Method and system for evaluating corrosion deterioration grade of in-service marine pipe pile based on chloride ion concentration at steel bar

Abstract

The application provides a method and system for evaluating the corrosion deterioration grade of a marine pipe pile in service based on the chlorine ion concentration at the steel bar, and belongs to the field of marine pipe pile corrosion evaluation. The method comprises the following steps: collecting the chlorine ion concentration data on the surface of the pipe pile, obtaining the structural parameters of the pipe pile, designing a diffusion model, the diffusion model being applicable to a cylindrical pipe pile with a cavity structure, evaluating the corrosion deterioration grade of the marine pipe pile in service, and manually intervening. The application evaluates the corrosion deterioration degree of the pipe pile steel bar by collecting the data of the chlorine ion concentration on the surface of the pipe pile, combining the structural parameters of the pipe pile and the diffusion model, and dynamically updating the corrosion time of the pipe pile steel bar by regularly collecting the chlorine ion concentration on the surface of the pipe pile, so as to dynamically evaluate the corrosion deterioration degree of the pipe pile. The system can monitor the corrosion time of the steel bar in real time, and quickly evaluate the corrosion deterioration degree of the pipe pile through data processing and analysis.

Description

Technical Field

[0001] This invention relates to the field of corrosion evaluation of marine engineering pipe piles, and in particular to a method and system for evaluating the corrosion deterioration level of in-service marine engineering pipe piles based on the chloride ion concentration at the reinforcing steel. Background Technology

[0002] Offshore pipe piles operating in marine environments are frequently corroded by chloride ions that penetrate the reinforcing steel bars. The corrosion products generate expansion stress, causing cracks in the protective layer of the steel bars, which in turn accelerates the rate of chloride ion corrosion, ultimately leading to the overall failure of the marine structure. Typically, the time it takes for chloride ions to penetrate the reinforcing steel bars is the longest during the corrosion failure life of offshore pipe piles. Once chloride ions penetrate and accumulate to the concentration required for corrosion initiation (the chloride ion concentration threshold), the corrosion rate of the offshore pipe pile increases dramatically. Therefore, the impact of chloride ion concentration is crucial in evaluating the corrosion deterioration of in-service offshore pipe piles.

[0003] Currently, the evaluation of the corrosion and deterioration degree of in-service marine engineering pipe piles mainly adopts non-destructive testing techniques, such as ultrasonic testing and electromagnetic wave testing. However, these techniques have certain limitations. For example, the test results are affected by factors such as the operator's skill level and the accuracy of the testing instruments, and they cannot directly reflect the impact of chloride ion concentration on the corrosion and deterioration of the pipe piles. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for evaluating the corrosion degradation level of in-service marine engineering pipe piles based on the chloride ion concentration at the reinforcing steel, thereby solving the technical problem that existing ultrasonic and electromagnetic wave detection methods for in-service marine engineering pipe piles cannot directly reflect the impact of chloride ion concentration on the corrosion degradation of the pipe piles.

[0005] This method evaluates the degree of corrosion and deterioration at the steel reinforcement of pipe piles by collecting data on the chloride ion concentration on the surface of the pipe piles and combining the structural parameters and diffusion model of the pipe piles.

[0006] This method evaluates the degree of corrosion degradation at the steel reinforcement of pipe piles by collecting data on the chloride ion concentration on the pile surface and combining this data with the pile's structural parameters and a diffusion model. The system comprises a pipe pile surface chloride ion concentration module, a pipe pile structural parameter module, a diffusion model module, and an evaluation module, enabling real-time monitoring and evaluation of pipe piles.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel, the method comprising the following steps:

[0009] Step 1: Collect chloride ion concentration data on the surface of the pipe pile;

[0010] Step 2: Obtain the structural parameters of the pipe pile;

[0011] Step 3: Design a diffusion model. The diffusion model is suitable for cylindrical pipe piles with a cavity structure.

[0012] Step 4: Evaluate the corrosion and deterioration level of in-service marine engineering pipe piles and intervene manually.

[0013] Furthermore, the specific process of step 1 is as follows:

[0014] Chloride ion concentration data on the surface of the pipe piles are collected periodically, and the collection time and corresponding chloride ion concentration data on the surface of the pipe piles are recorded. The obtained data are combined with the structural parameters of the pipe piles and the diffusion model to evaluate the degree of corrosion and deterioration at the steel reinforcement of the pipe piles.

[0015] Furthermore, the specific process of step 2 is as follows:

[0016] The structural parameters of the pipe pile include the inner and outer radii and diffusion coefficient of the pipe pile. The obtained parameters, combined with the collected chloride ion concentration data on the surface of the pipe pile and the diffusion model, are used to evaluate the degree of corrosion and deterioration at the steel reinforcement of the pipe pile.

[0017] 4. The method for evaluating the corrosion deterioration level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel as described in claim 1, characterized in that: the specific process of step 3 is as follows:

[0018] The diffusion model covers the outer diameter r of the pipe pile e Inner diameter r0, pipe pile diffusion coefficient D, seawater chloride ion concentration c s The time-dependent function f(t) is composed of the chloride ion invasion time t, the arbitrary radial distance r of the pipe pile, and the chloride ion concentration c(t, r) at r at time t, where 0 ≤ r ≤ r e D, c s f(t) and t are both non-negative numbers;

[0019] For any chloride ion intrusion time t and any radial distance r of the pipe pile, c(t, r) obeys the following governing equation:

[0020]

[0021] in, The sign for partial derivatives;

[0022] For the initial moment of the intrusion, i.e., t = 0, c(t, r) follows the following initial conditions:

[0023] c(0,r)=0 (20)

[0024] For the inner radius of the pipe pile, i.e., r = r0, c(t, r) satisfies the following inner boundary conditions:

[0025]

[0026] Equation (3) means that the inner boundary of the pipe pile is a free outflow boundary, which is more in line with reality.

[0027] For the outer radius of the pipe pile, i.e., r = r e c(t, r) follows the following outer boundary conditions:

[0028] c(t,r e ) = c s f(t) (22)

[0029] Equation (4) shows that the chloride ion concentration at the outer boundary of the pipe pile is a concentration that changes over time.

[0030] Equations (1) to (4) together constitute the mathematical model of the diffusion model of chloride ions invading coastal pipe piles considering the free flow of the inner wall of the pipe pile. By solving equations (1) to (4), the diffusion model of chloride ions invading coastal pipe piles considering the free flow of the inner wall of the pipe pile can be obtained.

[0031] Construct a new function as follows:

[0032] c(t,r)=c * (t,r)+c s f(t) (23)

[0033] Substituting equation (5) into the mathematical model of chloride ion intrusion and diffusion in coastal pipe piles considering free flow on the inner wall of the pipe pile, i.e. equations (1) to (4), we can obtain the following four equations:

[0034]

[0035] c * (0,r)=-c s f(t) (25)

[0036]

[0037] c * (t,r e )=0 (27)

[0038] The eigenvalue system corresponding to equations (6) to (9) above is shown below:

[0039]

[0040]

[0041] ψ m (β m ,re )=0 (30)

[0042] In equations (10) to (12) above, ψ m (β m (r) represents the arbitrary radial distance r from the pipe pile and the characteristic value β. m Functions related to the number of eigenvalue sequences m;

[0043] Equation (10) above is the Bessel equation, and ψ can be determined based on the two conditions in equations (11) to (12). m (β m The following is an example of the character (r):

[0044]

[0045] In equation (13), J0 and Y0 are the first and second kind of 0th order Bessel functions, respectively;

[0046] Construct a pair of transformations as follows:

[0047]

[0048]

[0049] In equations (14) to (15) above

[0050] Multiply both sides of equation (6) by Substituting equation (15) into the equation and rearranging, we get:

[0051]

[0052] In the above formula (16)

[0053]

[0054] G(t)=[G1(t) G2(t) … G L (t)] T ;

[0055]

[0056]

[0057] L is the number of terms to be summed, and is a positive integer.

[0058] Equation (16) above is a first-order variable coefficient equation in matrix form, and the solution is as follows:

[0059]

[0060] In the above formula (17)

[0061]

[0062] Substituting equation (17) back into equation (15) and then back into equation (5), we can obtain the analytical solution of the diffusion model considering free flow within the inner wall of the pipe pile, as follows:

[0063]

[0064] in

[0065] Furthermore, the specific process of step 4 is as follows:

[0066] The collected chloride ion concentration data on the pipe pile surface, pipe pile structural parameters, and diffusion model were used to evaluate the corrosion degradation level of in-service marine pipe piles, with the chloride ion concentration at the reinforcing steel as the evaluation index. The corrosion degradation levels for in-service marine pipe piles were set as follows: when the service life index of the marine pipe pile is 0-25% of the reinforcing steel corrosion initiation time, the degradation level is slight degradation, with manual intervention only involving the collection of chloride ion concentration data on the pipe pile surface; when the service life index of the marine pipe pile is 25%-50% of the reinforcing steel corrosion initiation time, the degradation level is mild degradation, with manual intervention only involving the collection of chloride ion concentration data on the pipe pile surface. In addition to collecting data on chloride ion concentration on the surface of the pipe pile, attention should also be paid to the structural health of the pipe pile. When the service life index of the marine engineering pipe pile is 50%-75% of the time when the steel reinforcement begins to corrode, the deterioration level is moderate. The intervention measures are to increase the frequency of monitoring the health of the pipe pile and reduce the frequency of collecting chloride ion concentration data on the surface of the pipe pile. When the service life index of the marine engineering pipe pile is 75%-100% of the time when the steel reinforcement begins to corrode, the deterioration level is severe. The intervention measures are to increase anti-corrosion measures for the pipe pile, such as applying anti-corrosion materials and increasing the thickness of the steel reinforcement protective layer.

[0067] Furthermore, the chloride ion concentration threshold is the minimum chloride ion concentration value for chloride ion-induced corrosion of reinforcing steel. After collecting the chloride ion concentration on the surface of the pipe pile for a fixed period of time, a regular development curve of the chloride ion concentration on the surface of the pipe pile can be obtained. The curve is in the form of exponential growth, that is, f(t) is an exponential growth function with time. The collected chloride ion concentration data on the surface of the pipe pile is continuously imported into the evaluation process of corrosion deterioration level of in-service marine engineering pipe piles to achieve dynamic adjustment of corrosion deterioration level of in-service marine engineering pipe piles. After obtaining the regular development curve of chloride ion concentration on the surface of the pipe pile, the frequency of collecting chloride ion concentration data on the surface of the pipe pile is reduced.

[0068] A system for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel reinforcement includes a pipe pile surface chloride ion concentration module, a pipe pile structural parameter module, a diffusion model module, and a degradation level evaluation module. The pipe pile surface chloride ion concentration module and the pipe pile structural parameter module are both connected to the diffusion model module, which in turn is connected to the degradation level evaluation module. The system periodically updates the collected pipe pile surface chloride ion concentration data to the pipe pile surface chloride ion concentration module in real time. The input data for the pipe pile surface chloride ion concentration module is the seawater chloride ion concentration c. s The time-dependent function f(t) does not need to be changed in the pipe pile structure parameter module if there are no changes after the specific offshore pipe pile settings. The input data for the pipe pile structure parameter module is the outer diameter r of the pipe pile. e The inner diameter r0, the pipe pile diffusion coefficient D, and the diffusion model module are the core modules of the deterioration level evaluation system. The diffusion model module automatically analyzes the data based on the data in the pipe pile surface chloride ion concentration module, the pipe pile structural parameter module, and the diffusion model module. The built-in program of the diffusion model module is the analytical solution of the diffusion model.

[0069] Furthermore, the deterioration level evaluation system operation process is as follows: Click Start to enter the pipe pile surface chloride ion concentration module and pipe pile structural parameter module, and input c(t, r)... e The chloride ion concentration on the surface of the pipe pile is updated to 0.55%, and the outer radius r of the pipe pile is adjusted accordingly. e =250mm, inner radius r e =150mm, diffusion coefficient is D=10 －12 m 2 / s Update Pipe Pile Structure Parameters Module, click Next to enter the Diffusion Model Module. The Diffusion Model Module automatically calculates and outputs the time-varying curve of chloride ion concentration at the pipe pile reinforcement based on the imported pipe pile surface chloride ion concentration data and pipe pile structure parameters. Click Next to enter the Deterioration Level Evaluation Module. The Deterioration Level Evaluation Module divides the in-service marine engineering pipe pile into 4 deterioration stages according to the definition of corrosion deterioration level of in-service marine engineering pipe piles. Each deterioration stage corresponds to a time interval, and the module evaluates which deterioration stage the marine engineering pipe pile is in within the time interval.

[0070] The present invention, by adopting the above-described technical solution, has the following beneficial effects:

[0071] This invention evaluates the degree of corrosion and deterioration of the steel reinforcement in pipe piles by collecting data on the chloride ion concentration on the surface of the pipe piles and combining it with the structural parameters and diffusion model of the pipe piles. By periodically collecting data on the chloride ion concentration on the surface of the pipe piles, the corrosion initiation time of the steel reinforcement is dynamically updated, thereby achieving a dynamic evaluation of the degree of corrosion and deterioration of the pipe piles. The system can monitor the corrosion initiation time of the steel reinforcement in real time and quickly evaluate the degree of corrosion and deterioration of the pipe piles through data processing and analysis. Attached Figure Description

[0072] Figure 1 This is a flowchart of the deterioration level evaluation system of the present invention;

[0073] Figure 2 This is a geometric dimension diagram of the marine pipe pile structure according to Embodiment 1 of the present invention;

[0074] Figure 3 This is the output diagram of the diffusion model module in Embodiment 1 of the present invention;

[0075] Figure 4 This is the output diagram of the degradation level evaluation module in Embodiment 1 of the present invention;

[0076] Figure 5 This is the output diagram of the diffusion model module in Embodiment 2 of the present invention;

[0077] Figure 6 This is the output diagram of the degradation level evaluation module in Embodiment 2 of the present invention. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0079] A method for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel, the method comprising the following steps:

[0080] I. Collect chloride ion concentration data on the surface of the pipe pile

[0081] Chloride ion concentration data on the surface of the pipe pile is collected periodically, and the collection time and corresponding chloride ion concentration data on the surface of the pipe pile are recorded. The obtained data can be combined with the structural parameters and diffusion model of the pipe pile to evaluate the degree of corrosion and deterioration at the steel reinforcement of the pipe pile.

[0082] II. Obtaining Pipe Pile Structure Parameters

[0083] This includes the inner and outer radii of the pipe pile and the diffusion coefficient. The obtained parameters can be combined with the collected chloride ion concentration data on the pipe pile surface and the diffusion model to evaluate the degree of corrosion and deterioration at the pipe pile reinforcement.

[0084] III. Diffusion Model

[0085] This diffusion model is applicable to cylindrical pipe piles with a cavity structure and can be used in coastal areas.

[0086] This diffusion model covers the outer diameter r of the pipe pile. e Inner diameter r0, pipe pile diffusion coefficient D, seawater chloride ion concentration c sThe time-dependent function f(t), the chloride ion intrusion time t, the arbitrary radial distance r of the pipe pile, and the chloride ion concentration c(t, r) at time t and r together constitute the total concentration. Where 0 ≤ r ≤ r e D, c s f(t) and t are both non-negative numbers.

[0087] For any chloride ion intrusion time t and any radial distance r of the pipe pile, c(t, r) obeys the following governing equation:

[0088]

[0089] For the initial moment of the intrusion, i.e., t = 0, c(t, r) follows the following initial conditions:

[0090] c(0,r)=0 (38)

[0091] For the inner radius of the pipe pile, i.e., r = r0, c(t, r) satisfies the following inner boundary conditions:

[0092]

[0093] Equation (3) implies that the inner boundary of the pipe pile is considered to be the free flow boundary, which is more in line with the actual situation.

[0094] For the outer radius of the pipe pile, i.e., r = r e c(t, r) follows the following outer boundary conditions:

[0095] c(t,r e ) = c s f(t) (40)

[0096] Equation (4) assumes that the chloride ion concentration at the outer boundary of the pipe pile is a concentration that changes with time.

[0097] Equations (1) to (4) together constitute the mathematical model of the diffusion model of chloride ions invading coastal pipe piles considering the free flow of chloride ions in the inner wall of the pipe pile. By solving equations (1) to (4), the diffusion model of chloride ions invading coastal pipe piles considering the free flow of chloride ions in the inner wall of the pipe pile can be obtained.

[0098] Construct a new function as follows:

[0099] c(t,r)=c * (t,r)+c s f(t) (41)

[0100] Substituting equation (5) into the mathematical model of chloride ion intrusion and diffusion in coastal pipe piles considering free flow on the inner wall of the pipe pile, i.e. equations (1) to (4), we can obtain the following four equations:

[0101]

[0102] c * (0,r)=-c s f(t) (43)

[0103]

[0104] c * (t,r e )=0 (45)

[0105] The eigenvalue system corresponding to equations (6) to (9) above is shown below:

[0106]

[0107]

[0108] ψ m (β m ,r e )=0 (48)

[0109] In equations (10) to (12) above, ψ m (β m (r) represents the arbitrary radial distance r from the pipe pile and the characteristic value β. m A function related to the number of eigenvalue sequences m.

[0110] Equation (10) above is the Bessel equation, and ψ can be determined based on the two conditions in equations (11) to (12). m (β m The following is an example of the character (r):

[0111]

[0112] In equation (13), J0 and Y0 are the first and second type 0 Bessel functions, respectively.

[0113] Furthermore, construct a set of transformation pairs as follows:

[0114]

[0115]

[0116] In equations (14) to (15) above

[0117] Multiply both sides of equation (6) by Substituting equation (15) into the equation and rearranging, we get:

[0118]

[0119] In the above formula (16)

[0120]

[0121] G(t)=[G1(t) G2(t) … G L (t)] T ;

[0122]

[0123]

[0124] L is the number of terms to be summed, which is a positive integer.

[0125] Equation (16) above is a first-order variable coefficient equation in matrix form, and its solution is as follows:

[0126]

[0127] In the above formula (17)

[0128] Substituting equation (17) back into equation (15) and then back into equation (5), we can obtain the analytical solution of the diffusion model considering free flow within the inner wall of the pipe pile, as shown below:

[0129]

[0130] in

[0131] IV. Deterioration Level Evaluation Method

[0132] Based on the collected chloride ion concentration data on the surface of the pipe pile, the structural parameters of the pipe pile, and the diffusion model, the chloride ion concentration at the reinforcing steel is used as the evaluation index to assess the corrosion degradation level of the in-service marine pipe piles. The corrosion degradation levels of the in-service marine pipe piles are set as shown in Table 1 below.

[0133] Table 1 Corrosion Deterioration Levels of In-Service Offshore Pipe Piles

[0134]

[0135] The above chloride ion concentration threshold is the minimum chloride ion concentration value for chloride-induced corrosion of steel bars.

[0136] It should be noted that after collecting the chloride ion concentration on the surface of the pipe pile for a period of time, a regular development curve of the chloride ion concentration on the surface of the pipe pile can be obtained. It is generally an exponential growth form, that is, f(t) is generally an exponential growth function with time.

[0137] It should be noted that by continuously importing the collected chloride ion concentration data on the surface of the pipe pile into the evaluation method for the corrosion deterioration level of in-service marine pipe piles, the corrosion deterioration level of in-service marine pipe piles can be dynamically adjusted.

[0138] After obtaining the regular development curve of chloride ion concentration on the surface of the pipe pile, the data acquisition frequency of chloride ion concentration on the surface of the pipe pile can be reduced.

[0139] V. Deterioration Level Evaluation System

[0140] The deterioration level evaluation system includes a chloride ion concentration module on the pipe pile surface, a pipe pile structural parameter module, a diffusion model module, and a deterioration level evaluation module. The chloride ion concentration module and the pipe pile structural parameter module are data input modules, the diffusion model module is a data processing module, and the deterioration level evaluation module is a data analysis module.

[0141] The chloride ion concentration on the surface of the pipe piles, collected periodically, can be updated in real time to the chloride ion concentration module on the surface of the pipe piles. The input data for this module is the seawater chloride ion concentration c. s The time-dependent function f(t). The pipe pile structure parameter module does not need to be modified if the settings for the specific marine pipe pile remain unchanged. The input data for this module is the outer diameter r of the pipe pile. e The inner diameter is r0, and the diffusion coefficient of the pipe pile is D. The diffusion model module is the core module of the deterioration level evaluation system. It can automatically analyze data based on the data in the pipe pile surface chloride ion concentration module, pipe pile structural parameter module, and diffusion model module. The built-in program of this module is the analytical solution of the diffusion model, as shown in equation (18). The deterioration level evaluation module is a custom module and can be defined according to the suggestions in Table 1.

[0142] Example 1

[0143] like Figure 2 To demonstrate the specific structure of offshore pipe piles;

[0144] Parameter definition: Only one data point was collected for the chloride ion concentration on the surface of the pipe pile, which is c(t, r). e ) = 0.55%; outer radius r of the pipe pile e =250mm, inner radius r e =150mm, diffusion coefficient is D=10 －12 m 2 / s; Reinforcing bar protective layer thickness d = 50mm; Chloride ion threshold at the reinforcing bar c c =0.3%.

[0145] Run the degradation level evaluation system:

[0146] (1) Click Start to enter the chloride ion concentration module on the surface of the pipe pile and the structural parameters module of the pipe pile.

[0147] (2) Let c(t, r) e Update the chloride ion concentration module on the surface of the pipe pile to 0.55%; adjust the outer radius r of the pipe pile. e =250mm, inner radius r e =150mm, diffusion coefficient is D=10 －12 m 2 / s Update Pipeline Structure Parameters Module; Click Next to enter the Diffusion Model Module.

[0148] (3) The diffusion model module automatically calculates and outputs the time-varying curve of chloride ion concentration at the pipe pile reinforcement based on the imported pipe pile surface chloride ion concentration data and pipe pile structural parameters, as shown in the figure below. Click Next to enter the deterioration level evaluation module.

[0149] Figure 3 Example 1: Diffusion Model Module Output Image

[0150] (4) The deterioration level evaluation module, according to the definition in Table 1, can divide in-service marine pipe piles into four deterioration stages, such as... Figure 4 As shown, each stage of degradation corresponds to a time interval. In other words, within this time interval, the stage of degradation of the offshore pipe pile can be evaluated.

[0151] Example 2

[0152] In Supplementary Example 1 and Example 2, only the parameters of the chloride ion concentration module on the surface of the pipe pile were updated; other parameters remained unchanged. After collecting chloride ion concentration data on the surface of the pipe pile for a period of time, it was found that the chloride ion concentration on the surface of the pipe pile followed the following development pattern: c(t, r e ) = c s f(t), c s =0.55%, t0 = 25 years.

[0153] Run the degradation level evaluation system:

[0154] (1) Click Start to enter the chloride ion concentration module on the surface of the pipe pile and the structural parameters module of the pipe pile.

[0155] (2) Let c(t, r) e ) = c s f(t), c s =0.55%, t0 = Update the chloride ion concentration module on the surface of the pipe pile in 25 years; the parameters of the pipe pile structure parameter module remain unchanged; click Next to enter the diffusion model module.

[0156] (3) The diffusion model module automatically calculates and outputs the time-varying curve of chloride ion concentration at the pipe pile reinforcement based on the imported pipe pile surface chloride ion concentration data and pipe pile structural parameters, as shown in the figure below. Click Next to enter the deterioration level evaluation module.

[0157] (4) The deterioration level evaluation module, according to the definition in Table 1, can divide in-service marine pipe piles into four deterioration stages, such as... Figure 6 As shown, each stage of degradation corresponds to a time interval.

[0158] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel bars, characterized in that: The method includes the following steps: Step 1: Collect chloride ion concentration data on the surface of the pipe pile; Step 2: Obtain the structural parameters of the pipe pile; Step 3: Design a diffusion model. The diffusion model is suitable for cylindrical pipe piles with a cavity structure. Step 4: Evaluate the corrosion and deterioration level of in-service marine engineering pipe piles and intervene manually; The specific process of step 3 is as follows: The diffusion model covers the outer diameter of the pipe pile r e , inner diameter r 0, diffusion coefficient of pipe pile D seawater chloride ion concentration c s Time-related functions f ( t Chloride ion intrusion time t And any radial distance of the pipe pile r ,and t time r Chloride ion concentration at c ( t , r Together they form a whole, where 0 ≤ r 0≤ r ≤ r e , D , c s , f ( t ), t All are non-negative numbers; For any chloride ion intrusion time t and radial distance of any pipe pile r , c ( t , r It follows the following governing equations: (1) For the initial moment of the intrusion, i.e. t =Time 0, c ( t , r The following initial conditions apply: (2) For the inner radius of the pipe pile, i.e. r = r 0, c ( t , r It must comply with the following internal boundary conditions: (3) Equation (3) means that the inner boundary of the pipe pile is a free outflow boundary, which is more in line with reality. For the outer radius of the pipe pile, i.e. r = r e , c ( t , r It must comply with the following outer boundary conditions: (4) Equation (4) shows that the chloride ion concentration at the outer boundary of the pipe pile is a concentration that changes over time. Equations (1) to (4) together constitute the mathematical model of the diffusion model of chloride ions invading coastal pipe piles considering the free flow of the inner wall of the pipe pile. By solving equations (1) to (4), the diffusion model of chloride ions invading coastal pipe piles considering the free flow of the inner wall of the pipe pile can be obtained. Construct a new function as follows: (5) Substituting equation (5) into the mathematical model of chloride ion intrusion and diffusion in coastal pipe piles considering free flow on the inner wall of the pipe pile, i.e. equations (1) to (4), we can obtain the following four equations: (6) (7) (8) (9) The eigenvalue system corresponding to equations (6) to (9) above is shown below: (10) (11) (12) In equations (10) to (12) above, For any radial distance from the pipe pile r eigenvalues and the number of eigenvalue sequences m Related functions; Equation (10) above is the Bessel equation, which can be determined based on the two conditions in equations (11) to (12). as follows: (13) In formula (13) , These are the first and second kind of zero-order Bessel functions, respectively; Construct a pair of transformations as follows: (14) (15) In equations (14) to (15) above ; Multiply both sides of equation (6) by Substituting equation (15) into the equation and rearranging, we get: (16) In the above formula (16) ; ； ； ； ； ， The number of terms to be summed is a positive integer; Equation (16) above is a first-order variable coefficient equation in matrix form, and the solution is as follows: (17) In the above formula (17) ; Substituting equation (17) back into equation (15) and then back into equation (5), we can obtain the analytical solution of the diffusion model considering free flow within the inner wall of the pipe pile, as follows: (18), of which ; The specific process of step 4 is as follows: The collected chloride ion concentration data on the pipe pile surface, pipe pile structural parameters, and diffusion model were used to evaluate the corrosion degradation level of in-service marine pipe piles, with the chloride ion concentration at the reinforcing steel as the evaluation index. The corrosion degradation levels for in-service marine pipe piles were set as follows: when the service life index of the marine pipe pile is 0-25% of the reinforcing steel corrosion initiation time, the degradation level is slight degradation, with manual intervention only involving the collection of chloride ion concentration data on the pipe pile surface; when the service life index of the marine pipe pile is 25%-50% of the reinforcing steel corrosion initiation time, the degradation level is mild degradation, with manual intervention only involving the collection of chloride ion concentration data on the pipe pile surface. In addition to collecting data on chloride ion concentration on the surface of the pipe pile, we also need to pay attention to the structural health of the pipe pile. When the service life index of the marine engineering pipe pile is 50%-75% of the time when the steel reinforcement begins to corrode, the deterioration level is moderate. The intervention measures are to increase the frequency of monitoring the health of the pipe pile and reduce the frequency of collecting chloride ion concentration data on the surface of the pipe pile. When the service life index of the marine engineering pipe pile is 75%-100% of the time when the steel reinforcement begins to corrode, the deterioration level is severe. The intervention measures are to increase anti-corrosion measures for the pipe pile, such as applying anti-corrosion materials and increasing the thickness of the steel reinforcement protective layer. The chloride ion concentration threshold is the minimum chloride ion concentration value that causes chloride ion corrosion of the reinforcing steel. After collecting the chloride ion concentration on the surface of the pipe pile for a fixed period of time, a regular development curve of the chloride ion concentration on the pipe pile surface can be obtained. The curve is exponentially increasing, meaning that... f ( t The function is an exponential growth function over time. The collected chloride ion concentration data on the surface of the pipe pile is continuously imported into the evaluation process of corrosion degradation level of in-service marine pipe piles to achieve dynamic adjustment of corrosion degradation level of in-service marine pipe piles. After obtaining the regular development curve of chloride ion concentration on the surface of the pipe pile, the frequency of collecting chloride ion concentration data on the surface of the pipe pile is reduced.

2. The method for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel reinforcement as described in claim 1, characterized in that: The specific process of step 1 is as follows: Chloride ion concentration data on the surface of the pipe piles are collected periodically, and the collection time and corresponding chloride ion concentration data on the surface of the pipe piles are recorded. The obtained data are combined with the structural parameters of the pipe piles and the diffusion model to evaluate the degree of corrosion and deterioration at the steel reinforcement of the pipe piles.

3. The method for evaluating the corrosion deterioration level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel reinforcement as described in claim 1, characterized in that: The specific process of step 2 is as follows: The structural parameters of the pipe pile include the inner and outer radii and diffusion coefficient of the pipe pile. The obtained parameters, combined with the collected chloride ion concentration data on the surface of the pipe pile and the diffusion model, are used to evaluate the degree of corrosion and deterioration at the steel reinforcement of the pipe pile.

4. The system for evaluating the corrosion degradation level of in-service marine pipe piles based on chloride ion concentration at the reinforcing steel, as described in any one of claims 1-3, is characterized in that: The system includes modules for chloride ion concentration on the pipe pile surface, pipe pile structural parameters, diffusion model, and degradation level evaluation. The pipe pile surface chloride ion concentration and structural parameter modules are connected to the diffusion model module, which in turn is connected to the degradation level evaluation module. The system periodically updates the collected chloride ion concentration data on the pipe pile surface to the pipe pile surface chloride ion concentration module. The input data for the pipe pile surface chloride ion concentration module is the seawater chloride ion concentration. c s Time-related functions f ( t The pipe pile structure parameter module does not need to be changed if there are no changes after the specific offshore pipe pile settings are configured. The data input to the pipe pile structure parameter module is the outer diameter of the pipe pile. r e , inner diameter r 0, diffusion coefficient of pipe pile D The diffusion model module is the core module of the deterioration level evaluation system. It automatically analyzes data based on the data in the pipe pile surface chloride ion concentration module, pipe pile structural parameter module, and diffusion model module. The built-in program of the diffusion model module is the analytical solution of the diffusion model. The deterioration level evaluation system operates as follows: Click "Start" to enter the pipe pile surface chloride ion concentration module and the pipe pile structural parameter module, and then... c ( t , r e The chloride ion concentration module on the surface of the pipe pile is updated to 0.55%, and the outer radius of the pipe pile is adjusted accordingly. r e =250mm, inner radius r 0 = 150 mm, diffusion coefficient is D = 10 -12 m 2 / s Update Pipe Pile Structure Parameters Module, click Next to enter the Diffusion Model Module. The Diffusion Model Module automatically calculates and outputs the time-varying curve of chloride ion concentration at the pipe pile reinforcement based on the imported pipe pile surface chloride ion concentration data and pipe pile structure parameters. Click Next to enter the Deterioration Level Evaluation Module. The Deterioration Level Evaluation Module divides the in-service marine engineering pipe pile into 4 deterioration stages according to the definition of corrosion deterioration level of in-service marine engineering pipe piles. Each deterioration stage corresponds to a time interval, and the module evaluates which deterioration stage the marine engineering pipe pile is in within the time interval.

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