Method for fast prediction of life of reinforced concrete pole in chlorine salt environment

Abstract

The application provides a method for rapidly predicting the service life of a reinforced concrete pole in a chlorine salt environment, relates to the technical field of concrete structure durability evaluation and service life prediction, and can obtain the chlorine ion erosion degree and the current corrosion activity of the steel bar under the premise of not damaging the pole structure by selecting at least two different depths as detection depths, obtaining potential values and converting the potential values into free chlorine ion concentrations, and utilizing polarization curves to obtain instantaneous corrosion current densities; the current state of the reinforced concrete pole is rapidly judged by comparing the instantaneous corrosion current densities with a corrosion starting threshold value, the residual service life is accurately calculated, the whole life cycle seamless evaluation from no corrosion to corrosion initiation and then to corrosion development to failure is realized, the limitations of traditional methods which only pay attention to corrosion initiation or only qualitatively judge the corrosion state are made up, and the residual service life prediction which is quantitative and based on real-time corrosion rate is provided for the poles which have entered the corrosion stage.

Description

Technical Field

[0001] This invention relates to the field of concrete structure durability assessment and life prediction technology, specifically a method for rapidly predicting the life of reinforced concrete poles in chloride salt environments. Background Technology

[0002] In coastal areas, offshore platforms, and near-shore infrastructure, reinforced concrete poles are exposed to seawater rich in chloride salts for extended periods. Chloride ions in the seawater penetrate the concrete protective layer through diffusion and capillary adsorption. When the concentration of free chloride ions on the surface of the steel bars accumulates to a critical value, it will damage the passivation film on the surface of the steel bars, severely weakening the load-bearing capacity and durability of the poles.

[0003] However, the equivalent surface chloride ion concentration and apparent diffusion coefficient are the core parameters of the chloride ion diffusion model. Existing technologies mostly adopt empirical values ​​recommended by specifications. Due to differences in construction, maintenance and microenvironment, the durability performance of poles of the same design and batch may vary greatly, which cannot provide accurate decision-making basis for the maintenance and replacement of offshore poles.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for rapidly predicting the lifespan of reinforced concrete utility poles in chloride environments, comprising the following steps: Step 1: On the reinforced concrete pole to be tested, select at least two different locations inside the concrete of the pole as the detection depth along the direction perpendicular to the radial direction of the pole, obtain the potential value corresponding to the detection depth, convert the potential value into free chloride ion concentration through the pre-calibrated potential-concentration curve, and obtain the instantaneous corrosion current density at the detection depth using the polarization curve of the reinforced concrete pole. Step 2: Using the free chloride ion concentration and instantaneous corrosion current density at each detection depth as constraints, construct an error function with chloride ion diffusion behavior as the core. By solving the corresponding simultaneous equations, minimize the error function and invert the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient that can simultaneously characterize the service status of the pole. Step 3: Set the critical chloride ion concentration for depassivation of the steel bar. Based on the equivalent surface chloride ion concentration and the apparent chloride ion diffusion coefficient, construct a corrosion prediction function for the diffusion of chloride ions from the concrete surface to the steel bar location. Determine the time point when the chloride ion concentration at the steel bar location first reaches the critical chloride ion concentration, which is taken as the surface chloride ion corrosion time, i.e. the starting time of steel bar corrosion. Step 4: Obtain the service life of the reinforced concrete pole, compare the surface chloride ion corrosion time with the service life of the reinforced concrete pole to determine whether the reinforced concrete pole is corroded, calculate the corrosion limit state time based on Faraday's law, and calculate the remaining life of the reinforced concrete pole by combining the surface chloride ion corrosion time, the corrosion limit state time, and the service life of the reinforced concrete pole.

[0007] Furthermore, the specific steps for calculating the free chloride ion concentration and the instantaneous corrosion current density are as follows: Obtain the potential value at the detection depth on the reinforced concrete pole to be tested. Convert the potential value into the measured free chloride ion concentration using a pre-calibrated potential-concentration curve. The mathematical expression for calculating the measured free chloride ion concentration at the two depths using the calibrated potential-concentration curve is as follows: In the formula, Indicates depth ,time The measured concentration of free chloride ions at the location; Indicates the calibration baseline potential; This indicates the obtained potential value; Indicates the slope of the calibration curve; The instantaneous corrosion current density at the detection depth was calculated using the polarization curve of the reinforced concrete pole.

[0008] Furthermore, the specific steps for obtaining the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient are as follows: The chloride ion diffusion value is obtained by multiplying the apparent diffusion coefficient by the service life of the reinforced concrete pole. The apparent chloride ion value is then compared with the chloride ion diffusion value (square root of 2) at each depth. This apparent chloride ion value is then substituted into the solution to obtain the apparent chloride ion error value. The difference between this apparent error value and the apparent chloride ion error value is calculated to obtain the chloride ion error value. The theoretical free chloride ion concentration at each depth is obtained by multiplying the equivalent surface chloride ion concentration by the chloride ion error value. Therefore, the mathematical expression for calculating the theoretical free chloride ion concentration at each depth is: in, In the formula, Indicates detection depth The theoretical free chloride ion concentration at the location; This indicates the service life of the reinforced concrete utility pole; Indicates the equivalent surface chloride ion concentration; Represents the error function; Indicates the apparent chloride ion diffusion coefficient; A chloride ion proportionality coefficient is set, the background corrosion current is obtained, and the product of the chloride ion proportionality coefficient and the theoretical free chloride ion concentration at the detection depth is calculated to obtain the first concentration product. The sum of the first concentration product and the background corrosion current is calculated to obtain the theoretical value of the corrosion current density. The mathematical expression for calculating the theoretical value of the corrosion current density is: In the formula, This represents the theoretical value of the corrosion current density; Indicates the chloride ion proportion coefficient; Indicates background corrosion current; By setting weighting coefficients for chloride ion concentration error and corrosion current density error, the theoretical and measured free chloride ion concentrations at each depth are calculated to obtain the chloride ion concentration difference at each depth. The square of the chloride ion concentration difference at each depth is calculated to obtain the squared chloride ion concentration at each depth. The squared chloride ion concentrations at all depths are calculated to obtain the first concentration sum. The first concentration sum is multiplied by the weighting coefficient of the chloride ion concentration error to obtain the second concentration product. The difference between the theoretical and measured corrosion current density at each depth is calculated to obtain the corrosion current density difference. The squared corrosion current density difference at each depth is calculated to obtain the squared corrosion current density at each depth. The squared corrosion current density is multiplied by the weighting coefficient of the corrosion current density error to obtain the second density product. The second concentration product is added to the second density product to obtain the comprehensive error value. The mathematical expression for the error function is then constructed as follows: In the formula, This represents the overall error value; The weighting coefficient representing the error in chloride ion concentration; The weighting coefficient representing the error in corrosion current density; Indicates corrosion current density; The error function is solved by nonlinear least squares fitting to obtain the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient.

[0009] Furthermore, the specific steps for constructing a surface chloride ion corrosion prediction function and obtaining the surface chloride ion corrosion time are as follows: To obtain the concrete cover thickness, the critical chloride ion concentration for rebar depassivation is calculated and compared with the equivalent surface chloride ion concentration to obtain the critical chloride ion ratio. The difference between 1 and the critical chloride ion ratio is calculated to obtain the critical chloride ion ratio difference. This critical chloride ion ratio difference is substituted into the inverse error function to obtain the first solution value. Taking the negative square of the first solution value yields the first value. The ratio of the square of the concrete cover thickness to four times the apparent chloride ion diffusion coefficient is calculated to obtain the first ratio. Multiplying the first value by the first ratio yields the surface chloride ion corrosion time. The mathematical expression for calculating the surface chloride ion corrosion time is: In the formula, Indicates the surface chloride ion corrosion time; This indicates the critical chloride ion concentration for depassivation of reinforcing bars; The inverse function of the error function is also called the inverse error function. This indicates the thickness of the concrete cover.

[0010] Furthermore, the logic for determining whether a reinforced concrete utility pole is corroded is as follows: The service life of the reinforced concrete pole is obtained, and the surface chloride ion corrosion time is compared with the service life of the reinforced concrete pole. If the surface chloride ion corrosion time is less than or equal to the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has not started corrosion; if the surface chloride ion corrosion time is greater than the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has started corrosion.

[0011] Furthermore, when corrosion begins to occur on reinforced concrete poles, the specific steps for calculating the lifespan of the reinforced concrete poles are as follows: To obtain the corrosion limit mass loss of reinforced concrete poles and the mass of steel corrosion per unit time, the corrosion limit state time is obtained by calculating the ratio of the corrosion limit mass loss to the mass of steel corrosion per unit time. The mathematical expression for calculating the corrosion limit state time is then: In the formula, Indicates the time to the corrosion limit state; Indicates the maximum mass loss due to corrosion; This indicates the mass of steel reinforcement corrosion per unit time; The corrosion duration is obtained by comparing the service life of the reinforced concrete pole with the time of chloride ion corrosion on its surface. The remaining life of the reinforced concrete pole is obtained by comparing the time to the limit state of corrosion with the corrosion duration. The mathematical expression for calculating the corrosion duration is as follows: In the formula, Indicates the duration of corrosion; The mathematical expression for calculating the remaining life of reinforced concrete poles is: In the formula, This indicates the remaining lifespan of the utility pole.

[0012] Furthermore, when corrosion has not yet started on the reinforced concrete pole, the specific steps for calculating the lifespan of the reinforced concrete pole are as follows: The total lifespan of a reinforced concrete pole is obtained by summing the surface chloride ion corrosion time and the corrosion limit state time. The remaining lifespan of the reinforced concrete pole is obtained by the difference between the total lifespan and the years the pole has been used. Therefore, the mathematical expression for calculating the remaining lifespan of a reinforced concrete pole is as follows: Furthermore, the specific steps for obtaining the corrosion limit mass loss of reinforced concrete poles are as follows: To obtain the density and corrosion limit volume loss of the reinforcing steel, multiply the density by the corrosion limit volume loss to obtain the corrosion limit mass loss. The mathematical expression for calculating the corrosion limit mass loss is then: In the formula, Indicates the density of the reinforcing steel; This indicates the maximum volume loss due to corrosion.

[0013] Furthermore, the specific steps for obtaining the steel reinforcement corrosion quality per unit time are as follows: To obtain the molar mass of iron, the surface area of ​​the corroded steel bar, the number of electrons transferred in the iron oxidation reaction, and the Faraday constant, multiply the molar mass of iron, the instantaneous corrosion density of the steel bar, and the surface area of ​​the corroded steel bar to obtain the first product. Multiply the number of electrons transferred in the iron oxidation reaction by the Faraday constant to obtain the second product. The ratio of the first product to the second product yields the mass of steel bar corrosion per unit time. Therefore, the mathematical expression for calculating the mass of steel bar corrosion per unit time is: In the formula, Indicates the molar mass of iron; This represents the instantaneous corrosion current density; This represents the surface area of ​​the steel reinforcement that has been corroded. Indicates the number of electrons transferred in the iron oxidation reaction; represents the Faraday constant, which represents the amount of charge carried by each mole of electrons.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention selects at least two different depths on the reinforced concrete pole under test as the detection depth, simultaneously acquires the potential value and converts it into free chloride ion concentration, and uses polarization curves to obtain the instantaneous corrosion current density. It can obtain dual information on the degree of chloride ion erosion and the current corrosion activity of the steel bars without damaging the pole structure. This solves the technical problem that traditional methods can only sample at a single point and cannot reflect the comprehensive corrosion state inside the pole in real time. This invention rapidly determines whether a steel bar is currently corroded by comparing the instantaneous corrosion current density with the corrosion initiation threshold. If it is not corroded, the remaining lifespan is the corrosion initiation time. If it is corroded, Faraday's law is used to calculate the time required for the steel bar to develop from the current corrosion state to the corrosion limit state based on the measured corrosion current density. Combined with the calculated corrosion duration, the precise remaining lifespan is finally calculated. This achieves seamless assessment of the entire life cycle from no corrosion to corrosion initiation to corrosion development and failure. For poles that have entered the corrosion stage, it provides a quantitative remaining lifespan prediction based on the real-time corrosion rate, making the assessment more comprehensive and accurate. It overcomes the limitations of traditional methods that only focus on corrosion initiation or only qualitatively judge the corrosion state, providing a complete, quantitative, and direct technical basis for the maintenance, repair, and replacement decisions of in-service poles (regardless of whether corrosion has begun). Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall method flow of the present invention; Figure 2 The curve showing the fitting of equivalent surface chloride ion concentration to free chloride ion concentration d2; Figure 3 This is a fitted curve of surface chloride ion corrosion time versus apparent chloride ion diffusion coefficient. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0017] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0018] Example: Please see Figures 1-3 The present invention provides a technical solution: A method for rapidly predicting the lifespan of reinforced concrete utility poles in chloride environments, comprising the following steps: Step 1: On the reinforced concrete pole to be tested, select at least two different locations inside the concrete of the pole as the detection depth along a direction perpendicular to the radial direction of the pole, obtain the potential value corresponding to the detection depth, convert the potential value into the free chloride ion concentration through a pre-calibrated potential-concentration curve, and obtain the instantaneous corrosion current density at the detection depth using the polarization curve of the reinforced concrete pole.

[0019] In this embodiment, the potential value of existing reinforced concrete poles can be obtained by electrochemical impedance spectroscopy inversion. This method involves applying AC perturbation signals of different frequencies to the reinforced concrete system and measuring the system's impedance spectrum (such as parameters like capacitive arc and charge transfer resistance). The surface conditions of the steel bars at different depths (such as passivation film thickness and corrosion degree) correspond to different impedance characteristics. Combined with a concrete dielectric property model (such as a multilayer dielectric impedance model), the potential distribution at different depths can be calculated by fitting and inverting the impedance spectrum. The potential value of newly built reinforced concrete poles can be obtained by distributed electrode array method. This method can achieve long-term layered potential monitoring by pre-embedded electrodes.

[0020] In this embodiment, the calibration requires concrete specimens with the same mix ratio and curing regime as the pole under test. At least three parallel specimens should be set for each standard concentration gradient (e.g., 0.01%, 0.05%, 0.1%, 0.5%). The test environment temperature should be controlled at 23±2℃ and the relative humidity above 95% to avoid baseline deviation caused by curing differences.

[0021] In this embodiment, the specific steps for calculating the free chloride ion concentration and the instantaneous corrosion current density are as follows: To obtain the potential value at the detection depth on the reinforced concrete pole to be tested, the potential value is converted into free chloride ion concentration using a pre-calibrated potential-concentration curve. The mathematical expression for calculating the free chloride ion concentration at the two depths using the calibrated potential-concentration curve is as follows: In the formula, Indicates depth ,time The measured free chloride ion concentration at a depth of [insert depth here] in the concrete is [insert value here]. The location of the free chloride ion concentration (a chloride salt component that can directly cause steel corrosion) at the time of testing. The calibration baseline potential is the open-circuit potential of a standard specimen with a known chloride ion concentration, obtained from an indoor calibration test (it is the intercept term of the calibration curve). The obtained potential value represents the depth of the pole under test. The natural corrosion potential of the steel bars relative to the reference electrode is superimposed with the combined effects of concrete temperature, humidity, and chloride ion concentration. The concrete surface temperature must be recorded simultaneously during on-site testing. If the temperature deviates from the 25℃ benchmark, temperature compensation should be performed according to the standard of ±2mV correction for every 1℃ deviation. The slope of the calibration curve is the potential-chloride ion concentration response coefficient determined by indoor calibration tests. It reflects the change in potential for every order of magnitude change in chloride ion concentration. For ordinary silicate concrete, The typical value is 59±5mV / dec (at 25℃). If fly ash, slag or other admixtures are added to the concrete, the slope needs to be recalibrated. The higher the amount of admixture, the slope may drop slightly to 50-55mV / dec. Using the polarization curve of a reinforced concrete pole, the instantaneous corrosion current density corresponding to the free chloride ion concentration is calculated. The polarization curve needs to be obtained through potentiodynamic polarization, and the scanning range is set to... (Relative to open circuit potential), the scan rate is controlled at 0.167 mV / s to avoid excessive polarization distortion due to an excessively fast scan rate; the instantaneous corrosion current density is solved using the Tafel extrapolation method, taking the current density corresponding to the intersection of the extended lines of the Tafel segments of the anodic and cathodic polarization curves. If the curve does not have a clear Tafel segment, the linear polarization resistance method can be used for auxiliary verification, i.e. ,in It is a constant (26mV for corroded steel bars and 52mV for passivated steel bars). It is a linearly polarized resistor.

[0022] Step 2: Using the free chloride ion concentration and instantaneous corrosion current density at each detection depth as constraints, construct an error function with chloride ion diffusion behavior as the core. By solving the corresponding simultaneous equations, minimize the error function and obtain the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient that can simultaneously characterize the service status of the pole.

[0023] In this embodiment, the specific steps for obtaining the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient are as follows: The chloride ion diffusion value is obtained by multiplying the apparent diffusion coefficient by the service life of the reinforced concrete pole. The apparent chloride ion value is then compared with the chloride ion diffusion value (square root of 2) at each depth. This apparent chloride ion value is then substituted into the solution to obtain the apparent chloride ion error value. The difference between this apparent error value and the apparent chloride ion error value is calculated to obtain the chloride ion error value. The theoretical free chloride ion concentration at each depth is obtained by multiplying the equivalent surface chloride ion concentration by the chloride ion error value. Therefore, the mathematical expression for calculating the theoretical free chloride ion concentration at each depth is: in, In the formula, Indicates depth The concentration of free chloride ions at that location; This indicates the service life of the reinforced concrete pole, which is the cumulative operating time from when the pole was put into service to the time of this test. This represents the equivalent surface chloride ion concentration, specifically the chloride ion concentration at the interface between concrete and the chloride environment (the input concentration of environmental chloride). The error function is a mathematical function describing an unsteady diffusion process, and its value range is... In this model, since the independent variable is positive, its range is... ; The apparent chloride ion diffusion coefficient is a parameter that reflects the ability of chloride ions to migrate in the pores of concrete. It is positively correlated with the water-cement ratio, strength, temperature and humidity of concrete. A chloride ion proportionality coefficient is set, the background corrosion current is obtained, and the product of the chloride ion proportionality coefficient and the theoretical free chloride ion concentration at the detection depth is calculated to obtain the first concentration product. The sum of the first concentration product and the background corrosion current is calculated to obtain the theoretical value of the corrosion current density. The mathematical expression for calculating the theoretical value of the corrosion current density is: In the formula, This represents the theoretical value of corrosion current density, and its value is derived from... and Decide; Indicates the chloride ion proportion coefficient; Indicates background corrosion current; By setting weighting coefficients for chloride ion concentration error and corrosion current density error, the theoretical and measured free chloride ion concentrations at each depth are calculated to obtain the chloride ion concentration difference at each depth. The square of the chloride ion concentration difference at each depth is calculated to obtain the squared chloride ion concentration at each depth. The squared chloride ion concentrations at all depths are calculated to obtain the first concentration sum. The first concentration sum is multiplied by the weighting coefficient of the chloride ion concentration error to obtain the second concentration product. The difference between the theoretical and measured corrosion current density at each depth is calculated to obtain the corrosion current density difference. The squared corrosion current density difference at each depth is calculated to obtain the squared corrosion current density at each depth. The squared corrosion current density is multiplied by the weighting coefficient of the corrosion current density error to obtain the second density product. The second concentration product is added to the second density product to obtain the comprehensive error. The mathematical expression for the error function is then constructed as follows: In the formula, This represents the overall error, used to measure the accuracy of the inversion parameters. The smaller the value, the more likely it is to be inversely derived. and The more reliable; The weighting coefficient representing the chloride ion concentration error is used to balance the dimensional differences and importance of the concentration and current terms. If both are considered equally important, it can be set to 0. If the concentration measurement is more accurate, the volume can be increased. ,That ; The weighting coefficient representing the error in corrosion current density; Indicates corrosion current density; The error function is solved by nonlinear least squares fitting to obtain the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient.

[0024] In this embodiment, the specific steps for solving the error function using nonlinear least squares fitting are as follows: Error function Decompose the problem into the sum of squares of several residual terms, and define the residual vector. , among which, the former Each residual term corresponds to the chloride ion concentration deviation at each depth (multiplied by the square root of the weighting factor): ;No. Each residual term corresponds to a corrosion current density deviation (multiplied by the square root of the weighting factor): Then the error function can be expressed as the sum of squares of the residual vectors: ; Set the initial value vector of the parameters to be solved ,in The chloride ion concentration was measured at the surface layer (minimum depth). times, Take empirical values ​​from similar concrete structures, such as to ; In the In this iteration, the following steps are performed: Calculate the residual vector : Set the current parameter Substitute the residual definition from the first step and calculate all n+1 residual values; Calculate the Jacobian matrix Calculate each residual For each parameter The first-order partial derivatives form the Jacobian matrix. : Specifically, for the chloride ion concentration residual term : For the corrosion current density residual term : Solving for parameter update amount : In the formula, Indicates the damping factor; Represents the identity matrix; Update parameters: Update damping factor: if If so, accept this update and reduce the size. (like ); if If so, then reject this update and increase the size. (like ), and resolve for the parameter update amount and update parameters; Iteration stops when any of the following conditions are met: Error change (like ); Parameter update volume (like ); Reaching the maximum number of iterations (e.g.) ) After iterative convergence, the current parameter value That is, to make the comprehensive error function The equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient that reach their minimum values.

[0025] In this embodiment, 50 sets of free chloride ion concentration equation data were statistically analyzed, among which... The partial data is shown below: Table 1: Data from the equation for free chloride ion concentration According to Table 1 and Figure 2 It can be seen that the concentration of free chloride ions ranges from 0.033% to 0.447%, with a relatively dispersed distribution; the corrosion current density ranges from 0.083 to 1.761 μA / cm², showing large fluctuations and reflecting significant differences in the corrosion activity of the reinforcing steel; the apparent diffusion coefficient is 1.21 × 10⁻⁶. - ¹²~9.83×10 - The concentrations were ¹²m² / s, all of the same order of magnitude, indicating the same diffusion level. The equivalent surface chloride ion concentration ranged from 0.35% to 2.8%, showing a continuous and uniform decrease. The comprehensive error ranged from 0.335 to 4.5, monotonically decreasing with increasing sequence number, indicating that the model fitting accuracy gradually improved. The equivalent surface chloride ion concentration decreased monotonically and linearly with the test sequence number, serving as the control variable in this experiment. The comprehensive error E decreased with decreasing Cs, indicating that the model prediction accuracy was higher at low surface chloride ion concentrations. The free chloride ion concentration, corrosion current density, and apparent diffusion coefficient did not exhibit a strict monotonic trend, reflecting the randomness and complexity of chloride ion transport and steel corrosion within concrete in actual engineering. The Da values ​​of all samples were within 10. - The result is on the order of ¹²m² / s, indicating that the chloride ion diffusion performance of the concrete material is stable and the data is reliable under the test conditions.

[0026] Step 3: Set the critical chloride ion concentration for steel bar depassivation. Based on the equivalent surface chloride ion concentration and the apparent chloride ion diffusion coefficient, construct a corrosion prediction function for chloride ion diffusion from the concrete surface to the steel bar location. Determine the time point when the chloride ion concentration at the steel bar location first reaches the critical chloride ion concentration, which is taken as the surface chloride ion corrosion time, i.e., the starting time of steel bar corrosion.

[0027] In this embodiment, the critical chloride ion concentration for steel bar depassivation is set using a standardized value method. For ordinary silicate concrete, the cement quality is specified. The critical chloride ion concentration for steel bar depassivation (based on total chloride ion content) is 0.4% of the cement mass for other concrete as the critical value for important projects.

[0028] In this embodiment, the specific steps for constructing the surface chloride ion corrosion prediction function and obtaining the surface chloride ion corrosion time are as follows: To obtain the concrete cover thickness, the critical chloride ion concentration for rebar depassivation is calculated and compared with the equivalent surface chloride ion concentration to obtain the critical chloride ion ratio. The difference between 1 and the critical chloride ion ratio is calculated to obtain the critical chloride ion ratio difference. This critical chloride ion ratio difference is substituted into the inverse error function to obtain the first solution value. Taking the negative square of the first solution value yields the first value. The ratio of the square of the concrete cover thickness to four times the apparent chloride ion diffusion coefficient is calculated to obtain the first ratio. Multiplying the first value by the first ratio yields the surface chloride ion corrosion time. The mathematical expression for calculating the surface chloride ion corrosion time is: In the formula, Indicates the surface chloride ion corrosion time; This indicates the critical chloride ion concentration for depassivation of reinforcing bars in ordinary low-carbon steel within silicate concrete. The typical value is 0.15% (based on concrete mass). If a rust inhibitor is added to the concrete, Upgradeable to The marine environment is continuously eroded by salt spray. Can be reduced to ; The inverse function of the error function is also called the inverse error function. This indicates the thickness of the concrete cover.

[0029] In this embodiment, the thickness of the concrete cover is obtained using a rebar detector. First, the direction and spacing of the rebars are determined within a selected area, and depth measurement is performed in the direction perpendicular to the direction of the rebars. The probe is accurately placed directly above a single rebar, and the instrument will directly display the distance from the upper surface of the rebar to the outer surface of the concrete, i.e., the thickness of the cover. The rebar detector needs to be calibrated in advance with a standard test block (calibration test block cover thickness error ±1mm). During testing, avoid cracks on the pole surface and the location of embedded parts. If there is a coating or rust on the surface, it needs to be removed before testing to avoid affecting the detection accuracy. For ring poles, one point needs to be measured in each of the four directions of east, south, west, and north on the same cross section, and the average value is taken as the cover thickness of that cross section.

[0030] In this embodiment, at least 3 stable data are read at each measuring point, and the average value is taken as the representative value of the point. In each selected area, at least 3-5 different steel bars are measured. The standard for judging stable data is that the difference between 3 consecutive readings is ≤0.5mm. If the difference is too large, it is necessary to check whether the probe is in close contact with the surface and whether there is interference from steel bar intersection. After eliminating the interference, the measurement is repeated.

[0031] In this embodiment, 50 sets of surface chloride ion corrosion time data were collected, and some of the data are shown below: Table 2: Surface chloride ion corrosion time data According to Table 2 and Figure 3 It can be seen that the critical chloride ion concentration for rebar depassivation is constant at 0.150%, which conforms to the classic critical value for rebar depassivation in concrete in the field of civil engineering (when the chloride ion concentration on the rebar surface reaches this value, the passivation film begins to break down, and corrosion begins); the equivalent surface chloride ion concentration increases linearly from 0.050% to 0.540%, with a gradient of 0.010%, covering the concentration range of low, medium, and high chloride salt corrosion environments at sea / coast; the concrete protective layer thickness increases from 30.000 mm to 79.000 mm, consistent with the commonly used design thickness range of concrete protective layers for utility poles; the apparent chloride ion diffusion coefficient increases from... Increment to The material properties are consistent with the positive correlation between concrete porosity and temperature and humidity. The surface chloride ion corrosion time increased from 0.852 years to 9.324 years, which is positively correlated with the equivalent surface chloride ion concentration. This verifies the technical principle that the higher the surface chloride ion concentration, the stronger the driving force for chloride ion migration to the steel reinforcement surface. However, the design logic of achieving a stable extension of corrosion time is achieved through the synergistic increase of protective layer thickness and diffusion coefficient.

[0032] In this embodiment, when At this point, the chloride ion concentration cannot reach the depassivation critical value. If the value approaches infinity, it can be determined that the steel bar will not be corroded by chloride ion attack, and other corrosion-inducing factors need to be focused on.

[0033] Step 4: Obtain the service life of the reinforced concrete pole, compare the surface chloride ion corrosion time with the service life of the reinforced concrete pole to determine whether the reinforced concrete pole is corroded, calculate the corrosion limit state time based on Faraday's law, and calculate the remaining life of the reinforced concrete pole by combining the surface chloride ion corrosion time, the corrosion limit state time, and the service life of the reinforced concrete pole.

[0034] In this embodiment, the logic for determining whether a reinforced concrete pole is corroded is as follows: The service life of the reinforced concrete pole is obtained, and the surface chloride ion corrosion time is compared with the service life of the reinforced concrete pole. If the surface chloride ion corrosion time is less than or equal to the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has not started corrosion; if the surface chloride ion corrosion time is greater than the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has started corrosion.

[0035] In this embodiment, if there are rust-induced cracks (width ≥ 0.2 mm) along the direction of the reinforcing bars on the surface of the pole, even if ≥ This also indicates that corrosion has begun, and corrections are needed at this point. This represents the time when the crack appeared, which can be estimated from crack observation records.

[0036] In this embodiment, the specific steps for calculating the lifespan of a reinforced concrete pole when corrosion begins are as follows: To obtain the corrosion limit mass loss of reinforced concrete poles and the mass of steel corrosion per unit time, the corrosion limit state time is obtained by calculating the ratio of the corrosion limit mass loss to the mass of steel corrosion per unit time. The mathematical expression for calculating the corrosion limit state time is then: In the formula, The corrosion limit state time is the duration from the moment corrosion begins to the corrosion limit state of the steel bar (i.e., the time from corrosion development to pole failure). It represents the ultimate mass loss due to corrosion, which is the cumulative mass loss when the steel reinforcement corrodes to its ultimate state (when this value is reached, the pole's load-bearing capacity or durability meets the failure criteria). It represents the mass of steel reinforcement corrosion per unit time, and is the corrosion rate of steel reinforcement (the amount of mass loss per unit time), which is calculated from the instantaneous corrosion current density; The corrosion duration is obtained by comparing the service life of the reinforced concrete pole with the time of chloride ion corrosion on its surface. The remaining life of the reinforced concrete pole is obtained by comparing the time to the limit state of corrosion with the corrosion duration. The mathematical expression for calculating the corrosion duration is as follows: In the formula, The duration of corrosion is the time it takes for corrosion to develop from the moment the steel bar depassivates (when the chloride ion concentration reaches a critical value) to the current test moment. Then Determined as This means that corrosion has not yet started and there is no duration of corrosion. The mathematical expression for calculating the remaining life of reinforced concrete poles is: In the formula, The remaining lifespan of the utility pole refers to the time remaining before it fails due to steel corrosion, from the current test moment. The pole has been determined to have reached its corrosion limit and must be immediately taken out of service for inspection or replacement.

[0037] In this embodiment, when corrosion of the reinforced concrete pole has not yet started, the specific steps for calculating the lifespan of the reinforced concrete pole are as follows: When corrosion of reinforced concrete poles has not yet begun, the total lifespan of the pole is obtained by summing the surface chloride ion corrosion time and the corrosion limit state time. The remaining lifespan of the pole is obtained by the difference between the total lifespan and the years already used. Therefore, the mathematical expression for calculating the remaining lifespan of a reinforced concrete pole is as follows: In this embodiment, the specific steps for obtaining the corrosion limit mass loss of the reinforced concrete pole are as follows: To obtain the density and corrosion limit volume loss of the reinforcing steel, multiply the density by the corrosion limit volume loss to obtain the corrosion limit mass loss. The mathematical expression for calculating the corrosion limit mass loss is then: In the formula, The density of reinforcing steel is the mass-to-volume ratio of steel materials, and it is usually taken as... or ; This indicates the maximum volume loss due to corrosion.

[0038] In this embodiment, the ultimate volume loss due to corrosion is calculated based on the stress design of the pole, determining how much cross-sectional loss of the reinforcing steel would cause its bending or tensile bearing capacity to drop below the safety factor. If the initial reinforcing steel radius is r and the ultimate loss rate is set to x%, then the ultimate volume loss... .

[0039] In this embodiment, the standard for determining the ultimate loss rate is as follows: for the reinforcing bars of a pole subjected to axial tensile force, Pick The reinforcing bars of the pole that bear bending moment, Pick (Reinforcement in the tension zone) (Reinforcement in the compression zone); the lower limit value is taken for important transmission line poles, and the upper limit value is taken for general agricultural and municipal poles; the ultimate loss rate needs to be determined in conjunction with the pole structure design calculation to ensure that the failure judgment matches the actual bearing capacity.

[0040] In this embodiment, the specific steps for obtaining the steel reinforcement corrosion mass per unit time are as follows: To obtain the molar mass of iron, the surface area of ​​the corroded steel bar, the number of electrons transferred in the iron oxidation reaction, and the Faraday constant, multiply the molar mass of iron, the instantaneous corrosion density of the steel bar, and the surface area of ​​the corroded steel bar to obtain the first product. Multiply the number of electrons transferred in the iron oxidation reaction by the Faraday constant to obtain the second product. The ratio of the first product to the second product yields the mass of steel bar corrosion per unit time. Therefore, the mathematical expression for calculating the mass of steel bar corrosion per unit time is: In the formula, This represents the molar mass of iron. In models of steel corrosion (electrochemical oxidation), it is usually assumed that iron is oxidized to ferrous ions (Fe2+). Therefore, the molar mass of iron participating in the reaction is taken as... ; This represents the instantaneous corrosion current density; It represents the surface area of ​​steel reinforcement corrosion, which is the total corroded area of ​​the steel reinforcement in the pole in contact with the concrete; The number of electrons transferred in the iron oxidation reaction is the stoichiometric number of electrons transferred in the steel corrosion reaction (iron loses electrons and becomes ferrous ions), which is taken as 2; The Faraday constant represents the amount of charge carried by each mole of electrons, and its standard value is [value missing]. .

[0041] In this embodiment, the surface area of ​​the corroded steel bar is calculated by multiplying the surface area of ​​a single steel bar by the number of steel bars. The surface area of ​​corrosion of a single steel bar = π × steel bar diameter × steel bar length. If the steel bar has localized corrosion, the surface area needs to be adjusted according to the proportion of the corroded area. , This represents the percentage of corroded area (determined through ultrasonic testing or core sampling); for severely corroded reinforcing bars, the impact of rust layer detachment must be considered. The area covered by the flaking rust layer needs to be deducted from the value.

[0042] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0043] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0044] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0045] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for rapidly predicting the lifespan of reinforced concrete utility poles in chloride-salt environments, characterized in that, The specific steps include: Step 1: On the reinforced concrete pole to be tested, select at least two different locations inside the concrete of the pole as the detection depth along the direction perpendicular to the radial direction of the pole, obtain the potential value corresponding to the detection depth, convert the potential value into free chloride ion concentration through the pre-calibrated potential-concentration curve, and obtain the instantaneous corrosion current density at the detection depth using the polarization curve of the reinforced concrete pole. Step 2: Using the free chloride ion concentration and instantaneous corrosion current density at each detection depth as constraints, construct an error function with chloride ion diffusion behavior as the core. By solving the corresponding simultaneous equations, minimize the error function and invert the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient that can simultaneously characterize the service status of the pole. Step 3: Set the critical chloride ion concentration for depassivation of the steel bar. Based on the equivalent surface chloride ion concentration and the apparent chloride ion diffusion coefficient, construct a corrosion prediction function for the diffusion of chloride ions from the concrete surface to the steel bar location. Determine the time point when the chloride ion concentration at the steel bar location first reaches the critical chloride ion concentration, which is taken as the surface chloride ion corrosion time, i.e. the starting time of steel bar corrosion. Step 4: Obtain the service life of the reinforced concrete pole, compare the surface chloride ion corrosion time with the service life of the reinforced concrete pole to determine whether the reinforced concrete pole is corroded, calculate the corrosion limit state time based on Faraday's law, and calculate the remaining life of the reinforced concrete pole by combining the surface chloride ion corrosion time, the corrosion limit state time, and the service life of the reinforced concrete pole.

2. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 1, characterized in that: The specific steps for calculating the free chloride ion concentration and the instantaneous corrosion current density are as follows: Obtain the potential value at the detection depth on the reinforced concrete pole to be tested. Convert the potential value into the measured free chloride ion concentration using a pre-calibrated potential-concentration curve. The mathematical expression for calculating the measured free chloride ion concentration at the two depths using the calibrated potential-concentration curve is as follows: In the formula, Indicates depth ,time The measured concentration of free chloride ions at the location; Indicates the calibration baseline potential; This indicates the obtained potential value; Indicates the slope of the calibration curve; The instantaneous corrosion current density at the detection depth was calculated using the polarization curve of the reinforced concrete pole.

3. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 1, characterized in that: The mathematical expressions for obtaining the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient are as follows: The chloride ion diffusion value is obtained by multiplying the apparent diffusion coefficient by the service life of the reinforced concrete pole. The apparent chloride ion value is then compared with the chloride ion diffusion value (square root of 2) at each depth. This apparent chloride ion value is then substituted into the solution to obtain the apparent chloride ion error value. The difference between this apparent error value and the apparent chloride ion error value is calculated to obtain the chloride ion error value. The theoretical free chloride ion concentration at each depth is obtained by multiplying the equivalent surface chloride ion concentration by the chloride ion error value. Therefore, the mathematical expression for calculating the theoretical free chloride ion concentration at each depth is: in, In the formula, Indicates detection depth The theoretical free chloride ion concentration at the location; This indicates the service life of the reinforced concrete utility pole; Indicates the equivalent surface chloride ion concentration; Represents the error function; Indicates the apparent chloride ion diffusion coefficient; A chloride ion proportionality coefficient is set, the background corrosion current is obtained, and the product of the chloride ion proportionality coefficient and the theoretical free chloride ion concentration at the detection depth is calculated to obtain the first concentration product. The sum of the first concentration product and the background corrosion current is calculated to obtain the theoretical value of the corrosion current density. The mathematical expression for calculating the theoretical value of the corrosion current density is: In the formula, This represents the theoretical value of the corrosion current density; Indicates the chloride ion proportion coefficient; Indicates background corrosion current; By setting weighting coefficients for chloride ion concentration error and corrosion current density error, the theoretical and measured free chloride ion concentrations at each depth are calculated to obtain the chloride ion concentration difference at each depth. The square of the chloride ion concentration difference at each depth is calculated to obtain the squared chloride ion concentration at each depth. The squared chloride ion concentrations at all depths are calculated to obtain the first concentration sum. The first concentration sum is multiplied by the weighting coefficient of the chloride ion concentration error to obtain the second concentration product. The difference between the theoretical and measured corrosion current density at each depth is calculated to obtain the corrosion current density difference. The squared corrosion current density difference at each depth is calculated to obtain the squared corrosion current density at each depth. The squared corrosion current density is multiplied by the weighting coefficient of the corrosion current density error to obtain the second density product. The second concentration product is added to the second density product to obtain the comprehensive error value. The mathematical expression for the error function is then constructed as follows: In the formula, This represents the overall error value; The weighting coefficient representing the error in chloride ion concentration; The weighting coefficient representing the error in corrosion current density; Indicates corrosion current density; The error function is solved by nonlinear least squares fitting to obtain the equivalent surface chloride ion concentration and apparent chloride ion diffusion coefficient.

4. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 1, characterized in that: The specific steps for constructing a surface chloride ion corrosion prediction function and obtaining the surface chloride ion corrosion time are as follows: To obtain the concrete cover thickness, the critical chloride ion concentration for rebar depassivation is calculated and compared with the equivalent surface chloride ion concentration to obtain the critical chloride ion ratio. The difference between 1 and the critical chloride ion ratio is calculated to obtain the critical chloride ion ratio difference. This critical chloride ion ratio difference is substituted into the inverse error function to obtain the first solution value. Taking the negative square of the first solution value yields the first value. The ratio of the square of the concrete cover thickness to four times the apparent chloride ion diffusion coefficient is calculated to obtain the first ratio. Multiplying the first value by the first ratio yields the surface chloride ion corrosion time. The mathematical expression for calculating the surface chloride ion corrosion time is: In the formula, Indicates the surface chloride ion corrosion time; This indicates the critical chloride ion concentration for depassivation of reinforcing bars; The inverse function of the error function is also called the inverse error function. This indicates the thickness of the concrete cover.

5. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 1, characterized in that: The logic for determining whether a reinforced concrete utility pole is corroded is as follows: The service life of the reinforced concrete pole is obtained, and the surface chloride ion corrosion time is compared with the service life of the reinforced concrete pole. If the surface chloride ion corrosion time is less than or equal to the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has not started corrosion; if the surface chloride ion corrosion time is greater than the service life of the reinforced concrete pole, it is determined that the reinforced concrete pole has started corrosion.

6. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 5, characterized in that: When corrosion begins to occur on reinforced concrete utility poles, the specific steps for calculating the lifespan of the poles are as follows: To obtain the corrosion limit mass loss of reinforced concrete poles and the mass of steel corrosion per unit time, the corrosion limit state time is obtained by calculating the ratio of the corrosion limit mass loss to the mass of steel corrosion per unit time. The mathematical expression for calculating the corrosion limit state time is then: In the formula, Indicates the time to the corrosion limit state; Indicates the maximum mass loss due to corrosion; This indicates the mass of steel reinforcement corrosion per unit time; The corrosion duration is obtained by comparing the service life of the reinforced concrete pole with the time of chloride ion corrosion on its surface. The remaining life of the reinforced concrete pole is obtained by comparing the time to the limit state of corrosion with the corrosion duration. The mathematical expression for calculating the corrosion duration is as follows: In the formula, Indicates the duration of corrosion; The mathematical expression for calculating the remaining life of reinforced concrete poles is: In the formula, This indicates the remaining lifespan of the utility pole.

7. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 5, characterized in that: When corrosion has not yet started, the specific steps for calculating the lifespan of reinforced concrete utility poles are as follows: The total lifespan of a reinforced concrete pole is obtained by summing the surface chloride ion corrosion time and the corrosion limit state time. The remaining lifespan of the reinforced concrete pole is obtained by the difference between the total lifespan and the years the pole has been used. Therefore, the mathematical expression for calculating the remaining lifespan of a reinforced concrete pole is as follows:

8. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 6, characterized in that: The specific steps for obtaining the corrosion limit mass loss of reinforced concrete poles are as follows: To obtain the density and corrosion limit volume loss of the reinforcing steel, multiply the density by the corrosion limit volume loss to obtain the corrosion limit mass loss. The mathematical expression for calculating the corrosion limit mass loss is then: In the formula, Indicates the density of the reinforcing steel; This indicates the maximum volume loss due to corrosion.

9. The method for rapidly predicting the lifespan of reinforced concrete poles in chloride-salt environments according to claim 6, characterized in that: The specific steps for obtaining the steel reinforcement corrosion quality per unit time are as follows: To obtain the molar mass of iron, the surface area of ​​the corroded steel bar, the number of electrons transferred in the iron oxidation reaction, and the Faraday constant, multiply the molar mass of iron, the instantaneous corrosion density of the steel bar, and the surface area of ​​the corroded steel bar to obtain the first product. Multiply the number of electrons transferred in the iron oxidation reaction by the Faraday constant to obtain the second product. The ratio of the first product to the second product yields the mass of steel bar corrosion per unit time. Therefore, the mathematical expression for calculating the mass of steel bar corrosion per unit time is: In the formula, Indicates the molar mass of iron; This represents the instantaneous corrosion current density; This represents the surface area of ​​the steel reinforcement that has been corroded. Indicates the number of electrons transferred in the iron oxidation reaction; represents the Faraday constant, which represents the amount of charge carried by each mole of electrons.

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