Environment zoning method for freeze-thaw damage of concrete structure

Abstract

The invention discloses an environment zoning method for freeze-thaw damage of a concrete structure, and belongs to the technical field of durability evaluation of the concrete structure, and the method comprises the following steps: obtaining material characteristic data of the concrete structure and historical meteorological data of a corresponding region; wherein the historical meteorological data comprises atmospheric temperature, solar radiation and wind speed; on the basis of a Holt-Winters method, meteorological data in a concrete structure design reference period are obtained according to historical meteorological prediction; dividing the map layout into grid points of 0.25 latitude * 0.25 longitude based on the spatial-temporal resolution of ERA5; randomly selecting any grid point as a target point, calculating to obtain a concrete surface temperature field of a target point daily scale according to the meteorological data, and calculating temperature field change along the depth direction of the concrete structure; obtaining the equivalent freezing and thawing times of the target point concrete structure at different depths according to the temperature field change, and calculating the overall equivalent freezing and thawing times of the daily-scale concrete structure; obtaining the overall equivalent freeze-thaw damage of the target point concrete structure in the design reference period according to the overall equivalent freeze-thaw times of the daily scale; and repeating the steps, and generating an environment zoning map of the freeze-thaw damage of the concrete structure according to the obtained overall equivalent freeze-thaw damage of all the grid points.

Description

Technical Field

[0001] This invention belongs to the technical field of concrete structure durability assessment, specifically relating to an environmental zoning method for freeze-thaw damage to concrete structures. Background Technology

[0002] Freeze-thaw damage is one of the core controlling factors inducing the degradation of the durability of concrete structures in severe cold and cold regions. The service environment of concrete exhibits significant spatiotemporal randomness and complex coupling characteristics. Therefore, quantitatively characterizing the performance evolution of concrete structures under the influence of the service environment is a highly challenging and key scientific problem in the field of civil engineering.

[0003] Existing technologies are mostly based on historical climate statistics over the past few decades to construct a freeze-thaw zoning system for concrete materials with indoor equivalent freeze-thaw cycles as the core indicator. However, this type of method has obvious limitations: the accuracy of historical climate data is insufficient, making it difficult to support the needs of refined zoning; the indoor equivalent indicators applicable to concrete materials deviate from the freeze-thaw damage response of actual engineering structures, which can easily lead to distorted structural damage assessment; and the evolution trend of the climate system is not considered, making it unable to adapt to structural durability analysis under future climate scenarios.

[0004] Therefore, there is an urgent need for an environmental zoning method for freeze-thaw damage to concrete structures to solve the problems existing in the current technology. Summary of the Invention

[0005] In view of this, the present invention provides an environmental zoning method for freeze-thaw damage of concrete structures, which solves the problem that existing technologies cannot couple with future climate evolution patterns to achieve accurate zoning of the service environment of freeze-thaw damage of concrete structures in different regions.

[0006] To achieve the above objectives, the present invention provides an environmental zoning method for freeze-thaw damage of concrete structures, comprising: Acquire material property data of the concrete structure and historical meteorological data of the corresponding area; the historical meteorological data includes: atmospheric temperature, solar radiation and wind speed; Based on the Holt-Winters method, meteorological data for the design reference period of concrete structures are obtained from historical meteorological forecasts. Based on ERA5's spatiotemporal resolution, the map area is divided into grid points of 0.25 latitude × 0.25 longitude; Randomly select any grid point as the target point, calculate the daily-scale concrete surface temperature field of the target point based on meteorological data, and calculate the temperature field change along the depth direction of the concrete structure. The equivalent freeze-thaw cycles at different depths of the concrete structure at the target point are obtained based on the temperature field changes, and the overall equivalent freeze-thaw cycles of the concrete structure on a daily scale are calculated. The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. Repeat the above steps to generate an environmental zoning map of freeze-thaw damage to concrete structures based on the overall equivalent freeze-thaw damage of all obtained grid points.

[0007] As an embodiment of the present invention, based on the Holt-Winters method, meteorological data for the design reference period of concrete structures are obtained from historical meteorological forecasts, including: The Holt-Winters additive model was used to obtain meteorological data for the design reference period of the concrete structure based on historical meteorological forecasts. The Holt-Winters additive model is shown below: In the formula, express( The actual value of the time series for the period. , and Both represent smoothing equations. Indicates the number of backward smoothing periods. Indicates the first An exponentially smoothed value that removes the long-term trend from a time series data set after removing periodic variations. Indicates the first Exponentially smoothed values ​​of long-term trend variables Indicates the first The periodic variation cycle is The exponentially smoothed value, , and All represent smoothing coefficients. Indicates the period length.

[0008] As an embodiment of the present invention, the daily-scale concrete surface temperature field at the target point is calculated based on meteorological data, and the temperature field variation along the depth direction of the concrete structure is calculated, including: The surface temperature of the concrete structure is calculated based on meteorological data, using the following formula: In the formula, Indicates the target point's location Surface temperature at any given time Indicates in The external temperature at any given moment, Indicates the solar radiation absorption coefficient. This indicates the amount of solar radiation. Indicates the overall heat exchange coefficient. Indicates wind speed.

[0009] Divide along the depth direction of the concrete structure The system consists of three equally spaced nodes, and the temperature data for each node is calculated. The nodes include: surface boundary nodes, internal nodes, and internal adiabatic boundary nodes. The temperature data of the surface boundary nodes is calculated using the following formula: In the formula, This indicates the node at the surface boundary at time step. Temperature data at that time Indicates a time step. This indicates the length of each time step.

[0010] The temperature data of the internal nodes is calculated using the following formula: In the formula, Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at that time i Indicates the number of the concrete layers to be divided. , Take the integer part.

[0011] The temperature data for the internal adiabatic boundary nodes is calculated using the following formula: In the formula, This indicates the internal adiabatic boundary node at time step ( Temperature data at that time. Indicates the internal adiabatic boundary node at time step Temperature data at that time This represents the distance between two adjacent nodes. This indicates the internal adiabatic boundary node at time step ( Temperature data at that time. This represents the thermal diffusivity.

[0012] The temperature data for the internal adiabatic boundary nodes and internal nodes are calculated as follows: The temperature field variation of the target point along the depth direction of the concrete structure is obtained based on the temperature data of the surface boundary nodes, internal nodes, and internal thermal insulation boundary nodes.

[0013] As an embodiment of the present invention, the equivalent freeze-thaw cycles at different depths of the concrete structure at the target point are obtained based on the temperature field change, including: According to the preset node division rules, the concrete structure of the target point is divided along the depth direction into ( There are ) concrete structural layers; among which, during the division, it will be divided into Each node.

[0014] Based on preset rules, the number of freeze-thaw cycles and the cooling rate of each concrete structural layer are determined according to the changes in the temperature field. The equivalent number of freeze-thaw cycles for each concrete structural layer is calculated based on the number of freeze-thaw cycles and the cooling rate, using the following formula: In the formula, Indicates the first The equivalent number of freeze-thaw cycles for each concrete structural layer. Indicates the porosity parameter of the material. Indicates the indoor cooling rate. Indicates the first The cooling rate of each concrete structural layer This represents an empirical coefficient; the formula for calculating the material porosity parameter is as follows: In the formula, This represents the spacing coefficient of the concrete structure at the target point. The porosity parameter of the concrete material at the target point. Indicates the radius of the gap. This indicates the volume fraction of cement-based materials. This indicates the air content in the concrete.

[0015] As an embodiment of the present invention, calculating the overall equivalent freeze-thaw cycles of a concrete structure on a daily scale includes: The volume weight of each concrete structural layer is calculated using the following formula: In the formula, Indicates the first Volume weight of each concrete structural layer Indicates the first The depth of each concrete structural layer Indicates the total depth of the concrete structure.

[0016] The freeze-thaw sensitivity weight for each concrete structural layer is calculated using the following formula: In the formula, Indicates the first The average temperature of each concrete structural layer Indicates the ( The average temperature of each concrete structural layer.

[0017] Based on the volumetric weight of the concrete structural layer, the equivalent number of freeze-thaw cycles based on the freeze-thaw sensitivity weight, and the overall equivalent number of freeze-thaw cycles, the calculation formula is as follows: In the formula, This indicates the overall equivalent number of freeze-thaw cycles for a concrete structure within one day. Indicates the first The overall weight of each concrete structural layer.

[0018] As an embodiment of the present invention, the overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles on a daily scale, including: The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. The calculation formula is as follows: In the formula, This represents the overall equivalent freeze-thaw damage at the target point within the baseline period. Indicates the total number of days for the baseline.

[0019] As an embodiment of the present invention, an environmental zoning map of freeze-thaw damage in a concrete structure is generated based on the overall equivalent freeze-thaw damage of all obtained grid points, including: Based on the overall equivalent freeze-thaw damage of all grid points within the design reference period, a one-dimensional data sequence is obtained; Sort the one-dimensional data sequence from smallest to largest, calculate the frequency distribution, mean, and standard deviation of the one-dimensional data sequence, and identify dense and blank intervals in the data; Based on the Jenks algorithm, all possible grouping methods are iteratively calculated to determine a set of breakpoints; Based on the project requirements, output the corresponding breakpoints and mark them on the map with different colors.

[0020] The beneficial effects of this invention are as follows: This technical solution is driven by hourly climate data of 0.25 latitude and longitude grids in ERA5, and innovatively introduces the Holt-Winters prediction method to dynamically extrapolate meteorological data within the design reference period, which can adapt to the full life cycle durability analysis under future climate scenarios; at the same time, by solving the composite temperature boundary and one-dimensional unsteady heat conduction, the freeze-thaw non-uniformity of the concrete structure in the depth direction is quantified, eliminating the deviation between indoor equivalent indicators and actual engineering response, and effectively avoiding damage assessment distortion; finally, by quantifying the cumulative freeze-thaw damage within the design reference period and combining it with the natural breakpoint method for scientific classification, accurate zoning is achieved, which is suitable for durability assessment in extreme environments.

[0021] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0022] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0023] like Figure 1 As shown, the present invention provides an environmental zoning method for freeze-thaw damage to concrete structures, comprising the following steps: S1: Obtain material property data of the concrete structure and historical meteorological data of the corresponding area; among which, historical meteorological data includes: atmospheric temperature, solar radiation and wind speed; S2: Based on the Holt-Winters method, meteorological data for the design reference period of concrete structures are obtained from historical meteorological forecasts. S3: Based on ERA5's spatiotemporal resolution, the map is divided into grid points of 0.25 latitude × 0.25 longitude; S4: Randomly select any grid point as the target point, calculate the daily-scale concrete surface temperature field of the target point based on meteorological data, and calculate the temperature field change along the depth direction of the concrete structure. S5: Based on the temperature field changes, obtain the equivalent freeze-thaw cycles at different depths of the concrete structure at the target point, and calculate the overall equivalent freeze-thaw cycles of the concrete structure on a daily scale. S6: The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. S7: Repeat steps S4-S6 above to generate an environmental zoning map of freeze-thaw damage to concrete structures based on the overall equivalent freeze-thaw damage of all grid points.

[0024] The working principle of the above technical solution is as follows: In the actual differentiation process, ERA5, the fifth-generation global atmospheric reanalysis dataset developed by the European Centre for Medium-Range Weather Forecasts (ECMWF), is used to construct a complete global climate picture from 1940 to the present by fusing multi-source observational data with advanced numerical models. Its data distribution is global, with a 0.25 latitude × 0.25 longitude grid (approximately 31 × 31 km) on the plane and 137 mixed data points vertically. σ - The pressure layer extends from the Earth's surface to an altitude of 80 km, and all data is output hourly, exhibiting extremely high spatiotemporal resolution. The meteorological data to be collected from ERA5 include: atmospheric temperature (2m temperature), total sky direct solar radiation at the surface, and wind speed (10mV component of wind).

[0025] Simultaneously, a benchmark concrete was established based on commonly used engineering concrete materials in the study area to clarify material properties, such as water-cement ratio. w / c ), cement-based volume fraction, air content, pore radius, etc.

[0026] The beneficial effects of the above technical solution are as follows: This technical solution, driven by hourly climate data of ERA5 with a 0.25 latitude and longitude grid, innovatively introduces the Holt-Winters prediction method to dynamically extrapolate meteorological data within the design reference period, which can adapt to the full life cycle durability analysis under future climate scenarios; at the same time, by solving the composite temperature boundary and one-dimensional unsteady heat conduction, the freeze-thaw non-uniformity of concrete in the depth direction is quantified, eliminating the deviation between indoor equivalent indicators and actual engineering response, and effectively avoiding damage assessment distortion; finally, by quantifying the cumulative freeze-thaw damage within the design reference period and combining it with the natural breakpoint method for scientific classification, accurate zoning is achieved, which is suitable for durability assessment under extreme environments.

[0027] In one embodiment, based on the Holt-Winters method, meteorological data for the design reference period of the concrete structure are obtained from historical meteorological forecasts, including: The Holt-Winters additive model was used to obtain meteorological data for the design reference period of the concrete structure based on historical meteorological forecasts. The Holt-Winters additive model is shown below: In the formula, express( The actual value of the time series for the period. , and Both represent smoothing equations. Indicates the number of backward smoothing periods. Indicates the first An exponentially smoothed value that removes the long-term trend from a time series data set after removing periodic variations. Indicates the first Exponentially smoothed values ​​of long-term trend variables Indicates the first The periodic variation cycle is The exponentially smoothed value, , and All represent smoothing coefficients. Indicates the period length.

[0028] The working principle and beneficial effects of the above technical solution are as follows: When predicting meteorological data for future periods within the baseline period, in order to consider the evolution trend of the climate system and adapt to the structural durability analysis under future climate scenarios, it is necessary to make predictions based on historical meteorological data; the Holt-Winters method is used to predict the collected meteorological data. The Holt-Winters method is a short-term prediction method for time series data containing trends and seasonality. It is an extension of the exponential smoothing method. Its core is to smooth historical data by weighted average to capture the three core features of time series: level, trend, and season, so as to achieve accurate extrapolation prediction. It is widely used in time series prediction scenarios such as meteorological, hydrological, and engineering environmental data.

[0029] In one embodiment, the daily-scale concrete surface temperature field at the target point is calculated based on meteorological data, and the temperature field variation along the depth direction of the concrete structure is calculated, including: The surface temperature of the concrete structure is calculated based on meteorological data, using the following formula: In the formula, Indicates the target point's location Surface temperature at any given time Indicates in The external temperature at any given moment, Indicates the solar radiation absorption coefficient. This indicates the amount of solar radiation. Indicates the overall heat exchange coefficient. Indicates wind speed.

[0030] Divide along the depth direction The system uses equidistant nodes and calculates the temperature data for each node. The nodes include surface boundary nodes, internal nodes, and internal adiabatic boundary nodes.

[0031] The temperature data of the surface boundary nodes is calculated using the following formula: In the formula, This indicates the node at the surface boundary at time step. Temperature data at that time Indicates a time step. This indicates the length of each time step.

[0032] The temperature data of the internal nodes is calculated using the following formula: In the formula, Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at time i Indicates the number of the concrete layers to be divided. , Take the integer part.

[0033] The temperature data for the internal adiabatic boundary nodes is calculated using the following formula: In the formula, This indicates the internal adiabatic boundary node at time step ( Temperature data at that time. Indicates the internal adiabatic boundary node at time step Temperature data at that time This represents the distance between two adjacent nodes. This indicates the internal adiabatic boundary node at time step ( Temperature data at that time. This represents the thermal diffusivity.

[0034] The temperature data for the internal adiabatic boundary nodes and internal nodes are calculated as follows: The temperature field variation of the target point along the depth direction of the concrete structure is obtained based on the temperature data of the surface boundary nodes, internal nodes, and internal thermal insulation boundary nodes.

[0035] The equivalent freeze-thaw cycles at different depths of the concrete structure at the target point were obtained based on changes in the temperature field, including: According to the preset node division rules, the concrete structure of the target point is divided along the depth direction. There are ) concrete structural layers; among which, during the division, it will be divided into Each node.

[0036] Based on preset rules, the number of freeze-thaw cycles and the cooling rate of each concrete structural layer are determined according to the changes in the temperature field. The equivalent number of freeze-thaw cycles for each concrete structural layer is calculated based on the number of freeze-thaw cycles and the cooling rate, using the following formula: In the formula, Indicates the first The equivalent number of freeze-thaw cycles for each concrete structural layer. Indicates the porosity parameter of the material. Indicates the indoor cooling rate. Indicates the first The cooling rate of each concrete structural layer This represents an empirical coefficient; the formula for calculating the material porosity parameter is as follows: In the formula, This represents the spacing coefficient of the concrete structure at the target point. The porosity parameter of the concrete material at the target point. Indicates the radius of the gap. This indicates the volume fraction of cement-based materials. This indicates the air content in the concrete.

[0037] The working principle and beneficial effects of the above technical solution are as follows: Based on preset rules, the number of freeze-thaw cycles and the cooling rate of each concrete structural layer are determined according to the temperature field changes. Specifically, based on predicted meteorological data, the distribution of a single freeze-thaw cycle and its corresponding cooling rate are determined on a daily scale. The number of freeze-thaw cycles is defined as the highest temperature of the day being greater than 0℃ and the lowest temperature being less than -3℃. If this condition is not met, no freeze-thaw occurs on that day. The corresponding cooling rate is calculated as follows: The cooling rate of the day in which the freeze-thaw cycle occurs is calculated and defined as the ratio of the temperature difference to the time interval between the highest and lowest temperatures.

[0038] The predefined node partitioning rules are as follows: Determine the calculation depth: it must cover the main areas affected by freeze-thaw damage; typically, the thickness of the concrete cover is used.c +(50~100)mm, or determined based on the temperature field calculation results, that is, when the temperature change at a certain depth is ≤0.5℃ / d, the extension can be stopped and it can be regarded as having no freeze-thaw effect; at the same time, the discrete domain is locally densified: due to the drastic temperature change on the surface and the more prominent freeze-thaw inhomogeneity, the surface densification and internal equidistant discretization method is preferred; it can be divided into surface and interior; among which the surface layer is 5~10mm (to capture the surface freeze-thaw peak), and the interior is 10~20mm (the temperature field tends to be stable, which can be simplified); after discretization, the stability condition of the temperature field calculation must be met to avoid numerical divergence.

[0039] In one embodiment, calculating the overall equivalent freeze-thaw cycles of a concrete structure on a daily scale includes: The volume weight of each concrete structural layer is calculated using the following formula: In the formula, Indicates the first Volume weight of each concrete structural layer Indicates the first The depth of each concrete structural layer Indicates the total depth of the concrete structure.

[0040] The freeze-thaw sensitivity weight for each concrete structural layer is calculated using the following formula: In the formula, Indicates the first The average temperature of each concrete structural layer Indicates the first The average temperature of each concrete structural layer.

[0041] Based on the volumetric weight of the concrete structural layer, the equivalent number of freeze-thaw cycles based on the freeze-thaw sensitivity weight, and the overall equivalent number of freeze-thaw cycles, the calculation formula is as follows: In the formula, This indicates the overall equivalent number of freeze-thaw cycles for a concrete structure within one day. Indicates the first The overall weight of each concrete structural layer.

[0042] In one embodiment, the overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles on a daily scale, including: The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. The calculation formula is as follows: In the formula, This represents the overall equivalent freeze-thaw damage at the target point within the baseline period. Indicates the total number of days for the baseline.

[0043] The working principle and beneficial effects of the above technical solution are as follows: The total equivalent freeze-thaw cycles per day are accumulated, and the cumulative equivalent freeze-thaw cycles within the design reference period are calculated using predicted meteorological data. The design reference period can refer to the "Standard for Durability Design of Concrete Structures" (GB / T 50082-2009) and the "Code for Design of Concrete Structures" (GB 50010-2010), applicable to ordinary buildings and important buildings (such as bridges, tunnels, and nuclear power structures).

[0044] In one embodiment, an environmental zoning map of freeze-thaw damage to the concrete structure is generated based on the overall equivalent freeze-thaw damage over the design reference period of the concrete structure at all obtained grid points, including: Based on the overall equivalent freeze-thaw damage of all grid points, a one-dimensional data sequence is obtained; Sort the one-dimensional data sequence from smallest to largest, calculate the frequency distribution, mean, and standard deviation of the one-dimensional data sequence, and identify dense and blank intervals in the data; Based on the Jenks algorithm, all possible grouping methods are iteratively calculated to determine a set of breakpoints; Based on the project requirements, output the corresponding breakpoints and mark them on the map with different colors.

[0045] 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 freeze-thaw damage in concrete structures, characterized in that, Includes the following steps: Acquire material property data of the concrete structure and historical meteorological data of the corresponding area; the historical meteorological data includes: atmospheric temperature, solar radiation and wind speed; Based on the Holt-Winters method, meteorological data for the design reference period of concrete structures are obtained from historical meteorological forecasts. Based on ERA5's spatiotemporal resolution, the map area is divided into grid points of 0.25 latitude × 0.25 longitude; Randomly select any grid point as the target point, calculate the daily-scale concrete surface temperature field of the target point based on meteorological data, and calculate the temperature field change along the depth direction of the concrete structure. The equivalent freeze-thaw cycles at different depths of the concrete structure at the target point are obtained based on the temperature field changes, and the overall equivalent freeze-thaw cycles of the concrete structure on a daily scale are calculated. The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. Repeat the above steps to generate an environmental zoning map of freeze-thaw damage to concrete structures based on the overall equivalent freeze-thaw damage of all obtained grid points.

2. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 1, characterized in that, Based on the Holt-Winters method, meteorological data for the design reference period of concrete structures were obtained from historical meteorological forecasts, including: The Holt-Winters additive model was used to obtain meteorological data for the design reference period of the concrete structure based on historical meteorological forecasts. The Holt-Winters additive model is shown below: In the formula, express( The actual value of the time series for the period. , and Both represent smoothing equations. Indicates the number of backward smoothing periods. Indicates the first An exponentially smoothed value that removes the long-term trend from a time series data set after removing periodic variations. Indicates the first Exponentially smoothed values ​​of long-term trend variables Indicates the first The periodic variation cycle is The exponentially smoothed value, , and All represent smoothing coefficients. Indicates the period length.

3. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 1, characterized in that, The daily-scale surface temperature field of the concrete structure at the target point was calculated based on meteorological data, and the temperature field variation along the depth direction of the concrete structure was also calculated, including: The surface temperature of the concrete structure is calculated based on meteorological data, using the following formula: In the formula, Indicates the target point's location Surface temperature at any given time Indicates in The external temperature at any given moment, Indicates the solar radiation absorption coefficient. This indicates the amount of solar radiation. Indicates the overall heat exchange coefficient. Indicates wind speed. Divide along the depth direction of the concrete structure The system uses equidistant nodes and calculates the temperature data for each node. The nodes include surface boundary nodes, internal nodes, and internal adiabatic boundary nodes. The temperature data of the surface boundary nodes is calculated using the following formula: In the formula, This indicates the time step at the surface boundary node. Temperature data at that time Indicates a time step. Indicates the length of each time step; The temperature data of the internal nodes is calculated using the following formula: In the formula, Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at that time Indicates the internal node at time step Temperature data at that time i Indicates the number of the concrete layers to be divided. , Take the integer part. The temperature data for the internal adiabatic boundary nodes is calculated using the following formula: In the formula, Indicates the internal adiabatic boundary node at time step Temperature data at that time Indicates the internal adiabatic boundary node at time step Temperature data at that time This represents the distance between two adjacent nodes. Indicates the internal adiabatic boundary node at time step Temperature data at that time. This represents the thermal diffusivity. The temperature data for the internal adiabatic boundary nodes and internal nodes are calculated as follows: The temperature field variation of the target point along the depth direction of the concrete structure is obtained based on the temperature data of the surface boundary nodes, internal nodes, and internal thermal insulation boundary nodes.

4. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 1, characterized in that, The equivalent freeze-thaw cycles at different depths of the concrete structure at the target point were obtained based on changes in the temperature field, including: According to the preset node division rules, the concrete structure of the target point is divided along the depth direction. One concrete structural layer; among which, during the division, it will be divided into Each node. Based on preset rules, the number of freeze-thaw cycles and the cooling rate of each concrete structural layer are determined according to the changes in the temperature field. The equivalent number of freeze-thaw cycles for each concrete structural layer is calculated based on the number of freeze-thaw cycles and the cooling rate, using the following formula: In the formula, Indicates the first The equivalent number of freeze-thaw cycles for each concrete structural layer. Indicates the porosity parameter of the material. Indicates the indoor cooling rate. Indicates the first The cooling rate of each concrete structural layer This represents an empirical coefficient; the formula for calculating the material porosity parameter is as follows: In the formula, The spacing coefficient of the concrete material at the target point. The porosity parameter of the concrete material at the target point. Indicates the radius of the gap. This indicates the volume fraction of cement-based materials. This indicates the air content in the concrete.

5. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 4, characterized in that, Calculate the overall equivalent freeze-thaw cycles of a concrete structure on a daily scale, including: The volume weight of each concrete structural layer is calculated using the following formula: In the formula, Indicates the first Volume weight of each concrete structural layer Indicates the first The depth of each concrete structural layer Indicates the total depth of the concrete structure. The freeze-thaw sensitivity weight for each concrete structural layer is calculated using the following formula: In the formula, Indicates the first The average temperature of each concrete structural layer Indicates the ( The average temperature of each concrete structural layer. Based on the volumetric weight of the concrete structural layer, the equivalent number of freeze-thaw cycles based on the freeze-thaw sensitivity weight, and the overall equivalent number of freeze-thaw cycles, the calculation formula is as follows: In the formula, This indicates the overall equivalent number of freeze-thaw cycles for a concrete structure within one day. Indicates the first The overall weight of each concrete structural layer.

6. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 5, characterized in that, The overall equivalent freeze-thaw damage of the concrete structure at the target point during the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale, including: The overall equivalent freeze-thaw damage of the concrete structure at the target point within the design reference period is obtained based on the overall equivalent freeze-thaw cycles at the daily scale. The calculation formula is as follows: In the formula, This represents the overall equivalent freeze-thaw damage at the target point within the baseline period. Indicates the total number of days for the baseline.

7. The environmental zoning method for freeze-thaw damage of concrete structures according to claim 1, characterized in that, An environmental zoning map of freeze-thaw damage to concrete structures is generated based on the overall equivalent freeze-thaw damage of all grid points within the design reference period, including: Based on the overall equivalent freeze-thaw damage of all grid points, a one-dimensional data sequence is obtained; Sort the one-dimensional data sequence from smallest to largest, calculate the frequency distribution, mean, and standard deviation of the one-dimensional data sequence, and identify dense and blank intervals in the data; Based on the Jenks algorithm, all possible grouping methods are iteratively calculated to determine a set of breakpoints; Based on the project requirements, output the corresponding breakpoints and mark them on the map with different colors.

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