A concrete intelligent spraying and curing control method for mountainous super-high pier columns during construction period

Abstract

The application discloses a kind of mountain super-high pier column construction period concrete intelligent spraying curing control method, the method includes: based on the temperature and humidity response data of each curing area, the concrete temperature field model of current construction section is constructed, and the concrete temperature field model is inverted, to determine the convection heat transfer boundary condition of each curing area;Combining heat mass transfer analogy relationship and temperature and humidity response data, obtain the moisture transport boundary condition;Based on the moisture transport boundary condition and the surface relative humidity after spraying is finished, solve the concrete moisture diffusion model, obtain the surface relative humidity time history of each curing area;According to the time when surface relative humidity first reaches preset humidity lower limit, determine the spraying interval time and generate partition spraying timing.The present application can implement spraying control according to the difference of different curing areas and reduce insufficient spraying or excessive spraying.

Description

Technical Field

[0001] This invention relates to the field of concrete construction period curing control technology, specifically to an intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas. Background Technology

[0002] Bridges in mountainous areas typically require tall piers to span deep canyons, steep slopes, and complex terrain. Ultra-high piers often employ segmented casting and climbing formwork construction, resulting in long construction periods. Furthermore, the different heights, orientations, and external surface locations of the piers are affected differently by local wind fields, terrain obstructions, scaffolding obstructions, sunlight conditions, and variations in ambient temperature and humidity. During construction, moisture continuously evaporates from the concrete surface into the ambient air. Excessive surface water loss can leave the concrete surface in an unfavorable curing condition, affecting the quality of curing during construction. Conversely, excessively frequent spraying increases water supply, the number of times spraying equipment operates, and on-site maintenance and management costs.

[0003] Existing concrete spray curing methods typically employ preset fixed spraying cycles and uniform spraying times, or control spraying by setting thresholds based on ambient temperature, relative humidity, or concrete surface moisture. While these methods can achieve basic spray curing, they still have at least the following problems: Firstly, the local airflow and moisture dissipation capacity vary in different maintenance areas. When a uniform spraying cycle is used, it is difficult to reflect the actual differences in moisture loss between areas of different pier heights and areas with different orientations, which can easily lead to problems such as insufficient spraying in some areas and excessive spraying in others.

[0004] Secondly, ambient temperature or relative humidity can only reflect external air conditions and cannot directly reflect the actual moisture exchange capacity between the concrete surface and the ambient air. Especially when there are differences in local wind fields, shading conditions, and sunlight conditions, it is difficult to accurately determine the surface moisture dissipation rate of different areas by relying solely on environmental parameters.

[0005] Third, the change in relative humidity on the concrete surface after spraying is affected not only by external environmental moisture dissipation conditions but also by the migration of moisture from the concrete interior to the surface. Determining the next spraying time solely based on a single surface humidity measurement or a fixed time rule after spraying cannot reflect the impact of the concrete's internal relative humidity distribution and internal moisture replenishment capacity on surface humidity changes.

[0006] Therefore, it is necessary to provide an intelligent spray curing control method that can predict the relative humidity change process of concrete surface in different curing areas based on the actual heat exchange, mass transfer and internal moisture migration state of different curing areas of ultra-high piers in mountainous areas, and determine the spraying interval time of each area accordingly. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the purpose of this invention is to provide an intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas. This method addresses the problem that, in the existing spray curing of concrete during the construction period of ultra-high piers in mountainous areas, due to differences in local environmental conditions and the internal moisture migration state of concrete in different curing areas, the use of a fixed and uniform spraying cycle or a single environmental threshold control method makes it difficult to match the spraying interval with the actual surface water loss process in each area.

[0008] To achieve the above objectives, this invention provides a method for intelligent spray curing control of concrete during the construction period of ultra-high piers in mountainous areas, comprising the following steps: Based on the temperature and humidity response data of each curing area, a concrete temperature field model for the current construction segment is constructed, and the concrete temperature field model is inverted to determine the convective heat transfer boundary conditions of each curing area. Based on the heat and mass transfer analogy and temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing zone. Based on the aforementioned moisture transport boundary conditions and the current surface relative humidity state after spraying, a concrete moisture diffusion model for the current construction segment is established and solved to generate the concrete surface relative humidity time history for each curing area. Based on the relative humidity time history of the concrete surface, the spraying interval time for each curing area is determined, and the corresponding zone spraying sequence is generated.

[0009] Furthermore, based on the temperature and humidity response data of each curing area, a concrete temperature field model for the current construction segment is constructed, including: Based on the pier structure information and the temperature response in the temperature and humidity response data, a concrete temperature field model is established with concrete temperature as the solution object. In the concrete temperature field model, the outer surface of the concrete corresponding to each curing area is set as a one-to-one boundary subdomain, and the surface convective heat transfer coefficient of each boundary subdomain is set as the parameter to be inverted.

[0010] Furthermore, the inversion of the concrete temperature field model to determine the convective heat transfer boundary conditions for each curing zone includes: The convective heat transfer process between the concrete outer surface and ambient air of each of the boundary subdomains is characterized by the third type of thermal boundary conditions, and the surface convective heat transfer coefficient in the third type of thermal boundary conditions is used as the parameter to be inverted. For different candidate surface convective heat transfer coefficients, the concrete temperature field model is solved to obtain the corresponding calculated concrete surface temperature; The calculated surface temperature of the concrete is matched with the surface temperature response of the concrete in the corresponding curing area to determine the convective heat transfer coefficient of the target surface. Substituting the convective heat transfer coefficient of the target surface into the third type of thermal boundary condition of the corresponding boundary subdomain, the convective heat transfer boundary condition of the corresponding curing area is obtained.

[0011] Furthermore, combining heat and mass transfer analogies and temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing zone, including: Based on the surface convective heat transfer coefficient and heat and mass transfer analogy in the convective heat transfer boundary conditions of each curing area, the surface convective mass transfer coefficient of each curing area is determined. Based on the ambient temperature and relative humidity in the temperature and humidity response data, determine the ambient air water vapor density of each maintenance area; Based on the surface convection mass transfer coefficient, the ambient air water vapor density, and the water vapor density corresponding to the concrete surface temperature and relative humidity, a water flux boundary relationship is established for the outer surface of the concrete in each curing area, and the water flux boundary relationship is used as the water transport boundary condition for each curing area.

[0012] Furthermore, the boundary relationships of moisture flux on the outer surface of concrete in each curing zone are established, including: The water vapor density on the concrete surface is determined based on the concrete surface temperature and relative humidity. Determine the water vapor density difference between the water vapor density on the concrete surface and the water vapor density in the ambient air; The normal water flux to the outer surface of the concrete is determined based on the water vapor density difference and the surface convective mass transfer coefficient. In solving the concrete moisture diffusion model, the normal water flux is updated based on the relative humidity of the concrete surface at the current solution time.

[0013] Furthermore, based on the water transport boundary conditions and the surface relative humidity state after the current spraying is completed, a concrete moisture diffusion model for the current construction segment is established and solved to generate the concrete surface relative humidity time history for each curing area, including: Based on the surface relative humidity status after the current spraying is completed and the relative humidity distribution results of the previous calculation cycle, determine the initial relative humidity status of the current construction segment; Using the initial relative humidity state as the initial condition and the moisture transport boundary condition as the outer surface boundary condition of the concrete, the concrete moisture diffusion model is established and solved to obtain the relative humidity distribution result of the overall concrete computational domain. The relative humidity of the concrete surface in each curing area is extracted from the relative humidity distribution results, and the relative humidity time history of the concrete surface in each curing area is generated in chronological order.

[0014] Furthermore, determine the initial relative humidity state of the current construction segment, including: For the curing area that has been sprayed within the current control calculation cycle, the surface relative humidity state after the current spraying is completed is configured as the initial relative humidity of the concrete outer surface of the corresponding curing area. For the outer surface and interior of the concrete in the curing area that has not been sprayed within the current control calculation cycle, the relative humidity distribution results of the previous calculation cycle are retained. The initial relative humidity of the concrete surface corresponding to the completed curing area and the relative humidity distribution results of the previous calculation period are used to determine the initial relative humidity state of the current construction segment.

[0015] Furthermore, determining the spraying interval for each curing area based on the relative humidity time history of the concrete surface includes: The target moment when the relative humidity of the concrete surface first reaches the preset lower limit of moisture content is determined from the time history of relative humidity of the concrete surface in each curing area; The spraying interval time for the corresponding maintenance area is determined based on the time difference between the target time and the current end time of spraying in the corresponding maintenance area.

[0016] Furthermore, the preset lower limit for moisture retention is determined based on the curing quality requirements corresponding to the concrete mix proportion used in construction and the results of curing tests.

[0017] Furthermore, the corresponding zone spray timing sequence is generated, including: The next spraying start time for each maintenance area is determined based on the current spraying end time and the corresponding spraying interval time. The area identifiers of each maintenance area are associated with the corresponding next spray start time in chronological order to generate a zoned spray sequence.

[0018] Compared with existing maintenance methods that use fixed spraying cycles or uniform spraying times, the present invention has at least the following advantages: 1. This invention obtains the corresponding convective heat transfer boundary conditions based on the temperature and humidity response data of each maintenance area, and further converts them into moisture transport boundary conditions, so that the local air flow, ambient temperature and humidity state and surface moisture dissipation capacity of different maintenance areas can be characterized respectively.

[0019] 2. This invention establishes a moisture diffusion model based on the surface relative humidity value after spraying, the relative humidity distribution inside the concrete, and the moisture transport boundary conditions. This model can predict the change process of the relative humidity of the concrete surface in each curing area in the subsequent period, thereby avoiding the need to determine the spraying time based solely on a fixed time or a single environmental parameter.

[0020] 3. The present invention determines the spraying interval based on the moment when the relative humidity of the concrete surface in each curing area first reaches the preset lower limit of moisture retention, and generates a zoned spraying sequence, so that different curing areas can be sprayed according to their respective surface moisture retention requirements, which helps to reduce local insufficient or excessive spraying. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0022] Figure 1 This is a flowchart of a method for intelligent spray curing control of concrete during the construction of ultra-high piers in mountainous areas, according to the present invention. Figure 2 This is a schematic diagram showing the division of maintenance areas and the location for collecting temperature and humidity response data for the construction segments of ultra-high piers in mountainous areas according to the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown in the figure, this embodiment provides a method for intelligent spray curing control of concrete during the construction period of ultra-high pier columns in mountainous areas, including the following steps: S1. Based on the temperature and humidity response data of each curing area, construct a concrete temperature field model for the current construction segment, and perform inversion on the concrete temperature field model to determine the convective heat transfer boundary conditions of each curing area. S2. Combining the heat and mass transfer analogy and temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing area. S3. Based on the boundary conditions of moisture transport and the surface relative humidity state after the current spraying is completed, establish and solve the concrete moisture diffusion model of the current construction segment, and generate the time history of the concrete surface relative humidity of each curing area. S4. Based on the relative humidity time history of the concrete surface, determine the spraying interval for each curing area and generate the corresponding zone spraying sequence.

[0025] High-rise piers in mountainous areas are typically constructed using segmented casting and climbing formwork. The outer surfaces of piers at different heights and orientations are affected differently by local wind fields, scaffolding obstruction, ambient temperature and humidity, and sunlight conditions, resulting in variations in heat dissipation and moisture dissipation capabilities across different areas. If all curing areas are set to the same spray interval, subsequent monitoring of surface water loss will not reflect the actual differences between windward and leeward areas, as well as areas at different heights. Therefore, this embodiment first uses temperature response to invert the convective heat transfer capacity of each curing area, then converts this convective heat transfer capacity into surface convective mass transfer capacity, and combines this with the process of moisture migration from the concrete interior to the surface to determine the spray interval for each curing area.

[0026] like Figure 2 As shown, in this embodiment, the concrete outer surface of the current construction segment is divided into multiple curing areas according to the independent control range of each spray branch. Figure 2 Taking four maintenance zones as an example, namely maintenance zone 1, maintenance zone 2, maintenance zone 3, and maintenance zone 4; each maintenance zone corresponds to a different location on the outer surface of the pier, and each zone is equipped with an independently controlled sprinkler branch. Each maintenance area corresponds to one spray branch and one boundary subdomain, where... , The number of curing areas is specified. Ambient temperature monitoring points are set up near each curing area, surface temperature monitoring points and surface relative humidity monitoring points are set up on the corresponding outer surface of the concrete, and internal concrete temperature monitoring points are set up inside the current construction segment. Data collected from all monitoring points are processed synchronously according to a unified time reference.

[0027] The boundary subdomains corresponding to each maintenance area are denoted as Boundary subdomain For the overall concrete calculation domain The outer surface components. Different curing areas correspond only to different boundary locations and different boundary conditions, and the concrete entity of the pier is not divided into independent concrete calculation domains.

[0028] The temperature and humidity response data includes at least: the internal temperature response of the concrete, the surface temperature response of the concrete in each curing area, the corresponding ambient temperature response, the corresponding relative humidity response, and the ambient atmospheric pressure response in each curing area, as well as the surface relative humidity status after the current spraying is completed and the start / stop records of the spraying branches. All response data are collected synchronously according to a unified time reference. The acquisition system performs time alignment on the data from each sensor and removes invalid data based on sensor communication status, measurement range, and continuous sampling status.

[0029] To determine the relative humidity change process of concrete surfaces in each curing area during the predicted period after the current spraying is completed, environmental boundary data for the predicted period is further determined within each control calculation cycle. This environmental boundary data includes at least the environmental temperature time history, environmental relative humidity time history, and atmospheric pressure time history at the construction location for each curing area; when the corresponding curing area is affected by solar radiation, the corresponding net radiative heat flux time history is also included. The environmental temperature time history, environmental relative humidity time history, and atmospheric pressure time history at the construction location for the predicted period can be determined based on short-term meteorological forecast data from the construction site, and the initial state of the predicted time history is corrected using the actual detection values ​​of the corresponding environmental monitoring units for each curing area at the start of the current control calculation cycle; if short-term meteorological forecast data is not available, short-term extrapolation can be performed based on the environmental temperature response, environmental relative humidity response, and environmental atmospheric pressure response continuously collected within a preset time window before the start of the current control calculation cycle, and the data is updated on a rolling basis after obtaining new measured responses.

[0030] For curing areas with direct sunlight, the net radiative heat flux is determined by the radiation monitoring data of the corresponding area, or calculated based on the solar radiation intensity and the radiation parameters of the concrete surface; for curing areas without direct sunlight or not affected by direct sunlight during the current forecast period, the corresponding net radiative heat flux can be set to zero.

[0031] S1. Based on the temperature and humidity response data of each curing area, construct a concrete temperature field model for the current construction segment, and perform inversion on the concrete temperature field model to determine the convective heat transfer boundary conditions of each curing area. S101. Based on the pier structure information and the temperature response in the temperature and humidity response data, establish a concrete temperature field model with concrete temperature as the solution object. First, the pier structure information for the current construction segment is obtained. This information includes at least the cross-sectional shape, dimensions, height, and spatial location of each curing zone on the pier's outer surface, as well as the placement of internal and surface temperature sensors within the concrete. Then, based on this pier structure information, a computational domain for the concrete temperature field model is established, and the pier's outer surface is divided into multiple boundary subdomains according to the spatial extent of each curing zone.

[0032] It should be noted that each boundary subdomain is only used within the same overall concrete calculation domain. Applying different convective heat transfer boundary conditions to the outer surface does not mean that the concrete structure of the pier is divided into multiple independent temperature field models or moisture diffusion models.

[0033] The concrete temperature field model is represented by a heat conduction equation that includes a hydration heat source term:

[0034] In the formula, Represents the concrete calculation domain Internal space location At any moment The temperature of the concrete; This indicates the density of concrete, in units of... ; This indicates the specific heat capacity of concrete, in units of 1. ; This represents the thermal conductivity of concrete, measured in units of... ; Indicates the concrete at time Hydration heat source item, unit is ; Indicates the spatial location within the concrete calculation domain; Indicates the calculation time; Among them, concrete density The determination can be made based on the mass and volume of concrete specimens with the same mix proportion used in construction:

[0035] In the formula, Indicates the measured mass of the concrete specimen; This indicates the volume of the concrete specimen.

[0036] concrete specific heat capacity and thermal conductivity The specific heat capacity and thermal conductivity of the concrete are determined by the test results of the thermal properties of concrete specimens with the same mix proportion. In actual calculations, when the concrete temperature is between adjacent temperature test points, the specific heat capacity and thermal conductivity of the concrete at the current temperature are obtained by interpolation using the specific heat capacity and thermal conductivity corresponding to the adjacent temperature points.

[0037] In this embodiment, to determine the hydration heat source term in the temperature field model, concrete specimens with the same mix proportion as the pier columns were fabricated before construction and placed in an adiabatic temperature rise test device. The specimen temperatures were recorded at preset time intervals to obtain the adiabatic temperature rise curves. .

[0038] For two adjacent adiabatic temperature rise sampling times and The corresponding hydration heat source items for the time period are:

[0039] In the formula, Indicates time adiabatic temperature rise; Indicates time adiabatic temperature rise; This represents the hydration heat source item within the corresponding time period. Among them, under adiabatic conditions, the heat generated by the hydration reaction of concrete is not lost to the outside, and the adiabatic temperature rise can reflect the heat release rate of concrete with the same mix proportion within the corresponding age period.

[0040] After establishing the temperature field model, the initial temperature field of the entire concrete computational domain at the start of the current calculation cycle is determined. Based on the spatial coordinates of the internal temperature detection locations within the concrete, the internal temperature responses collected at the start of the current calculation cycle are mapped to the corresponding calculation locations. Furthermore, based on the measured temperatures at each internal temperature detection location, spatial interpolation is performed on calculation locations without temperature detection units to form a comprehensive temperature field covering the entire concrete computational domain. initial temperature field ,in, This indicates the start time of the current calculation cycle.

[0041] When the temperature field calculation results of the previous calculation cycle exist, the temperature field at the end of the previous calculation cycle can be used as the basis for the initial temperature field of the current calculation cycle, and the temperature status of the corresponding detection location can be checked by using the internal temperature response of the concrete at the beginning of the current calculation cycle; when performing the temperature field calculation for the first time, the initial temperature field is constructed based on the pouring temperature of the concrete in the current construction segment and the currently collected internal temperature response of the concrete.

[0042] The ambient temperature response of each curing zone is used as the ambient temperature input for each boundary subdomain. The concrete surface temperature response is not directly used as the boundary temperature input for the temperature field model, but rather as a measured reference quantity for subsequent inversion of the surface convective heat transfer coefficient.

[0043] For the The boundary subdomain corresponding to each maintenance area The convective heat transfer process between the outer surface of the concrete and the ambient air is represented by a third-order thermal boundary condition:

[0044] In the formula, Represents the outward normal unit vector of the concrete outer surface; Indicates the first The surface convective heat transfer coefficient of each maintenance area, in units of ; Indicates the first Each maintenance area is at all times Ambient temperature; Indicates the first Each maintenance area is at all times The net radiative heat flux.

[0045] Specifically, when net radiative heat flux is input from the environment to the concrete surface, Take a positive value; for maintenance areas without direct sunlight, or maintenance areas not during direct sunlight periods, it can be set to... For maintenance areas with direct sunlight, the net radiative heat flux is used as the known thermal boundary input, while the surface convective heat transfer coefficient... It is used only to characterize the convective heat transfer capacity between the concrete surface and the ambient air.

[0046] After processing in this sub-step, a concrete temperature field model is obtained, consisting of multiple boundary subdomains, initial temperature state, hydration heat source term, and ambient temperature input.

[0047] S102. Invert the concrete temperature field model to determine the convective heat transfer boundary conditions for each curing zone. The heat dissipation capacity of the surface of ultra-high piers in mountainous areas varies due to local wind fields, local shading, and local airflow conditions. Therefore, this step uses the surface convective heat transfer coefficient of the boundary subdomain as the parameter to be identified. By matching the calculated surface temperature of the concrete with the measured surface temperature, the convective heat transfer boundary conditions of each curing zone are determined.

[0048] For the For each maintenance area, the time window for inversion is selected when the area has not been sprayed and the temperature response is continuously effective. For maintenance areas with direct sunlight, the inversion is performed during periods without direct sunlight. For cases where inversion must be performed during periods of direct sunlight, the net radiative heat flux of the corresponding area is input into the temperature field model.

[0049] For different candidate surface convective heat transfer coefficients A forward calculation was performed on the temperature field model, yielding results consistent with the first... The theoretical surface temperature value corresponding to the surface temperature detection location of each maintenance area The theoretical and actual surface temperatures are compared, and the mean square error of the surface temperature is used as the objective function for the inversion.

[0050] In the formula, The candidate surface convective heat transfer coefficient is... The mean square error of the surface temperature at that time; Indicates the first The number of effective temperature sampling points in each maintenance area within the current inversion time window; Indicates the first time within the current inversion time window Each sampling time; Indicates the use of candidate surface convective heat transfer coefficient After performing forward temperature field calculations, at time... The theoretical value of the surface temperature obtained; Indicates the first The surface temperature sensor of each maintenance area is constantly... The actual value of the surface temperature collected.

[0051] Since the number of effective sampling points may vary in different maintenance areas—for example, some areas may experience spraying, sensor communication interruptions, or sunlight interference at certain times—using the surface temperature mean square error allows for comparison of temperature deviation per unit sampling point across different areas, preventing incomparability of error values ​​due to varying sampling point numbers. The candidate surface convective heat transfer coefficient that minimizes the surface temperature mean square error is determined as the target surface convective heat transfer coefficient for that area.

[0052] In the formula, Indicates the first The target surface convective heat transfer coefficient for each maintenance area; This indicates that within the candidate range where the surface convective heat transfer coefficient is positive, the parameter value that minimizes the mean square error of the surface temperature is selected.

[0053] In the specific calculation, a bounded nonlinear least squares iterative method is used to update the convective heat transfer coefficients of candidate surfaces. In each iteration, the current convective heat transfer coefficient of the candidate surface is substituted into the temperature field model to obtain a new theoretical value of the surface temperature, and the mean square error of the surface temperature is recalculated. The inversion stops when the change in the mean square error of the surface temperature obtained from two consecutive iterations meets a preset convergence condition, or when the number of iterations reaches a preset maximum. Finally, the convective heat transfer coefficient of the target surface is... Substituting the thermal boundary conditions of the corresponding boundary subdomain, we obtain the first... Convection heat transfer boundary conditions for each maintenance area.

[0054] After determining the target surface convective heat transfer coefficient for each curing area, the target surface convective heat transfer coefficient is used as the convective heat transfer parameter for each boundary subdomain within the prediction period. Combined with the ambient temperature time history, net radiative heat flux time history, and hydration heat source term for the prediction period, the temperature field model is further solved to obtain the concrete temperature at each spatial location within the prediction period. And the theoretical surface temperature values ​​corresponding to the surface humidity detection locations in each maintenance area. Concrete temperature and theoretical surface temperature Input steps S2 and S3 to determine water vapor density, moisture transport boundary conditions, and temperature-dependent moisture capacity and moisture diffusion coefficient.

[0055] S2. Combining the heat and mass transfer analogy and temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing area. After step S1, the convective heat transfer boundary conditions corresponding to each curing area have been obtained. The convective heat transfer boundary conditions are used to characterize the heat exchange process between the concrete surface and the ambient air, while the determination of the spraying interval depends on the process of moisture loss from the concrete surface to the ambient air.

[0056] Therefore, it is necessary to determine the corresponding surface convection mass transfer capacity based on the surface convection heat transfer capacity of each curing area; and then, in combination with the environmental temperature and humidity response, concrete surface temperature and concrete surface relative humidity, establish the boundary relationship of water flux on the outer surface of concrete in each curing area.

[0057] In this embodiment, step S2 includes the following steps: S201. Determine the surface convection mass transfer coefficient of each curing area based on the target surface convective heat transfer coefficient and the heat and mass transfer analogy. The air boundary layer near the concrete surface participates in both heat transfer and water vapor transfer. For the same curing area, the stronger the local airflow, the faster the concrete surface dissipates heat, and the stronger the ability of water vapor to migrate into the ambient air. Therefore, this embodiment uses the Chilton-Colburn heat and mass transfer analogy to convert the target surface convective heat transfer coefficient obtained in step S102 into the surface convective mass transfer coefficient.

[0058] First, obtain the number The ambient air outside each maintenance area is constantly... ambient temperature and atmospheric pressure at the construction location The ambient temperature is obtained from an ambient temperature sensor located near the corresponding maintenance area; the atmospheric pressure at the construction location is obtained from an on-site barometric pressure sensor. If no on-site barometric pressure sensor is available, it is determined based on the altitude of the construction location and meteorological records.

[0059] Using ambient temperature and atmospheric pressure at the construction location as indexes, the system retrieves air thermal conductivity, air density, and air specific heat capacity at constant pressure from a pre-stored air-water vapor property data table. When the current ambient temperature and atmospheric pressure are between adjacent property data points, interpolation is performed using adjacent property data to obtain the corresponding air thermal conductivity. air density and specific heat capacity of air at constant pressure .

[0060] Subsequently, the number was determined The air outside each maintenance area is constantly Thermal diffusivity:

[0061] In the formula, Indicates the first The air outside each maintenance area is constantly Thermal diffusivity; Indicates the thermal conductivity of air; Indicates air density; This indicates the specific heat capacity of air at constant pressure.

[0062] The surface convective heat transfer coefficient obtained in step S1 is used to characterize the convective heat transfer capacity between the outer surface of the concrete and the ambient air. In order to convert the convective heat transfer capacity into water vapor transfer capacity based on the heat and mass transfer analogy, it is necessary to first determine the diffusion capacity of water vapor in the corresponding ambient air.

[0063] In this embodiment, moisture lost from the concrete surface enters the outer air boundary layer in the form of water vapor. The migration of water vapor in the air can be regarded as a binary gas diffusion process consisting of water vapor and air. Therefore, the Fuller-Schettler-Giddings binary gas diffusion coefficient calculation method is used to determine the binary diffusion coefficient of water vapor in the air based on the ambient air temperature, atmospheric pressure at the construction location, and molecular physical properties of water vapor and air.

[0064] It should be noted that the above binary diffusion coefficient is used to calculate the Lewis number of ambient air and is not used as the diffusion coefficient for the migration of moisture inside the concrete; the moisture diffusion coefficient corresponding to the migration of moisture inside the concrete is determined in step S302 based on the concrete test with the same mix proportion.

[0065] Therefore, in order to determine the diffusion coefficient of water vapor in ambient air, this embodiment adopts the Fuller-Schettler-Giddings binary gas diffusion coefficient calculation method.

[0066] First, determine the reduced molar masses of water vapor and air:

[0067] In the formula, This represents the reduced molar mass of water vapor and air. This indicates the molar mass of water vapor; This represents the average molar mass of air, where all molar masses are expressed in units of... .

[0068] No. Each maintenance area is at all times The diffusion coefficient of water vapor in a binary gas in air is:

[0069] In the formula, Indicates the first Each maintenance area is at all times The diffusion coefficient of water vapor in a binary gas in air; Indicates the first The ambient temperature corresponding to each maintenance area; 273.15 is used to convert Celsius temperature to thermodynamic temperature; Indicates the construction location at time Atmospheric pressure; This represents the reduced molar mass of water vapor and air. This represents the Fuller diffusion volume of water vapor; This represents the Fuller diffusion volume of air.

[0070] in, , , and The fixed molecular parameters of water vapor and air are pre-stored in the gas property parameter table and do not change with the curing area or construction time.

[0071] It should be noted that the unit of the binary diffusion coefficient calculated by the above formula is 1. To maintain consistency with the SI units used in subsequent models of air thermal diffusivity and moisture diffusion, the aforementioned binary diffusion coefficients have been converted to SI units. The binary diffusion coefficient of water vapor :

[0072] After obtaining the thermal diffusivity of air and the binary diffusivity of water vapor, the first... Each maintenance area, at all times Lewis number:

[0073] In the formula, Indicates the first Each maintenance area is at all times Lewis number; This represents the diffusion coefficient of water vapor in the corresponding ambient air.

[0074] After obtaining the Lewis number, the chilton-Colburn heat and mass transfer analogy is used to determine the... Surface convective mass transfer coefficient of each maintenance area:

[0075] In the formula, Indicates the first Each maintenance area is at all times Surface convective mass transfer coefficient; This indicates the air density outside the corresponding area; This represents the isobaric specific heat capacity of the air outside the corresponding region. The surface convective mass transfer coefficient is also included. It is used to characterize the ability of water vapor on a concrete surface to migrate into ambient air.

[0076] It should be noted that even under the same ambient temperature and humidity conditions, different curing areas will have different surface convective mass transfer coefficients if the convective heat transfer coefficient of the target surface is different. Therefore, the subsequent moisture transport boundary conditions can reflect the differences in the actual airflow and heat dissipation states of different curing areas.

[0077] S202. Establish the boundary relationship of water flux based on the surface convection mass transfer coefficient, ambient air water vapor density and concrete surface water vapor density. After obtaining the surface convection mass transfer coefficient in step S201, the driving force for the migration of moisture from the concrete surface to the ambient air is further determined, which is determined by the difference between the water vapor density near the concrete surface and the water vapor density of the ambient air.

[0078] For the For each curing area, determine the water vapor density on the concrete surface based on the theoretical value of the current surface temperature and the current relative humidity:

[0079] In the formula, Indicates the first Each maintenance area is at all times The water vapor density on the concrete surface, in units of ; Indicates the first Each maintenance area is at all times The relative humidity of the concrete surface; Indicates temperature as The saturated vapor pressure of water at that time; This represents the gas constant of water vapor.

[0080] It should be noted that the surface relative humidity at the moment the spraying ends is... The relative surface humidity during the subsequent prediction period is determined by the stable detection results of the surface humidity detection unit. The saturated water vapor pressure is calculated in step S3 and dynamically updated within each calculation step. The saturated water vapor pressure is determined using temperature-saturated water vapor pressure data generated from the IAPWS saturated water property relationship. When the current temperature falls between adjacent temperature data points, interpolation is performed using adjacent temperature data to obtain the saturated water vapor pressure corresponding to the current temperature.

[0081] Subsequently, based on the ambient temperature and relative humidity, the density of water vapor in the ambient air was determined:

[0082] In the formula, Indicates the first The ambient air outside each maintenance area is constantly... Water vapor density; Indicates the corresponding ambient air at time The relative humidity.

[0083] After obtaining the water vapor density on the concrete surface and the water vapor density in the ambient air, the first... Water flux boundary relationships in each maintenance zone:

[0084] In the formula, Indicates the first Each maintenance area is at all times Normal water flux; This indicates the water vapor density on the concrete surface. This indicates the density of water vapor in the ambient air.

[0085] when

[0086] At this time, the water vapor density near the concrete surface is higher than the water vapor density of the ambient air, and the normal moisture flux is positive, indicating that moisture on the concrete surface migrates to the ambient air.

[0087] when

[0088] When the normal water flux is negative, it indicates that water vapor in the ambient air migrates to the concrete surface.

[0089] Therefore, for the first In each curing zone, the boundary conditions for moisture transport between the concrete outer surface and the ambient air are determined by the aforementioned normal moisture flux relationship, that is: the boundary conditions for moisture transport between the concrete outer surface and the ambient air at time... The amount of water exchanged is determined by the normal water flux. Confirmed. The above-mentioned normal water flux Used to characterize the The concrete exterior surface of each maintenance area is constantly... The rate at which moisture is lost to the ambient air or migrated from the ambient air to the concrete surface. Therefore, the moisture exchange relationship on the concrete surface, characterized by the aforementioned normal moisture flux relationship, constitutes the first... The moisture transport boundary conditions for each curing area. In subsequent step S3, the normal water flux is re-determined based on the concrete surface relative humidity, concrete surface temperature, ambient temperature, and ambient relative humidity at the current solution time. It was used as the outer surface boundary condition of the concrete moisture diffusion model.

[0090] It should be noted that step S202 establishes the parameters for calculating the normal water flux. The water flux boundary relationship is not used as a fixed flux that remains unchanged after being determined once at the end of the spraying process. Instead, it is re-determined within each calculation step of step S3 based on the current relative humidity of the calculated surface, the current temperature of the calculated surface, the ambient temperature, and the ambient relative humidity.

[0091] S3. Based on the boundary conditions of moisture transport and the surface relative humidity state after the current spraying is completed, establish and solve the concrete moisture diffusion model of the current construction segment, and generate the time history of the concrete surface relative humidity of each curing area. After step S2, the moisture transport boundary conditions for each curing area have been obtained. These boundary conditions characterize the moisture exchange process between the concrete outer surface and the ambient air under the current temperature and humidity conditions. However, after spraying, the concrete outer surface remains in a high humidity state due to the spraying replenishment, while the relative humidity distribution at different depths within the concrete remains consistent with the previous calculation period. Therefore, subsequent changes in surface relative humidity are influenced not only by the concrete's ability to lose moisture to the ambient air but also by its ability to migrate moisture from the concrete's interior to the outer surface.

[0092] Therefore, this step uses the surface relative humidity value after the current spraying is completed and the relative humidity distribution result at the end of the previous calculation cycle as the initial basis, and uses the moisture transport boundary conditions obtained in step S2 as the outer surface boundary conditions to establish and solve the concrete moisture diffusion model, and obtain the concrete surface relative humidity time history in the subsequent prediction period of each curing area.

[0093] It should be noted that, in this embodiment, the concrete moisture diffusion model uses the overall concrete calculation domain corresponding to the current construction segment. The solution object is defined as follows: each curing zone corresponds to a different region on the outer surface of the overall concrete computational domain, and corresponding moisture transport boundary conditions are applied to each; rather than establishing independent concrete solid models for each curing zone.

[0094] In this embodiment, step S3 includes the following steps: S301. Determine the initial relative humidity state of the current construction segment based on the surface relative humidity state after the current spraying is completed and the relative humidity distribution results of the previous calculation cycle. To ensure the continuity of the internal moisture migration process in concrete between adjacent calculation cycles, the initial conditions of the current calculation cycle should not only be determined by the surface relative humidity after the current spraying ends, but should also retain the relative humidity distribution formed inside the concrete in the previous calculation cycle.

[0095] Let the first The start time of each control calculation cycle is When the first Each maintenance area corresponds to a spray branch at a specific time. When water supply is stopped, the actual time when water supply to the sprinkler branch is stopped shall be taken as the current end time of sprinkler operation in the maintenance area.

[0096] When the current control calculation cycle is triggered after spraying is completed in a maintenance area, the following occurs:

[0097] When multiple maintenance areas complete spraying at the same control moment, these multiple maintenance areas are considered as the set of maintenance areas that have completed spraying within the current control calculation cycle, denoted as... .

[0098] For the For each maintenance area, the stop record of the corresponding spray branch is read, and the stable detection value of the corresponding surface humidity detection unit is obtained after the spraying stops. This value is the surface relative humidity detection value obtained after excluding the instantaneous abnormal changes caused by the direct adhesion of spray water droplets to the surface of the detection unit. It is used to characterize the actual wetness of the concrete surface after the spraying is completed.

[0099] Let the first The surface relative humidity value of the maintenance area after the current spraying is [value missing]. The surface relative humidity value is obtained from the surface humidity detection unit set on the concrete surface of the corresponding curing area, or by conversion from the detection value that has been calibrated to reflect the relative humidity of the concrete surface pores.

[0100] Assume the relative humidity distribution within the overall concrete calculation domain at the end of the previous calculation cycle is as follows:

[0101] In the formula, Indicates the first At the end of each calculation cycle, the spatial location The relative humidity at that location; This indicates the instantaneous calculation state prior to the start of the current control calculation cycle; Represents the overall concrete computational domain The spatial location within.

[0102] The initial relative humidity state for the current control calculation cycle is expressed as:

[0103] In the formula, Indicates the first At the start of each control calculation cycle, the spatial position The initial relative humidity at the location.

[0104] With the above configuration, the surface relative humidity value after the spraying is completed in the curing area is used as the initial relative humidity of the corresponding outer surface; for the curing area that has not been sprayed and the interior of the concrete, the relative humidity distribution result at the end of the previous calculation cycle is retained.

[0105] Therefore, while updating the wet state of the outer surface of the concrete after spraying water, the water migration state that has already formed inside the concrete is preserved, providing continuous initial conditions for subsequent water diffusion calculations.

[0106] In the initial calculation, the relative humidity distribution at the end of the previous calculation cycle has not yet been established. Therefore, the initial pore relative humidity of the concrete in the current construction segment at the initial age of pouring is determined first. This initial pore relative humidity is determined based on the pore relative humidity test results of concrete specimens using the same raw materials and mix proportions as the current construction segment at the initial age of pouring, and is used as the initial relative humidity state of the overall concrete calculation domain at the time of concrete pouring. When multiple initial pore relative humidity test values ​​are obtained, the initial relative humidity distribution of the overall concrete calculation domain is determined according to the corresponding test location or test state; when a representative initial pore relative humidity test value is used, this representative initial pore relative humidity is used as the initial relative humidity of the overall concrete calculation domain. After determining the initial relative humidity state at the time of pouring, the concrete pouring time is used as the starting point for moisture calculation. Based on historical environmental temperature and humidity data after pouring, historical spraying records, the concrete temperature field obtained in step S1, and material parameters, a historical back-calculation of the concrete moisture diffusion model is performed to obtain the relative humidity distribution result within the overall concrete calculation domain at the beginning of the first control calculation cycle.

[0107] It should be noted that the concrete specimens with the same mix proportion are used in this step to determine the representative pore relative humidity at the initial age of pouring, and to determine material parameters such as moisture capacity and moisture diffusion coefficient. The spatial relative humidity distribution inside the specimen is not directly mapped to the relative humidity distribution inside the solid pier column.

[0108] S302. Using the initial relative humidity state as the initial condition and the moisture transport boundary condition as the boundary condition of the concrete outer surface, establish and solve the concrete moisture diffusion model to obtain the relative humidity distribution result of the overall concrete computational domain. After processing in step S301, the initial relative humidity state at the start of the current control calculation cycle has been obtained. The initial relative humidity state includes: the relative humidity of the concrete outer surface of the currently sprayed curing area after spraying, and the relative humidity distribution results of the previous calculation period retained on the concrete outer surface and inside of the currently unsprayed curing area. The moisture transport boundary conditions obtained in step S2 are derived from the... Each maintenance area is at all times normal water flux Characterization is used to characterize the rate of moisture exchange between the outer surface of the corresponding concrete and the ambient air in the curing area.

[0109] Therefore, this step is based on the initial relative humidity state. As the initial condition for the concrete moisture diffusion model, the normal water flux corresponding to each curing zone was used. A concrete moisture diffusion model is established and solved using the moisture flux boundary conditions on the outer surface of the concrete. The concrete moisture diffusion model takes the overall concrete computational domain corresponding to the current construction segment as the solution object. Different curing zones correspond to different areas on the overall concrete outer surface, and different moisture flux boundary conditions are applied to their respective outer surface locations to obtain the relative humidity distribution results covering each curing zone.

[0110] In the moisture diffusion model, the relative humidity of concrete pores is used as the calculation variable to describe the internal moisture state of the concrete. Based on the relative humidity gradient inside the concrete pores, concrete temperature, concrete age, and moisture flux at the outer surface, the model calculates the migration of moisture inside the concrete and the moisture exchange process between the concrete outer surface and the ambient air during the current prediction period. The moisture diffusion model describes the process by which moisture inside the concrete migrates from areas with higher relative humidity to areas with lower relative humidity, and is then lost to the ambient air via the concrete surface, or migrates from the ambient air to the concrete surface when the water vapor density in the ambient air is high.

[0111] After processing in this step, the relative humidity distribution of the overall concrete calculation domain within the current prediction period is obtained, and step S303 extracts the relative humidity time history of the concrete surface corresponding to each curing area from the relative humidity distribution result.

[0112] S3021. Establish the wet storage capacity relationship and determine the wet storage capacity corresponding to the current node; During the migration of moisture within concrete, changes in the relative humidity of the pores correspond to changes in the equilibrium moisture content per unit volume of concrete. Moisture capacity is used to characterize the change in equilibrium moisture content per unit volume corresponding to a change in relative humidity per unit pore space, and it is expressed as:

[0113] In the formula, Indicates moisture content; This indicates the relative humidity per unit volume of concrete in the pores. The concrete age is The concrete temperature is The equilibrium moisture content at that time; Indicates the relative humidity of concrete pores; Indicates the age of the concrete; Indicates the temperature of the concrete.

[0114] Among them, concrete age Determined based on the time difference between the current calculation time and the concrete pouring time:

[0115] In the formula, This indicates the concrete pouring time for the current construction segment.

[0116] To obtain the moisture content, concrete specimens using the same raw materials and mix proportions as the pier concrete were prepared before construction. Water vapor adsorption / desorption equilibrium tests were then conducted under different ages, temperatures, and relative humidity conditions. Specifically, the specimens were placed in an environment with preset temperature and relative humidity. After the specimen mass stabilized, the stable mass, volume, age, temperature, and relative humidity of the specimens were recorded.

[0117] For the Trial age , No. Test temperature Passing the exam Relative humidity of each test The corresponding equilibrium water content is expressed as:

[0118] In the formula, Indicates the experimental age as The test temperature is The relative humidity of the test was The corresponding equilibrium water content under the given conditions; This indicates the mass of the corresponding specimen after it has reached quality stability under the stated test age, test temperature, and test relative humidity conditions; This represents the baseline dry mass of the corresponding concrete specimen used in the equilibrium moisture content test, obtained after undergoing a predetermined drying procedure until the quality stabilizes. This indicates the volume of the specimen at the corresponding age.

[0119] Since the equilibrium moisture content is obtained through discrete test points, and a continuous derivative cannot be directly obtained, the ratio of the difference in equilibrium moisture content to the difference in relative humidity under adjacent relative humidity test conditions is used to perform a discrete approximation of the moisture capacity within the corresponding relative humidity range.

[0120] In the formula, Indicates the trial age as The test temperature is The relative humidity of the test is located at to Discrete approximation of moisture content capacity over intervals; and These represent the equilibrium moisture content under two adjacent relative humidity test conditions; and These represent two adjacent relative humidity states respectively; This indicates the relative humidity difference between two adjacent relative humidity test conditions.

[0121] In the actual solution process, the concrete age of the current calculation node is considered. Concrete temperature and pore relative humidity The moisture content of the current calculation node is obtained by interpolating the moisture content data corresponding to adjacent test ages, test temperatures, and test relative humidity.

[0122] S3022, The Bažant-Najjar moisture diffusion coefficient model is adopted, and the model parameters are calibrated based on the internal relative humidity response; The ability of water to migrate within concrete is not constant. When the relative humidity of the concrete pores is high, more water can migrate within the pores, resulting in a stronger water migration capacity. As the relative humidity of the pores decreases, the continuity of liquid water decreases, and the water migration capacity decreases.

[0123] Therefore, this embodiment adopts the Bažant-Najjar unsaturated concrete moisture diffusion coefficient model, expressing the concrete moisture diffusion coefficient as a function of pore relative humidity, concrete age, and concrete temperature:

[0124] In the formula, This indicates the corresponding pore relative humidity is The trial period is and the test temperature is The concrete moisture diffusion coefficient at that time; This represents the moisture diffusion coefficient in the high porosity relative humidity range at the corresponding age and temperature. Indicates the water diffusion coefficient in the low porosity relative humidity range and The ratio; This represents the characteristic pore relative humidity corresponding to the shift of the moisture diffusion coefficient from a high value region to a low value region; The curve shape parameter representing the change of moisture diffusion coefficient with pore relative humidity To determine the parameters of the aforementioned moisture diffusion coefficient model, plate-shaped or prismatic concrete specimens with the same mix proportions as the pier concrete were fabricated, and all surfaces except the target exposed surface were sealed. Pore relative humidity monitoring units were placed at different depths along the normal direction of the target exposed surface of the specimens to collect pore relative humidity data at different test times and depths. The temperature and humidity boundary conditions in the material parameter calibration test were provided by a constant temperature and humidity chamber or environmental simulation device, and specimen-level moisture transport boundary conditions were established based on the ambient temperature, ambient relative humidity, and airflow conditions of the chamber. These specimen-level moisture transport boundary conditions were used to calibrate the material parameters and did not directly employ the surface convection heat transfer coefficients or surface convection mass transfer coefficients obtained from the inversion of various curing areas of the ultra-high pier at the construction site.

[0125] For the Trial age Passing the exam Test temperature The parameter set of the moisture diffusion coefficient model is expressed as follows:

[0126] In the formula, This represents the model parameter set for the moisture diffusion coefficient at the corresponding age and temperature conditions; superscript Indicates transpose; For each candidate parameter set, the candidate parameter set is substituted into the specimen-level moisture diffusion model to obtain the calculated pore relative humidity at each sampling time corresponding to the detection location of the internal pore relative humidity. Based on the difference between the calculated pore relative humidity and the actual measured pore relative humidity, the target parameter set is determined using the bounded nonlinear least squares method.

[0127] In the formula, Indicates the trial age as The test temperature is The target moisture diffusion coefficient model parameter set at that time; Indicates the number of relative humidity detection locations in the internal pores; This indicates the number of sampling times at each detection location that are included in the comparison; This indicates the result of calculating the first parameter using the current parameter set. Each detection location and time Pore ​​relative humidity; Indicates the first Each detection location and time The measured relative humidity.

[0128] In actual calculations, the concrete age at the current calculation node is taken into account. and the concrete temperature obtained in step S1 Interpolation is performed on the target parameter set under adjacent age and temperature conditions to obtain the model parameters of the moisture diffusion coefficient corresponding to the current computing node. Then, combined with the pore relative humidity of the current computing node, the moisture diffusion coefficient corresponding to the current computing node is obtained.

[0129] S3023. Establish and solve the concrete moisture diffusion model to obtain the corresponding relative humidity distribution results; Based on the moisture content relationship determined in step S3021 and the moisture diffusion coefficient relationship determined in step S3022, the overall concrete calculation domain is used. Relative humidity of internal pores As the solution variable, a concrete moisture diffusion model is established:

[0130] In the formula, Represents the overall concrete computational domain Internal space location At any moment Pore ​​relative humidity; This indicates the moisture content corresponding to the current computing node; This represents the moisture diffusion coefficient corresponding to the current calculation node.

[0131] Within each calculation step, the concrete age and concrete temperature corresponding to the current calculation node are used as known state parameters within that calculation step, and the moisture content and moisture diffusion coefficient are updated based on the current pore relative humidity, concrete age, and concrete temperature.

[0132] Within this calculation step, the left side of the equation

[0133] It represents the rate of change of equilibrium moisture content per unit volume corresponding to the change of pore relative humidity over time under the current concrete age and temperature conditions.

[0134] right side of the equation

[0135] This represents the net water migration rate per unit volume driven by the spatial difference in relative humidity within the pores of the concrete under the current concrete age and temperature conditions. Between adjacent calculation steps, the moisture capacity and water diffusion coefficient are re-determined based on the updated concrete age, temperature, and relative humidity within the pores.

[0136] For the Concrete outer surface corresponding to each curing area The normal water flux determined in step S2 As a boundary condition for water flux:

[0137] In the formula, Represents the outward normal unit vector of the concrete outer surface; when A value greater than zero indicates that moisture has been lost from the concrete surface to the ambient air; when... When the value is less than zero, it indicates that water vapor in the ambient air is migrating to the concrete surface.

[0138] In this embodiment, the ambient temperature, relative humidity, and surface convection mass transfer coefficient within each curing area are used as representative environmental parameters for that area; the normal water flux obtained accordingly... This serves as the boundary condition for the regional moisture flux on the outer surface of the concrete in the curing area. For the outer surface of the concrete still covered by the formwork, a zero moisture flux boundary condition is set; for the outer surface of the concrete without spray branches but exposed to ambient air, the corresponding moisture flux boundary condition is established in the same way as in step S2, based on the ambient temperature and humidity response of its location.

[0139] because:

[0140] The unit is The normal water flux obtained in step S2 Since the units are consistent, the normal water flux can be used as the boundary condition for the water flux on the outer surface of the concrete in the corresponding curing area.

[0141] The initial conditions for the current control calculation cycle are:

[0142] In the formula, This indicates the start time of the current control calculation cycle. The Galerkin finite element method is used to spatially discretize the overall concrete computational domain, and the backward Euler implicit time integration method is used for time-step solution. Within each calculation time step, the system first updates the corresponding moisture content and water diffusion coefficient based on the pore relative humidity of the current calculation node, the concrete age, and the concrete temperature obtained in step S1.

[0143] Subsequently, based on the calculated relative humidity values ​​of the corresponding outer surfaces of each curing area within the current calculation step, the water vapor density of the concrete surface is re-determined, and the normal water flux of the corresponding curing area is updated according to the water flux relationship in step S2. That is, the water transport boundary conditions obtained in step S2 are not fixed after being determined once at the end of the spraying, but are dynamically updated in each calculation step of the water diffusion model based on the current relative humidity of the calculated surface, the concrete surface temperature, the ambient temperature, and the ambient relative humidity.

[0144] After obtaining the moisture capacity, moisture diffusion coefficient, and normal moisture flux at the current calculation step, the pore relative humidity at each calculation node within the current calculation step is calculated. This is because the normal moisture flux... Related to the current relative humidity of the concrete surface, the surface relative humidity and normal water flux are updated iteratively in each calculation step until the relative humidity of the pores at the calculation nodes obtained in two adjacent iterations meets the preset numerical convergence condition.

[0145] After this step, the relative humidity distribution results at each calculation time and spatial location within the overall concrete calculation domain are obtained:

[0146] In the formula, Indicates the first Each calculation time.

[0147] S303. Extract the relative humidity of the concrete outer surface from the relative humidity distribution results, and generate the relative humidity time history of the concrete surface of each curing area in chronological order. Step S302 yields the relative humidity distribution results at various spatial locations and calculation times within the overall concrete calculation domain. Step S4, however, requires determining the spraying interval for each curing area based on the moment when the relative humidity of the concrete surface in each curing area first reaches the preset lower limit of moisture retention.

[0148] Therefore, the system extracts the relative humidity distribution result obtained in step S302 from the result related to the first step. The relative humidity of the concrete surface corresponding to the surface humidity detection location of each maintenance area is recorded, and a time history of the relative humidity of the concrete surface is formed in chronological order.

[0149] Let the first In each maintenance area, the spatial coordinates corresponding to the surface humidity detection location are: The surface humidity detection location is used to obtain the actual measured surface relative humidity value after the current spraying ends; in subsequent prediction periods, it is used to extract the concrete surface relative humidity calculated by the moisture diffusion model.

[0150] When the surface humidity detection location coincides with the location of a node on the outer surface of the finite element, the system directly extracts the porosity relative humidity of that outer surface node at each calculation time. When the surface humidity detection location does not completely coincide with the location of a node on the outer surface of the finite element, the system uses the finite element shape function interpolation method to determine the calculated relative humidity corresponding to that detection location based on the porosity relative humidity of each node in the outer surface element where the detection location is located.

[0151] No. Each maintenance area is at all times The relative humidity of concrete surface is expressed as:

[0152] In the formula, Indicates the first Each maintenance area is at all times The relative humidity of the concrete surface; Indicates the first Spatial coordinates corresponding to the surface humidity detection locations in each maintenance area; Indicates spatial location At any moment Calculate the relative humidity.

[0153] By using the same surface humidity detection location as in step S301, the current surface relative humidity detection value after spraying and the subsequently predicted concrete surface relative humidity have a consistent spatial location basis. Finally, the system correlates the concrete surface relative humidity corresponding to each calculation time within the current prediction period in chronological order to form the... Time history of relative humidity on concrete surface in each curing area:

[0154] In the formula, Indicates the first The relative humidity time history of concrete surface in each maintenance area.

[0155] Step S4, which inputs the relative humidity time history of the concrete surface, is used to determine the first... The moment when the relative humidity of the concrete surface in the maintenance area first reaches the preset lower limit of moisture retention.

[0156] S4. Based on the relative humidity time history of the concrete surface, determine the spraying interval time for each curing area and generate the corresponding zone spraying sequence. After step S3, the relative humidity time history of the concrete surface in each curing area after the current spraying ends and during the subsequent predicted period has been obtained. The local airflow, surface convective mass transfer capacity, ambient temperature and humidity, and the ability of internal concrete moisture to migrate to the surface differ among different curing areas. Therefore, the time at which the relative humidity of the concrete surface reaches the lower limit of moisture retention varies in different curing areas.

[0157] Therefore, this step does not adopt a uniform fixed spraying cycle for all curing areas. Instead, it determines the next spraying time for each curing area based on the relative humidity time history of the concrete surface corresponding to each curing area, and generates the corresponding zone spraying sequence.

[0158] In this embodiment, step S4 includes the following steps: S401. Determine the preset lower limit of moisture retention based on the curing quality requirements corresponding to the concrete mix proportion used in construction and the curing test results. Preset moisturizing lower limit This indicates the minimum control level to which the relative humidity of the concrete surface can be allowed to drop. When the relative humidity of the concrete surface in a certain curing area reaches the preset lower limit of moisture retention, it indicates that the curing area needs to be sprayed again to maintain the surface moisture required for curing during the construction period. Before construction, graded moisture retention curing tests are conducted using concrete specimens with the same raw materials and mix proportions as those used in the pier construction.

[0159] Specifically, multiple candidate moisturizing lower limits are set. ,in, , This indicates the number of candidate lower limits of moisture content. For each candidate lower limit of moisture content corresponding to the test group, curing was carried out under the same test age, the same specimen size, the same spraying duration, and the same environmental conditions.

[0160] When the relative humidity on the surface of the concrete specimens in this test group reaches the corresponding candidate lower limit of moisture retention At that time, the specimen was sprayed to restore the relative humidity of the specimen surface to the moist state after spraying.

[0161] After the curing of each test group is completed, the curing quality of each test group is judged according to the curing quality requirements corresponding to the concrete mix proportion used in construction.

[0162] The maintenance quality requirements may include at least one of the following: (1) No early cracking that did not meet the construction technical requirements was observed in the specimens; (2) The strength of the specimens at the specified age meets the construction technical requirements; (3) The surface quality of the specimens meets the construction technical requirements; (4) The shrinkage state of the specimen meets the construction technical requirements.

[0163] Among the test groups that meet the aforementioned maintenance quality requirements, the candidate moisturizing lower limit with the lowest corresponding candidate moisturizing lower limit is determined as the preset moisturizing lower limit:

[0164] In the formula, Indicates the preset lower limit of hydration; Indicates the first Candidate lower limits of hydration for each experimental group; This represents the set of test group numbers that meet the maintenance quality requirements.

[0165] The preset moisture retention lower limit, as described above, is not an artificially predetermined empirical threshold, but rather determined based on the concrete mix design used in construction, curing quality requirements, and curing test results. After this step, the preset moisture retention lower limit corresponding to the concrete mix design used in construction is obtained. And input it into step S402.

[0166] S402. Determine the spraying interval for each curing area based on the relative humidity time history of the concrete surface. After processing in step S303, the first... Time history of relative humidity of concrete surface in each curing area:

[0167] For the For each curing area, the target moment when the relative humidity of the concrete surface first reaches the preset lower limit of moisture retention is determined from the relative humidity time history of the concrete surface:

[0168] In the formula, Indicates the first The target time for each maintenance area; Indicates the first The current end time of spraying in each maintenance area; Indicates the first Each maintenance area is at all times The relative humidity of the concrete surface. Wherein, the current spraying end time... According to the The actual time when the water supply to the corresponding sprinkler branch in each maintenance area was stopped was determined.

[0169] When the preset lower limit for moisture retention is between the relative humidity of the concrete surface at two adjacent calculation times, and satisfies:

[0170] The target time is determined by linear interpolation using the relative humidity of the concrete surface at adjacent calculation times.

[0171] In the formula, This indicates the previous calculation time when the relative humidity of the concrete surface was still higher than the preset lower limit for moisture retention. This indicates the next calculation time after the relative humidity of the concrete surface drops to or below the preset moisture retention lower limit. Determining the target time through interpolation can reduce the error in spraying demand time caused by the discrete calculation time steps used in the moisture diffusion model.

[0172] At the moment of setting the target Then, based on the time difference between the target time and the current end time of spraying in the corresponding maintenance area, the spraying interval time for that maintenance area is determined:

[0173] In the formula, Indicates the first Spraying interval for each maintenance area.

[0174] If the relative humidity of the concrete surface at the current spraying end time is lower than or equal to the preset moisture retention limit, then the curing area is marked as a curing area that needs to be sprayed immediately, and the corresponding spraying interval is set to zero. If the relative humidity of the concrete surface is always higher than the preset moisture retention limit during the current prediction period, then the prediction period of step S3 is extended until the target time when the relative humidity of the concrete surface in the curing area first reaches the preset moisture retention limit is determined.

[0175] After this step, the spraying interval time corresponding to each maintenance area is obtained.

[0176] S403. Based on the current spraying end time and corresponding spraying interval time of each maintenance area, determine the next spraying start time of each maintenance area and generate the zone spraying sequence. For the Each maintenance area is determined based on the current spraying end time of that maintenance area. and the corresponding spray interval time Determine the start time for the next spray cycle:

[0177] In the formula, Indicates the first The next start time for spraying in each maintenance area.

[0178] Subsequently, the area identifiers of each maintenance zone are associated with the corresponding next spray start time, and sorted from earliest to latest according to the next spray start time to generate the zone spray sequence:

[0179] In the formula, Indicates the spraying sequence for each zone; Indicates the number of maintenance areas; This indicates that the sprinklers are sorted from earliest to latest according to the time of their next start-up.

[0180] When the next spray start time is the same for multiple maintenance areas, the area identifiers of these multiple maintenance areas are associated with the same timing node to form a synchronous spray command. When the next spray start time is different for different maintenance areas, the control system outputs spray start commands to the corresponding maintenance areas sequentially according to the zone spray sequence. After any maintenance area completes its current spray cycle, the current spray end time of that maintenance area is updated based on the actual water supply stop record of the corresponding spray branch, and steps S1 to S4 are re-executed to continuously update the next spray start time of that maintenance area.

[0181] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for intelligent spray curing control of concrete during the construction of ultra-high piers in mountainous areas, characterized in that, Includes the following steps: Based on the temperature and humidity response data of each curing area, a concrete temperature field model for the current construction segment is constructed, and the concrete temperature field model is inverted to determine the convective heat transfer boundary conditions of each curing area. Based on the heat and mass transfer analogy and temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing zone. Based on the aforementioned moisture transport boundary conditions and the current surface relative humidity state after spraying, a concrete moisture diffusion model for the current construction segment is established and solved to generate the concrete surface relative humidity time history for each curing area. Based on the relative humidity time history of the concrete surface, the spraying interval time for each curing area is determined, and the corresponding zone spraying sequence is generated.

2. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 1, characterized in that, Based on the temperature and humidity response data of each curing area, a concrete temperature field model for the current construction segment is constructed, including: Based on the pier structure information and the temperature response in the temperature and humidity response data, a concrete temperature field model is established with concrete temperature as the solution object. In the concrete temperature field model, the outer surface of the concrete corresponding to each curing area is set as a one-to-one boundary subdomain, and the surface convective heat transfer coefficient of each boundary subdomain is set as the parameter to be inverted.

3. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 2, characterized in that, The inversion of the concrete temperature field model to determine the convective heat transfer boundary conditions for each curing zone includes: The convective heat transfer process between the concrete outer surface and ambient air of each of the boundary subdomains is characterized by the third type of thermal boundary conditions, and the surface convective heat transfer coefficient in the third type of thermal boundary conditions is used as the parameter to be inverted. For different candidate surface convective heat transfer coefficients, the concrete temperature field model is solved to obtain the corresponding calculated concrete surface temperature; The calculated surface temperature of the concrete is matched with the surface temperature response of the concrete in the corresponding curing area to determine the convective heat transfer coefficient of the target surface. Substituting the convective heat transfer coefficient of the target surface into the third type of thermal boundary condition of the corresponding boundary subdomain, the convective heat transfer boundary condition of the corresponding curing area is obtained.

4. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 1, characterized in that, Based on the analogy of heat and mass transfer and the temperature and humidity response data, the convective heat transfer boundary conditions are converted into moisture transport boundary conditions for each curing zone, including: Based on the surface convective heat transfer coefficient and heat and mass transfer analogy in the convective heat transfer boundary conditions of each curing area, the surface convective mass transfer coefficient of each curing area is determined. Based on the ambient temperature and relative humidity in the temperature and humidity response data, determine the ambient air water vapor density of each maintenance area; Based on the surface convection mass transfer coefficient, the ambient air water vapor density, and the water vapor density corresponding to the concrete surface temperature and relative humidity, a water flux boundary relationship is established for the outer surface of the concrete in each curing area, and the water flux boundary relationship is used as the water transport boundary condition for each curing area.

5. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 4, characterized in that, Establish the boundary relationships of moisture flux on the outer surface of concrete in each curing zone, including: The water vapor density on the concrete surface is determined based on the concrete surface temperature and relative humidity. Determine the water vapor density difference between the water vapor density on the concrete surface and the water vapor density in the ambient air; The normal water flux to the outer surface of the concrete is determined based on the water vapor density difference and the surface convective mass transfer coefficient. In solving the concrete moisture diffusion model, the normal water flux is updated based on the relative humidity of the concrete surface at the current solution time.

6. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 1, characterized in that, Based on the water transport boundary conditions and the surface relative humidity state after the current spraying is completed, a concrete water diffusion model for the current construction segment is established and solved to generate the time history of the concrete surface relative humidity of each curing area, including: Based on the surface relative humidity status after the current spraying is completed and the relative humidity distribution results of the previous calculation cycle, determine the initial relative humidity status of the current construction segment; Using the initial relative humidity state as the initial condition and the moisture transport boundary condition as the outer surface boundary condition of the concrete, the concrete moisture diffusion model is established and solved to obtain the relative humidity distribution result of the overall concrete computational domain. The relative humidity of the concrete surface in each curing area is extracted from the relative humidity distribution results, and the relative humidity time history of the concrete surface in each curing area is generated in chronological order.

7. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 6, characterized in that, Determine the initial relative humidity state of the current construction segment, including: For the curing area that has been sprayed within the current control calculation cycle, the surface relative humidity state after the current spraying is completed is configured as the initial relative humidity of the concrete outer surface of the corresponding curing area. For the outer surface and interior of the concrete in the curing area that has not been sprayed within the current control calculation cycle, the relative humidity distribution results of the previous calculation cycle are retained. The initial relative humidity of the concrete surface corresponding to the completed curing area and the relative humidity distribution results of the previous calculation period are used to determine the initial relative humidity state of the current construction segment.

8. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 1, characterized in that, The determination of the spraying interval for each curing area based on the relative humidity time history of the concrete surface includes: The target moment when the relative humidity of the concrete surface first reaches the preset lower limit of moisture content is determined from the time history of relative humidity of the concrete surface in each curing area; The spraying interval time for the corresponding maintenance area is determined based on the time difference between the target time and the current end time of spraying in the corresponding maintenance area.

9. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 8, characterized in that, The preset lower limit for moisture retention is determined based on the curing quality requirements corresponding to the concrete mix proportion used in construction and the results of curing tests.

10. The intelligent spray curing control method for concrete during the construction period of ultra-high piers in mountainous areas according to claim 8, characterized in that, Generate the corresponding zone spray timing sequence, including: The next spraying start time for each maintenance area is determined based on the current spraying end time and the corresponding spraying interval time. The area identifiers of each maintenance area are associated with the corresponding next spray start time in chronological order to generate a zoned spray sequence.

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