Methods, devices, and equipment for predicting corrosion current and rust in reinforced concrete under low atmospheric pressure.

Abstract

This application provides a method, apparatus, and equipment for predicting corrosion current and rust in reinforced concrete under low-pressure environments, belonging to the field of engineering simulation modeling technology. The method includes: establishing a coupled transport model within the concrete considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; establishing a model for predicting the corrosion current density and corrosion depth of the reinforcing steel, used to predict the charge number at different locations within the reinforcing steel, and calculating the corrosion depth and rust product content based on the corrosion current density; and establishing a linear elastic damage model, used to simulate the evolution of concrete damage caused by steel corrosion based on the rust product content output by the steel corrosion current density prediction model, thereby achieving accurate prediction of rust and damage. This method considers changes in oxygen concentration under low pressure, and by describing oxygen diffusion, incorporates the output of the transport model as a dynamic variable into the corrosion current calculation process, improving the accuracy of corrosion current and steel corrosion prediction.

Description

Technical Field

[0001] This application relates to the field of computer-aided design technology in engineering simulation modeling, and in particular to a method, apparatus and equipment for predicting corrosion current and rust in steel reinforcement in concrete under low pressure environment. Background Technology

[0002] Steel corrosion is a significant factor contributing to the performance degradation of reinforced concrete structures. After steel bars corrode, the volume of corrosion products increases. In the early stages of corrosion, these products fill the pores around the steel bars. As corrosion progresses, when the rust expansion force exceeds the tensile strength of the concrete, it causes cracking, further accelerating the intrusion of corrosive ions. Furthermore, steel corrosion reduces the effective cross-sectional area of ​​the steel bars, thereby decreasing their load-bearing capacity and consequently reducing the load-bearing capacity of the reinforced concrete structure, ultimately affecting its service life.

[0003] Traditional steel reinforcement corrosion simulation and damage prediction are primarily conducted in plains environments. In plains environments, the oxygen partial pressure of reinforced concrete structures is normal, cathodic reactions are sufficient, and the corrosion rate is high. Oxygen diffusion is mainly affected by the density of the concrete. However, in plateau environments, the corrosion of steel reinforcement in reinforced concrete structures differs significantly from that in plains environments. Directly applying the treatment methods used in plains environments may lead to substantial deviations. This is because: the low air pressure in plateau environments (only 50%–70% of that in plains) directly affects oxygen supply, resulting in insufficient cathodic reactants and thus inhibiting the steel reinforcement corrosion rate; simultaneously, the low oxygen concentration reduces the net diffusion of oxygen in the concrete, also affecting steel reinforcement corrosion; finally, oxygen concentration cells (surface oxygen-rich / internal oxygen-deficient) are easily formed in plateau reinforced concrete structures, leading to localized pitting corrosion.

[0004] Currently, there is a relative lack of research on the changes in corrosion current density around steel bars caused by oxygen concentration and ion erosion in plateau environments. Alternatively, existing methods directly treat steel bar corrosion in reinforced concrete structures in plateau environments as the same as in plain environments. However, due to the influence of the above factors, the accuracy of existing methods for simulating steel bar corrosion inside concrete in plateau environments is not high, and the results differ significantly from actual measurements. Summary of the Invention

[0005] The purpose of this application is to provide a method, apparatus, and equipment for predicting the corrosion current and rust of steel bars in concrete under low-pressure environments, so as to improve the accuracy of predicting the corrosion current and rust of steel bars under low-pressure environments.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] In a first aspect, this application provides a method for predicting the corrosion current and rust of reinforcing steel bars in concrete under low-pressure environments, including:

[0008] A coupled transport model is established inside concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; the coupled transport model includes: chloride ion transport model, sulfate ion transport model, and oxygen diffusion model;

[0009] Establish a prediction model for steel reinforcement corrosion current density and corrosion depth;

[0010] The steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of the steel reinforcement inside the concrete under different oxygen concentrations based on the coupled transport model, thereby obtaining the corrosion current density of the steel reinforcement inside the concrete; and based on the corrosion current density, calculate the corrosion depth and the content of rust products.

[0011] Establish a linear elastic damage model;

[0012] The linear elastic damage model is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the content of corrosion products output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage.

[0013] The aforementioned scheme constructs a three-tiered progressive structure: a coupled transport model, a steel reinforcement corrosion current density and corrosion depth prediction model, and a linear elastic damage model. Starting from ion transport, proceeding through electrochemical reactions, and ultimately linking to structural damage, it forms a complete computational chain from environmental erosion to concrete cracking. Simultaneously, it incorporates the low-pressure environment of high-altitude areas into the modeling system, using an oxygen diffusion model to reflect the impact of low oxygen partial pressure on the corrosion process. This supports the spatial distribution prediction of corrosion current density at different locations on the steel reinforcement, accurately reflecting the characteristics of localized corrosion under low-pressure environments and improving the accuracy of steel reinforcement corrosion and damage prediction.

[0014] In conjunction with the first aspect, in some optional implementations, Fick's second law is used to describe the diffusion of chloride ions and sulfate ions in concrete in the coupled transport model, thereby obtaining the chloride ion transport model and the sulfate ion transport model.

[0015] Based on Fick's second law, a high-altitude low-pressure correction factor is introduced to correct oxygen diffusion, resulting in an oxygen diffusion model. This oxygen diffusion model is used to reflect the impact of the low-pressure environment.

[0016] The expression for the plateau low-pressure correction factor is as follows: In the formula, , These represent air pressure at plains and at high altitudes, respectively.

[0017] In the above scheme, chloride ions, sulfate ions and oxygen are all modeled based on Fick's second law, ensuring the consistency of the model system. By introducing a high-altitude low-pressure correction factor, macroscopic environmental parameters (pressure) are integrated into the microscopic diffusion process, making the oxygen diffusion model environmentally adaptable and improving the realism of oxygen diffusion simulation. Moreover, this correction factor is given in the form of a ratio, with a clear numerical range, which makes it easy to directly assign values ​​in numerical simulation without the need for additional calibration of complex parameters.

[0018] In conjunction with the first aspect, in some optional embodiments, the coupled transport model is also used to describe the time difference between chloride ions and sulfate ions reaching the surface of the reinforcing steel, and in a low-pressure environment, the time difference has a phased impact on the corrosion process with the participation of oxygen.

[0019] In conjunction with the first aspect, in some optional embodiments, the time difference between chloride ions and sulfate ions reaching the surface of the reinforcing steel, in a low-pressure environment, this time difference, with the participation of oxygen, has a phased impact on the corrosion process, specifically as follows:

[0020] Chloride ions first diffuse to the surface of the steel reinforcement, where charge exchange occurs, and the corrosion current density is then calculated.

[0021] Sulfate ions diffuse to the surface of the steel bar later than chloride ions. They expand and destroy the passivation film on the steel bar. Chloride ions further penetrate the passivation film, directly causing localized corrosion of the steel bar. In a low-pressure environment, oxygen participates and further accelerates the corrosion.

[0022] In conjunction with the first aspect, in some optional implementations, based on the aforementioned coupled transport model, the charge number at different locations of the reinforcing steel bars inside the concrete is predicted to obtain the corrosion current density of the reinforcing steel bars inside the concrete, specifically as follows:

[0023] Based on electrochemical kinetics theory, the Tafel equation was used to calculate the anodic current density and cathodic current density, and then the corrosion current density of the steel reinforcement inside the concrete was calculated.

[0024] In conjunction with the first aspect, some optional implementations employ the Tafel equation to calculate the anodic current density and the cathode current density, and further include: directly embedding the chloride ion concentration into the expression for the anodic Tafel slope to dynamically adjust the corrosion rate by influencing the electrochemical polarization behavior.

[0025] In conjunction with the first aspect, in some optional implementations, the chloride ion concentration is directly embedded into the expression of the anode Tafel slope. Specifically, the chloride ion concentration is embedded into the expression of the anode Tafel slope in the form of a power function to characterize the nonlinear characteristics of chloride ion concentration being significant at low concentrations and tending to saturate at high concentrations.

[0026] In conjunction with the first aspect, some optional implementations, which use the Tafel equation to calculate the anode current density and the cathode current density respectively, further include: when the electrode reaction is controlled by the oxygen content, introducing a limiting current density during the electrode reaction process at the cathode to correct the cathode current density.

[0027] Secondly, this embodiment provides a device for predicting the corrosion current and rust of reinforcing steel bars in concrete under low atmospheric pressure. The device is used to perform the method provided in any of the above embodiments, and the device includes:

[0028] The diffusion modeling unit is configured to establish a coupled transport model inside concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; the coupled transport model includes: chloride ion transport model, sulfate ion transport model, and oxygen diffusion model.

[0029] The corrosion modeling unit is configured to establish a prediction model for steel reinforcement corrosion current density and corrosion depth.

[0030] The steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of the steel reinforcement inside the concrete under different oxygen concentrations based on the coupled transport model, thereby obtaining the corrosion current density of the steel reinforcement inside the concrete; and based on the corrosion current density, calculate the corrosion depth and the content of rust products.

[0031] The corrosion simulation unit is configured to establish a linear elastic damage model, which is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the content of corrosion products output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage.

[0032] Thirdly, this embodiment provides a computer device, including a memory and a processor, wherein the memory and the processor are connected; the memory is used to store computer execution instructions; and the processor is used to invoke the computer execution instructions to perform the steps of the method provided in any of the above embodiments.

[0033] The technical effects of the second and third aspects of this application can be referred to the description of the first aspect, and will not be repeated here. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a method for predicting corrosion current and rust in concrete under low-pressure environments, provided according to some embodiments of this application.

[0035] Figure 2 This is an example of a process for predicting corrosion current and rust in steel reinforcement within concrete in a low-pressure environment, according to some embodiments of this application.

[0036] Figure 3 This is a schematic diagram illustrating the process of steel reinforcement corrosion caused by the intrusion of corrosive media in a low-pressure environment at high altitudes.

[0037] Figure 4 The diagram shows the test and simulation under the low air pressure environment of the plateau. (a) is a schematic diagram of the cross-sectional structure of the concrete specimen in the test, and (b) is a schematic diagram of the structure and key dimensions of the concrete specimen in the numerical simulation.

[0038] Figure 5 This is a schematic diagram of the chloride ion concentration distribution inside concrete.

[0039] Figure 6 This is a schematic diagram showing the distribution of sulfate ion concentration inside concrete.

[0040] Figure 7 This is a schematic diagram of the oxygen concentration distribution and flow lines inside concrete.

[0041] Figure 8 This is a schematic diagram comparing the numerical simulation results and experimental data of the corrosion current density of steel bars over time in a high-altitude, low-pressure environment.

[0042] Figure 9 This is a schematic diagram of the failure mode of concrete protective layer during the rust expansion of steel bars in a low-pressure environment at high altitude.

[0043] Figure 10 The diagram shows a comparison between numerical and experimental results of concrete damage caused by steel corrosion, where (a) represents the experimental results and (b) represents the simulation results of this application.

[0044] Figure 11 This is a schematic diagram of the structure of a computer device. Detailed Implementation

[0045] This application provides a method, apparatus, and equipment for predicting corrosion current and rust in concrete under low-pressure environments. The technical solution establishes a coupled transport model of the concrete interior under low-pressure conditions at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior. It predicts the charge number at different locations within the concrete reinforcement at different times under varying oxygen concentrations, thereby predicting the corrosion current value of the reinforcement. Based on this, it quantifies the content of rust products and simulates the formation and propagation process of internal cracks in the concrete caused by reinforcement corrosion. From the perspective of the coupled transport model, this solution, on the one hand, incorporates oxygen transport into the model, reflecting the influence of low oxygen partial pressure on corrosion and avoiding systematic bias caused by treating high-altitude environments as equivalent to plain environments. On the other hand, although the diffusion behaviors of oxygen, sulfate ions, and chloride ions are independent, they are coupled in time series, forming a complete erosion path, laying the foundation for subsequent dynamic prediction of corrosion current. Regarding corrosion current prediction, oxygen is introduced as a dynamic variable into the corrosion current calculation process, reflecting its controlling effect on the cathodic reaction rate. This enables modeling of the environmental dependence of the dynamic changes in corrosion current density under different oxygen concentrations, significantly improving the accuracy of corrosion current density prediction in high-altitude environments. Corrosion depth is derived from corrosion current density, and the accumulation of rust products is further predicted. This prediction is then used as input for the mechanical effect analysis of a linear elastic damage model, enabling accurate prediction of rust and damage. This improves the accuracy of predicting corrosion current and rust within reinforced concrete under low-pressure conditions in high-altitude environments. Furthermore, this scheme integrates the entire process from environmental conditions to multi-ion transport, electrochemical reactions, and concrete damage evolution, forming a closed-loop, dynamic, and visualized simulation system for the entire degradation process. It provides a systematic tool for studying the performance degradation of reinforced concrete structures under complex corrosive environments, and is suitable for accurately simulating coupled degradation behavior under complex environments in the western high-altitude region.

[0046] The embodiments of this application will now be described with reference to the accompanying drawings.

[0047] The embodiments of this application can be applied to Figure 11 The computer devices shown may be, but are not limited to, mobile terminals such as mobile phones, tablets, handheld computers, and personal digital assistants (PDAs), smart home devices such as smart TVs and smart cameras, wearable devices such as smart bracelets, smartwatches, and smart glasses, or other desktop, laptop, notebook, ultra-mobile personal computer (UMPC), netbook, and smart screen computer devices.

[0048] like Figure 11As shown, the computer device 200 may include one or more of the following components: a processor 201, a memory 203, a communication interface 202, and a communication bus 204. The memory 203 can be connected to the processor 201 via the bus 204. The bus can transfer data between the processor 201 and the memory 203. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0049] Processor 201 may include one or more processing cores. Processor 201 can connect to various parts within the computer device 200 using various interfaces and lines. It performs various functions of the computer device 200 and processes data by running or executing instructions, programs, code sets, or instruction sets stored in memory 203, and by calling data stored in memory 203. For example, processor 201 may include an application processor (AP), a modem processor, a CPU, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic array (PLA), and / or a neural network processing unit (NPU). Among these, the CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content to be displayed; the NPU is used to implement artificial intelligence (AI) functions; and the modem is used to handle wireless communication. Different processing units can be independent devices or integrated into one or more processors. For example, the multiple processing units shown above are all integrated into a single SoC, or the AP is a separate semiconductor chip, while other processing units are integrated into a single SoC. This application does not limit this to any particular type.

[0050] The memory 203 may include random access memory (RAM), read-only memory (ROM), or non-transitory computer-readable storage medium. The memory 203 can be used to store instructions, programs, code, code sets, or instruction sets. The memory 203 may include a program storage area and a data storage area. The program storage area may store instructions for implementing an operating system or instructions for at least one function, such as a method for predicting the corrosion current and rust of steel reinforcement in concrete under low-pressure environments. The data storage area may store data created based on the use of the computer device 200, such as input data for numerical solutions.

[0051] In addition, those skilled in the art will understand that the structure of the computer device 200 shown in the above figures does not constitute a limitation on the computer device 200. The computer device may include more or fewer components than shown, or combine certain components, or have different component arrangements. For example, the computer device 200 also includes components such as a microphone, speaker, radio frequency circuit, sensor, audio circuit, power supply, and Bluetooth module, which will not be described in detail here.

[0052] This embodiment provides a method for predicting the corrosion current and rust of reinforcing steel bars in concrete under low-pressure environments. This method can be executed using the aforementioned computer equipment, such as... Figure 1 As shown, the method includes the following steps:

[0053] Step S1: Establish a coupled transport model (hereinafter referred to as the transport model) within concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior. The coupled transport model includes: a chloride ion transport model, a sulfate ion transport model, and an oxygen diffusion model. By constructing a coupled transport model that considers the diffusion of oxygen, chloride ions, and sulfate ions, the transport behavior of chloride ions, sulfate ions, and oxygen in concrete is simulated.

[0054] Step S2: Establish a prediction model for the current density and corrosion depth of steel reinforcement corrosion (referred to as the corrosion model).

[0055] Among them, the steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of steel reinforcement inside concrete under different oxygen concentrations based on the coupled transport model, so as to obtain the corrosion current density of steel reinforcement inside concrete; and based on the corrosion current density, the corrosion depth and rust product content are calculated.

[0056] In the coupled transport model, ion diffusion behavior involves the transport of oxygen, chloride ions, and sulfate ions at high altitudes and low pressures, with each ion influencing the others: chloride ions, as the fastest diffusing ions, accumulate on the surface of the reinforcing steel and begin to cause electrochemical corrosion, generating a corrosion current. As sulfate ions diffuse to the surface of the reinforcing steel, the passivation film is destroyed, the corrosion current continues to increase, and under the action of oxygen, it causes the reinforcing steel to rust. This process continuously acquires corrosion current values. When the content of rust products in the reinforcing steel reaches a certain amount, the concrete cracks. As time increases, the rust expansion and cracking of the concrete continue to develop, yielding the degree of concrete damage at different times.

[0057] Step S3: Establish a linear elastic damage model (referred to as the damage model).

[0058] Among them, the linear elastic damage model is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the corrosion product content output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage.

[0059] In this embodiment, a coupled transport model of the internal structure of concrete considering oxygen, chloride ions, and sulfate ions under low-pressure conditions at high altitudes is constructed. Based on this coupled transport model, a prediction model for the corrosion current density and corrosion depth of reinforcing steel is established to predict the corrosion current density and estimate the content of corrosion products. Subsequently, a linear elastic damage model is used to simulate the damage evolution. This approach overcomes the limitation of existing models that ignore the influence of oxygen concentration, and can realistically reflect the physical mechanism by which the corrosion current density is suppressed under low-oxygen conditions at high altitudes. This provides a prerequisite for subsequent corrosion prediction and damage evolution, improves the environmental adaptability and accuracy of reinforcing steel corrosion prediction, and provides a scientific and systematic numerical analysis tool for the durability design, life prediction, and maintenance decisions of reinforced concrete structures in high-altitude areas.

[0060] In a further improved scheme, in the coupled transport model of step S1, Fick's second law is used to describe the diffusion of chloride ions and sulfate ions in concrete, resulting in chloride ion transport model and sulfate ion transport model. Based on Fick's second law, a plateau low-pressure correction factor is introduced to correct oxygen diffusion, resulting in an oxygen diffusion model. The oxygen diffusion model is used to reflect the influence of low-pressure environment. The plateau low-pressure correction factor is the ratio between plateau pressure and plain pressure.

[0061] In this embodiment, the constructed diffusion models for oxygen, chloride, and sulfate ions are consistent and are all described using Fick's second law. Specifically, the diffusion of chloride and sulfate ions within concrete is described using the classic Fick's second law; the specific diffusion equations can be constructed with reference to existing technologies, but for the sake of brevity, they will not be elaborated upon here.

[0062] In this embodiment, the oxygen diffusion model is a diffusion model that considers the correction for low atmospheric pressure at high altitudes. This model is used to reflect the dynamic impact of oxygen concentration changes at different time points on steel corrosion under low atmospheric pressure at high altitudes. Specifically, during the transport of oxygen inside concrete, it does not react with other ions or cement hydration products. The oxygen transport process inside concrete is a concentration-driven, unsteady-state diffusion process based on low atmospheric pressure. Fick's second law is used to describe the oxygen transport inside concrete. By introducing a low atmospheric pressure correction factor at high altitudes, the oxygen diffusion behavior is accurately described. The low atmospheric pressure correction factor at high altitudes is the ratio between the atmospheric pressure at high altitudes and the atmospheric pressure at plains. Thus, the oxygen diffusion model is as follows:

[0063] (1)

[0064] In the formula, Indicates time, Indicates the oxygen concentration inside the concrete (mol / m³) 3 ); The oxygen diffusion coefficient (m) in the pore solution of concrete is expressed as... 2 / s), value ; , These represent the air pressure at plains and at high altitudes, respectively. The pressure ratio is used as a pressure correction factor to correct oxygen diffusion behavior; its typical value range is 1.4-2.0.

[0065] Unlike traditional models that typically assume oxygen diffusion is only affected by concrete density and humidity, this embodiment explicitly models low atmospheric pressure at high altitudes as a key external parameter affecting oxygen diffusion. By incorporating ambient atmospheric pressure as an independent variable into the diffusion model, it characterizes how low atmospheric pressure at high altitudes leads to a decrease in oxygen partial pressure, which in turn affects the cathodic reaction rate and corrosion process, thereby simulating the differences in steel corrosion mechanisms under high-altitude environments.

[0066] Furthermore, the coupled transport model in step S1 is also used to describe the time difference between chloride ions and sulfate ions reaching the surface of the reinforcing steel. In a low-pressure environment, this time difference, with the participation of oxygen, has a phased impact on the corrosion process. Specifically, chloride ions diffuse to the surface of the reinforcing steel first, undergoing charge exchange and initiating the calculation of corrosion current density; sulfate ions diffuse to the surface of the reinforcing steel later than chloride ions, destroying the passivation film through expansion. Chloride ions further penetrate the passivation film, directly causing localized corrosion of the reinforcing steel, and in a low-pressure environment, oxygen further accelerates the corrosion.

[0067] In the above technical steps, the coupled transport model is also used to describe the difference in diffusion rates between chloride ions and sulfate ions in concrete, and the time-series relationship between their arrival at the steel reinforcement surface at different times. Because chloride ions ( The diffusion coefficient of ) is significantly greater than that of sulfate ions ( During corrosion, chloride ions preferentially diffuse to and accumulate on the surface of the reinforcing steel. When chloride ions reach the surface, they compete with hydroxide ions in the passivation film for adsorption, forming soluble iron ion complexes, i.e., charge exchange occurs. At this point, the corrosion current density is calculated. Sulfate ions, due to their slower diffusion rate, arrive at the steel surface area later than chloride ions. In other words, sulfate ions diffuse to the steel surface later than chloride ions. Subsequently, sulfate ions indirectly damage the integrity of the passivation film by inducing concrete expansion and cracking. Chloride ions further penetrate the passivation film, directly causing localized corrosion of the steel, which is further accelerated by oxygen. This allows us to obtain the corrosion current density value under the low-pressure environment of high altitude.

[0068] Specifically, in the low-pressure environment of high altitudes, oxygen, a key participant in the cathodic reaction, experiences a decrease in concentration due to the reduced pressure, leading to weakened cathodic depolarization and overall suppression of the corrosion reaction. When chloride ions arrive first and trigger the formation of a local anodic zone, although the oxygen concentration is low, a weak cathodic reaction can still be maintained, generating an initial corrosion current and initiating the early rusting process. However, under low-oxygen conditions, early corrosion is limited by the cathodic reaction, and even after depassivation, significant rust expansion is difficult to achieve. Subsequently, sulfate ions gradually diffuse to the surface of the reinforcing steel, undergoing sulfate erosion within the concrete to generate expansive products such as ettringite. This causes the propagation of microcracks in the concrete, further damaging the integrity of the steel-concrete interface and indirectly weakening the protective effect of the passivation film. Simultaneously, the concrete cracking caused by sulfate ions improves the oxygen transport path, accelerating corrosion. Therefore, in the presence of oxygen, this process promotes the stable establishment of the corrosion cell, significantly increasing the corrosion current density and entering the accelerated corrosion stage.

[0069] In summary, by considering the differences in arrival time of chloride and sulfate ions, the coupled transport model can transmit these differences to the steel reinforcement corrosion current density and corrosion depth prediction model in real time. Combined with the influence of oxygen concentration changes under low air pressure at high altitudes, the steel reinforcement corrosion current density and corrosion depth prediction model can dynamically simulate the stage evolution characteristics of the corrosion process, thereby improving the dynamism and accuracy of corrosion current density prediction.

[0070] For example, the staged evolution can be divided into two phases: the first phase is chloride ion-induced depassivation + low-oxygen current-limiting corrosion, and the second phase is sulfate-induced interface degradation + corrosion channel establishment + corrosion intensification. In another example, the staged evolution can also be divided into an initiation phase and an acceleration phase. By introducing the time-varying effects of ion arrival time difference and oxygen participation, the staged influence of different ions on corrosion current is described, revealing the nonlinear characteristics of slow initiation and rapid development of the corrosion process under low-pressure conditions, which is closer to the measured degradation behavior in plateau areas.

[0071] Based on the completion of the coupled transmission model construction, in step S2, a prediction model for the corrosion current density and corrosion depth of the steel reinforcement is established, and the charge number at different locations of the steel reinforcement inside the concrete is predicted to obtain the corrosion current density of the steel reinforcement inside the concrete. Specifically, based on the electrochemical kinetics theory, the Tafel equation is used to calculate the anodic current density and cathodic current density respectively, and then the corrosion current density of the steel reinforcement inside the concrete is calculated.

[0072] The following reference Figure 3 Describe the calculation process of corrosion current density.

[0073] Figure 3 The upper half of the diagram displays the chemical reaction equations for the corrosion products, including two key chemical reaction equations: and The lower half illustrates the electrochemical corrosion process at the interface between the reinforcing steel and concrete. According to electrochemical kinetics, when chloride ions reach the surface of the reinforcing steel, they compete with hydroxide ions in the passivation film for adsorption, forming soluble iron ion complexes and initiating an anodic dissolution reaction. ), generate charge ( The material is transferred to the cathode region (the interface between concrete and steel reinforcement, i.e., the corrosion interface), where a reduction reaction occurs. The reaction formula is: This provides the electronic circuit for anodizing, and the electrochemical process initiates the corrosion current. By monitoring or calculating the change of this current density over time, the dynamic prediction of the steel corrosion process can be achieved. The relevant simplified chemical reaction formula is as follows:

[0074] Fe (passivation film) + 2Cl - →FeCl2+2 e - (2)

[0075] In this embodiment, the electrochemical corrosion reaction at the steel / concrete interface is described using the basic equation of electrode kinetics, and the local corrosion current density is... Determined by both the anodic oxidation reaction and the cathodic reduction reaction, its expression is shown in formula (3):

[0076] (3)

[0077] In the formula: The local current density of the electrode reaction (A / m) 2 ); The number of charges; The exchange current density of the electrode reaction (A / m) 2 ); It is the Faraday constant (96485 C / mol); It is the ideal gas constant; Absolute temperature; and Let be the charge transfer coefficients of the anode and cathode, and satisfy . ; This represents the overpotential at the electrode-electrolyte interface. The calculation formula is as follows:

[0078] (4)

[0079] In the formula, The external electric potential of the reinforcing steel; The electrolyte potential; The equilibrium potential (V) of the electrode reaction.

[0080] When the overpotential at the electrode-electrolyte interface When the value is higher, formula (3) can be simplified to formula (5), which is as follows:

[0081] (5)

[0082] In the formula, It is the exchange current density of the anodic reaction (A / m). 2 Let the Tafel slope of the anode be... ,in, The charge number at the anode can be used to derive the anodic corrosion current density as shown in Formula 6:

[0083] (6)

[0084] In the formula, the Tafel slope of the anode is... The unit is V / decade.

[0085] Similarly, the cathodic corrosion current density can be obtained, as shown in formula (7):

[0086] (7)

[0087] In the formula: The Tafel slope (V / decade) of the cathode. The exchange current density of the cathode reaction (A / m) 2 ).

[0088] The above formulas (6) and (7) were used to calculate the anode current density and cathode current density using the Tafel equation, respectively.

[0089] Furthermore, after the steel reinforcement is depassivated, the chloride ion concentration around it directly affects the Tafel slope of the anodic reaction. Considering the influence of chloride ion concentration, a chloride ion concentration influence factor is introduced to modify the corrosion current density of the anode. That is, the chloride ion concentration is directly embedded into the expression of the anode Tafel slope to dynamically adjust the corrosion rate by influencing the electrochemical polarization behavior. The expression is as follows:

[0090] (8)

[0091] In the formula: The chloride concentration around the reinforcing bar is the factor affecting the slope of the anode Tafel, i.e., the chloride concentration influence factor.

[0092] In traditional corrosion current prediction, chloride ion concentration is typically used to determine whether depassivation has occurred, or as an empirical input parameter for corrosion current. The formula above explicitly uses chloride ion concentration... A power-law correction to the anolyte Tafel slope is introduced, meaning that the traditional electrochemical model incorporates the quantitative influence of environmental ion concentration on kinetic parameters, thereby affecting the anolyte corrosion current density and enabling dynamic prediction of the corrosion current density. Furthermore, the chloride ion concentration is embedded into the expression for the anolyte Tafel slope in a power-law form, making... Including constant terms and negative power-law relation terms ( This can characterize the nonlinear characteristics of chloride ions, which have a significant impact at low concentrations and tend to saturate at high concentrations.

[0093] In some embodiments, the Tafel equation is used to calculate the anode current density and the cathode current density respectively, and the method further includes: when the electrode reaction is controlled by the oxygen content, a limiting current density is introduced during the electrode reaction process at the cathode to correct the cathode current density.

[0094] Specifically, when the electrode reaction is controlled by the oxygen content, a limiting current density needs to be introduced during the electrode reaction at the cathode. The modified cathode current density is obtained by modifying formula (3), and the expression is as follows:

[0095] (9)

[0096] (10)

[0097] In the formula: Corrosion current density of cathodic reaction (A / m) 2 ); The limiting current density; The thickness is the diffusion layer.

[0098] Based on the above description, the corrosion current density prediction process in the steel reinforcement corrosion current density and corrosion depth prediction model can be summarized as follows: The corrosion current densities of the anode and cathode are calculated according to formulas (6) and (7). When calculating the corrosion current density of the anode, the dynamic influence of chloride ion concentration on the corrosion current density is considered by formula (8). When calculating the corrosion current density of the cathode, the corrosion current density of the cathode reaction is corrected by formulas (9) and (10).

[0099] Based on the dynamic prediction of steel reinforcement corrosion current density, step S2 further calculates the corrosion depth and rust product content based on the corrosion current density, as follows: When chloride ions penetrate the passivation film and directly cause localized corrosion of the steel reinforcement, according to Faraday's law, the change in the mass of rust products on the steel reinforcement surface is directly proportional to the charge around the electrode. Therefore, the corrosion depth of steel reinforcement in concrete is closely related to the corrosion current density. The corrosion current density is used to quantify the rust products; the higher the corrosion current density, the faster the steel reinforcement rusts. The relevant calculation formulas are as follows:

[0100] (11)

[0101] In the formula: For the depth of steel corrosion ( ); The chemical equivalence coefficient (value = 2); The molar mass of iron is 0.056 kg / mol. The density of iron (7860 kg / m³) 3 ); The number of valence electrons of iron participating in the reaction (value = 2, corresponding to...) ), Let be the corrosion current density, where .

[0102] Substituting the calculated corrosion current density into formula (11), the corrosion depth of the steel reinforcement can be calculated, thereby quantifying the corrosion products of the steel reinforcement.

[0103] In step S3, the linear elastic damage model is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the corrosion product content output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage.

[0104] In other words, this embodiment describes the process of concrete crack propagation based on the quantified content of steel corrosion products using a concrete linear elastic damage model, characterizing the formation and expansion of cracks; it simulates the entire process of concrete cracking caused by harmful ion erosion, steel corrosion, and steel corrosion expansion under high-altitude low-pressure conditions.

[0105] Specifically, regarding the process by which increased steel corrosion products lead to concrete crack propagation, a linear elastic damage model is established based on continuum mechanics, and internal variable damage parameters of the concrete are introduced. To characterize the crack formation and propagation process in the cement matrix, a scalar damage model is used to describe the cracking in the concrete region. The expressions for the scalar damage model are shown in formulas (12) and (13):

[0106] (12)

[0107] (13)

[0108] Furthermore, damage evolution is driven by nonlocal equivalent strains, and the implicit gradient method is used to describe these nonlocal equivalent strains. Equivalent variation The relationship between them is shown in formula (14):

[0109] (14)

[0110] In the formula: This would impair stiffness; It is a lossless linear elastic stiffness; It is a state variable; Let be the internal length dimension under the implicit gradient. It should be noted that the equivalent strain follows the Rankine stress criterion.

[0111] The damage evolution during crack propagation can be expressed as exponential strain softening, as shown in formulas (15) and (16):

[0112] (15)

[0113] (16)

[0114] In the formula: This is the critical strain value at which damage begins; The fracture energy per unit area of ​​concrete; The feature unit size; It refers to the tensile strength of concrete; This is the initial elastic modulus of concrete.

[0115] Numerical simulations are conducted using computer numerical simulation software. Material parameters (such as water-cement ratio, initial elastic modulus of concrete, etc.), multi-ion transport parameters (such as chloride ion, sulfate ion, oxygen concentration, etc.) dynamically calculated by the coupled transport model, and electrochemical parameters (such as anodic and cathodic corrosion current density, etc.) calculated by the corrosion model are substituted into the above damage model to simulate the distribution of concrete damage.

[0116] As an example, embodiments of this application can also be implemented according to... Figure 2 The steps shown are to be performed, including:

[0117] A transport model (i.e., a coupled transport model) considering the diffusion of oxygen, chloride ions, and sulfate ions under low atmospheric pressure at high altitudes was constructed to simulate the transport behavior of chloride ions, sulfate ions, and oxygen in concrete.

[0118] By using an ion transport model (i.e., a coupled transport model), the charge transfer of steel bars inside concrete is calculated, and the corrosion current of steel bars inside concrete is further predicted.

[0119] The content of corrosion products in steel bars is quantified by using a model of steel bar corrosion current density and corrosion depth.

[0120] A model simulating the linear elastic damage of concrete under low-pressure conditions at high altitudes was developed to describe the crack propagation process and characterize crack formation and extension.

[0121] In summary, this embodiment constructs a coupled transport model that considers oxygen, chloride ions, and sulfate ions. Under the staged influence of multi-ion transport, the corrosion current density at different times and locations is dynamically calculated using the corrosion model, filling the research gap on the changes in corrosion current density under the combined effects of oxygen concentration and chloride and sulfate ion erosion in plateau environments.

[0122] In specific embodiments, the coupled transport model explicitly distinguishes the modeling differences between plateau and plain environments, abandoning the traditional plain model and proposing a low-pressure correction mechanism for plateaus to accurately describe oxygen diffusion behavior. Furthermore, this embodiment not only considers the three key media—oxygen, chloride ions, and sulfate ions—simultaneously, but also distinguishes their diffusion rates, mechanisms of action, and temporal relationships, revealing the synergistic degradation mechanism of chloride ion depassivation, sulfate ion damage, and oxygen rate control under low-pressure environments, enabling in-depth research on multi-factor coupling mechanisms.

[0123] In the corrosion model, oxygen concentration is used as a variable during the electrode reaction at the cathode. A limiting current density is introduced to correct the cathode current density, reflecting the controlling effect of oxygen concentration changes at different times and locations on the cathode reaction rate. Based on this, numerical simulation is used to obtain the corrosion current density at different locations on the steel reinforcement surface to reflect the local pitting corrosion caused by oxygen concentration cells.

[0124] In summary, this embodiment establishes a transmission model, a corrosion model, and a damage model to describe the physical and chemical processes involved in the prediction of corrosion current and the rusting process of steel reinforcement inside concrete under low-pressure conditions at high altitudes, thereby expressing its deterioration mechanism.

[0125] To verify the method proposed in this embodiment, the experimental process and numerical simulation process are described below.

[0126] First, concrete specimens were prepared. During the experiment, concrete with a water-cement ratio of 0.45 and a cement content of 350 kg / m³ was used. 3 12mm diameter steel bars were used. The bars were fixed in the center of a cylindrical mold with an inner diameter of 75mm, and concrete was poured into the mold. After demolding, the specimens were placed in a concrete curing chamber for 28 days. After curing, the cylindrical reinforced concrete specimens were immersed in a 5% NaCl and 4% Na2SO4 solution. After the concrete specimens were prepared, the experiment was conducted in a low-pressure environment simulating a high-altitude region (approximately 70kPa), and the corrosion rate of the steel bars was measured periodically. To maintain the stability of the corrosion solution concentration in the container, the solution was changed every two weeks during the experiment.

[0127] Secondly, numerical simulations are conducted using computer software. Figure 4 This is a schematic diagram illustrating experiments and simulations conducted in a high-altitude, low-pressure environment. (Example) Figure 4 In part (a), the cross-section of the concrete specimen is cylindrical, with a reinforcing bar at the center. The concrete surrounds the reinforcing bar, and the contact area between the two is the corrosion interface, which is the main location where the corrosion reaction occurs. Figure 4 Section (b) shows the structure and key dimensions of the concrete specimens in the numerical simulation. Indicates the diameter of the reinforcing bar ( ), Indicates the thickness of the protective film ( φ represents the diameter of the concrete specimen (i.e., the specimen size, φ=75mm). Numerical simulation parameters are detailed in Table 1, as follows:

[0128] Table 1. Main parameters of the numerical simulation process

[0129]

[0130] In the table, This indicates the concentration of sulfate ions on the external surface (exposed concrete surface). Indicates the external chloride ion concentration; Indicates the initial sulfate ion concentration; Indicates the initial chloride ion concentration; Indicates the initial calcium aluminate content; This represents the initial porosity, determined from experimental data. Indicates the diffusion coefficient of sulfate ions; Indicates the diffusion coefficient of chloride ions; Indicates the anode equilibrium potential; Indicates the cathode equilibrium potential; The threshold strain (4.0 × 10⁻⁶) represents the time at which microcrack formation begins and linear elastic expansion ends. -5 ); , Indicates the reaction rate of sulfate ions; Indicates the chemical reaction rate of chloride ions; This represents the fitting parameters based on the Ikumi method.

[0131] Using the model parameters shown in Table 1 and the transport, corrosion, and damage models described in this application, numerical simulations were performed on the concentration distribution of different ions in reinforced concrete specimens immersed in 5% NaCl and 4% Na2SO4 solutions under high-altitude low-pressure environments using the electrochemical and partial differential equation modules of COMSOL software. The numerical simulation results for chloride ion concentration distribution are shown below. Figure 5 As shown, the numerical simulation results of sulfate ion concentration distribution are as follows: Figure 6 As shown, the numerical simulation results of oxygen concentration are as follows: Figure 7 As shown in the figure. Based on this, the corrosion current density on the electrode surface was calculated, and the corrosion current density on the electrode surface was used to reflect the corrosion rate of the steel reinforcement in the concrete. The results were compared with the experimental results, as shown in the figure. Figure 8 As shown. From Figure 8 It can be seen that the numerical simulation results are in good agreement with the experimental results. Considering the errors in the experimental process and the discreteness of the data, the predicted values ​​of the numerical models (including the transport model, corrosion model, and damage model) established in this embodiment have a good degree of agreement with the measured data, thus verifying the feasibility of these models in quantitatively predicting the corrosion of steel bars inside concrete under the low-pressure environment of high altitude.

[0132] Damage modes of concrete cover caused by steel corrosion expansion in high-altitude, low-pressure environments, such as Figure 9 As shown. From Figure 9It can be seen that the front end of the reinforcing bar corrodes due to the intrusion of corrosive media (including chloride ions, sulfate ions, etc.), producing expansive corrosion products. When the expansion stress of the reinforcing bar is greater than or equal to the tensile strength of the concrete, the concrete will crack. Concrete damage first occurs at the front end of the reinforcing bar and then gradually extends to the surrounding area. With increasing corrosion time, the concrete damage around the reinforcing bar becomes more severe, the crack width increases, and it continues to extend towards the concrete surface. When t=120d, macroscopic cracks have appeared on the exposed concrete surface. When t=130d, a slight crack damage zone has formed between the two reinforcing bars. When t=140d, this crack damage zone evolves into a significant crack, and the concrete cover is at risk of complete spalling. Figure 10 As shown. From... Figure 10 It can be seen that the numerical simulation results of concrete cracking caused by steel corrosion under low air pressure are in good agreement with the experimental results, proving the accuracy of the prediction results of this application.

[0133] Based on experimental verification, it can be seen that the method provided in this embodiment can realistically simulate the impact of oxygen concentration and diffusion issues on steel corrosion in concrete under low-pressure conditions at high altitudes. Considering that charge exchange and corrosion current generation begin as soon as chloride ions reach the steel surface, the corrosion current density is predicted, thereby obtaining the content of steel corrosion products. The corrosion current generation process is more in line with the actual situation, and the results are more accurate. The study of ion transport and concrete cracking based on chloride ion diffusion, sulfate ion diffusion, and oxygen diffusion is more in line with the actual situation of high-altitude environments, and the prediction results are more accurate.

[0134] Based on the same inventive concept, this embodiment provides a device for predicting the corrosion current and rust of steel bars in concrete under low-pressure environments. This device is used to execute the method for predicting the corrosion current and rust of steel bars in concrete under low-pressure environments provided in any of the above embodiments. The device includes:

[0135] The diffusion modeling unit is configured to establish a coupled transport model inside concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; the coupled transport model includes: a chloride ion transport model, a sulfate ion transport model, and an oxygen diffusion model;

[0136] The corrosion modeling unit is configured to establish a prediction model for steel reinforcement corrosion current density and corrosion depth.

[0137] The steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of the steel reinforcement inside the concrete based on the coupled transmission model, thereby obtaining the corrosion current density of the steel reinforcement inside the concrete; and to calculate the corrosion depth and rust product content based on the corrosion current density.

[0138] The corrosion simulation unit is configured to establish a linear elastic damage model, which is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the content of corrosion products output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage.

[0139] The device for predicting the corrosion current and rust of steel bars in concrete under low pressure environment provided in this embodiment can realize the steps and processes of the method for predicting the corrosion current and rust of steel bars in concrete under low pressure environment provided in any of the above embodiments, and achieve the same technical effect, which will not be described in detail here.

[0140] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for predicting corrosion current and rust in steel reinforcement within concrete in a low-pressure environment, characterized in that, include: A coupled transport model is established inside concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; the coupled transport model includes: chloride ion transport model, sulfate ion transport model, and oxygen diffusion model; Establish a prediction model for steel reinforcement corrosion current density and corrosion depth; The steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of the steel reinforcement inside the concrete under different oxygen concentrations based on the coupled transport model, thereby obtaining the corrosion current density of the steel reinforcement inside the concrete; and based on the corrosion current density, calculate the corrosion depth and the content of rust products. Establish a linear elastic damage model; The linear elastic damage model is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the content of corrosion products output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage. In the coupled transport model, Fick's second law is used to describe the diffusion of chloride ions and sulfate ions in concrete, and the chloride ion transport model and the sulfate ion transport model are obtained accordingly. Based on Fick's second law, a high-altitude low-pressure correction factor is introduced to correct oxygen diffusion, resulting in an oxygen diffusion model. This oxygen diffusion model is used to reflect the impact of low-pressure environments. The expression for the plateau low-pressure correction factor is as follows: In the formula, , These represent air pressure at plains and at high altitudes, respectively. The coupled transport model is also used to describe the time difference between chloride ions and sulfate ions reaching the surface of the reinforcing steel. In a low-pressure environment, this time difference, with the participation of oxygen, has a phased impact on the corrosion process, specifically: Chloride ions first diffuse to the surface of the steel reinforcement, where charge exchange occurs, and the corrosion current density is then calculated. Sulfate ions diffuse to the surface of the steel bar later than chloride ions. They expand and destroy the passivation film on the steel bar. Chloride ions further penetrate the passivation film, directly causing localized corrosion of the steel bar. In a low-pressure environment, oxygen participates and further accelerates the corrosion.

2. The method according to claim 1, characterized in that, Based on the aforementioned coupled transport model, the charge number at different locations of the steel reinforcement inside the concrete is predicted under different oxygen concentrations, resulting in the corrosion current density of the steel reinforcement inside the concrete. Specifically: Based on electrochemical kinetics theory, the Tafel equation was used to calculate the anodic current density and cathodic current density, and then the corrosion current density of the steel reinforcement inside the concrete was calculated.

3. The method according to claim 2, characterized in that, The Tafel equation is used to calculate the anode current density and cathode current density, respectively, including: The chloride ion concentration is directly embedded into the expression for the anodic Tafel slope to dynamically regulate the corrosion rate by influencing the electrochemical polarization behavior.

4. The method according to claim 3, characterized in that, The chloride ion concentration is directly embedded into the expression for the anode Tafel slope. Specifically, the chloride ion concentration is embedded into the expression for the anode Tafel slope in the form of a power function to characterize the nonlinear characteristics of chloride ion concentration being significant at low concentrations and tending to saturate at high concentrations.

5. The method according to claim 2, characterized in that, The calculation of anode current density and cathode current density using the Tafel equation also includes: When the electrode reaction is controlled by the oxygen content, a limiting current density is introduced during the electrode reaction at the cathode to correct the cathode current density.

6. A device for predicting corrosion current and rust in reinforced concrete under low-pressure environments, characterized in that, The apparatus is used to perform the method as described in any one of claims 1 to 5, the apparatus comprising: The diffusion modeling unit is configured to establish a coupled transport model inside concrete under low atmospheric pressure at high altitudes, considering oxygen concentration, sulfate ion diffusion behavior, and chloride ion diffusion behavior; the coupled transport model includes: a chloride ion transport model, a sulfate ion transport model, and an oxygen diffusion model; The corrosion modeling unit is configured to establish a prediction model for steel reinforcement corrosion current density and corrosion depth. The steel reinforcement corrosion current density and corrosion depth prediction model is used to predict the charge number at different locations of the steel reinforcement inside the concrete under different oxygen concentrations based on the coupled transport model, thereby obtaining the corrosion current density of the steel reinforcement inside the concrete; and based on the corrosion current density, calculate the corrosion depth and the content of rust products. The corrosion simulation unit is configured to establish a linear elastic damage model, which is used to simulate the damage evolution of concrete cracking caused by steel corrosion based on the content of corrosion products output by the steel corrosion current density prediction model, so as to achieve accurate prediction of corrosion and damage. In the coupled transport model, Fick's second law is used to describe the diffusion of chloride ions and sulfate ions in concrete, and the chloride ion transport model and the sulfate ion transport model are obtained accordingly. Based on Fick's second law, a high-altitude low-pressure correction factor is introduced to correct oxygen diffusion, resulting in an oxygen diffusion model. This oxygen diffusion model is used to reflect the impact of the low-pressure environment. The expression for the plateau low-pressure correction factor is as follows: In the formula, , These represent air pressure at plains and at high altitudes, respectively. The coupled transport model is also used to describe the time difference between chloride ions and sulfate ions reaching the surface of the reinforcing steel. In a low-pressure environment, this time difference, with the participation of oxygen, has a phased impact on the corrosion process, specifically: Chloride ions first diffuse to the surface of the steel reinforcement, where charge exchange occurs, and the corrosion current density is then calculated. Sulfate ions diffuse to the surface of the steel bar later than chloride ions. They expand and destroy the passivation film on the steel bar. Chloride ions further penetrate the passivation film, directly causing localized corrosion of the steel bar. In a low-pressure environment, oxygen participates and further accelerates the corrosion.

7. A computer device, comprising a memory and a processor, the memory and the processor being connected; the memory being configured to store computer execution instructions; the processor being configured to invoke the computer execution instructions to perform the method as described in any one of claims 1 to 5.

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