A method for dividing a highland concrete freeze-thaw action environment

Abstract

The application discloses a highland concrete freeze-thaw action environment zoning method, and belongs to the technical field of environment zoning of concrete structure design, and comprises the following steps: acquiring high-resolution daily weather data sets of a highland region in a future design reference period; determining the number of natural effective freeze-thaw cycles of each grid point in the highland region in the future design reference period based on the high-resolution daily weather data sets, and acquiring a salt acceleration factor of each grid point in the highland region; for each grid point, correcting the number of natural effective freeze-thaw cycles in the future design reference period based on the salt acceleration factor, and determining the number of corrected effective freeze-thaw cycles; and dividing the service environment of a concrete structure in the highland region based on the number of corrected effective freeze-thaw cycles of each grid point in the highland region. The method combines the influence of salt and freeze coupling damage on concrete, and can improve the accuracy of concrete freeze-thaw action environment zoning in the highland region.

Description

Technical Field

[0001] This invention belongs to the field of environmental zoning technology for concrete structure design, and specifically relates to a method for environmental zoning of concrete freeze-thaw effects in plateau regions. Background Technology

[0002] The Qinghai-Tibet Plateau region possesses unique and harsh environmental characteristics, including high altitude, strong radiation, extreme aridity, and widespread salt lakes and saline soils, leading to freeze-thaw damage to concrete structures. Accurately assessing the severity of the freeze-thaw environment in this region and conducting scientific durability environmental zoning are fundamental to guiding the freeze-thaw resistance design of concrete structures, ensuring safe service throughout the entire life cycle of engineering projects, and reducing maintenance costs. However, due to the complexity of the plateau environment, directly applying zoning methods from plains areas often results in significant deviations in engineering design parameters. Zoning of the freeze-thaw environment for concrete structures typically employs statistical analysis methods based on historical meteorological observation data. The general process is as follows: First, the average temperature of the coldest month or the number of freeze-thaw cycles per year is selected as a single representative indicator of environmental severity. Second, the statistical data from sparse meteorological stations is interpolated and generalized to the entire study area using the inverse distance weighting method or Kriging interpolation, creating a spatial distribution map of meteorological parameters. Finally, based on the numerical range of meteorological statistical values, the region is directly divided into different environmental action levels, such as severe cold and cold, which serves as the basis for selecting the freeze-thaw resistance level in engineering design. However, this approach fails to consider the damage mechanism of concrete caused by salt-freezing coupling, resulting in lower accuracy in the environmental zoning of concrete freeze-thaw cycles in plateau regions.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0005] This disclosure provides a method for environmental zoning of concrete freeze-thaw effects in plateau regions, which incorporates the effects of salt-freeze coupled damage to concrete, thereby improving the accuracy of environmental zoning of concrete freeze-thaw effects in plateau regions.

[0006] In some embodiments, a method for environmental zoning of concrete freeze-thaw action in plateau regions includes: Obtain high-resolution daily meteorological datasets for plateau regions during the future design reference period; Based on high-resolution daily meteorological datasets, the number of natural effective freeze-thaw cycles for each grid point in the plateau region during the future design baseline period was determined, and the salinity acceleration factor for each grid point in the plateau region was obtained. For each grid point in the plateau region, the number of natural effective freeze-thaw cycles in the future design reference period is corrected based on the salt acceleration factor, and the cumulative equivalent standard freeze-thaw cycle number in the future design reference period is determined. The service environment of concrete structures in plateau regions is classified based on the cumulative equivalent standard freeze-thaw cycles of each grid point within the future design reference period.

[0007] The beneficial effects of this invention are as follows: By acquiring high-resolution daily meteorological datasets for the plateau region during the future design reference period, the number of natural effective freeze-thaw cycles for each grid point within the plateau region during this period is determined. Then, by acquiring the salinity acceleration factor for each grid point within the plateau region, the number of natural effective freeze-thaw cycles for the corresponding grid points during the future design reference period is corrected to account for the impact of salt-freeze coupling damage on concrete. This results in a more accurate determination of the effective freeze-thaw cycle number for each grid point within the plateau region during the future design reference period, i.e., the cumulative equivalent standard freeze-thaw cycle number. Based on the cumulative equivalent standard freeze-thaw cycle number for each grid point within the plateau region during the future design reference period, the service environment of concrete structures in the plateau region is classified to improve the accuracy of the environmental zoning of concrete freeze-thaw action in the plateau region, taking into account the impact of salt-freeze coupling damage on concrete.

[0008] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0009] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a flowchart of an environmental zoning method for concrete freeze-thaw action in plateau regions provided by the present invention. Detailed Implementation

[0010] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0011] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0012] Unless otherwise stated, the term "multiple" means two or more.

[0013] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0014] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0015] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0016] Existing technologies suffer from three fundamental problems. First, they neglect the crucial role of moisture as a necessary condition for freeze-thaw damage. According to the critical saturation theory, if the surface moisture content of concrete does not reach a critical value, substantial frost heave damage will not occur even if the temperature is below freezing. The Qinghai-Tibet Plateau has an extremely arid climate, and existing methods, relying solely on temperature indicators for zoning, significantly overestimate the freeze-thaw risk in the typical dry and cold climate of the plateau region. Second, they fail to consider the salt-freeze coupling damage mechanism of concrete. Salt lakes and saline soils are widely distributed in western China, and salt has strong hygroscopicity and crystallization expansion effects, allowing concrete to maintain high saturation and suffer dual damage even in dry environments. Existing technologies fail to decouple and quantify this mechanism, leading to a significant underestimation of the extreme damage risk in areas surrounding salt lakes. In reality, for widely distributed semi-buried structures such as power tower foundations and bridge piers, saline water in the soil rises capillarily to the exposed structural roots (i.e., the capillary uptake zone). This area suffers from both drastic atmospheric temperature changes and freeze-thaw cycles, and the rapid accumulation of salt concentration on the surface due to moisture evaporation, making it the most severely damaged part of the project. The third problem is that existing technologies are also ill-suited to the data processing needs of major projects on the Tibetan Plateau. Due to the extremely complex topography of the Tibetan Plateau, the sparse distribution of meteorological stations, and the discontinuous nature of meteorological data, traditional spatial interpolation methods struggle to capture the local microclimate differences caused by topographic factors such as altitude and aspect. This results in low spatial resolution of the zoning results, hindering refined assessments. Furthermore, existing zoning is largely based on static historical data from the past few decades, failing to consider future climate evolution trends under global warming, and thus failing to accurately reflect the cumulative effects of freeze-thaw cycles faced by major infrastructure during its future service life.

[0017] This disclosure constructs a plateau concrete freeze-thaw environment zoning system that deeply integrates data-driven downscaling and mechanism-driven damage assessment. Compared to existing methods that rely solely on sparse meteorological stations to statistically analyze temperature indicators, this disclosure utilizes the MINet deep learning network to fuse SRTM topographic physical priors, achieving high-precision spatiotemporal downscaling of the global climate model (CMIP6). This not only overcomes the assessment blind spots in plateau areas lacking observational data but also accurately predicts the environmental evolution trends throughout the entire life cycle of the project under future climate warming. Simultaneously, this disclosure introduces an unsteady moisture balance equation for the concrete surface and a critical saturation criterion, correcting the mechanism of salt-induced freezing point reduction, screening out freeze-thaw cycle counts where saturation in arid and cold regions does not meet requirements, and considering extreme salinity conditions in salt lake areas. Furthermore, this disclosure establishes an indoor-outdoor equivalent conversion model, normalizing the complex coupling effects of natural temperature variations, freeze-thaw cycles, and salt corrosion into a commonly used equivalent standard freeze-thaw cycle count index in engineering. This transformation breaks down the technical barriers between macro-meteorological parameters and current engineering design specifications, enabling zoning results to directly guide the selection of concrete frost resistance grades. This method avoids the economic waste caused by blindly implementing protection measures in arid areas while ensuring the long-term durability and safety of major infrastructure in saline-alkali soil regions, demonstrating significant engineering application value and economic benefits.

[0018] Combination Figure 1 As shown in the embodiments of this disclosure, a method for environmental zoning of concrete freeze-thaw action in plateau areas is provided, including: Step S101: Obtain high-resolution daily meteorological datasets for the plateau region during the future design reference period.

[0019] The future design baseline period represents the period from the present moment to the next 50 years.

[0020] Step S102: Based on the high-resolution daily meteorological dataset, determine the number of natural effective freeze-thaw cycles for each grid point in the plateau region during the future design baseline period, and obtain the salinity acceleration factor for each grid point in the plateau region.

[0021] Step S103: For each grid point in the plateau region, the number of natural effective freeze-thaw cycles in the future design reference period is corrected based on the salinity acceleration factor, and the cumulative equivalent standard freeze-thaw cycle number in the future design reference period is determined.

[0022] Step S104: Based on the cumulative equivalent standard freeze-thaw cycles of each grid point in the plateau region during the future design reference period, the service environment of the concrete structure in the plateau region is classified.

[0023] This disclosure provides a method for environmental zoning of concrete freeze-thaw cycles in plateau regions. It involves acquiring high-resolution daily meteorological data for the plateau region during the future design reference period and using this data to determine the natural effective freeze-thaw cycle count for each grid point within the plateau region during that period. Then, by acquiring the salinity acceleration factor for each grid point within the plateau region and using this factor to correct the natural effective freeze-thaw cycle count for the corresponding grid point during the future design reference period, the method considers the impact of salt-freeze coupling damage on concrete. This results in a more accurate determination of the effective freeze-thaw cycle count for each grid point within the plateau region during the future design reference period, i.e., obtaining the cumulative equivalent standard freeze-thaw cycle count. Based on the cumulative equivalent standard freeze-thaw cycle count for each grid point within the plateau region during the future design reference period, the service environment of concrete structures in the plateau region is classified. This approach aims to improve the accuracy of environmental zoning of concrete freeze-thaw cycles in plateau regions by incorporating the impact of salt-freeze coupling damage on concrete.

[0024] Preferably, a high-resolution daily meteorological dataset of the plateau region during the future design reference period is obtained, including: From the CMIP6 global climate model dataset, daily low-resolution meteorological element fields of the plateau region during the future design reference period are extracted to obtain daily low-resolution meteorological element field sets. Extract the geospatial static feature field corresponding to the plateau region from the SRTM digital elevation model data; Using a low-resolution meteorological element field and a geospatial static feature field from the daily low-resolution meteorological element field set as the first joint input feature, a pre-trained target MINet model is used to predict and determine the high-resolution daily meteorological dataset for the plateau region in the future design baseline period; wherein, the target MINet model is used to predict the corresponding high-resolution meteorological element field based on the low-resolution meteorological element field of the plateau region under the static topographic constraints of the plateau region.

[0025] Spatiotemporal downscaling is a nonlinear mapping process designed to extrapolate high-resolution local meteorological data from low-resolution global climate model data. Unlike traditional statistical downscaling methods that rely solely on statistical correlations between meteorological variables, this disclosure constructs a deep neural network function. (i.e., the target MINet model) takes a low-resolution dynamic meteorological field (i.e., a daily low-resolution meteorological element field set) and a high-resolution static geographic field (a geospatial static feature field) as joint inputs and a meteorological field with a higher spatial resolution as output, thereby being able to downscale and reconstruct coarse global climate prediction data into a future high-resolution daily meteorological dataset covering 0.1° grid points across the entire region.

[0026] In this embodiment of the disclosure, the daily low-resolution meteorological element field set includes the low-resolution meteorological element field for each day.

[0027] Preferably, the target MINet model is obtained in the following way: Low-resolution meteorological field data for multiple historical moments corresponding to the plateau region were extracted from the CMIP6 global climate model dataset. Obtain the ERA5 land surface reanalysis dataset and extract high-resolution meteorological element fields for multiple historical moments corresponding to the plateau region from the ERA5 land surface reanalysis dataset. Based on the relationship of time matching, a training sample set is determined based on the first low-resolution meteorological element field, the geospatial static feature field and the high-resolution meteorological element field of multiple different historical times. Among them, each sample in the training sample set includes a second joint input feature and a label. The second joint input feature includes the low-resolution meteorological element field and the geospatial static feature field of a historical time, and the label includes a high-resolution meteorological element field of a corresponding historical time. The MINet model is trained based on the training sample set to obtain the target MINet model.

[0028] In this way, by using the low-resolution meteorological element field corresponding to the plateau region in the CMIP6 global climate model dataset and the geospatial static feature field corresponding to the plateau region in the SRTM digital elevation model dataset as joint inputs, and using the high-resolution meteorological element field corresponding to the plateau region in the ERA5 land surface reanalysis dataset as prediction labels, the MINet model (Multi-scale Interactive Network) is trained to obtain the target MINet model, so as to obtain a model that can extrapolate high-resolution local meteorological data from low-resolution global climate model data.

[0029] In this embodiment, the CMIP6 global climate model dataset originates from the Sixth Coupled Model Intercomparison Project (CMIP6). Global climate models with superior performance simulating the Tibetan Plateau region (such as MPI-ESM1-2-HR and EC-Earth3) are selected as trends for future climate prediction. This embodiment collects key meteorological variables from this dataset, including daily maximum and minimum temperatures (using both as daily temperatures), precipitation, hourly atmospheric relative humidity, and surface shortwave radiation. These variables cover the historical retrospective period (1950-2014) and the future projection period (2015-2100), and include multiple shared socioeconomic path scenarios such as SSP2-4.5 (moderate forcing) and SSP5-8.5 (high forcing). Although its original spatial resolution is low (approximately 1 degree of longitude × 1 degree of latitude), it can provide large-scale trends in the evolution of the climate background field. In this embodiment, it serves as a low-resolution dynamic input to a deep learning downscaling model, driving the model to generate future climate scenarios.

[0030] For example, from the CMIP6 global climate model dataset, daily maximum and minimum temperatures (using daily maximum and minimum temperatures as daily temperatures), precipitation, and hourly atmospheric relative humidity variables for the plateau region are extracted. These variables are pre-adjusted to the target grid size using bicubic interpolation to provide large-scale climate background information that evolves over time, serving as a low-resolution meteorological element field, i.e., a low-resolution dynamic input tensor. The CMIP6 global climate model dataset originates from the Sixth Coupled Model Intercomparison Project (CMIP6). Global climate models with superior performance simulating the Tibetan Plateau region (such as MPI-ESM1-2-HR and EC-Earth3) are selected as trends for future climate predictions. This disclosure collects key meteorological variables from this dataset, including daily maximum and minimum temperatures, precipitation, hourly relative humidity, and surface shortwave radiation. It covers the historical retrospective period (1950-2014) and the future projection period (2015-2100), and includes multiple shared socioeconomic path scenarios such as SSP2-4.5 (moderate forcing) and SSP5-8.5 (high forcing). Although its original spatial resolution is low (approximately 1 degree of longitude × 1 degree of latitude), it can provide large-scale trends in the evolution of the climate background field. In this disclosure, it serves as a low-resolution dynamic input to a deep learning downscaling model to drive the model to generate future climate scenarios.

[0031] Digital elevation data and normalized latitude and longitude coordinate grids for the plateau region are extracted from the SRTM digital elevation model data. This time-invariant data provides terrain constraints, serving as the corresponding geospatial static feature field for the plateau region, i.e., a high-resolution static auxiliary tensor. The SRTM digital elevation model dataset originates from the Shuttle Radar Topography Mission (SRTM) and provides high-precision topographic information covering the entire Tibetan Plateau. Its spatial resolution is 1 / 3601 latitude × 1 / 3601 longitude. Since the temperature on the Tibetan Plateau decreases significantly with increasing altitude, this static dataset plays a crucial physical guiding role in this embodiment. As a covariate input into the deep learning network, it enables the model to learn the nonlinear mapping relationship between altitude, temperature, and precipitation, thereby significantly improving interpolation accuracy under complex terrain.

[0032] From the ERA5 land surface reanalysis dataset, variables such as daily maximum and minimum temperatures, precipitation, and hourly relative humidity (i.e., the first relative humidity of each hour) corresponding to the plateau region are extracted and used as a high-resolution meteorological element field, namely, a high-resolution meteorological forecast tensor. The spatial resolution is set to 0.1 longitude × 0.1 latitude (approximately 9 km in the latitudinal region of the Qinghai-Tibet Plateau). The ERA5 land surface reanalysis dataset is the fifth-generation land surface reanalysis data released by the European Centre for Medium-Range Weather Forecasts (ECMWF), and is widely recognized as one of the most accurate and spatiotemporally continuous meteorological datasets globally. This embodiment collects data from the ERA5 land surface reanalysis dataset, including air temperature at a height of 2 meters, total precipitation, dew point temperature, and shallow soil moisture content (mainly including daily air temperature, hourly first relative humidity, and precipitation at each grid point). Its spatial resolution is approximately 0.25 latitude × 0.25 longitude, and its temporal resolution is 1 hour, covering the period from 1950 to the present. In this embodiment, the 1-hour resolution of the ERA5 dataset is converted to a 1-day timeframe to output the daily maximum and minimum temperatures. This dataset is considered to be the true value reflecting the actual climate conditions on the Earth's surface. It serves as a high-resolution label in the subsequent training phase of the MINet (Multi-scale Interactive Network) model. The network parameters are updated by calculating the loss function between the predicted values ​​and the true values, ensuring that the downscaling model can learn the true atmospheric physical characteristics.

[0033] This mapping relationship can be expressed by the following mathematical formula: In the formula, Characterizing high-resolution weather forecast tensors, Characterizes low-resolution dynamic input tensors. Characterizing high-resolution static auxiliary tensors, This represents the set of parameters to be trained in the deep neural network, including convolutional kernel weights and bias terms. Through this mapping function, the model can... Macroclimate trends and Effective integration of micro-topographic features.

[0034] The MINet model uses a multi-scale interactive network (MINet) as the mapping function. The backbone architecture of this network is specifically designed for image super-resolution reconstruction tasks. Its core feature lies in the introduction of a multi-scale interaction module. In traditional encoder-decoder structures, features are typically downsampled and then upsampled layer by layer, which easily leads to the loss of details. MINet, however, establishes bidirectional connections between feature branches at different resolutions, enabling continuous information exchange between large-scale climate background and small-scale elevation details. To achieve physical guidance, a channel splicing strategy is used at the network input, fusing static elevation data as an independent feature channel with meteorological data. During convolution operations, elevation data participates in feature extraction as a priori condition. Due to the significant correlation between temperature on the Tibetan Plateau, the network automatically captures the strong correlation between the numerical gradients of the elevation channel and the temperature channel during training.

[0035] In this embodiment, to ensure the physical realism of the refined data generated by the downscaling model, a supervised learning strategy is employed to train the model. Historically high-precision ERA5-Land reanalysis data is used as the ground truth label. The period from 1950 to 2014 was selected as the timeframe for model construction and training. During training, the predicted values ​​were required to be numerically close to the true values. The mathematical expression of the loss function is as follows: In the formula, Characterize the loss value, Represents the number of training samples. Characterizing the first training samples, Characterizing the first A truth value label, Characterizing the first After training and parameter fixing of the MINet model, the target MINet model is used to predict and reconstruct meteorological parameters for the Tibetan Plateau within the future design baseline period (50 years in this example). First, representative shared socioeconomic paths (SSPs) scenario data from the CMIP6 database are selected as driving inputs. Typically, SSP2-4.5 (moderate forcing) and SSP5-8.5 (high forcing) scenarios are chosen to cover the uncertainties of future climate change. These low-resolution future daily temperature, precipitation, and relative humidity data are constructed as dynamic input tensors for the prediction stage and simultaneously input into the trained target MINet model along with the high-resolution static topographic tensor of the study area. The model performs forward inference with parameters frozen, and uses the learned topographic-climate nonlinear mapping rules to downscale and reconstruct the coarse global climate prediction data into a future high-resolution daily meteorological dataset covering 0.1° grid points across the entire region, thus obtaining the high-resolution daily meteorological dataset.

[0036] Preferably, the high-resolution daily meteorological dataset includes daily temperature, hourly first relative humidity, and precipitation for each grid point, where the first relative humidity characterizes the atmospheric relative humidity; the determination of the number of natural effective freeze-thaw cycles for each grid point in the plateau region within the future design reference period based on the high-resolution daily meteorological dataset includes: For each grid point, based on the hourly first relative humidity of that grid point, determine the hourly second relative humidity, and... The soil conductivity at this grid point is obtained, and the corresponding equilibrium hygroscopic saturation is determined based on the soil conductivity at this grid point and the hourly second relative humidity. Based on the hourly precipitation and equilibrium hygroscopic saturation of the grid point, the hourly surface saturation of the concrete was determined, and Based on the critical saturation and salt-induced freezing point reduction mechanism, combined with daily temperature, the effective freeze-thaw damage assessment for each hour is determined; among them, the second relative humidity characterizes the relative humidity within the pores of the concrete surface, and the effective freeze-thaw damage assessment includes whether effective freeze-thaw has occurred. Based on the hourly effective freeze-thaw damage assessment of each grid point, the number of natural effective freeze-thaw cycles for each grid point within the future design reference period is determined.

[0037] Atmospheric relative humidity is only a boundary condition for the concrete surface, while the pore humidity of the concrete surface layer lags behind the actual atmospheric humidity. Therefore, the relative humidity within the pores of the concrete surface layer is determined based on the hourly relative humidity of the ambient air at each grid point; then, the corresponding equilibrium hygroscopic saturation is determined by combining soil conductivity and the hourly second relative humidity. This is achieved by introducing soil conductivity... As a correction term, it reflects the enhancing effect of salt deliquescence on hygroscopic capacity. Since natural precipitation triggers capillary water absorption, a process much faster than adsorption and rapidly saturates the pores, the hourly surface saturation of concrete can be accurately determined by using hourly precipitation data and equilibrium hygroscopic saturation based on the grid points. According to Fagerlund's critical saturation theory, only when the pore water content of concrete exceeds a certain threshold (critical saturation) can the surface saturation be accurately determined. Only when the volumetric expansion pressure generated by pore water freezing exceeds the tensile strength of the concrete matrix will substantial freeze-thaw damage occur. Simultaneously, considering the widespread salinization environment of the Qinghai-Tibet Plateau, the salt ion concentration in the pore solution significantly lowers the freezing point of the liquid phase. By combining critical saturation and the salt-induced freezing point reduction mechanism with daily air temperature, the effective freeze-thaw damage assessment for each hour can be accurately determined.

[0038] Preferably, determining the hourly second relative humidity based on the hourly first relative humidity of the grid point includes: iteratively calculating the relative humidity of the concrete surface. : In the formula, The second relative humidity at time t is the relative humidity within the pores of the concrete surface. The first relative humidity at time t is output by the target MINet model. Relative humidity of the atmospheric environment at any time; Characterized by the relative humidity within the pores of the concrete surface at the previous moment (i.e. (second relative humidity at time). The humidity response coefficient characterizes the rate at which the surface concrete responds to changes in the external environment, and its value ranges from 0 to 1. > hour, Take 0.2, otherwise take 0.05.

[0039] Preferably, the hourly equilibrium hygroscopic saturation is determined based on the soil conductivity and the hourly relative humidity at the grid point, including: In the formula, Characterizes the equilibrium moisture saturation at time t, that is, the surface saturation caused solely by moisture absorption; The limiting hygroscopic saturation of concrete at 100% humidity is taken as 0.85; The second relative humidity at time t; The moisture absorption index of the material is taken as 5. The soil conductivity, i.e. the saturated mud conductivity, is characterized by data from the HWSD database. The coefficient characterizing the hygroscopic enhancement of salt is used to quantify the increase in equilibrium moisture content caused by an increase in salt concentration.

[0040] During non-rainfall periods, the moisture content within concrete is primarily controlled by adsorption mechanisms. Based on the characteristics of concrete adsorption isotherms, and simplifying engineering calculations using power functions, soil electrical conductivity is introduced, based on the colligative property principle of dilute solutions. As a correction term, it reflects the enhancing effect of salt deliquescence on hygroscopic capacity.

[0041] Preferably, based on the hourly precipitation and hourly equilibrium hygroscopic saturation of the grid point, the hourly concrete surface saturation is determined, including: integrating the above-mentioned hygroscopic model with precipitation events to estimate... Surface saturation of concrete at time : In the formula, Characterization The surface saturation of concrete at any given time. Characterization Rainfall at any given time; The effective precipitation threshold is defined as 0.1 mm / h. The equilibrium hygroscopic saturation at time t is represented. This logic indicates that once effective rainfall occurs, the surface saturation is forcibly reset to 1.0; after the rain stops, the saturation will decrease accordingly. It decreased and then slowly declined.

[0042] Preferably, daily temperatures include the daily maximum and minimum temperatures. Based on the critical saturation and salt-induced freezing point depression mechanism, and combined with daily temperatures, the effective freeze-thaw damage assessment for each hour is determined, including: In the formula, Characterizes the effective freeze-thaw damage assessment at time t. (Modified freezing point) characterization takes into account the decrease in freezing point caused by the salt concentration of the pore solution. The critical saturation level, representing the moisture threshold at which concrete suffers frost heave damage, is set to 0.85 in this embodiment. That is, only when the surface saturation exceeds 85% and the temperature crosses the corrected freezing point is a valid freeze-thaw cycle counted. If =1, then the effective freeze-thaw damage at time t is determined to be an effective freeze-thaw event. If the value is 0, then the effective freeze-thaw damage at time t is determined as no effective freeze-thaw has occurred.

[0043] Preferably, the salinity acceleration factor for each grid point within the plateau region is obtained, including: Based on the HWSD soil database, the soil electrical conductivity at each grid point in the plateau region was determined. For each grid point within the plateau region, the salinization acceleration factor for that grid point is determined using the following formula, based on the soil electrical conductivity of that grid point: In the formula, Characterizing the salt-accelerating factor, Characterizing the growth coefficient, Characterizes the preset effective threshold. This represents the preset maximum acceleration limit. Characterizes soil electrical conductivity.

[0044] Because the Qinghai-Tibet Plateau is widely covered with salt lakes and saline soils, the sulfates and chlorides in the soil not only generate crystallization expansion pressure but also react chemically with concrete hydration products, leading to a loose microstructure in the concrete. This coupling effect of chemical corrosion and physical frost heave significantly accelerates the deterioration process of concrete. Therefore, this disclosure does not consider salt erosion as an independent destructive process but instead constructs a damage acceleration factor based on soil conductivity to correct for the physically effective freeze-thaw cycle. First, a quantitative characterization index for salt erosion intensity is determined. This disclosure extracts the surface saturated mud conductivity from the HWSD soil database, i.e., soil conductivity (…). (unit: dS / m) is used as the core parameter. The value reflects the total concentration of soluble salt ions in the soil. Based on this physical law, embodiments of this disclosure construct a salt acceleration factor. With soil electrical conductivity A nonlinear mapping function between the two regions. This function is designed in a piecewise form to take into account the different destructive characteristics of the non-saltified area, the transition zone, and the heavily saline area.

[0045] In this embodiment, To preset the effective threshold (4 dS / m in this embodiment), when Below this value, it is considered a non-salinized environment, and the acceleration factor is set to 1.0, that is, only pure physical freeze-thaw is considered; The saturation threshold (30 dS / m in this embodiment) is when When the value is higher than this, it is considered a highly saline soil or salt lake environment, at which point the salt solution concentration is close to the eutectic point or reaches the upper limit of the chemical reaction rate. The maximum acceleration limit is set to 2.5 in this embodiment, which means that under extreme salt freezing conditions, the damage rate is 2.5 times that of pure water freeze-thaw under the same conditions.

[0046] Preferably, the high-resolution daily meteorological dataset includes daily temperatures for each grid point; the determination of the cumulative equivalent standard freeze-thaw cycle number within the future design reference period, based on the salt acceleration factor correction for the number of natural effective freeze-thaw cycles, includes: For each grid point within the plateau region, based on daily air temperature, determine the average cooling rate and actual freezing temperature difference for each natural effective freeze-thaw cycle during the future design reference period, as well as... Based on the salt acceleration factor, the number of naturally effective freeze-thaw cycles in the future design reference period, the average cooling rate at each naturally effective freeze-thaw cycle, and the actual freezing temperature difference, the cumulative equivalent standard freeze-thaw cycle count for this grid point in the future design reference period is determined using the following formula: In the formula, Characterizes the cumulative equivalent standard freeze-thaw cycles during the future design reference period. Characterizes the number of naturally effective freeze-thaw cycles within the future design baseline period. Characterizing the salt-accelerating factor, Characterizing the first Average cooling rate of one natural effective freeze-thaw cycle Characterizing the cooling rate of a standard laboratory rapid freezing test, Characterizing the first The actual freezing temperature difference of one natural effective freeze-thaw cycle. Characterizing the center freezing temperature of a standard laboratory rapid freezing test, , Characterizes the fatigue correction index of materials.

[0047] Assuming that the damage to concrete in a single freeze-thaw cycle is independent, and the total damage is equal to the linear sum of the damage from each cycle, based on Powers' hydrostatic pressure theory and the fatigue damage characteristics of concrete, the damage caused by a single freeze-thaw cycle mainly depends on the cooling rate (determining the rate of ice pressure formation) and the extreme freezing temperature difference (determining the maximum ice pressure). Therefore, this disclosure defines the first... The equivalent factor of the second-corrected effective freeze-thaw cycles relative to the laboratory standard cycles This means obtaining the cumulative equivalent standard freeze-thaw cycle count within the future design reference period.

[0048] In this embodiment of the disclosure, Used to introduce the amplification effect of chemical corrosion on physical damage; Characterizing the first Average cooling rate of one natural effective freeze-thaw cycle ( The mean of the first derivative of the temperature time history curve output by MINet during the cooling phase is determined; The cooling rate, characterized by a laboratory standard rapid freezing test, is taken as the standard value of 12. ; Characterizing the first The actual freezing temperature difference of one natural effective freeze-thaw cycle, i.e. (0 - ); The core freezing temperature, characterized by the standard laboratory rapid freezing test, is taken as the specified value of 18. ; , The fatigue correction index characterizes the material and reflects the sensitivity of the concrete microstructure to cooling rate and temperature difference. In this embodiment... Take 0.946, Take 1.0.

[0049] In this embodiment, a sinusoidal-exponential composite interpolation model is used to discretize the daily temperature output by the MINet model into an hourly time series. Based on atmospheric physical laws, this model divides the daily temperature change into a daytime warming period and a nighttime cooling period: a sinusoidal function is used to simulate the warming process caused by solar radiation from sunrise to sunset, and an exponential function is used to simulate the cooling process caused by long-wave radiation from sunset to the next day's sunrise. Specifically, the hourly temperature... The calculation formula is as follows: In the formula, Time (0~23h); and These are the highest and lowest temperatures of the day; , These are the sunrise and sunset times, determined by the local latitude and date. Daytime length; The lag time for the highest temperature (usually taken as 2-3 hours); Temperature at sunset; This represents the nighttime cooling attenuation coefficient. This will be the lowest temperature of the following day. This represents the day / night offset.

[0050] Based on hourly temperature The average cooling rate and the actual freezing temperature difference of each corrected effective freeze-thaw cycle were determined.

[0051] Preferably, the service environment of concrete structures in plateau areas is classified based on the cumulative equivalent standard freeze-thaw cycles of each grid point within the future design reference period, including: The cumulative equivalent standard freeze-thaw cycles of all grid points in the plateau region during the future design reference period are statistically analyzed to form a one-dimensional attribute dataset. The Jenks algorithm is used to find natural inflection points in a one-dimensional attribute dataset and determine the optimal threshold set. Based on the cumulative equivalent standard freeze-thaw cycles and optimal threshold set of each grid point in the plateau region during the future design reference period, the severity level of each grid point in the plateau region is determined to classify the service environment of concrete structures in the plateau region.

[0052] Because freeze-thaw cycles in nature are highly random, their cooling rate, freezing temperature difference, and duration all fluctuate with meteorological conditions. The concrete freeze-thaw resistance design code GB / T50082-2009 is based on a standard rapid freezing method with a constant cooling rate and fixed temperature difference. To enable environmental zoning results to directly guide engineering design, this embodiment utilizes a salt concentration acceleration factor to perform indoor equivalent corrections on the effective freeze-thaw cycle count within the future design reference period, obtaining the cumulative equivalent standard freeze-thaw cycle count for each grid point in the plateau region within the future design reference period. Based on the spatial distribution characteristics of the cumulative equivalent damage index, the freeze-thaw resistance design level of concrete structures on the Qinghai-Tibet Plateau is scientifically classified. Considering the non-uniformity of data distribution and the convenience of engineering application, this embodiment uses Jenks' natural breakpoint method for cluster analysis. Based on the calculated optimal threshold set, the service environment of concrete structures on the Qinghai-Tibet Plateau is classified, thus breaking down the technical barriers between macroscopic meteorological parameters and current engineering design codes, allowing the zoning results to directly guide the selection of concrete freeze-thaw resistance levels. This method avoids the economic waste caused by blindly setting up defenses in arid areas, and ensures the long-term durability and safety of major infrastructure in saline soil areas, thus having significant engineering application value and economic benefits.

[0053] Preferably, the Jenks algorithm is used to find natural inflection points in a one-dimensional attribute dataset to determine the optimal threshold set. This includes using the Jenks algorithm to find natural inflection points in the data sequence, the calculation principle of which is to reduce the variance within the same category and increase the variance between different categories. That is, through iterative calculation, a set of classification thresholds is found. This minimizes the data differences within each category while maximizing the differences between different categories. Mathematically, this can be expressed as minimizing the following objective function. (Goodness of Variance Fit): In the formula, This is the sum of squared deviations for class means. The sum of squared deviations for array mean is used to obtain the optimal threshold set.

[0054] Preferably, the optimal threshold set includes a first threshold, a second threshold, and a third threshold; the determination of the severity level of each grid point in the plateau region based on the cumulative equivalent standard freeze-thaw cycles and the optimal threshold set within the future design reference period includes: For each grid point within the plateau region, if the cumulative equivalent standard freeze-thaw cycles during the future design reference period are less than the first threshold, then the severity level of that grid point is arid zone. If the first threshold ≤ the cumulative equivalent standard freeze-thaw cycles within the future design reference period < the second threshold, then the severity level of this grid point is a general freeze-thaw zone. If the second threshold ≤ the cumulative equivalent standard freeze-thaw cycles within the future design reference period < the third threshold, then the severity level of this grid point is a severe freeze-thaw zone. If the cumulative equivalent standard freeze-thaw cycles during the future design reference period are greater than or equal to the third threshold, then the severity level of the grid point is a salt-freezing extremely dangerous zone; where the first threshold < the second threshold < the third threshold.

[0055] Based on the calculated optimal threshold set, the service environment of concrete structures on the Qinghai-Tibet Plateau is divided into four severity levels. Characterized by the cumulative equivalent standard freeze-thaw cycles during the future design reference period. Zone I (Slightly Dry / Dry Zone): (First preset threshold). This area is mainly distributed in extremely arid or low-altitude regions. Although the temperature is low, the lack of water or salinity results in minimal actual damage, and general protection can be carried out according to structural requirements. Zone II (General freeze-thaw zone): (Second preset threshold). This area is a typical freeze-thaw environment and requires freeze-thaw resistance design according to standard cold region requirements. Zone III (Severe Freeze-Thaw Zone): (Third preset threshold). This area experiences high rainfall and drastic temperature fluctuations, classifying it as a high-risk zone requiring the use of high-performance air-entrained concrete. Zone IV (Extremely Risky Salt-Freezing Zone): (Third preset threshold). This area mainly overlaps with highly saline soils or the vicinity of salt lakes (such as the Qaidam Basin), and is subjected to both physical frost heave and chemical corrosion, necessitating the adoption of combined salt-frost resistance measures. This allows for the scientific and rapid delineation of the service environment of concrete structures on the Qinghai-Tibet Plateau.

[0056] Preferably, a method for zoning the freeze-thaw environment of concrete in plateau regions further includes: generating a visual zoning map based on the results of classifying the service environment of concrete structures in plateau regions.

[0057] In this way, by generating a visual zoning map, the severity level of the service environment of plateau concrete structures becomes clear.

[0058] Preferably, a method for environmental zoning of concrete freeze-thaw action in plateau regions further includes: For each grid point in the plateau region, the corrected effective freeze-thaw cycle count for the future design reference period is obtained by correcting the natural effective freeze-thaw cycle count for that grid point based on the salinity acceleration factor using the following formula: In the formula, Characterizes the corrected effective freeze-thaw cycle count during the future design baseline period. Characterizes the number of naturally effective freeze-thaw cycles during the future design reference period. Characterizing the salt acceleration factor.

[0059] Thus, using the calculated salt acceleration factor, the number of natural effective freeze-thaw cycles can be determined. By performing point-by-point corrections, the corrected effective freeze-thaw cycle count considering the salt-freeze coupling effect is obtained. This index equates the additional damage caused by chemical corrosion to an increase in the number of physical freeze-thaw cycles, thus enabling it to be combined with the damage mechanism of concrete under salt-freeze coupling, and to assess the effective number of natural freeze-thaw cycles. The corrections were made to obtain a more accurate effective number of freeze-thaw cycles.

[0060] In this embodiment of the disclosure, a visual effective freeze-thaw cycle count map can also be formed based on the corrected effective freeze-thaw cycle count of each grid point in the future design reference period, so as to make the effective freeze-thaw cycle count of concrete in plateau areas in the future design reference period more intuitive.

[0061] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for environmental zoning of concrete freeze-thaw action in plateau regions, characterized in that, include: Obtain high-resolution daily meteorological datasets for plateau regions during the future design reference period; Based on high-resolution daily meteorological datasets, the number of natural effective freeze-thaw cycles for each grid point in the plateau region during the future design baseline period was determined, and the salinity acceleration factor for each grid point in the plateau region was obtained. For each grid point in the plateau region, the number of natural effective freeze-thaw cycles in the future design reference period is corrected based on the salt acceleration factor, and the cumulative equivalent standard freeze-thaw cycle number in the future design reference period is determined. The service environment of concrete structures in plateau regions is classified based on the cumulative equivalent standard freeze-thaw cycles of each grid point within the future design reference period.

2. The method according to claim 1, characterized in that, The acquisition of high-resolution daily meteorological datasets for the plateau region during the future design reference period includes: From the CMIP6 global climate model dataset, daily low-resolution meteorological element fields of the plateau region during the future design reference period are extracted to obtain a daily low-resolution meteorological element field set. Extract the geospatial static feature field corresponding to the plateau region from the SRTM digital elevation model data; Using a low-resolution meteorological element field and a geospatial static feature field from the daily low-resolution meteorological element field set as the first joint input feature, a pre-trained target MINet model is used to predict and determine the high-resolution daily meteorological dataset for the plateau region in the future design baseline period; wherein, the target MINet model is used to predict the corresponding high-resolution meteorological element field based on the low-resolution meteorological element field of the plateau region under the static topographic constraints of the plateau region.

3. The method according to claim 2, characterized in that, The target MINet model is obtained in the following way: Low-resolution meteorological field data for multiple historical moments corresponding to the plateau region were extracted from the CMIP6 global climate model dataset. We acquired the ERA5 land surface reanalysis dataset and extracted high-resolution meteorological field data for multiple historical moments corresponding to the plateau region from the ERA5 land surface reanalysis dataset. Based on the relationship of time matching, a training sample set is determined based on the first low-resolution meteorological element field, the geospatial static feature field and the high-resolution meteorological element field of multiple different historical times. Among them, each sample in the training sample set includes a second joint input feature and a label. The second joint input feature includes the low-resolution meteorological element field and the geospatial static feature field of a historical time, and the label includes a high-resolution meteorological element field of a corresponding historical time. The MINet model is trained based on the training sample set to obtain the target MINet model.

4. The method according to claim 1, characterized in that, The high-resolution daily meteorological dataset includes daily temperature, hourly first relative humidity, and precipitation for each grid point. The first relative humidity represents the relative humidity of the atmospheric environment. The determination of the number of natural effective freeze-thaw cycles for each grid point in the plateau region within the future design baseline period based on high-resolution daily meteorological datasets includes: For each grid point, based on the hourly first relative humidity of that grid point, determine the hourly second relative humidity, and... The soil conductivity at this grid point is obtained. Based on the soil conductivity at this grid point and the hourly relative humidity, the hourly equilibrium hygroscopic saturation is determined. Based on the hourly precipitation and hourly equilibrium hygroscopic saturation of the grid point, the hourly surface saturation of the concrete was determined, and Based on the critical saturation and salt-induced freezing point reduction mechanism, combined with daily temperature, the effective freeze-thaw damage assessment for each hour is determined; among them, the second relative humidity characterizes the relative humidity within the pores of the concrete surface, and the effective freeze-thaw damage assessment includes whether effective freeze-thaw has occurred. Based on the hourly effective freeze-thaw damage assessment of each grid point, the number of natural effective freeze-thaw cycles for each grid point within the future design reference period is determined.

5. The method according to claim 1, characterized in that, The acquisition of the salinity acceleration factor at each grid point in the plateau region includes: Based on the HWSD soil database, the soil electrical conductivity at each grid point in the plateau region was determined. For each grid point within the plateau region, the salinization acceleration factor for that grid point is determined using the following formula, based on the soil electrical conductivity of that grid point: In the formula, Characterizing the salt-accelerating factor, Characterizing the growth coefficient, Characterizes the preset effective threshold. This represents the preset maximum acceleration limit. Characterizes soil electrical conductivity.

6. The method according to claim 1, characterized in that, The high-resolution daily meteorological dataset includes daily temperatures for each grid point; the determination of the cumulative equivalent standard freeze-thaw cycle number within the future design reference period, based on the salt acceleration factor correction, includes: For each grid point within the plateau region, based on daily air temperature, determine the average cooling rate and actual freezing temperature difference for each natural effective freeze-thaw cycle during the future design reference period, as well as... Based on the salt acceleration factor, the number of naturally effective freeze-thaw cycles in the future design reference period, the average cooling rate at each naturally effective freeze-thaw cycle, and the actual freezing temperature difference, the cumulative equivalent standard freeze-thaw cycle count for this grid point in the future design reference period is determined using the following formula: In the formula, Characterizes the cumulative equivalent standard freeze-thaw cycles during the future design reference period. Characterizes the number of naturally effective freeze-thaw cycles within the future design baseline period. Characterizing the salt-accelerating factor, Characterizing the first Average cooling rate of one natural effective freeze-thaw cycle Characterizing the cooling rate of a standard laboratory rapid freezing test, Characterizing the first The actual freezing temperature difference of one natural effective freeze-thaw cycle. Characterizing the center freezing temperature of a standard laboratory rapid freezing test, , Characterizes the fatigue correction index of materials.

7. The method according to claim 1, characterized in that, The service environment of concrete structures in plateau regions is classified based on the cumulative equivalent standard freeze-thaw cycles of each grid point within the future design reference period, including: The cumulative equivalent standard freeze-thaw cycles of all grid points in the plateau region during the future design reference period are statistically analyzed to form a one-dimensional attribute dataset. The Jenks algorithm is used to find natural inflection points in a one-dimensional attribute dataset and determine the optimal threshold set. Based on the cumulative equivalent standard freeze-thaw cycles and optimal threshold set of each grid point in the plateau region during the future design reference period, the severity level of each grid point in the plateau region is determined to classify the service environment of concrete structures in the plateau region.

8. The method according to claim 7, characterized in that, The optimal threshold set includes a first threshold, a second threshold, and a third threshold; the severity level of each grid point in the plateau region is determined based on the cumulative equivalent standard freeze-thaw cycles and the optimal threshold set during the future design reference period, including: For each grid point within the plateau region, if the cumulative equivalent standard freeze-thaw cycles during the future design reference period are less than the first threshold, then the severity level of that grid point is arid zone. If the first threshold ≤ the cumulative equivalent standard freeze-thaw cycles within the future design reference period < the second threshold, then the severity level of this grid point is a general freeze-thaw zone. If the second threshold ≤ the cumulative equivalent standard freeze-thaw cycles within the future design reference period < the third threshold, then the severity level of this grid point is a severe freeze-thaw zone. If the cumulative equivalent standard freeze-thaw cycles during the future design reference period are greater than or equal to the third threshold, then the severity level of the grid point is a salt-freezing extremely dangerous zone; where the first threshold < the second threshold < the third threshold.

9. The method according to any one of claims 1 to 8, characterized in that, Also includes: Based on the results of classifying the service environment of concrete structures in plateau areas, a visual zoning map is generated.

10. The method according to any one of claims 1 to 8, characterized in that, Also includes: For each grid point in the plateau region, the corrected effective freeze-thaw cycle count for the future design reference period is obtained by correcting the natural effective freeze-thaw cycle count for that grid point based on the salinity acceleration factor using the following formula: In the formula, Characterizes the corrected effective freeze-thaw cycle count during the future design baseline period. Characterizes the number of naturally effective freeze-thaw cycles during the future design reference period. Characterizing the salt acceleration factor.

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