A method and system for diagnosing multi-point corrosion status of a sling considering the effect of annular magnetic field

Abstract

The present invention discloses a method and system for diagnosing the multi-point corrosion state of a cable considering the effect of a circumferential magnetic field, and relates to the technical field of diagnosing corrosion damage of a cable structure of a bridge, including: testing the cable and collecting feedback data; calculating dimensionless magnetic parameters and distribution and determining the section of the corrosion position of the cable; calculating the circumferential dimensionless magnetic parameter distribution of the section of the corrosion position; judging the number of circumferential corrosion defects at the corrosion position according to the circumferential dimensionless magnetic parameter distribution; and judging the corrosion state parameters of the cable again according to the judgment result by selecting a judgment criterion. The present invention is based on the spontaneous magnetic leakage technology, establishes two judgment criteria suitable for different cable damage conditions, realizes the location and quantitative identification of cable damage through dimensionless physical indicators, and proposes a diagnostic method considering the circumferential magnetic field effect for the multi-point corrosion state damage of the cable of an in-service bridge, which can effectively detect the multi-point corrosion parameters of the cable in service, and the detection results are accurate.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion damage diagnosis of bridge suspension cable structures, and more particularly to a method and system for diagnosing multi-point corrosion states of suspension cables taking into account the toroidal magnetic field effect. Background Art

[0002] The cable is the main load-bearing structure of the cable-supported bridge. Its durability will directly affect the safety of the entire bridge. However, due to long-term environmental erosion and the coupling of alternating loads, the PE sheath of the cable is very easy to age and crack, causing the internal steel wire to be exposed to the natural environment, resulting in corrosion and wire breakage. These damages are random and there may be multiple points of damage in the same cross section, which not only threatens the structural stability of the bridge, but also endangers the safety of personnel. Therefore, timely and accurate detection of the damage of the internal steel wire of the cable has great scientific significance and engineering practical value.

[0003] In 1997, Russian scholar Dubov proposed the spontaneous magnetic flux leakage detection technology, which does not require an artificial external magnetic field. At present, this technology has also been vigorously developed in the field of civil engineering. As a typical ferromagnetic material, the use of spontaneous magnetic flux leakage detection technology for damage detection of slings has great advantages, and can make qualitative judgments on the internal damage (corrosion, broken wires) of slings. However, due to the randomness of damage, slings often have multi-point corrosion. Existing diagnostic methods are difficult to accurately locate the distribution of multi-point damage in slings, and there is a lack of methods to accurately assess the degree of damage to slings. At the same time, due to the different magnetization histories between different slings, there will be differences in the numerical values ​​of magnetic signals, which will affect the further advancement of spontaneous magnetic flux leakage technology in quantitative damage assessment and actual engineering.

[0004] Therefore, how to propose a multi-point corrosion status diagnosis method and system for the pull rope that takes into account the annular magnetic field effect, and realize the multi-point damage distribution positioning and accurate damage degree assessment of the pull rope is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a method and system for diagnosing the multi-point corrosion state of a cable pull rope considering the toroidal magnetic field effect, so as to realize the multi-point damage distribution positioning and accurate damage degree assessment of the cable pull rope. In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for diagnosing the multi-point corrosion state of a cable considering the effect of the annular magnetic field. Figure 1 As shown, including:

[0007] Test the slings and collect feedback data;

[0008] Calculate dimensionless magnetic parameters and distribution based on feedback data and determine the cross-section of the corrosion position of the cable;

[0009] The dimensionless magnetic parameter distribution of the circumferential section at the corrosion location is calculated;

[0010] The number of corrosion defects around the corrosion position is preliminarily determined based on the circumferential dimensionless magnetic parameter distribution;

[0011] According to the preliminary judgment results, the judgment criteria are selected to judge the corrosion state parameters of the sling again.

[0012] Optionally, the detection of the sling and the collection of feedback data include: fixing the distance between the magnetic sensor and the surface of the sling, recording the z-direction component Bz of the measured magnetic induction intensity of the sling along the length direction z of the sling, calculating its dimensionless magnetic parameter K, and drawing a zK distribution curve. The calculation formula of the dimensionless magnetic parameter K is: Where Bz and Bz0 are the z-direction components of the magnetic induction intensity measured after corrosion and in the non-corrosion state, respectively.

[0013] Optionally, it also includes recording position information and distance information, wherein the position information is the length position with the straight line where the sling is located as the horizontal axis, and the distance information is the distance between the magnetic sensor and the surface of the sling when collecting the magnetic induction intensity Bz.

[0014] Optionally, calculating the dimensionless magnetic parameters and distribution according to the feedback data and determining the corrosion position section of the sling cable includes:

[0015] The zK distribution curve is differentiated to obtain the extreme point position z0, which is the corrosion position of the cable. According to the extreme point position z0 of the zK distribution curve, the corrosion section Q of the cable at the extreme point position is determined.

[0016] Optionally, the calculation of the circumferential dimensionless magnetic parameter distribution of the corrosion position section includes: drawing a φ-K circumferential distribution curve on the corrosion position section Q of the pull rope along the circumferential φ direction of the pull rope, and the circumferential position of the pull rope corresponds to the circumferential arrangement position of the magnetic sensor.

[0017] Optionally, the preliminarily judging the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution includes: preliminarily judging the number of corrosion defects in the circumferential direction of the sling according to the number of peaks of the φ-K circumferential distribution curve, if the φ-K circumferential distribution curve has 1 peak, it is judged that there are 1 or n defects; if the φ-K circumferential distribution curve has n peaks, n≥2, it is judged that there are n defects.

[0018] Optionally, the method of selecting a criterion according to the preliminary judgment result to judge the corrosion state parameter of the sling again includes:

[0019] If the φ-K circumferential distribution curve has one peak, it is judged that there is one or n defects, and the Type I judgment criterion is selected. According to the Type I judgment criterion, the corrosion state parameters under the condition of one peak of the φ-K circumferential distribution curve are diagnosed;

[0020] If the φ-K circumferential distribution curve has n peaks (n≥2), it is judged that there are n defects, and the Type II judgment criterion is selected. According to the Type II judgment criterion, the corrosion state parameters when the φ-K circumferential distribution curve exceeds 2 peaks are diagnosed.

[0021] Optionally, the type I determination criteria include

[0022] Calculate the characteristic values ​​of the magnetic curve, including the peak value a, valley value b, the angle corresponding to the peak value φ, the peak-to-valley ratio β, the cumulative magnetic field intensity A, and the annular distribution area S;

[0023] According to the α-S relationship curve and the α-A relationship curve, the cross-sectional loss rate α is calculated respectively. S and α A ;

[0024] According to |α S -α A | Determine the number of defects and calculate the corrosion loss rate α respectively;

[0025] Calculate the major axis p of the closed curve eigenvalue l , short axis p s and ellipticity e;

[0026] If e>1, the θ-e relationship curve is used for judgment. If e≤1, the θ-e relationship curve and the θ-β relationship curve are used for judgment at the same time to obtain the corrosion defect angle θ or the defect influence range angle θ.

[0027] Optionally, the Type II determination criteria include:

[0028] When the curve has two peaks: calculate the characteristic values ​​of the magnetic curve, including peak values ​​a1 and a2, peak corresponding angles φ1 and φ2, and cumulative magnetic field intensity A; calculate the corrosion rate α according to the α-A relationship curve A ; If the magnetic curve is asymmetric, the total cross-sectional loss rate α = α A ; If the magnetic curve is symmetrical, the corrosion loss rate α1=α2=α A / 2, the defect position corresponds to φ1 and φ2;

[0029] When the curve has n peaks, n>2: calculate the characteristic values ​​of the magnetic curve, including peaks a1, a2…a n , peak corresponding angles φ1, φ2…φ n , cumulative magnetic field intensity A; calculate the corrosion rate α according to the α-A relationship curve A ; Total loss rate of n defects α = αA , the corrosion defect positions are φ1, φ2…φ n .

[0030] Optionally, a system for diagnosing the multi-point corrosion status of a sling considering the effect of a toroidal magnetic field comprises:

[0031] Collection module: used to detect the sling and collect feedback data;

[0032] Position calculation module: used to calculate dimensionless magnetic parameters and distribution according to feedback data and determine the corrosion position section of the sling;

[0033] Circumferential distribution calculation module: used to calculate the circumferential dimensionless magnetic parameter distribution of the corrosion position section;

[0034] Preliminary judgment module: used to preliminarily judge the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution;

[0035] Result output module: It is used to select the judgment criteria according to the preliminary judgment results to judge the corrosion state parameters of the sling again.

[0036] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method and system for diagnosing the multi-point corrosion state of a sling considering the toroidal magnetic field effect, which has the following beneficial effects:

[0037] The present invention discloses a method for diagnosing the multi-point corrosion state of a cable that takes into account the toroidal magnetic field effect, including: testing the cable and collecting feedback data; calculating the dimensionless magnetic parameters and distribution according to the feedback data and determining the section of the corrosion position of the cable; calculating the circumferential dimensionless magnetic parameter distribution of the corrosion position section; preliminarily judging the number of circumferential corrosion defects at the corrosion position according to the circumferential dimensionless magnetic parameter distribution; and selecting a judgment criterion to judge the corrosion state parameters of the cable again according to the preliminary judgment result. The present invention is based on the spontaneous magnetic leakage technology and establishes two judgment criteria suitable for different cable damage conditions. Through dimensionless physical indicators, a method for locating and quantitatively identifying cable damage is proposed. A diagnostic method considering the toroidal magnetic field effect is proposed for the multi-point corrosion state damage of the cable of the bridge in service, which can effectively realize the multi-point corrosion parameter detection of the cable in service and overcome the problem of inaccurate multi-point corrosion detection of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0039] Figure 1 A schematic flow chart of a method for diagnosing the multi-point corrosion status of a sling cable taking into account the toroidal magnetic field effect provided by the present invention.

[0040] Figure 2 It is a schematic diagram of the correlation model (α-S relationship curve) between the corrosion rate α of the sling provided by the present invention and the annular distribution area S.

[0041] Figure 3 It is a schematic diagram of the correlation model (α-A relationship curve) between the corrosion rate α of the pull rope and the cumulative magnetic field intensity A provided by the present invention.

[0042] Figure 4 Schematic diagram of the defect influence range angle θ and ellipticity e correlation model (θ-e relationship curve) provided by the present invention.

[0043] Figure 5 It is a schematic diagram of the correlation model (θ-β relationship curve) between the defect influence range angle θ and the peak-to-valley ratio β provided by the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The embodiment of the present invention discloses a method for diagnosing the multi-point corrosion status of a pull rope taking into account the circumferential magnetic field effect, comprising: detecting the pull rope and collecting feedback data; calculating dimensionless magnetic parameters and distribution according to the feedback data and determining the corrosion position section of the pull rope; calculating the circumferential dimensionless magnetic parameter distribution of the corrosion position section; preliminarily judging the number of corrosion defects circumferentially at the corrosion position according to the circumferential dimensionless magnetic parameter distribution; and selecting a judgment criterion according to the preliminary judgment result to judge the corrosion status parameters of the pull rope again.

[0046] In a specific implementation, a method for diagnosing the multi-point corrosion state of a cable considering the circumferential magnetic field effect is used to obtain the circumferential distribution position of the cable damage and accurately diagnose the degree of cable damage, such as Figure 1 As shown, specifically including:

[0047] S1. The distance between the magnetic sensor and the surface of the sling cable remains unchanged. Along the length direction (z direction) of the sling cable, the z-direction component Bz of the magnetic induction intensity of the sling cable is recorded, its dimensionless magnetic parameter K is calculated, and the zK distribution curve is drawn;

[0048] S2. Obtain the extreme point position (z0) of the zK distribution curve and determine the corrosion section Q (z=z0) of the pull rope;

[0049] S3, along the circumference of the sling ( direction), draw the cross section Q of the sling Circumferential distribution curve;

[0050] S4. According to The number of peaks in the circumferential distribution curve can be used to preliminarily determine the number of corrosion defects in the circumferential direction of the sling;

[0051] S5. Accurate diagnosis based on type I criteria Corrosion state parameters for the case of “only 1 peak” of the curve;

[0052] S6. Accurate diagnosis based on type II criteria Corrosion state parameters when the curve has “more than 2 peaks”.

[0053] The present invention applies spontaneous magnetic leakage detection technology to the detection of cable damage, constructs two judgment criteria suitable for different cable damage conditions, and uses the dimensionless physical quantity to determine the damage position of the cable, establishes a cable damage degree diagnosis method, and realizes the cable damage location and damage degree evaluation.

[0054] Further, step S1 specifically includes: recording the magnetic induction intensity Bz in the z direction of the sling rope also includes position information and distance information, wherein the position information is the length position of the straight line where the sling rope is located as the horizontal axis, and the distance information is the distance between the magnetic sensor and the surface of the sling rope when collecting the magnetic induction intensity Bz. The dimensionless magnetic parameter K is defined as:

[0055]

[0056] In the formula, B z and B z0 It is the z-direction component of the magnetic induction intensity measured after the specimen is corroded and in the non-corroded state.

[0057] Furthermore, step S2 specifically includes: finding the extreme point position z0 by differentiating the zK distribution curve, where the extreme point represents the position where the sling is corroded.

[0058] Further, step S3 specifically includes: pulling the circumferential position of the sling ( direction) corresponds to the circumferential arrangement position of the magnetic sensor.

[0059] Further, step S4 specifically includes: if the curve has 1 peak, it is judged that there are 1 or n defects, and the type I judgment criterion is selected; if the curve has n peaks (n≥2), it is judged that there are n defects, and the type II judgment criterion is selected.

[0060] Furthermore, step S5 specifically includes:

[0061] S501, calculate the characteristic values ​​of the magnetic curve, including the peak value a, the valley value b, and the angle corresponding to the peak value Peak-to-valley ratio β, cumulative magnetic field intensity A, annular distribution area S, etc.;

[0062] Among them, the calculation formulas for the cumulative magnetic field intensity A and the annular distribution area S are:

[0063]

[0064] S502. According to the corrosion of the sling, draw the "α-S relationship curve" and "α-A relationship curve", such as Figure 2 , Figure 3 As shown, where S = 0.70α + 6.54α 2 , R 2 =0.942; A=23.99α-14.64α 2 , R 2 =0.990; calculate the section loss rate α S and α A ;

[0065] S503, according to |α S -α A |Judge the number of defects, when |α S -α A |≤1%, it is judged that there is only one defect, and the corrosion loss rate is α1; when |α S -α A |>1%, it is judged that there are n defects, the corrosion loss rate is α2, and α2=α A ;

[0066] The calculation formula of corrosion loss rate α1 is:

[0067]

[0068] S504, calculate the major axis p of the closed curve eigenvalue l , short axis p s and ellipticity e;

[0069] Major axis p l , short axis p s And the calculation formula of ellipticity e is:

[0070] p l =a+b;

[0071]

[0072] Where a and b are the peak and valley values ​​of the annular closed curve of the magnetic field distribution, respectively, and n is the number of magnetic sensors arranged annularly on the sling.

[0073] S505, such as Figure 4 , Figure 5 As shown in the figure, if e>1, only the “θ-e relationship curve” is used to judge and obtain the corrosion defect angle; if e≤1, both the “θ-e relationship curve” and the “θ-β relationship curve” are used to judge and obtain the defect influence range angle θ, where e=2.01-0.01θ+0.00002θ 2 , R 2 =0.986;β=12.01-0.05θ+0.00005θ 2 , R 2 =0.926.

[0074] S506, obtaining the corrosion defect angle or the defect influence range angle θ.

[0075] Further, step S6 specifically includes:

[0076] (1) When the curve has two peaks

[0077] S601, calculate the characteristic values ​​of the magnetic curve, including peak values ​​a1 and a2, and the angle corresponding to the peak values and Cumulative magnetic field strength A;

[0078] S602, such as Figure 3 As shown, according to the "α-A relationship curve", the corrosion rate α is calculated A ;

[0079] S603. If the magnetic curve is asymmetric, we can only determine the total cross-sectional loss rate α = α A ; If the magnetic curve is symmetrical, the corrosion loss rate of the two defects is α1=α2=α A / 2, the defect position corresponds to and

[0080] (2) When the curve has n peaks (n>2)

[0081] S601, calculate the characteristic values ​​of the magnetic curve, including peak values ​​a1, a2, ... a n , peak corresponding angle Cumulative magnetic field strength A;

[0082] S602, such as Figure 3 As shown, according to the "α-A relationship curve", the corrosion rate α is calculated A ;

[0083] S603, total loss rate of n defects α=α A The corrosion defect locations are

[0084] The present invention proposes a method for diagnosing the multi-point corrosion status of a cable pull rope taking into account the toroidal magnetic field effect, accurately locating the multi-point damage positions of the cable pull rope and quantitatively evaluating the damage degree of the cable pull rope, thereby improving the practical application effect of the spontaneous magnetic leakage detection technology and laying a foundation for the maintenance work of the cable pull rope structure.

[0085] In a specific embodiment, a system for diagnosing multi-point corrosion status of a sling considering the toroidal magnetic field effect includes:

[0086] Collection module: used to detect the sling and collect feedback data;

[0087] Position calculation module: used to calculate dimensionless magnetic parameters and distribution according to feedback data and determine the corrosion position section of the sling;

[0088] Circumferential distribution calculation module: used to calculate the circumferential dimensionless magnetic parameter distribution of the corrosion position section;

[0089] Preliminary judgment module: used to preliminarily judge the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution;

[0090] Result output module: It is used to select the judgment criteria according to the preliminary judgment results to judge the corrosion state parameters of the sling again.

[0091] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0092] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for diagnosing the multi-point corrosion state of a sling considering the effect of a toroidal magnetic field, characterized in that: include: Test the slings and collect feedback data; The detection of the sling rope and collection of feedback data include: fixing the distance between the magnetic sensor and the surface of the sling rope, recording the z-direction component Bz of the magnetic induction intensity of the sling rope along the length direction z of the sling rope, calculating its dimensionless magnetic parameter K, and drawing a zK distribution curve; Calculate dimensionless magnetic parameters and distribution based on feedback data and determine the cross-section of the corrosion position of the cable; The method of calculating the dimensionless magnetic parameters and distribution according to the feedback data and determining the corrosion position section of the cable pull includes: Differentiate the zK distribution curve to obtain the extreme point position z0, where the extreme point position z0 is the corrosion position of the cable, and determine the corrosion cross section Q of the cable at the extreme point position according to the extreme point position z0 of the zK distribution curve; The dimensionless magnetic parameter distribution of the circumferential section at the corrosion location is calculated; The calculating of the circumferential dimensionless magnetic parameter distribution of the corrosion position section includes: drawing a φ-K circumferential distribution curve on the corrosion position section Q of the pull rope along the circumferential φ direction of the pull rope, and the circumferential position of the pull rope corresponds to the circumferential arrangement position of the magnetic sensor; The number of corrosion defects around the corrosion position is preliminarily determined based on the circumferential dimensionless magnetic parameter distribution; The method of preliminarily judging the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution includes: preliminarily judging the number of corrosion defects in the circumferential direction of the sling according to the number of peaks of the φ-K circumferential distribution curve, if the φ-K circumferential distribution curve has 1 peak, then judging that there are 1 or n defects; if the φ-K circumferential distribution curve has n peaks, n ≥ 2, then judging that there are n defects; According to the preliminary judgment results, the judgment criteria are selected to judge the corrosion state parameters of the sling again; The corrosion state parameters of the sling rope are judged again by selecting the judgment criteria according to the preliminary judgment result, including: If the φ-K circumferential distribution curve has one peak, it is judged that there is one or n defects, and the Type I judgment criterion is selected. According to the Type I judgment criterion, the corrosion state parameters under the condition of one peak of the φ-K circumferential distribution curve are diagnosed; If the φ-K circumferential distribution curve has n peaks (n≥2), it is judged that there are n defects, and the Type II judgment criterion is selected. According to the Type II judgment criterion, the corrosion state parameters when the φ-K circumferential distribution curve exceeds 2 peaks are diagnosed.

2. The method for diagnosing multi-point corrosion status of a sling considering the toroidal magnetic field effect according to claim 1 is characterized in that: It also includes recording position information and distance information, wherein the position information is the length position with the straight line where the sling is located as the horizontal axis, and the distance information is the distance between the magnetic sensor and the surface of the sling when collecting the magnetic induction intensity Bz.

3. The method for diagnosing multi-point corrosion status of a sling considering the toroidal magnetic field effect according to claim 1 is characterized in that: The Type I criteria include Calculate the characteristic values ​​of the magnetic curve, including the peak value a, valley value b, the angle φ corresponding to the peak value, the peak-to-valley ratio β, the cumulative magnetic field intensity A, and the annular distribution area S; According to the α-S relationship curve and the α-A relationship curve, the cross-sectional loss rate α is calculated respectively. S and α A ; According to |α S -α A | Determine the number of defects and calculate the corrosion loss rate α respectively; Calculate the major axis p of the closed curve eigenvalue l , short axis p s and ellipticity e; If e>1, the θ-e relationship curve is used for judgment. If e≤1, the θ-e relationship curve and the θ-β relationship curve are used for judgment at the same time to obtain the corrosion defect angle θ or the defect influence range angle θ.

4. The method for diagnosing multi-point corrosion status of a sling considering the toroidal magnetic field effect according to claim 1 is characterized in that: The Type II criteria include: When the curve has two peaks: calculate the characteristic values ​​of the magnetic curve, including peak values ​​a1 and a2, peak corresponding angles φ1 and φ2, and cumulative magnetic field intensity A; calculate the corrosion rate α according to the α-A relationship curve A ; If the magnetic curve is asymmetric, the total cross-sectional loss rate α=α A ; If the magnetic curve is symmetrical, the corrosion loss rate α1=α2=α A / 2, the defect position corresponds to φ1 and φ2; When the curve has n peaks, n>2: calculate the characteristic values ​​of the magnetic curve, including peaks a1, a2…a n , the peaks correspond to angles φ1, φ2…φ n , cumulative magnetic field intensity A; calculate the corrosion rate α according to the α-A relationship curve A ; The total loss rate of n defects α=α A , the corrosion defect positions are φ1, φ2…φ n .

5. A system for diagnosing the multi-point corrosion status of a sling considering the effect of a toroidal magnetic field, characterized in that: include: Collection module: used to detect the sling and collect feedback data; The detection of the sling rope and collection of feedback data include: fixing the distance between the magnetic sensor and the surface of the sling rope, recording the z-direction component Bz of the magnetic induction intensity of the sling rope along the length direction z of the sling rope, calculating its dimensionless magnetic parameter K, and drawing a zK distribution curve; Position calculation module: used to calculate dimensionless magnetic parameters and distribution according to feedback data and determine the corrosion position section of the cable pull rope; the calculation of dimensionless magnetic parameters and distribution according to feedback data and determination of the corrosion position section of the cable pull rope includes: differentiating the zK distribution curve to obtain the extreme point position z0, the extreme point position z0 is the corrosion position of the cable pull rope, and determining the corrosion section Q of the cable pull rope at the extreme point position according to the extreme point position z0 of the zK distribution curve; Circumferential distribution calculation module: used to calculate the circumferential dimensionless magnetic parameter distribution of the cross section at the corrosion position at the corrosion position; the calculation of the circumferential dimensionless magnetic parameter distribution of the cross section at the corrosion position includes: drawing a φ-K circumferential distribution curve on the cross section Q of the corrosion position of the pull rope along the circumferential φ direction of the pull rope, and the circumferential position of the pull rope corresponds to the circumferential arrangement position of the magnetic sensor; A preliminary judgment module is used to preliminarily judge the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution; the preliminarily judging the number of corrosion defects in the circumferential direction of the corrosion position according to the circumferential dimensionless magnetic parameter distribution includes: preliminarily judging the number of corrosion defects in the circumferential direction of the sling according to the number of peaks of the φ-K circumferential distribution curve, if the φ-K circumferential distribution curve has 1 peak, it is judged that there is 1 or n defects; if the φ-K circumferential distribution curve has n peaks, n ≥ 2, it is judged that there are n defects; Result output module: used to select the judgment criteria according to the preliminary judgment result to judge the corrosion state parameters of the sling again; the selection of the judgment criteria according to the preliminary judgment result to judge the corrosion state parameters of the sling again includes: If the φ-K circumferential distribution curve has one peak, it is judged that there is one or n defects, and the Type I judgment criterion is selected. According to the Type I judgment criterion, the corrosion state parameters under the condition of one peak of the φ-K circumferential distribution curve are diagnosed; If the φ-K circumferential distribution curve has n peaks (n≥2), it is judged that there are n defects, and the Type II judgment criterion is selected. According to the Type II judgment criterion, the corrosion state parameters when the φ-K circumferential distribution curve exceeds 2 peaks are diagnosed.

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