A dam construction steel form plate with anti-cracking function and cooling control system

Abstract

The application discloses a dam construction steel formwork with anti-cracking effect and a cooling control system, which comprises a steel formwork 10 and a cooling water spray head 20, wherein the steel formwork 10 is a concrete pouring formwork arranged on an upstream face of a concrete dam. The control system detects the temperature of each cooling area of the steel formwork in real time, detects the temperature of a cooling water source, detects the environmental temperature, wind speed and solar radiation intensity of a dam construction site, and takes the above parameters as boundary conditions for finite element calculation. The control system detects the dynamic irradiation area of the sun on the steel formwork and the temperature gradient inside the dam concrete, calculates the water flow required for cooling of the steel formwork, and controls the cooling water spray head 20 to spray cooling water on the cooling area 11. The application is provided with multiple independently partitioned cooling areas, and the temperature control of the steel formwork is accurately adjusted, so that the temperature peak of the concrete is reduced, the internal and external temperature difference stress is reduced, and the anti-cracking purpose is achieved.

Description

Technical Field

[0001] This invention relates to the field of temperature control and crack prevention technology for concrete dams, and in particular to a steel formwork and cooling control system for dam construction with water spray cooling and crack prevention functions. Background Technology

[0002] During the construction of roller-compacted concrete dams, the upstream face typically employs a modified concrete layer structure. Due to the high cement content in this layer, the cementitious materials react intensely, resulting in a significantly higher heat release during hydration compared to ordinary roller-compacted concrete layers. At the peak of the hydration reaction, the internal temperature of the modified concrete layer rises rapidly, often exceeding the temperature of the main dam concrete. As heat dissipation and cooling occur later, a large temperature gradient develops between the internal and external concrete, easily leading to surface cracks due to tensile stress concentration. Furthermore, in rockfill concrete dams, to ensure the seepage prevention performance and surface smoothness of the upstream face, a self-compacting concrete layer approximately 0.5m-1m thick is typically poured on the upstream surface. This layer of concrete has high fluidity and strong cohesion; to achieve good molding results, its mix proportion also contains a high proportion of cement. This high-cement-content concrete exhibits characteristics of adiabatic temperature rise and drastic temperature gradient changes, easily forming localized high-temperature zones on the surface during the hydration reaction. When the concrete temperature drops rapidly in the later stages, the outer layer cools down quickly while the inner layer remains at a relatively high temperature, resulting in a significant temperature difference between the inside and outside. This generates large tensile stress, which can easily lead to surface cracking.

[0003] This demonstrates that both roller-compacted concrete dams and rockfill concrete dams face the same temperature control challenge in their upstream thin-layer concrete structures—the upstream surface is prone to cracking due to high temperatures. This high-cement-content thin-layer concrete structure is located on the outermost side of the entire dam body and comes into direct contact with the steel formwork during pouring. However, the steel formwork experiences significant temperature increases during high-temperature seasons and under strong solar radiation, with its surface temperature reaching approximately 50-60°C. The high-temperature formwork not only fails to promote heat dissipation from the concrete surface but also conducts solar radiation heat back into the concrete through thermal conduction, further raising the surface temperature. As the temperature difference between the inner and outer layers widens, thermal stress concentration becomes increasingly pronounced, significantly increasing the risk of surface cracking. This problem is particularly prominent in regions with strong radiation and high temperatures, such as western and southern my country, threatening the appearance quality and long-term durability of dams.

[0004] To address the aforementioned issues, traditional dam temperature control and crack prevention measures primarily involve two approaches: 1. Strictly controlling the concrete's initial temperature and pouring time, reducing initial temperature rise through methods such as low-temperature mixing and nighttime construction; 2. Pre-embedding circulating water cooling pipes inside the dam body to carry away the heat of hydration, thereby lowering the internal temperature of the concrete. However, these methods have significant limitations in thin-layer concrete structures. Due to the thin layer and limited internal space, traditional cooling water pipe systems cannot be installed. Simultaneously, during construction, solar radiation directly affects the steel formwork, causing a significant temperature increase. This heat is transferred to the concrete surface, leading to a rapid rise in concrete temperature. Cooling the surface by sprinkling water after formwork removal misses the peak temperature rise period, resulting in limited cooling effectiveness and failing to effectively alleviate internal thermal stress accumulation. Under these circumstances, surface cracking of the concrete is common, affecting not only the dam's appearance but also reducing its seepage prevention performance and jeopardizing structural safety. Summary of the Invention

[0005] The purpose of this invention is to propose a dam construction steel formwork and cooling control system with crack prevention function. By implementing a zoned water spray cooling measure for the steel formwork, the temperature of the steel formwork can be adjusted in real time to reduce the peak temperature of the dam concrete, reduce internal and external temperature stress, and prevent cracking of the dam concrete surface.

[0006] To achieve the above objectives, the technical solution of the present invention is: a steel formwork for dam construction with anti-cracking function, comprising a steel formwork 10 and a water spray nozzle 20, wherein the steel formwork 10 is a concrete pouring formwork set on the upstream face of the concrete dam, the steel formwork 10 is provided with a temperature sensor 30, and the water spray nozzle 20 sprays cooling water onto the steel formwork 10.

[0007] Furthermore, in order to precisely control the temperature of the steel formwork by zone, the steel formwork is divided into multiple cooling zones 11, and each cooling zone corresponds to a water spray nozzle 20. The water spray nozzle 20 sprays cooling water onto the cooling zone 11, covering the entire cooling zone 11.

[0008] Furthermore, a preferred distribution of the cooling zones is that the cooling zones 11 are arranged in a matrix on the steel template 10.

[0009] Furthermore, in order to introduce cooling water into each spray nozzle, the steel template is provided with a main spray water pipe 40, which is connected to multiple branch spray water pipes 41, and each branch spray water pipe 41 is provided with a spray nozzle 20.

[0010] Furthermore, in order to accurately position the water spray nozzle, the steel formwork 10 is provided with a telescopic bracket 50, the water spray branch pipe 41 is installed on the telescopic bracket 50, the telescopic bracket 50 adjusts the distance between the water spray branch pipe 41 and the steel formwork 10, the water spray branch pipe 41 is provided with a water pipe support rod 42, and the water pipe support rod 42 is supported on the steel formwork 10.

[0011] A cooling control system for steel formwork used in dam construction with crack prevention function includes the aforementioned steel formwork for dam construction with crack prevention function. The control system monitors the temperature of each cooling area of ​​the steel formwork in real time, monitors the temperature of the cooling water source, and monitors the ambient temperature, wind speed, and solar radiation intensity at the dam construction site. The control system uses the SAPTIS finite element method program, taking the temperature of each cooling area of ​​the steel formwork, the temperature of the cooling water source, and the ambient temperature, wind speed, and solar radiation intensity at the dam construction site as boundary conditions for finite element calculation. The control system monitors the dynamic irradiation area of ​​the steel formwork by the sun, monitors the temperature gradient inside the dam concrete, calculates the water flow rate required for cooling the steel formwork, and controls the cooling water nozzles 20 to spray cooling water onto the cooling areas 11.

[0012] Furthermore, the control system calculates the required water flow rate for each cooling zone 11:

[0013]

[0014] In the formula: Q req The unit is m 3 / s, I solar α represents solar radiation intensity, expressed in W / m². s ρ is the radiation absorptivity of the steel formwork, h is the water film reflectivity, and ρ is the radiation absorptivity of the steel formwork. c The convective heat transfer coefficient, expressed in W / (m²·℃), is calculated by the control system based on the on-site wind speed. T a T represents real-time atmospheric temperature in °C. s λ represents the real-time surface temperature of the cooling zone of the steel formwork, in °C; λ is the thermal conductivity of concrete, in W / (m·K); ▽T in The temperature gradient along the normal direction inside the concrete, expressed in °C / m, L v The latent heat of vaporization of water is expressed in J / kg, η is the effective evaporation efficiency coefficient, and c is the evaporation efficiency coefficient. w T is the specific heat capacity of water, expressed in J / (kg·K). w ρ represents the cooling water source temperature in °C, A represents the area of ​​the cooling water spray range in m², and ρ represents the area of ​​the cooling water source in °C. w This refers to the density of water, expressed in kg / m³.

[0015] Furthermore, the control system obtains the distribution of high-radiation and low-radiation regions within the system based on a dynamic shadow distribution map. The distribution of high-radiation and low-radiation regions within the system affects the solar radiation intensity I. solar The control system obtains the real-time atmospheric temperature, wind speed, and solar radiation intensity through a small weather station; it obtains the real-time surface temperature of the cooling area of ​​the steel formwork through the temperature sensor 30; it obtains the temperature gradient along the normal direction inside the concrete through the temperature gradient meter 61; and it obtains the cooling water source temperature T through the water temperature sensor. w .

[0016] Furthermore, the temperature gradient meter 61 is installed in the dam concrete. The temperature gradient meter 61 is equipped with multiple temperature sensors embedded in the dam concrete. The multiple temperature sensors extend from the position near the steel formwork towards the inside of the dam. The temperature gradient meter 61 detects the temperature at multiple points inside the dam concrete.

[0017] Furthermore, the control system uses a ray tracing algorithm to generate a dynamic shadow distribution map covering the surface of the dam template based on a pre-set three-dimensional digital elevation model (DEM) of the construction site and the current pouring elevation data of the dam. A small weather station is set up in the dam construction area, which is equipped with an atmospheric thermometer, anemometer, wind vane and solar radiometer.

[0018] The beneficial effects of this invention are as follows: It employs steel formwork equipped with temperature sensors and cooling water nozzles, setting up multiple independently zoned cooling areas. This is synchronized with the dam concrete pouring construction, allowing for precise temperature control of the steel formwork. Furthermore, it addresses the issues of high formwork temperature caused by solar radiation and the accumulation of hydration heat in the concrete, achieving synergistic control of "external cooling – internal crack prevention." By forming zoned, controllable water spray cooling measures on the formwork surface, the steel formwork maintains a consistently low temperature. This not only effectively reduces the impact of solar shortwave radiation heat conduction to the concrete surface but also utilizes the close contact between the steel formwork and the concrete surface to dissipate heat from the thin layer of high hydration heat concrete, thereby reducing temperature peaks, minimizing internal and external temperature stress, and achieving the technical objective of crack prevention.

[0019] This invention integrates multi-dimensional sensing, including environmental parameters, steel formwork surface parameters, and concrete internal parameters, with intelligent control functions to construct a control system that combines holographic perception, advanced prediction, zoned adjustment, and precise execution. The system can automatically adjust the spraying frequency, spraying duration, and flow rate parameters of each cooling zone based on real-time environmental conditions at the construction site, the actual temperature gradient inside the concrete, and its thermal response characteristics, achieving fully automated and refined management throughout the entire process.

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the temperature-controlled steel template of the present invention;

[0022] Figure 2 This is a structural diagram of the steel template and support rod of the present invention;

[0023] Figure 3 This is a structural diagram of the steel formwork, water pipe system, water pipe support rod and telescopic bracket of the present invention;

[0024] Figure 4 This is an exploded view of the structure of the water pipe support rod and telescopic bracket of the present invention;

[0025] Figure 5 This is a schematic diagram of the water spray nozzle of the present invention spraying cooling water;

[0026] Figure 6 This is a schematic diagram of the cooling water covering multiple cooling zones according to the present invention;

[0027] Figure 7 This is a structural diagram of the temperature gradient meter installed on the dam concrete according to the present invention;

[0028] Figure 8 This is a schematic diagram of the system of the present invention;

[0029] Figure 9 This is a technical roadmap for the intelligent cooling system for steel formwork in dam construction according to the present invention;

[0030] Figure 10 These are comparison images of the internal temperature control effects in a simulated dam concrete structure.

[0031] Figure 11 This is a comparison chart of the simulated temperature control effects of steel formwork. Detailed Implementation

[0032] Example 1:

[0033] like Figures 1 to 6 A steel formwork for dam construction with crack-resistant properties includes a steel formwork 10 and a cooling water nozzle 20.

[0034] The steel formwork 10 is a concrete pouring formwork set on the upstream face of the concrete dam. The steel formwork 10 is divided into multiple cooling zones 11. The steel formwork 10 is provided with horizontal ribs 12 and vertical ribs 13, which divide the steel formwork 10 into multiple cooling zones 11. The cooling zones 11 are arranged in a matrix on the steel formwork 10. In this embodiment, the cooling zone 11 is a square area.

[0035] The steel formwork 10 is equipped with a support rod 14, which is a triangular support rod with an adjustable support angle.

[0036] A temperature sensor 30 is installed on the steel formwork 10 to detect the temperature of the steel formwork at its location in real time. In this embodiment, a temperature sensor 30 is installed at the center of each cooling zone 11.

[0037] A main water spraying pipe 40 is provided on the steel formwork 10. The main water spraying pipe is connected to multiple branch water spraying pipes 41 via hoses 43. The branch water spraying pipes 41 are vertically parallel to the steel formwork 10. Multiple spraying nozzles 20 are installed on the branch water spraying pipes 41. Each spraying nozzle 20 corresponds to a temperature sensor 30, that is, to the center of a cooling zone 11. Each spraying nozzle 20 is controlled by a solenoid valve, and the spraying time and flow rate of the sprayed cooling water can be controlled separately for each nozzle. In this embodiment, the main cooling water pipe is located on the upper edge of the steel formwork 10. A telescopic support 50 is provided on the steel formwork 10. The telescopic support 50 includes a support rod 51 and a telescopic rod 52. The support rod 51 is fixedly installed on the upper edge of the steel formwork 10 and extends laterally beyond the steel formwork. The telescopic rod 52 extends and retracts along the support rod 51 to adjust its extension length. The water spraying branch pipe 41 is installed at the end of the telescopic rod 52. The water spraying branch pipe 41 moves with the telescopic rod 52 to adjust the distance between it and the steel formwork 10.

[0038] To ensure the stability of the spray water branch pipe 41, a water pipe support rod 42 is provided on the spray water branch pipe 41. The water pipe support rod 42 extends towards the steel template, and a support foot 44 is provided at the end of the water pipe support rod 42. The length of the water pipe support rod 42 can be adjusted by telescopic extension and retraction. The length of the water pipe support rod 42 is adjusted by telescopic extension and retraction of the telescopic rod 52. The support foot 44 presses against the steel template 10 through threads, so that the water pipe support rod 42 is supported on the steel template 10, maintaining the stability of the spray water branch pipe 41 and preventing displacement during the cooling water spraying process.

[0039] like Figure 5 , Figure 6 As shown, the spray nozzles 20 spray cooling water onto the cooling area 11. The position of the spray branch pipes 41 can be adjusted according to the spray coverage area of ​​the spray nozzles, i.e., the distance between the spray nozzles and the steel template, so that the cooling water sprayed by each spray nozzle 20 covers its corresponding entire cooling area 11. In this embodiment, each cooling area 11 is a 150cm × 150cm square area, and correspondingly, multiple spray nozzles 20 are arranged in a matrix with a spacing of 150cm × 150cm. With a spray cone angle β of 60°, the relationship between the distance h between the spray nozzle 20 and the steel template and the diameter D of the cooling water coverage area is as follows:

[0040] D = 2•h·tan(β / 2)

[0041] If the lateral spacing Sx between adjacent spray nozzles 20 is 150cm and the lateral spacing Sy is 150cm, then the spacing Ss between two spray nozzles 20 in the diagonal direction is:

[0042] Ss = Sqr(Sx 2 + Sy 2 = Sqr(150) 2 +150 2 =212.1cm

[0043] Sqr is the square root function.

[0044] To ensure full coverage of the entire cooling area 11, a certain coverage overlap rate η is required. The coverage overlap rate η can be taken as 0.1 to 0.3, and we will choose η = 0.1.

[0045] D = Ss × (1 + η) = 212 × 1.1 = 233.3 cm. Therefore, we can calculate:

[0046] h = D / 2 / tan(β / 2) =233 / 2 / tan(30°)=202.2cm

[0047] Therefore, the water spray nozzle 20 should be installed at a distance of 2m from the steel formwork.

[0048] In this embodiment, the cooling water main pipe 40 and the spray water branch pipe 41 are made of high-temperature resistant stainless steel pipes, and the hose 43 is made of composite rubber hose. To facilitate assembly, disassembly and maintenance on the construction site, the two ends of the hose 43 are connected to the spray water main pipe 40 and the spray water branch pipe 41 respectively with detachable connectors.

[0049] In addition, to prevent cooling water from overflowing and affecting the dam construction environment, a water collection tank can be installed at the bottom of the steel formwork. The water collection tank collects the cooling water flowing over the surface of the steel formwork and discharges the cooling water in an orderly manner through the return water pipeline. The cooling water can also be collected and reused.

[0050] To ensure that each sprinkler head receives sufficient and stable spray pressure, the inner diameter and length of the pipeline must be designed and matched according to the system's hydraulic conditions to guarantee that the terminal nozzles still have sufficient atomization pressure under the most unfavorable operating conditions. Its head loss and local resistance loss should satisfy the following relationship:

[0051]

[0052] Where: ΔP pipe The total head loss along the pipe is expressed in Pa, f is the Darcy friction coefficient (dimensionless), L is the pipe length in meters, d is the pipe inner diameter in meters, and ρ is the fluid density in kg / m³.3 v is the average flow velocity in m / s; The local drag coefficient is dimensionless.

[0053] The atomization pressure P of the cooling water nozzle 20 n The nozzle model and specifications are provided by the manufacturer. Specific selection values ​​can be optimized based on spray height, atomized particle size, and spray angle. When the template arrangement is long or the number of nozzles is large, a pressure stabilizing system should be added to ensure that the effective pressure of the furthest nozzle is not lower than the design atomization value, thus meeting the water supply pressure requirements.

[0054] P m ≥P n +ΔP pipe

[0055] Among them, P m P represents the water supply pressure, expressed in Pa. n ΔP is the atomization pressure of the spray nozzle, expressed in Pa. pipe This represents the total head loss along the route, expressed in Pa.

[0056] This embodiment of the crack-resistant dam construction steel formwork adopts a zoned temperature regulation technology. Addressing temperature differences in the steel formwork caused by environmental variations, such as changes in sunlight exposure leading to different temperature zones, the temperature control of the steel formwork can be precisely adjusted, more effectively achieving coordinated control of "external cooling—internal crack prevention" for the dam concrete.

[0057] Example 2:

[0058] A crack-resistant steel formwork and cooling control system for dam construction, utilizing the crack-resistant steel formwork for dam construction described in Example 1, controls the temperature gradient of the dam concrete.

[0059] The inventors discovered through research that during the concrete pouring process of a dam, the highest internal temperature of the concrete typically occurs before the removal of the steel formwork. Simultaneously, the thin layer of concrete on the upstream face, due to its thin structure, cannot be cooled by laying cooling water pipes. During hot seasons, the hydration reaction of freshly poured concrete is intense, releasing a large amount of heat. Combined with the long-term exposure of the formwork to strong solar radiation and high temperatures, the temperature of the steel formwork itself rises significantly, further exacerbating the temperature rise of the concrete surface through heat conduction. Existing surface cooling measures commonly used in engineering are mostly implemented after formwork removal, such as cooling the outer surface of the concrete through spraying or running water. However, these methods have significant limitations: firstly, the cooling timing is delayed, missing the peak temperature rise stage of the concrete and failing to control the temperature before it reaches its peak; secondly, while artificial surface spraying or running water on the thin layer of concrete can effectively reduce the temperature of the outer layer, its effect on regulating the internal temperature is limited, making it difficult to reduce the temperature difference between the inside and outside of the concrete. Consequently, a large temperature gradient and stress concentration easily form inside the dam concrete, leading to surface cracks, affecting the appearance quality and seepage prevention performance of the dam, and even threatening the long-term safety and durability of the structure.

[0060] During the concrete pouring process of a dam, the contact area between the formwork and the concrete is large and the contact time is long. Steel formwork can be used to regulate the temperature of the dam concrete. In the synchronous stage of concrete pouring construction, combined with its temperature evolution law, especially before the internal temperature reaches its peak, the steel formwork is precisely controlled by zones, and internal temperature sensing and advanced pre-cooling algorithms are used to achieve active cooling and temperature control of the concrete, thereby simultaneously achieving the comprehensive goals of pouring construction, temperature control and crack prevention.

[0061] like Figure 1 The steel formwork structure shown is used in the dam concrete pouring construction. Several steel formwork pieces are connected to each other by connectors to form a structure that has a large contact area with the dam concrete. The steel formwork is made of steel and has good thermal conductivity.

[0062] like Figure 7 , Figure 8As shown, in this control system, a temperature gradient meter 61 is installed on the dam concrete 60. The temperature gradient meter has multiple temperature sensors embedded in the dam concrete 60. These temperature sensors extend from near the steel formwork 10 towards the inside of the dam. The temperature gradient meter 61 detects the temperature at multiple points inside the dam concrete, and the control system collects the detection data from the temperature gradient meter. In this embodiment, the temperature gradient meter 61 has eight temperature sensors. The eight temperature sensors are located at distances of 5cm, 10cm, 20cm, 30cm, 50cm, 100cm, 150cm, and 200cm from the steel formwork. The temperature gradient meter 61 and the temperature sensors 30 installed on the steel formwork constitute a multi-point temperature detection system extending from the surface of the dam concrete, which can monitor the temperature change trend inside the steel formwork and concrete in real time.

[0063] This control system also includes a small weather station set up in the dam construction area. The small weather station is equipped with an atmospheric thermometer, anemometer, wind vane and solar radiometer, which can be used to monitor parameters such as ambient temperature, wind speed and solar radiation intensity at the construction site in real time, providing real-time data support for the external environmental conditions of the system.

[0064] The control system includes a non-uniform radiation field adaptive control module, which generates a dynamic shadow distribution map covering the steel formwork. The dynamic shadow distribution map divides the area of ​​sunlight irradiation on the steel formwork at different times and the dynamic changes therein.

[0065] In this embodiment, the spray nozzle 20 of the temperature-controlled steel formwork uses river water from the construction site as the cooling water source. The control system collects the water temperature information of the river water and uses the water temperature of the river water as the cooling control parameter of the steel formwork. If the river water temperature is too high, ice can be added to lower the river water temperature to the target temperature before it is sprayed as cooling water.

[0066] The control system includes a data processing unit and a control unit. The data processing unit collects real-time detection data from the temperature sensor 30 of the steel formwork 10 to obtain real-time temperature information for each cooling zone 11 of the steel formwork. The data processing unit also collects temperature gradient information inside the dam concrete detected by the temperature gradient meter 61. Furthermore, the data processing unit collects atmospheric temperature, wind speed, wind direction, solar radiation information, and cooling water temperature information from a small weather station. The control system, combined with a dynamic shading distribution map, distinguishes the radiation load of each cooling zone, analyzes and calculates the changing trends inside the steel formwork and dam concrete, and formulates a temperature adjustment plan and parameters for the steel formwork. Based on the steel formwork temperature adjustment parameters formulated by the data processing unit, the control unit controls the spray nozzles 20 to spray cooling water onto the steel formwork 10, forming a water film on the surface of the steel formwork to adjust the temperature of each cooling zone.

[0067] Cooling water is delivered to the spray nozzles 20 via the main spray pipe 40, hose 43, and branch spray pipe 41. The spray nozzles 20 spray the cooling water in atomized or fine stream onto the outer surface of the steel formwork 10, forming a uniformly covered water curtain. The sprayed water quickly spreads into a thin water film on the formwork surface; part of the water film flows along the outer surface of the formwork, while part evaporates and absorbs heat, carrying away the heat from the steel formwork. Because the steel formwork is tightly bonded to the concrete surface, the temperature of the steel formwork decreases and is transferred to the dam concrete surface through heat conduction, effectively reducing its temperature rise rate. Through the synergistic effect of continuous water spraying and evaporative heat exchange, the outer surface temperature of the formwork is maintained at a low and stable state, significantly reducing the temperature gradient between the concrete surface and the interior. The entire cooling process can be summarized into four stages: "water supply distribution—nozzle spraying—heat absorption and evaporation—heat conduction." This achieves overall cooling of the steel formwork and the thin-layer concrete structure of the dam.

[0068] The control system achieves more precise control of the internal and external temperature difference by measuring the cooling water temperature in real time. Water temperature, as a key parameter of the cooling water source, directly affects the efficiency of the spray cooling. The system dynamically adjusts its control strategy through the following closed-loop process to ensure that the internal and external temperature difference of the concrete is stably maintained at around 10℃. First, the data acquisition and communication module collects data from various sensors, including a water source temperature sensor for collecting cooling water temperature, a temperature sensor 30 for the steel formwork, a temperature gradient meter inside the dam concrete, and a small weather station. It continuously collects parameters such as the water source temperature Tw, the steel formwork surface temperature Ts, the internal temperature Ti of the dam concrete, and solar radiation intensity. The control system integrates this multi-source data to construct a complete "internal-external-space" sensing network. Then, it calls upon the three-dimensional digital elevation model (DEM) of the construction site, combining the current time, latitude and longitude, and the dam pouring elevation, and uses a ray tracing algorithm to simulate the sun's trajectory in real time, generating a dynamic shadow distribution map covering the surface of the steel formwork. The control system compares the physical coordinates of the cooling water nozzle array with a dynamic shadow map, dynamically dividing the spray zones into two categories: high-radiation-load zones directly exposed to sunlight, and low-radiation-load zones located in the shadow of terrain or structures. For high-radiation-load zones directly exposed to sunlight, the corresponding cooling water nozzles are controlled to execute continuous spraying commands. For low-radiation-load zones located in the shadow of terrain, the system further incorporates the internal temperature of the concrete as a criterion. If it is determined that the internal temperature of the area, although in shadow, is higher than a set safety threshold, the cooling water nozzles are controlled to execute low-frequency spraying, actively dissipating internal heat using the temperature difference of the steel formwork. Only when it is determined that the area is in shadow and the internal temperature is lower than the set threshold (i.e., insufficient hydration heat release) will the system automatically send a cut-off command to the corresponding cooling water nozzles in that zone, thus achieving precise control based on graded differentiation.

[0069] To achieve precise quantitative control, the control system in this embodiment abandons empirical spraying and adopts a built-in dynamic water demand calculation model based on the principle of surface thermal balance. The control system uses the finite element method (SAPTI) to calculate the temperature field, combining source water temperature and environmental data to optimize prediction accuracy. The calculation model inputs include real-time water temperature, air temperature, wind speed, radiation intensity, and concrete hydration heat parameters. The SAPTI algorithm simulates the heat exchange process between the sprayed water and the formwork surface. Based on the real-time collected multi-dimensional parameters, the system calculates the theoretical water flow rate Q required to maintain the target temperature in each cooling zone using the following formula. req :

[0070]

[0071] In the formula: Q req The unit is m 3 / s, I solar α represents solar radiation intensity, expressed in W / m². s ρ is the radiation absorptivity of the steel formwork, dimensionless; h is the water film reflectivity, dimensionless. c The convective heat transfer coefficient, expressed in W / (m²·℃), is calculated by the control system based on the on-site wind speed. T a T represents real-time atmospheric temperature in °C. s λ represents the real-time surface temperature of the cooling zone of the steel formwork, in °C; λ is the thermal conductivity of concrete, in W / (m·K); ▽T in The temperature gradient along the normal direction inside the concrete, expressed in °C / m, L v The latent heat of vaporization of water is expressed in J / kg, η is the effective evaporation utilization coefficient, which is dimensionless, and c w T is the specific heat capacity of water, expressed in J / (kg·K). w ρ represents the cooling water source temperature in °C, A represents the area of ​​the cooling water spray range in m², and ρ represents the area of ​​the cooling water source in °C. w This refers to the density of water, expressed in kg / m³.

[0072] Based on this, the system calculates the temperature trend for the next hour, focusing on predicting whether the temperature difference between the inside and outside of the dam concrete is within 15℃ and whether the internal temperature is too high. Based on the calculation results, the system executes differentiated commands for each cooling water nozzle: for the high-radiation-load cooling area 11, the system executes a continuous spray command, and calculates the flow rate Q. req On top of this, a moderate water curtain flow rate is added to form a flowing water film to isolate radiation, reduce the surface temperature of the formwork, keep the internal temperature gradient within a safe range, and prevent heat backflow. For low radiation load areas, the system continuously monitors the temperature gradient ▽T along the normal direction inside the concrete in that area. in And compare it with the target value of 10℃. When ▽T inWhen the temperature exceeds the allowable range, the system will further analyze the internal temperature of the dam concrete. If the value is high, it indicates a significant accumulation of internal hydration heat. In this case, the system will activate the cooling water nozzles 20 for low-frequency pulsed spraying, setting the spraying cycle to 60 seconds (20 seconds spray, 40 seconds pause) to gradually reduce the temperature difference in the low-radiation zone. The cooled steel formwork will then act as a heat sink to dissipate the internal heat. If the temperature gradient along the normal direction inside the dam concrete is low, the system will reduce or even stop spraying to prevent the generation of additional stress.

[0073] The telescopic support 50 on the steel formwork 10 can adjust the coverage of the cooling water, achieving uniform cooling in conjunction with the water source temperature. The entire control process forms a closed loop through data feedback and remote monitoring functions of the control system. After the cooling water spray is executed, the temperature sensor 30 and the internal temperature gradient meter 61 monitor the synergistic effect of the actual temperature difference and water temperature in real time. Then, combined with the synergistic effect of water temperature and environmental factors, the control system iteratively optimizes the data. If the temperature difference is not within the 10℃ range, the control system will recalibrate the various calculation parameters in the finite element model and adjust the control commands. This closed-loop mechanism of "predictive optimization - dynamic execution - feedback calibration" ensures the robustness of temperature difference control and fundamentally improves the crack prevention effect.

[0074] Figure 9 This invention illustrates the system concept. It utilizes crack-resistant steel formwork for dam construction to replace conventional steel formwork. Temperature sensors 30 detect the zoned temperature of the steel formwork 10, a temperature gradient meter 61 detects the temperature gradient within the dam concrete, and a small weather station 70 obtains environmental information. The system control unit 80 (including a data processing unit and a control unit) centrally analyzes and processes this multi-layered information, employing zoned spray control technology to precisely regulate the temperature of the concrete pouring formwork on the upstream face of the dam.

[0075] like Figure 10 As shown in the figure, the blue curve indicates that without temperature control measures, the internal temperature of the concrete rapidly increases in a "step-like" manner due to the hindered release of hydration heat and the influx of high external temperatures, ultimately reaching a peak close to 47℃. The curve also exhibits significant diurnal fluctuations, indicating that the external ambient temperature has profoundly affected the interior of the concrete, easily generating significant tensile stress on the surface. The orange curve shows the internal temperature of the concrete under the action of this system. Thanks to the steel formwork consistently maintaining low-temperature boundary conditions, the internal heat of the concrete is dissipated steadily. The temperature curve is smooth and linear, without significant diurnal oscillations, and the maximum temperature is effectively controlled at around 30℃. Compared to the uncontrolled condition, the internal peak temperature is reduced by 17℃, and the temperature gradient is significantly slowed, fundamentally reducing the risk of cracking caused by temperature stress.

[0076] Figure 11As shown in the figure, the blue curve represents the temperature change of conventional uncontrolled steel formwork. Directly affected by solar radiation, its temperature exhibits dramatic periodic fluctuations. During the afternoon when radiation is strongest, the surface temperature of the steel formwork reaches a maximum of 51°C, and due to heat accumulation, the peak temperature further increases the following day. At this point, the high-temperature steel formwork becomes a heat source continuously inputting heat into the dam body. In contrast, the orange curve represents the temperature of the steel formwork using the intelligent spraying system of this invention, calculated through a finite element method. Under the dynamic adjustment of the system, the sprayed cooling water effectively cools the steel plate while isolating it from external short-wave solar radiation. The steel formwork temperature curve is flat, maintaining a low temperature range throughout the process. Notably, even at the highest outside temperature, the formwork temperature only rises slightly, demonstrating the system's strong "peak shaving and valley filling" capability against external thermal shock.

Claims

1. A cooling control system for steel formwork in dam construction with anti-cracking function, comprising a steel formwork (10) and a cooling water nozzle (20), wherein the steel formwork (10) is a concrete pouring formwork set on the upstream face of a concrete dam, the steel formwork (10) is provided with a temperature sensor (30), and the cooling water nozzle (20) sprays cooling water onto the steel formwork (10); the steel formwork is divided into multiple cooling zones (11), each cooling zone corresponds to one cooling water nozzle (20), and the cooling water nozzle (20) sprays cooling water onto the cooling zone (11) and covers the entire cooling zone (11); Its features are, The control system monitors the temperature of each cooling zone of the steel formwork in real time, monitors the temperature of the cooling water source, monitors the ambient temperature, wind speed and solar radiation intensity of the dam construction site, and uses the finite element SAPTIS program to take the temperature of each cooling zone of the steel formwork, the temperature of the cooling water source, the ambient temperature, wind speed and solar radiation intensity of the dam construction site as boundary conditions for finite element calculation; the control system monitors the dynamic irradiation area of ​​the steel formwork by the sun, monitors the temperature gradient inside the dam concrete, calculates the water flow required for cooling the steel formwork, and controls the cooling water nozzle (20) to spray cooling water onto the cooling zone (11); The control system calculates the required water flow rate for each cooling zone (11): In the formula: Q req The unit is m 3 / s, I solar α represents solar radiation intensity, expressed in W / m². s ρ is the radiation absorptivity of the steel formwork, h is the water film reflectivity, and ρ is the radiation absorptivity of the steel formwork. c The convective heat transfer coefficient, expressed in W / (m²·℃), is calculated by the control system based on the on-site wind speed. T a T represents real-time atmospheric temperature in °C. s λ represents the real-time surface temperature of the cooling zone of the steel formwork, in °C; λ is the thermal conductivity of concrete, in W / (m·K); ▽T in The temperature gradient along the normal direction inside the concrete, expressed in °C / m, L v The latent heat of vaporization of water is expressed in J / kg, η is the effective evaporation efficiency coefficient, and c is the evaporation efficiency coefficient. w T is the specific heat capacity of water, expressed in J / (kg·K). w ρ represents the cooling water source temperature in °C, A represents the area of ​​the cooling water spray range in m², and ρ represents the area of ​​the cooling water source in °C. w This refers to the density of water, expressed in kg / m³.

2. The cooling control system according to claim 1, characterized in that, The control system obtains the distribution of high-radiation and low-radiation regions within the system based on a dynamic shadow distribution map. The distribution of high-radiation and low-radiation regions within the system affects the solar radiation intensity I. solar The magnitude of the values; the control system obtains the real-time atmospheric temperature, wind speed and solar radiation intensity through a small weather station; the control system obtains the real-time surface temperature of the cooling area of ​​the steel formwork through the temperature sensor (30); the control system obtains the temperature gradient along the normal direction inside the concrete through a temperature gradient meter (61); the control system obtains the cooling water source temperature T through a water temperature sensor. w .

3. The cooling control system according to claim 2, characterized in that, The temperature gradient meter (61) is installed in the dam concrete. The temperature gradient meter (61) is equipped with multiple temperature sensors embedded in the dam concrete. The multiple temperature sensors extend from the position close to the steel formwork towards the inside of the dam. The temperature gradient meter (61) detects the temperature at multiple points inside the dam concrete.

4. The cooling control system according to claim 2, characterized in that, The control system is based on a pre-set three-dimensional digital elevation model (DEM) of the construction site and the current pouring elevation data of the dam. It uses a ray tracing algorithm to generate the dynamic shadow distribution map covering the surface of the dam template. A small weather station is set up in the dam construction area. The small weather station is equipped with an atmospheric thermometer, anemometer, wind vane and solar radiometer.

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