Method and system for evaluating corrosion of reinforced concrete of power transmission and transformation project

Abstract

The invention provides a power transmission and transformation project reinforced concrete corrosivity evaluation method and system, and relates to the technical field of civil engineering durability evaluation.The method comprises the steps that temperature data of a project location and the total volume, the water content and the pore volume of reinforced concrete are collected, and a freeze-thaw failure index formula is constructed; the product type is judged according to the measured sulfate concentration, different sulfate erosion index formulas are constructed in combination with related data, and the magnesium ion concentration is independently considered in the marine environment; constructing a chlorine salt erosion index formula according to the chloride ion concentration; extracting data from the research report to construct a carbonization erosion index formula; and giving a weight to each erosion type to establish a comprehensive corrosivity evaluation index formula, and judging the erosion degree according to a result. By means of the method, various erosion factors can be comprehensively considered, the erosion degree can be effectively judged according to the evaluation result, and a key basis and scientific guidance are provided for durability guarantee, protective measure making and maintenance decision making of the reinforced concrete structure of the power transmission and transformation project.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering durability assessment, and in particular to a method and system for assessing the corrosion of reinforced concrete in power transmission and transformation engineering. Background Art

[0002] In the field of power transmission and transformation engineering, reinforced concrete structures are widely used in key parts such as tower foundations and substation building foundations. Their durability is directly related to the safe and stable operation of the entire power transmission and transformation system. However, in the actual service process, reinforced concrete will inevitably be affected by various corrosive factors. For example, freeze-thaw damage is more common in power transmission and transformation projects in cold areas. In power transmission and transformation projects in cold areas in northern my country in winter, tower foundations and substation building foundations are often subject to freeze-thaw cycles, resulting in erosion, cracking and other diseases on the surface of reinforced concrete. Sulfate erosion damages reinforced concrete components, causing reinforced concrete to absorb water, expand and crack, and eventually become a non-viscous paste. Chloride salts enter the interior of reinforced concrete in the form of penetration, diffusion, convection, etc., which is prone to problems such as steel rust and reinforced concrete spalling. The corrosion problem is becoming increasingly prominent.

[0003] However, the reinforced concrete structures of power transmission and transformation projects are often affected by multiple corrosion factors at the same time. Currently, most of the assessment methods for reinforced concrete corrosion focus on a single corrosion factor, which cannot accurately reflect the actual corrosion state of the structure and lacks a systematic assessment of the combined effects of multiple corrosion factors.

[0004] In summary, the present invention aims to provide a comprehensive, accurate and practical method and system for evaluating the corrosion of reinforced concrete in power transmission and transformation projects. By comprehensively considering multiple corrosion factors such as freeze-thaw damage, sulfate corrosion, chloride corrosion, and carbonization, a corresponding corrosion index formula is constructed, and weights are assigned according to the importance of each corrosion type on the overall corrosion, and a comprehensive corrosion evaluation index formula is established, which can more truly reflect the corrosion status of reinforced concrete structures in actual service environments.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a method and system for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, comprising the following specific steps: Step 1: Collect temperature data of the location of the power transmission and transformation project and the characteristic data of the reinforced concrete to be evaluated, and construct a freeze-thaw damage index formula based on the collected temperature data and the characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the characteristic data includes the total volume, water content and pore volume of the reinforced concrete; Step 2: According to the groundwater sulfate concentration data at the location of the power transmission and transformation project, the type of corrosion product generated is determined. According to the type of corrosion product, the corresponding sulfate corrosion index formula is constructed through the groundwater pH value, corrosion time, aluminum ion concentration, and calcium ion concentration data. When in the marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate corrosion index formula; Step 3: Preset the chloride ion content threshold, and construct the chloride salt erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; Step 4: Extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonation erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; Step 5: Assign corresponding weights according to the importance of the corrosion types represented by each formula on the overall corrosion resistance, establish a comprehensive corrosion evaluation index formula that can comprehensively evaluate the corrosion resistance, and determine the degree of corrosion based on the results.

[0008] Furthermore, the temperature cycle is the time span of a complete change process from the time when reinforced concrete begins to be used, from the ambient temperature dropping from above 0°C to below 0°C, and then rising back to above 0°C; The temperature variation range is the difference between the highest temperature and the lowest temperature in a temperature cycle; The temperature change time is the time it takes for the temperature to change from the highest value to the lowest value, or from the lowest value to the highest value within a temperature cycle.

[0009] Furthermore, the volume of water in reinforced concrete is calculated based on the water content and the total volume of reinforced concrete: ; In the formula, Expressed as the volume of water in reinforced concrete, Expressed as the moisture content of reinforced concrete, Expressed as the total volume of reinforced concrete, the volume of ice is calculated based on the volume of water in the reinforced concrete: ; In the formula, is the density of water, is the density of ice, It is expressed as the volume of ice, and then according to the duration of low temperature and the amplitude of temperature change, the pressure exerted by the ice in the pore on the pore wall during each freezing and thawing process is calculated: ; In the formula, It is expressed as the pressure exerted by ice in the pores on the pore wall during each freezing and thawing process. is a coefficient related to the material properties of reinforced concrete, is the pore volume, Expressed as The temperature variation within a temperature cycle is Expressed as Temperature change time within a temperature cycle, ,in, It is expressed as the number of temperature cycles, and then the freeze-thaw damage index formula is constructed: ; In the formula, Expressed as freeze-thaw damage index.

[0010] Furthermore, the generated erosion products are determined based on the sulfate concentration measured in the groundwater; When the sulfate concentration is less than When considering the ettringite erosion, the sulfate erosion index formula is constructed: ; In the formula, Expressed as the sulfate attack index, is the coefficient related to the contribution of sulfate ion concentration to sulfate attack, is the coefficient related to the effect of pH on sulfate attack, is the coefficient related to the effect of erosion time on sulfate erosion, is the coefficient related to the effect of aluminum ion concentration on sulfate attack, is the sulfate concentration, is the pH value of reinforced concrete, It is the baseline value at which ettringite begins to corrode. It is the period of reinforced concrete service life. The duration of erosion, i.e., the erosion time; When the sulfate concentration is When the erosion rate is between 2.5 and 3.5, the combined erosion of ettringite and gypsum is considered, and the sulfate erosion index formula is constructed: ; In the formula, is the concentration of aluminum ions in reinforced concrete, is the concentration of calcium ions in reinforced concrete, is the coefficient related to the contribution of aluminum ions to corrosion, is the coefficient related to the contribution of calcium ions to erosion, is a coefficient used to adjust the combined impact of ettringite and gypsum erosion; When the sulfate concentration is greater than When considering gypsum erosion, the sulfate erosion index formula is constructed: .

[0011] Furthermore, when in a marine environment, and the sulfate concentration in seawater is greater than , considering magnesium salt erosion, construct the sulfate erosion index formula: ; In the formula, Expressed as the sulfate attack index, is the concentration of magnesium ions in seawater, It is a coefficient that adjusts the combined effect of magnesium salt and sulfate erosion; When the sulfate concentration in seawater is less than 4000ppm, ettringite erosion is considered, and the sulfate erosion index formula is: ; The sulfate concentration in seawater is When the erosion of calcium sulfide and gypsum is considered, the sulfate erosion index formula is: .

[0012] Furthermore, the groundwater chloride ion concentration at the location of the power transmission and transformation project is calibrated as , with a pre-set chloride ion content threshold In contrast, When the chloride ions are considered to have a corrosive effect, the chloride salt corrosion index formula is constructed: ; In the formula, Expressed as the chloride attack index, Expressed as a coefficient related to the contribution of chloride salt erosion, Expressed as porosity, .

[0013] Furthermore, the humidity influence function is constructed: ; In the formula, Expressed as humidity influence function, It is represented by the relative humidity of the environment at the location of the power transmission and transformation project collected in real time. Expressed as a constant; Construct the carbonization erosion index formula: ; In the formula, is the carbonization corrosion contribution coefficient related to the pore volume ratio, is the coefficient related to the humidity influence function on carbonization corrosion, is the water-cement ratio of reinforced concrete, is the carbon dioxide concentration in the environment where the power transmission and transformation project is located. is the coefficient related to the effect of the water-cement ratio of reinforced concrete on carbonation corrosion, It is the coefficient related to the effect of carbon dioxide concentration in the environment on carbonation corrosion.

[0014] Furthermore, the weight of the freeze-thaw damage index is set as , the weight of the sulfate attack index is , the weight of the chloride erosion index is , the weight of the carbonization erosion index is , establish the comprehensive corrosiveness evaluation index formula: ; In the formula, Expressed as a comprehensive corrosion assessment index.

[0015] Furthermore, the erosion degree threshold is preset as ,and ,when When When When It is judged to be extremely severe corrosion.

[0016] The present invention further provides a system for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, the system being used to execute the above-mentioned method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, comprising: The freeze-thaw damage index construction module is used to collect temperature data of the location of the power transmission and transformation project and the self-characteristic data of the reinforced concrete to be evaluated, and to construct a freeze-thaw damage index formula based on the collected temperature data and the self-characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the self-characteristic data includes the total volume, water content and pore volume of the reinforced concrete; The sulfate erosion index construction module is used to identify the type of erosion products generated based on the groundwater sulfate concentration data at the location of the power transmission and transformation project. Based on the type of erosion products, the corresponding sulfate erosion index formula is constructed through the groundwater pH value, erosion time, aluminum ion concentration, and calcium ion concentration data. When in a marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate erosion index formula; The chloride erosion index construction module is used to pre-set the chloride ion content threshold and construct the chloride erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; The carbonization erosion index construction module is used to extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonization erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; The comprehensive corrosion assessment index construction module is used to assign corresponding weights according to the importance of the corrosion type represented by each formula on the overall corrosion, establish a comprehensive corrosion assessment index formula that can comprehensively evaluate the corrosion, and determine the degree of corrosion based on the results.

[0017] Compared with the prior art, the present invention has the following beneficial effects: By deeply considering the core factors such as freeze-thaw damage, sulfate corrosion, chloride corrosion and carbonation, it can comprehensively cover all kinds of major corrosion threats faced by reinforced concrete structures in power transmission and transformation projects during actual service. This comprehensiveness avoids the one-sidedness of the evaluation results caused by the previous single factor evaluation or the omission of some factors.

[0018] Special index formulas are constructed for different types of corrosion. The freeze-thaw damage index formula combines the key parameters of temperature cycle, variation range, time, and the volume, water content and pore volume of reinforced concrete itself, which can accurately reflect the degree of damage to the structure caused by freeze-thaw. The sulfate attack index formula under different circumstances fully considers the concentration difference of sulfate, the pH value of reinforced concrete, corrosion time, aluminum ion and calcium ion concentration, and also reasonably incorporates the influence of magnesium ion concentration in the marine environment, so as to accurately quantify the degree of harm of sulfate attack under different conditions. The chloride attack index formula measures the corrosion effect of chloride on reinforced concrete structures based on the relationship between chloride ion concentration and set threshold value and porosity. The carbonation corrosion index formula uses the humidity influence function and data such as the total volume of reinforced concrete, total pore volume, environmental carbon dioxide concentration and water-cement ratio to accurately evaluate the corrosive effect of carbonation.

[0019] Finally, the comprehensive corrosion evaluation index formula in the present invention constructs index formulas and assigns weights to multiple factors such as freeze-thaw damage, sulfate corrosion, chloride corrosion, and carbonization, thereby avoiding the evaluation deviation caused by traditional evaluation methods that only focus on one or several types of corrosion and ignore other factors, thereby making the evaluation results more in line with the actual situation and providing a comprehensive and reliable basis for subsequent protection and repair measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall method flow of the present invention; Figure 2 Schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0022] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Example: See also Figure 1 , the present invention provides a technical solution: A method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, comprising the following specific steps: Step 1: Collect temperature data of the location of the power transmission and transformation project and the characteristic data of the reinforced concrete to be evaluated, and construct a freeze-thaw damage index formula based on the collected temperature data and the characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the characteristic data includes the total volume, water content and pore volume of the reinforced concrete; In step 1, after the reinforced concrete is put into use, a temperature sensor is set in the surrounding environment, or the meteorological bureau data is queried to collect temperature data. The collected temperature data covers the temperature cycle, temperature change amplitude and temperature change time. The specific temperature data collection method is as follows: After the starting time of the reinforced concrete being put into use is determined, the next nearest hour is taken as the time point for the first temperature data collection. After that, the surrounding temperature data is collected at a fixed frequency of one hour. For example, if the starting time is 12:03, the first collection time is 13:00, and the subsequent collection times are 14:00, 15:00... until 23:00. This cycle is repeated to ensure that the temperature information of different time periods can be obtained completely and systematically.

[0024] Freeze-thaw damage manifests itself macroscopically as peeling of the surface of reinforced concrete, a gradual decrease in quality and strength until complete loss. In essence, water that enters the pores of reinforced concrete freezes into ice in a low temperature environment (below the freezing point of water). The volume expansion creates pressure on the pores, causing damage to the internal structure. When the temperature rises above the freezing point, the ice in the pores begins to melt, which creates tensile stress on the pore walls. The continuous freeze-thaw cycle causes continuous damage to the internal structure of reinforced concrete. In severe cases, it manifests as a macroscopic reduction in strength and damage to reinforced concrete components.

[0025] The temperature cycle refers to the time when the ambient temperature drops from above 0°C to below 0°C and then rises back to above 0°C. The time span of such a complete change process can be monitored by collecting temperature data to determine whether the ambient temperature frequently crosses the time span. situation; The temperature variation range refers to the difference between the highest temperature and the lowest temperature in each temperature cycle. If the difference between the highest temperature and the lowest temperature in a temperature cycle is large, the difference in the expansion and contraction of reinforced concrete and steel bars will be more obvious. Therefore, the temperature variation range is a key factor in the corrosion assessment of reinforced concrete. Temperature change time refers to the time it takes for the temperature to change from the highest value to the lowest value, or from the lowest value to the highest value within a temperature cycle. When the temperature change time is long, the internal thermal stress changes relatively slowly. Since the thermal expansion and contraction process of the material caused by the temperature change has enough time to buffer, the possibility of cracks will be reduced. When the temperature change time is very short, the material does not have time to adapt to the rapid temperature change, and a large temperature gradient will be formed on the surface and inside of the structure, causing a large tensile stress on the surface, leading to cracks in the steel bars.

[0026] Then collect data on the total volume, water content and pore volume of reinforced concrete at the location of the power transmission and transformation project.

[0027] First, find the design drawings of the power transmission and transformation project, and calculate the total volume of reinforced concrete according to the size parameters in the design drawings; The moisture content of reinforced concrete is obtained by drying method, and the mass of The sample is placed in a temperature controlled The dried product was placed in an oven and dried to constant weight. The mass after drying was weighed as , the moisture content of reinforced concrete at the location of the power transmission and transformation project is calculated by the mass of the sample drilled from the reinforced concrete structure and the mass after drying: ; In the formula, It is expressed as the moisture content of reinforced concrete at the location of the power transmission and transformation project; From the reinforced concrete at the site of the power transmission and transformation project, a cutting saw is used to cut a volume of The sample is placed in a drying oven for drying, and then placed in a vacuum container to make the pores in a vacuum state. The vacuumed sample is weighed and its initial mass is recorded. , and then put it into the sample chamber of the mercury intrusion instrument and start the mercury intrusion instrument. As the pressure gradually increases, mercury will gradually fill the pores under the action of pressure and output the mercury intrusion curve.

[0028] The data of each pressure stage are obtained from the mercury injection curve. The surface tension of mercury is a known physical constant, and its value is Based on a lot of experimental research and experience of the research team, the contact angle between mercury and the pore wall of concrete is obtained. for , construct the Washburn equation: ; In the formula, Expressed as the pore radius corresponding to each pressure stage, Expressed as the surface tension of mercury, Expressed as pressure, the pore radius corresponding to each pressure stage is calculated using the Washburn equation , the pore volume increment within this radius , and then sum the pore volume increments at all pressure stages to obtain the pore volume .

[0029] According to the collected temperature data, the freeze-thaw damage index formula of the total volume, water content and pore volume of reinforced concrete is constructed, which includes the following steps: Calculate the volume of water in reinforced concrete based on the water content and the total volume of reinforced concrete: ; In the formula, is the water content of reinforced concrete, is the total volume of reinforced concrete, and the volume of ice is calculated based on the volume of water in the reinforced concrete: ; In the formula, is the density of water, is the density of ice, is the volume of ice, and then according to the duration of low temperature and the amplitude of temperature change, the pressure exerted by ice in the pore on the pore wall during each freezing and thawing process is calculated: ; In the formula, It is expressed as the pressure exerted by ice in the pores on the pore wall during each freezing and thawing process. is a coefficient related to the material properties of reinforced concrete, is the pore volume, Expressed as The temperature variation within a temperature cycle is Expressed as Temperature change time within a temperature cycle, ,in, is the number of temperature cycles, and then the freeze-thaw damage index formula is constructed: ; In the formula, Expressed as freeze-thaw damage index, when the number of temperature cycles The larger it is, the more freeze-thaw cycles the reinforced concrete structure has experienced. The results of each cycle are accumulated, and the greater the impact of the results is as the number of freeze-thaw cycles increases. This item indicates that water expands when it freezes. This volume change will produce greater pressure on the pore structure, thereby aggravating the degree of freeze-thaw damage. This indicates that the greater the temperature change and the shorter the duration of each freeze-thaw cycle, the greater the degree of freeze-thaw damage.

[0030] Among the durability issues of reinforced concrete, freeze-thaw damage is the most common and one of the most destructive ways to reinforced concrete. Therefore, the quality of anti-freezing performance has become one of the most important indicators for evaluating the durability of reinforced concrete.

[0031] Given that the principle of freeze-thaw damage is closely related to the water and pore structure inside reinforced concrete, data such as the total volume, water content and pore volume of reinforced concrete are key to accurately assessing the extent of freeze-thaw damage. By collecting these data and constructing a freeze-thaw damage index formula, the potential risk and actual degree of damage caused by freeze-thaw damage can be quantified, thereby providing a scientific basis for judging the frost resistance of reinforced concrete in a specific environment, and thus becoming one of the core indicators for evaluating the durability of reinforced concrete.

[0032] Step 2: According to the groundwater sulfate concentration data at the location of the power transmission and transformation project, the type of corrosion product generated is determined. According to the type of corrosion product, the corresponding sulfate corrosion index formula is constructed through the groundwater pH value, corrosion time, aluminum ion concentration, and calcium ion concentration data. When in the marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate corrosion index formula; For sodium sulfate attack, when sulfate concentration is low (<1000 ppm SO4 2- ), mainly produces ettringite; when the sulfate concentration is high (>8000 ppm SO4 2- ), mainly produces gypsum; when the sulfate concentration is 1000~8000 ppm SO4 2- When ettringite and gypsum exist together.

[0033] Among them, ettringite has low solubility and is combined with a large amount of crystal water in its chemical structure. After the reaction, the solid phase volume can increase by 94%. The increase in volume causes the reinforced concrete to expand and crack, forming large cracks on the surface of the structure, and even causing the reinforced concrete to peel off. When the alkalinity of reinforced concrete is low, the ettringite generated is mostly large lath-shaped crystals, which are generally not harmful; when the alkalinity is high, the ettringite is mostly needle-shaped or flaky crystals with strong adsorption capacity, absorbing water and expanding, forming great crystallization stress. Therefore, reasonable control of the alkalinity of reinforced concrete can reduce the expansion damage of ettringite. The formation of gypsum can increase the solid phase volume by 124%, causing the reinforced concrete to expand. At the same time, the formation of gypsum will consume calcium hydroxide, resulting in a decrease in the strength and durability of reinforced concrete. Gypsum-type corrosion damage generally does not cause large cracks, but reinforced concrete will collapse.

[0034] Usually at 0℃~5℃, calcium silicate will be formed. When the pH value of calcium silicate in the pore solution is higher than 10.5 and there is SO4 2- 、CO3 2- If there is calcium silicate in the presence of carbon, sulfur and calcium silicate, it will continue to react and generate, consuming calcium silicate hydrate gel. Since calcium silicate in the presence of carbon, sulfur and calcium silicate has no bonding force and calcium silicate hydrate gel is consumed, the material loses strength, thus causing the structure to be damaged. Therefore, considering the calcium ion concentration and the corrosion time of reinforced concrete, the corrosion time is the time in the use time. Length of time.

[0035] Therefore, the generated erosion products are first determined based on the sulfate concentration measured in the groundwater; When the sulfate concentration is less than When considering the ettringite erosion, the sulfate erosion index formula is constructed: ; In the formula, is the coefficient related to the contribution of sulfate ion concentration to sulfate attack, is the coefficient related to the effect of pH on sulfate attack, is the coefficient related to the effect of erosion time on sulfate erosion, is the coefficient related to the effect of aluminum ion concentration on sulfate attack, is the sulfate concentration, is the pH value of reinforced concrete, It is the baseline value at which ettringite begins to corrode. is the erosion time, i.e. the time during which reinforced concrete is in service. Length of time; When the sulfate concentration is When the erosion rate is between 2.5 and 3.5, the combined erosion of ettringite and gypsum is considered, and the sulfate erosion index formula is constructed: ; In the formula, is the concentration of aluminum ions in reinforced concrete, is the concentration of calcium ions in reinforced concrete, is the coefficient related to the contribution of aluminum ions to corrosion, is the coefficient related to the contribution of calcium ions to erosion, is a coefficient used to adjust the combined impact of ettringite and gypsum erosion; When the sulfate concentration is greater than When considering gypsum erosion, the sulfate erosion index formula is constructed: ; MgSO4 corrosion is the most serious type of sulfate corrosion that damages reinforced concrete, because the Mg 2+ and SO4 2- Both will cause corrosion to reinforced concrete. The two will overlap each other and cause serious corrosion to reinforced concrete, and even make reinforced concrete lose its cementation. Seawater contains a large amount of Mg 2+ and SO4 2- For magnesium sulfate corrosion, at lower concentrations (<4000 ppm SO4 2- ), ettringite is generated; when the concentration is high (>7500 ppm SO4 2- ), mainly magnesium salt erosion; medium concentration (4000~7500 ppm SO4 2- ) when ettringite and gypsum are produced simultaneously, so when in a marine environment and the sulfate concentration is greater than , considering magnesium salt erosion, construct the sulfate erosion index formula: ; In the formula, is the concentration of magnesium ions in seawater, is the coefficient related to the effect of magnesium ion concentration on sulfate attack, It is a coefficient that adjusts the combined effect of magnesium salt and sulfate erosion; When the sulfate concentration in seawater is less than 4000ppm, ettringite erosion is considered, and the sulfate erosion index formula is: ; The sulfate concentration in seawater is When the erosion of calcium sulfide and gypsum is considered, the sulfate erosion index formula is: .

[0036] Step 3: Preset the chloride ion content threshold, and construct the chloride salt erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; When chloride ions in the environment enter the reinforced concrete in the form of penetration, diffusion, convection, etc., a small amount of chloride ions may react with Ca(OH)2 in the reinforced concrete to form CaCl2. Since CaCl2 is accompanied by a large amount of crystal water, it is easy to expand and damage the reinforced concrete structure. For example, in the salt lake area in the northwest of my country and the northern region, spraying a large amount of deicing salt in winter will also cause chloride salt erosion and damage to the reinforced concrete structure. When the concentration of chloride ions entering the reinforced concrete is too high, the oxygen and water in the pores provide environmental conditions for electrochemical corrosion between chloride ions and steel bars in the internal environment, and rapid electrochemical corrosion causes the corrosion of reinforced concrete components. In the groundwater environment, high-concentration chloride ions mostly exist in a free state. After invading the interior of reinforced concrete, it is easy to cause local acidification of reinforced concrete, thereby destroying the passivation film on the surface of the steel bar, causing steel bar corrosion, greatly reducing the durability of reinforced concrete, and becoming one of the most deadly corrosive media for reinforced concrete.

[0037] First, determine the chloride ion concentration of groundwater at the location of the power transmission and transformation project, and use a pipette to accurately draw The underground water at the location of the volumetric power transmission and transformation project is added with 3 drops of potassium chromate indicator and the concentration is Titrate with silver nitrate standard solution until the solution changes from yellow to brick red, and record the volume of silver nitrate solution consumed. , calculate the chloride ion concentration: ; In the formula, It is expressed as the chloride ion concentration of groundwater at the location of the power transmission and transformation project.

[0038] The nominal porosity is , the calculation method is: ; At the same time, there is a critical chloride ion concentration in the reinforced concrete solution. When the chloride ion concentration on the surface of the steel bar reaches this critical value, the steel bar begins to rust. A survey of bridges in the UK showed that when expressed in terms of total chloride ion concentration, the critical chloride ion concentration is ; British national standards stipulate that the chloride ion content in reinforced concrete structures should be less than , so the chloride ion content threshold is set , the groundwater chloride ion concentration at the location of the power transmission and transformation project is calibrated as , with a pre-set chloride ion content threshold In contrast, When the chloride ions are considered to have a corrosive effect, the chloride salt corrosion index formula is constructed: ; In the formula, is a coefficient related to the contribution of chloride salt erosion, the chloride ion concentration of groundwater at the location of the power transmission and transformation project The higher it is, the greater the chloride erosion index will be.

[0039] Step 4: Extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonation erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; The carbonization of reinforced concrete is actually a process in which CO2 in the air diffuses into the interior of reinforced concrete and reacts with alkaline hydration products such as internal Ca(OH)2 to form calcium carbonate and water, causing the alkalinity of reinforced concrete to decrease and tend to be neutral. Calcium carbonate has extremely low solubility. After it is generated, it will be deposited on the surface of the pore wall, which reduces the concentration of calcium ions in the pore solution of reinforced concrete. In order to replenish the calcium ions lost in the pore solution due to the formation of calcium carbonate, calcium hydroxide dissolves and calcium carbonate increases. In this cycle, the calcium hydroxide in the reinforced concrete is completely dissolved and the pH value decreases. The strong alkalinity of reinforced concrete is the primary condition for the formation of a passivation film on the surface of the steel bar, and the passivation film can protect the steel bar from corrosion. After the reinforced concrete is carbonized, the internal pH value decreases, affecting the passivation film on the surface of the steel bar and causing the steel bar to rust.

[0040] Existing studies have shown that the carbonation of reinforced concrete is correlated to a certain extent with the water-cement ratio, CO2 concentration, and the internal porosity of reinforced concrete. The relative humidity in the air and the corresponding carbonation degree data are presented, so the humidity influence function is constructed: ; In the formula, Expressed as humidity influence function, It is represented by the relative humidity of the environment at the location of the power transmission and transformation project collected in real time. Expressed as a constant, according to a large number of experiments, the relative humidity is When the corresponding carbonization degree is different, the humidity influence function is set according to the carbonization effect. The result is and , substituting into the humidity influence function, we can get ; set up It is expressed as the water-cement ratio of reinforced concrete. The numerical value is obtained from the concrete mix design report, which will record in detail the calculation process, basis, and trial mix results of the water-cement ratio; Using the detector, after introducing a known concentration of carbon dioxide standard gas, the sampling probe of the detector is placed in the air to be tested. The detector can output the concentration of carbon dioxide in the environment where the power transmission and transformation project is located and calibrate it as .

[0041] Because reinforced concrete has a certain correlation with porosity, the carbonization erosion index formula is constructed: ; In the formula, is the carbonization corrosion contribution coefficient related to the pore volume ratio, is the coefficient related to the humidity influence function on carbonization corrosion, is the water-cement ratio of reinforced concrete, is the carbon dioxide concentration in the environment where the power transmission and transformation project is located. is the coefficient related to the effect of the water-cement ratio of reinforced concrete on carbonation corrosion, It is a coefficient related to the effect of carbon dioxide concentration in the environment on carbonation erosion. The water-cement ratio, humidity influence function, pore volume of reinforced concrete and carbon dioxide concentration in the environment are positively correlated with the carbonation erosion index.

[0042] Step 5: Assign corresponding weights according to the importance of the corrosion types represented by each formula on the overall corrosion, establish a comprehensive corrosion evaluation index formula that can comprehensively evaluate the corrosion, and determine the degree of corrosion based on the results; The weight of freeze-thaw damage index is set as , the weight of the sulfate attack index is , the weight of the chloride erosion index is , the weight of the carbonization erosion index is , and subjectively evaluate the relative importance of the four types of corrosion: freeze-thaw damage, sulfate attack, chloride attack, and carbonation. For example, in a power transmission and transformation project scenario in a cold region with a large amount of deicing salt used, the weights of freeze-thaw damage and chloride attack may be considered relatively high; while in areas close to industrial pollution areas or coastal areas with high sulfate content in groundwater, the weight of sulfate attack will be given special consideration. Each type of corrosion is given a relatively reasonable weight value. Under general environmental conditions without special requirements, the weight value is set according to the degree of influence of each type of corrosion on reinforced concrete structures. .

[0043] Then the comprehensive corrosion evaluation index formula was established: ; Through long-term observation of actual engineering conditions, the erosion threshold is pre-set as: ,and , thus the erosion degree is divided into four levels. When the corrosion degree is 0.04, it means that the current reinforced concrete structure is subjected to various corrosion factors, namely freeze-thaw damage, sulfate corrosion, chloride corrosion, and carbonation. The corrosion degree is relatively light, but it has not yet posed a significant threat to the overall performance and safety of the structure. It is judged to be a slight corrosion degree. when When the corrosion degree is 90%, it indicates that multiple corrosion factors have worked together to cause obvious damage to the reinforced concrete structure. The structure may have some problems such as cracks and local degradation of reinforced concrete performance, which have had a noticeable impact on some of the performance and stability of the structure, but the overall structure can still maintain basic functions and safety, and is judged to be of medium corrosion degree; when When the corrosion level reaches 0.04, it means that the corrosion of the reinforced concrete structure is very serious, and the key performance of the structure, such as integrity, bearing capacity and durability, is greatly threatened. At this time, the structure may have large-scale cracks, spalling of reinforced concrete, rusting of steel bars and other serious problems, which are judged as severe corrosion; when This means that the corrosion suffered by the reinforced concrete structure has reached an extremely serious degree. The entire structure is almost on the verge of collapse. Its various performance indicators have seriously deteriorated, posing a very high risk to the safe operation of the power transmission and transformation project. It is judged to be a very serious corrosion degree.

[0044] See also Figure 2 In addition, a system for evaluating the corrosion of reinforced concrete in power transmission and transformation projects is provided. The system is used to perform the above-mentioned method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, including: The freeze-thaw damage index construction module is used to collect temperature data of the location of the power transmission and transformation project and the self-characteristic data of the reinforced concrete to be evaluated, and to construct a freeze-thaw damage index formula based on the collected temperature data and the self-characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the self-characteristic data includes the total volume, water content and pore volume of the reinforced concrete; The sulfate erosion index construction module is used to identify the type of erosion products generated based on the groundwater sulfate concentration data at the location of the power transmission and transformation project. Based on the type of erosion products, the corresponding sulfate erosion index formula is constructed through the groundwater pH value, erosion time, aluminum ion concentration, and calcium ion concentration data. When in a marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate erosion index formula; The chloride erosion index construction module is used to pre-set the chloride ion content threshold and construct the chloride erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; The carbonization erosion index construction module is used to extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonization erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; The comprehensive corrosion evaluation index construction module is used to assign corresponding weights according to the importance of the corrosion type represented by each formula on the overall corrosion, establish a comprehensive corrosion evaluation index formula that can comprehensively evaluate the corrosion, and determine the degree of corrosion based on the results. The above formulas are all dimensionless and calculated using their numerical values. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0045] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0046] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0047] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, characterized in that: The specific steps include: Step 1: Collect temperature data of the location of the power transmission and transformation project and the characteristic data of the reinforced concrete to be evaluated, and construct a freeze-thaw damage index formula based on the collected temperature data and the characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the characteristic data includes the total volume, water content and pore volume of the reinforced concrete; Step 2: According to the groundwater sulfate concentration data at the location of the power transmission and transformation project, the type of corrosion product generated is determined. According to the type of corrosion product, the corresponding sulfate corrosion index formula is constructed through the groundwater pH value, corrosion time, aluminum ion concentration, and calcium ion concentration data. When in the marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate corrosion index formula; Step 3: Preset the chloride ion content threshold, and construct the chloride salt erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; Step 4: Extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonation erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; Step 5: Assign corresponding weights according to the importance of the corrosion types represented by each formula on the overall corrosion resistance, establish a comprehensive corrosion evaluation index formula that can comprehensively evaluate the corrosion resistance, and determine the degree of corrosion based on the results.

2. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1, characterized in that: In step 1, the temperature cycle, change amplitude and temperature change time are: The temperature cycle is the time span of a complete change process from the time when reinforced concrete begins to be used, from the ambient temperature dropping from above 0℃ to below 0℃, and then rising back to above 0℃. The temperature variation range is the difference between the highest temperature and the lowest temperature in a temperature cycle; The temperature change time is the time it takes for the temperature to change from the highest value to the lowest value, or from the lowest value to the highest value within a temperature cycle.

3. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1 is characterized in that: In step 1, constructing a freeze-thaw damage index formula based on the collected temperature data and its own characteristic data includes the following steps: Calculate the volume of water in reinforced concrete based on the water content and the total volume of reinforced concrete: ； In the formula, Expressed as the volume of water in reinforced concrete, Expressed as the moisture content of reinforced concrete, Expressed as the total volume of reinforced concrete, the volume of ice is calculated based on the volume of water in the reinforced concrete: ； In the formula, is the density of water, is the density of ice, It is expressed as the volume of ice, and then according to the duration of low temperature and the amplitude of temperature change, the pressure exerted by the ice in the pore on the pore wall during each freezing and thawing process is calculated: ； In the formula, It is expressed as the pressure exerted by ice in the pores on the pore wall during each freezing and thawing process. is a coefficient related to the material properties of reinforced concrete, is the pore volume, Expressed as The temperature variation within a temperature cycle is Expressed as Temperature change time within a temperature cycle, ,in, It is expressed as the number of temperature cycles, and then the freeze-thaw damage index formula is constructed: ； In the formula, Expressed as freeze-thaw damage index.

4. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1 is characterized in that: In step 2, constructing the corresponding sulfate attack index formula includes the following steps: Determine the erosion products generated based on the sulfate concentration measured in the groundwater; When the sulfate concentration is less than When considering the ettringite erosion, the sulfate erosion index formula is constructed: ； In the formula, Expressed as the sulfate attack index, is the coefficient related to the contribution of sulfate ion concentration to sulfate attack, is the coefficient related to the effect of pH on sulfate attack, is the coefficient related to the effect of erosion time on sulfate erosion, is the coefficient related to the effect of aluminum ion concentration on sulfate attack, is the sulfate concentration, is the pH value of reinforced concrete, It is the baseline value at which ettringite begins to corrode. It is the period of reinforced concrete service life. The duration of erosion, i.e., the erosion time; When the sulfate concentration is When the erosion rate is between 2.5 and 3.5, the combined erosion of ettringite and gypsum is considered, and the sulfate erosion index formula is constructed: ； In the formula, is the concentration of aluminum ions in reinforced concrete, is the concentration of calcium ions in reinforced concrete, is the coefficient related to the contribution of aluminum ions to corrosion, is the coefficient related to the contribution of calcium ions to erosion, is a coefficient used to adjust the combined impact of ettringite and gypsum erosion; When the sulfate concentration is greater than When considering gypsum erosion, the sulfate erosion index formula is constructed: 。 5. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1 is characterized by: In step 2, when in a marine environment, constructing a new sulfate attack index formula includes the following steps: When in a marine environment, and the sulfate concentration in seawater is greater than , considering magnesium salt erosion, construct the sulfate erosion index formula: ； In the formula, Expressed as the sulfate attack index, is the concentration of magnesium ions in seawater, It is a coefficient that adjusts the combined effect of magnesium salt and sulfate erosion; When the sulfate concentration in seawater is less than 4000ppm, ettringite erosion is considered, and the sulfate erosion index formula is: ； The sulfate concentration in seawater is When the erosion of calcium sulfide and gypsum is considered, the sulfate erosion index formula is: 。 6. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1, characterized in that: In step 3, constructing the chloride erosion index formula includes the following steps: The groundwater chloride ion concentration at the location of the power transmission and transformation project is calibrated as , with a pre-set chloride ion content threshold In contrast, When the chloride ions are considered to have a corrosive effect, the chloride salt corrosion index formula is constructed: ； In the formula, Expressed as the chloride attack index, Expressed as a coefficient related to the contribution of chloride salt erosion, Expressed as porosity, .

7. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1, characterized in that: In step 4, constructing the carbonization erosion index formula includes the following steps: Construct the humidity impact function: ； In the formula, Expressed as humidity influence function, It is represented by the relative humidity of the environment at the location of the power transmission and transformation project collected in real time. Expressed as a constant; Construct the carbonization erosion index formula: ； In the formula, Expressed as the carbonization erosion index, is the carbonization corrosion contribution coefficient related to the pore volume ratio, is the coefficient related to the humidity influence function on carbonization corrosion, is the water-cement ratio of reinforced concrete, is the carbon dioxide concentration in the environment where the power transmission and transformation project is located. is the coefficient related to the effect of the water-cement ratio of reinforced concrete on carbonation corrosion, It is the coefficient related to the effect of carbon dioxide concentration in the environment on carbonation corrosion.

8. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1 is characterized by: In step 5, the method for establishing a comprehensive corrosion evaluation index formula that can comprehensively evaluate the corrosion is: The weight of freeze-thaw damage index is set as , the weight of the sulfate attack index is , the weight of the chloride erosion index is , the weight of the carbonization erosion index is , establish the comprehensive corrosiveness evaluation index formula: ； In the formula, Expressed as a comprehensive corrosion assessment index.

9. The method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects according to claim 1, characterized in that: In step 5, the method for determining the degree of erosion based on the results is: The erosion threshold is preset as ,and ,when When When When It is judged to be extremely severe corrosion.

10. A system for evaluating the corrosion of reinforced concrete in power transmission and transformation projects, characterized in that: The system is used to implement a method for evaluating the corrosion of reinforced concrete in power transmission and transformation projects as described in any one of claims 1 to 9: The freeze-thaw damage index construction module is used to collect temperature data of the location of the power transmission and transformation project and the self-characteristic data of the reinforced concrete to be evaluated, and to construct a freeze-thaw damage index formula based on the collected temperature data and the self-characteristic data. The temperature data covers the temperature cycle, change amplitude and temperature change time, and the self-characteristic data includes the total volume, water content and pore volume of the reinforced concrete; The sulfate erosion index construction module is used to identify the type of erosion products generated based on the groundwater sulfate concentration data at the location of the power transmission and transformation project. Based on the type of erosion products, the corresponding sulfate erosion index formula is constructed through the groundwater pH value, erosion time, aluminum ion concentration, and calcium ion concentration data. When in a marine environment, the magnesium ion concentration data in the ocean is included in the analysis system to construct a new sulfate erosion index formula; The chloride erosion index construction module is used to pre-set the chloride ion content threshold and construct the chloride erosion index formula based on the groundwater chloride ion concentration, chloride ion content threshold and reinforced concrete porosity data at the location of the power transmission and transformation project; The carbonization erosion index construction module is used to extract the relative humidity data of the air at the location of the power transmission and transformation project, construct the humidity influence function, and construct the carbonization erosion index formula based on the humidity influence function, the total volume of reinforced concrete, the total volume of reinforced concrete pores, the carbon dioxide concentration in the environment of the power transmission and transformation project, and the water-cement ratio of reinforced concrete; The comprehensive corrosion assessment index construction module is used to assign corresponding weights according to the importance of the corrosion type represented by each formula on the overall corrosion, establish a comprehensive corrosion assessment index formula that can comprehensively evaluate the corrosion, and determine the degree of corrosion based on the results.

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