the large-volume concrete structure during construction is provided, which effectively improves the overall quality and durability of the large-volume concrete structure.

[0011] The present invention provides a method for accurately monitoring the multi-layer coordinated temperature change inside a large-volume concrete structure during construction, characterized in that the method comprises the following steps:

[0012] S1: Production of mass concrete at the bottom floor;

[0013] S2: curing of mass concrete at the bottom layer;

[0014] S3: Upper concrete pouring and curing.

[0015] In step S1, a mold should be made first, and then a steel cage should be tied inside the mold, and strain sensors and temperature sensors should be evenly buried inside the steel cage.

[0016] The strain sensors and temperature sensors are arranged in pairs at the intersection of the transverse reinforcement and the longitudinal reinforcement, and fixed to the reinforcement cage by adhesive or iron wire, and evenly distributed inside the bottom mass concrete; the bottom mass concrete is also provided with a first layer of heating water pipes, a second layer of heating water pipes, and a third layer of heating water pipes, and then concrete is poured into the mold to cast the bottom mass concrete (1);

[0017] Preferably, all heating water pipes are located on the surface of the bottom mass concrete, and the distance from the pipes to the upper surface of the concrete is greater than the larger of 5 times the diameter of the steel bar and 20 mm.

[0018] As a preference, if the thickness of the bottom mass concrete is large, multiple layers of heating water pipes should be arranged along the thickness direction;

[0019] As a preference, if the upper concrete layer has a smaller plane area, heating water pipes can be densely arranged on the contact surface between the upper concrete layer and the bottom mass concrete layer;

[0020] Furthermore, in step S2, after pouring the bottom mass concrete, it should be cured in a formwork, and a film and felt should be used on the top surface for insulation. Subsequently, the temperature and stress inside the bottom mass concrete are monitored using embedded strain sensors and temperature sensors, and then the temperature is adjusted using a heating water pipe.

[0021] Preferably, the film should be a water-retaining film that can block the diffusion of moisture from the concrete into the air. The felt should be a multi-layer insulation felt, with insulation cotton layers filling between each layer of felt. The overall thickness of the felt should not be less than 1 cm.

[0022] Preferably, the temperatures in the first layer of heating water pipes, the second layer of heating water pipes, and the third layer of heating water pipes should be different, wherein the water temperature in the outermost layer of heating water pipes should be higher than the water temperature in the innermost layer of heating water pipes;

[0023] As a preference, steam insulation measures can also be used to cure the concrete;

[0024] Preferably, the sampling frequency of the strain sensor and the temperature sensor is: starting from the completion of concrete pouring, once every 2 hours on the first day, once every 4 hours on the second day, once every 12 hours on the 4th to 7th days, and once every 24 hours on the 8th to 28th days;

[0025] Preferably, the side forms are removed after the bottom mass concrete is cured with the formwork for 7 days, and the film and felt are continued to be used for insulation. On the 5th day after the concrete pouring, the temperature is increased through the heating water pipe. The inlet temperature of the water in the outermost heating water pipe is initially maintained at around 50°C, and is adjusted to 60°C after one day. The inlet temperature of the water in the innermost heating water pipe is initially maintained at around 40°C, and is adjusted to 50°C after one day.

[0026] Furthermore, when the bottom mass concrete is poured, the concrete begins to hydrate and release heat. The heat accumulation develops rapidly at the bottom of the bottom mass concrete, then migrates upward along the height of the structure and accumulates heat, and maintains a higher temperature in the middle for a long time. During this process, the internal temperature of the bottom mass concrete should be adjusted by heating water pipes to avoid excessive internal temperature differences.

[0027] Furthermore, the strain and cumulative strain trend diagrams of the upper, middle and lower layers were drawn by measuring the strain sensor points inside the bottom mass concrete, and the changes in the internal temperature of the bottom mass concrete with curing time were analyzed.

[0028] Furthermore, when the curing time of the bottom mass concrete reaches 12 to 13 days, the bottom mass concrete should be heated as a whole through the first layer of heating water pipes, the second layer of heating water pipes, and the third layer of heating water pipes. The overall temperature of the bottom mass concrete should be controlled to increase by 5 to 10 degrees Celsius.

[0029] Furthermore, in step S3, an upper layer of concrete is poured on the upper surface of the bottom mass concrete. A mold is first created for the upper surface of the bottom mass concrete. A steel cage is then tied inside the mold, and strain sensors and temperature sensors are evenly embedded within the cage. Concrete is then poured into the mold to cast the upper layer of concrete. After pouring the concrete, the mold is cured, with the top surface insulated with thermal foam panels. After seven days of curing, the side forms are removed, and insulation is continued with film and felt. During the curing process, the bottom mass concrete is heated via a heating water pipe on the upper surface, and strain and temperature sensors are used to monitor changes in temperature and stress within the upper layer of concrete.

[0030] Furthermore, after the upper layer of concrete is poured, a heating water pipe on top of the bottom mass concrete is used to raise the temperature of the upper concrete root, thereby raising the temperature of the entire upper concrete layer, while monitoring the internal stress of the upper concrete layer;

[0031] Furthermore, the internal stress of the upper concrete layer is adjusted according to the data of the stress measurement points, and it is necessary to ensure that the temperature deformation of the bottom mass concrete and the upper concrete layer is consistent;

[0032] As a preferred method, the upper concrete reinforcement can be tied in advance to shorten the time interval between the upper concrete and the bottom mass concrete pouring, in order to reduce the deformation difference;

[0033] Preferably, the internal stress of the upper concrete layer should be controlled within 1 MPa, and whether temperature cracks occur should be determined based on the stress curve.

[0034] As a preferred method, in order to prevent temperature cracks, the method of reducing the diameter of steel bars and increasing the number of steel bars can be used to resist cracking, and the upper concrete should adopt a concrete mix ratio that dissipates a large amount of heat in the middle and late stages.

[0035] Compared with the prior art, the advantages and positive effects of the present invention are:

[0036] The present invention provides a method for accurately monitoring multi-layer coordinated temperature changes within a large-volume concrete structure during construction. Compared with the existing technology, the present invention achieves the ability to regulate the temperature of the upper layer of concrete by arranging a heating water pipe on the top of the bottom large-volume concrete. By evenly arranging temperature and strain sensors in layers within the bottom large-volume concrete and upper concrete when pouring, real-time monitoring of the bottom constraint force and temperature time-varying characteristics during the layered pouring process is achieved. Ultimately, a method is obtained that can ensure that temperature cracks will not occur in the upper concrete layer. The method for accurately monitoring temperature deformation within the structure involved in the present invention is efficient and feasible, and the method for regulating the temperature on the top of the bottom large-volume concrete involved helps to improve the problem of excessive bottom constraint force, and can effectively improve the overall quality and durability of large-volume concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0038] Figure 1 A schematic diagram of a process for accurately monitoring multi-layer coordinated temperature changes within a large-volume concrete structure during construction provided in Example 1;

[0039] Figure 2 A schematic diagram of the distribution of control components for precise monitoring of multi-layer coordinated temperature changes within a large concrete structure under construction, provided in Example 1;

[0040] Figure 3 A detailed schematic diagram of a process for precisely monitoring multi-layer coordinated temperature changes within a large-volume concrete structure under construction, provided in Example 2;

[0041] In the above figures, 1. Bottom layer of large-volume concrete; 2. First layer of heating water pipes; 3. Second layer of heating water pipes; 4. Third layer of heating water pipes; 5. Felt; 6. Film; 7. Upper layer of concrete; 8. Strain sensor; 9. Temperature sensor. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other in the absence of conflict.

[0043] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0044] Example 1: This example aims to implement a method for accurately monitoring the temperature change of multiple layers in a large concrete structure during construction. Figures 1-2 When monitoring internal temperature deformation, the following steps need to be followed to ensure the effectiveness of monitoring:

[0045] 1. Production of the bottom mass concrete: First, a mold is made, then a steel cage is tied inside the mold, and strain sensors (8) and temperature sensors (9) are evenly buried inside the steel cage. Then, a first layer of heating water pipes (2), a second layer of heating water pipes (3), and a third layer of heating water pipes (4) are arranged on the surface of the bottom mass concrete. Then, concrete is poured into the mold to cast the bottom mass concrete (1).

[0046] 2. Curing of the bottom mass concrete: After pouring the bottom mass concrete (1), it is cured with a formwork, and the top surface is insulated with a film (6) and a felt (5). During the curing process, the temperature and stress inside the bottom mass concrete (1) are monitored using embedded strain sensors (8) and temperature sensors (9). Then, the temperature is adjusted using the first layer of heating water pipes (2), the second layer of heating water pipes (3), and the third layer of heating water pipes (4). The sampling frequency of the strain sensors (8) and the temperature sensors (9) is: from the beginning of pouring the concrete, once every 2 hours on the first day, once every 4 hours on the second day, once every 12 hours on the 4th to 7th day, and once every 24 hours on the 8th to 28th day. After the bottom mass concrete (1) is cured with the formwork for 7 days, the side formwork is removed and the film (6) and the felt (5) are continued to be used for insulation. On the 5th day after the concrete pouring, the temperature is increased through the first layer of heating water pipes (2), the second layer of heating water pipes (3), and the third layer of heating water pipes (4). The inlet water temperature is initially maintained at around 50°C and is adjusted to 60°C after one day.

[0047] 3. Casting and curing of the upper layer of concrete: First, a mold is made on the upper surface of the bottom mass concrete (1), and then a steel cage is tied inside the mold. Strain sensors (8) and temperature sensors (9) are evenly buried inside the steel cage. Then, concrete is poured into the mold to cast the upper layer of concrete (7). After the concrete is cast, it is cured with a mold, and the top surface is insulated with a thermal insulation foam board. After 7 days of curing with a mold, the side mold is removed, and the film (6) and felt (5) are continued to be used for insulation. During the curing process, the upper layer of concrete (7) is heated by the first layer of heating water pipes (2), the second layer of heating water pipes (3), and the third layer of heating water pipes (4), and the internal temperature and stress changes of the upper layer of concrete (7) are monitored by the strain sensors (8) and the temperature sensors (9).

[0048] Example 2: This example aims to demonstrate the details of a multi-layer coordinated temperature change monitoring process for a large concrete structure under construction. Figure 3 When precisely controlling the internal temperature deformation of a structure, the following steps need to be followed to ensure the effectiveness of the control:

[0049] 1. Temperature control of the bottom mass concrete: When the bottom mass concrete (1) is poured, the concrete begins to hydrate and release heat. The heat accumulation develops rapidly at the bottom of the bottom mass concrete (1), and then migrates upward along the height direction of the structure to accumulate heat, and maintains a higher temperature in the middle for a long time. During this process, the internal temperature of the bottom mass concrete (1) should be adjusted through the first layer of heating water pipes (2), the second layer of heating water pipes (3), and the third layer of heating water pipes (4) to avoid excessive temperature differences.

[0050] 2. Strain control of the bottom mass concrete: The strain and cumulative strain trend diagrams of the upper, middle and lower layers are drawn through the measuring points of the strain sensor (8) inside the bottom mass concrete (1). The internal temperature of the bottom mass concrete (1) rises sharply to the highest level in the first two days, then decreases until it begins to gradually rise after the 12th day, causing the strain of the bottom mass concrete (1) to increase with the increase of thickness.

[0051] 3. Overall temperature supplementation of the bottom mass concrete: When the curing time of the bottom mass concrete (1) reaches 12 to 13 days, the bottom mass concrete (1) should be overall temperature supplemented through the first layer of heating water pipes (2), the second layer of heating water pipes (3), and the third layer of heating water pipes (4). The overall temperature of the bottom mass concrete (1) should be controlled to increase by 5 to 10°C.

[0052] 4. Upper concrete temperature and strain maintenance: After the upper concrete (7) is poured, the upper concrete (7) is constrained by the bottom of the bottom mass concrete (1), and the strain contraction gradually increases with the height of the structure, showing an "upward arch" feature. The risk of cracking in the upper and middle parts of the upper concrete (7) is high. Therefore, a heating water pipe at the top of the bottom mass concrete (1) is used to raise the temperature of the root of the upper concrete (7), and then raise the temperature of the entire upper concrete (7). At the same time, the internal stress of the upper concrete (7) is monitored and controlled within 1MPa. The occurrence of temperature cracks is determined based on the stress curve.

Claims

1. A method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction, characterized by: The mass concrete layered construction structure comprises a bottom mass concrete (1) and an upper concrete (7), wherein the upper concrete (7) is cast on the upper surface of the bottom mass concrete (1); a first layer of heating water pipes (2), a second layer of heating water pipes (3), and a third layer of heating water pipes (4) are built into the top of the bottom mass concrete (1), and the heating water pipes are arranged in parallel at equal intervals inside the bottom mass concrete (1); a film (6) and a felt (5) are laid on the surface of the upper concrete (7) in sequence, and the film (6) is tightly fitted to the surface of the upper concrete (7); strain sensors (8) and temperature sensors (9) are embedded inside the bottom mass concrete (1) and the upper concrete (7), and the strain sensors (8) and temperature sensors (9) are arranged in pairs and are evenly arranged inside the bottom mass concrete (1) and the upper concrete (7).

2. A method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction, characterized by: The method comprises the following steps: S1: Production of mass concrete at the bottom floor; S2: curing of mass concrete at the bottom layer; S3: Upper concrete pouring and curing.

3. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The method for making the bottom mass concrete in step S1 includes evenly burying strain sensors and temperature sensors inside the steel cage; The strain sensors and temperature sensors should be arranged in pairs at the intersection of the transverse and longitudinal reinforcements, fixed to the reinforcement cage by adhesive or wire, and evenly distributed inside the bottom mass concrete.

4. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The bottom mass concrete curing method of step S2 includes performing formwork curing after pouring the bottom mass concrete, and using a film and felt on the top surface for insulation, then using embedded strain sensors and temperature sensors to monitor the temperature and stress inside the bottom mass concrete, and then using a heating water pipe to adjust the temperature. The film is a water-retaining film, and the selected felt is a multi-layer thermal insulation felt. Thermal insulation cotton layers are used to fill between each layer of felt, and the overall thickness of the felt should not be less than 1 cm.

5. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The bottom mass concrete curing method of step S2 further includes setting the sampling frequencies of the strain sensor and the temperature sensor to: Starting from the completion of concrete pouring, check once every 2 hours on the first day, once every 4 hours on the second day, once every 12 hours on the 4th to 7th days, and once every 24 hours on the 8th to 28th days.

6. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The bottom mass concrete curing method of step S2 further includes drawing strain and cumulative strain trend diagrams of the upper, middle, and lower layers of the bottom mass concrete using strain sensor measuring points inside the bottom mass concrete, and analyzing changes in the internal temperature of the bottom mass concrete with curing time.

7. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The bottom mass concrete curing method of step S2 also includes, when the curing time of the bottom mass concrete reaches 12 to 13 days, comprehensively heating the bottom mass concrete through the first layer of heating water pipes, the second layer of heating water pipes, and the third layer of heating water pipes, so as to control the overall temperature of the bottom mass concrete to increase by 5 to 10°C.

8. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2 is characterized in that: The method for pouring and curing the upper layer of concrete in step S3 includes first creating a mold on the upper surface of the bottom layer of mass concrete, then tying a steel cage inside the mold and evenly embedding strain sensors and temperature sensors within the cage. Concrete is then poured into the mold to cast the upper layer of concrete. After pouring the concrete, the mold is cured, with the top surface insulated with thermal foam panels. After seven days of curing, the side molds are removed and insulation is continued with film and felt. During the curing process, the bottom layer of mass concrete is heated via a heating water pipe on its upper surface, and strain sensors and temperature sensors are used to monitor changes in temperature and stress within the upper layer of concrete.

9. The method for accurately monitoring multi-layer coordinated temperature changes inside a large-volume concrete structure during construction according to claim 2, characterized in that: The upper layer concrete pouring and curing method of step S3 further includes using a heating water pipe on the top of the bottom mass concrete to raise the temperature of the root of the upper layer concrete, and then raising the temperature of the entire upper layer concrete, while monitoring the internal stress of the upper layer concrete and ensuring that the temperature deformation of the bottom mass concrete and the upper layer concrete are consistent.

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