Concrete structure steel bar corrosion rate magnetic evaluation method for eliminating stress interference

Abstract

The invention discloses a concrete structure steel bar corrosion rate magnetic evaluation method for eliminating stress interference, and relates to the technical field of civil engineering. Comprising the following steps: scanning spontaneous leakage magnetic field intensity of reinforcing steel bars before and after concrete structure corrosion, and calculating spontaneous leakage magnetic field change information of the corroded reinforcing steel bars; determining the concrete structure reinforcement corrosion type according to the spontaneous leakage magnetic field change information of the corroded reinforcement; calculating a concrete structure steel bar magnetization intensity change rate caused by stress change before and after concrete structure corrosion; calculating a spontaneous magnetic flux leakage quantitative index according to the corrosion type of the concrete structure steel bar; the spontaneous magnetic flux leakage quantitative index is corrected according to the concrete structure steel bar corrosion type and the concrete structure steel bar magnetization intensity change rate; and calculating a concrete structure steel bar corrosion rate evaluation value for eliminating stress interference. According to the method, the existing spontaneous magnetic flux leakage assessment method for the corrosion rate of the bare steel bar is greatly improved, the stress change interference can be quantitatively corrected, and the high-precision estimation of the corrosion rate of the steel bar in the concrete structure is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering, and particularly relates to a magnetic evaluation method for the corrosion rate of steel bars in concrete structures to eliminate stress interference. Background Art

[0002] As a core component of concrete structures, the health status of steel bars directly affects the load-bearing capacity and durability of the entire concrete structure. However, steel bars are prone to corrosion after being eroded by the external environment. Corrosion not only causes the cracking of the concrete cover layer but also accelerates the further corrosion of the steel bars, forming a vicious cycle. Therefore, in order to ensure the load-bearing capacity and durability of concrete structures, it is necessary to accurately detect the corrosion of steel bars.

[0003] Currently, for the detection of steel bar corrosion inside concrete, there are mainly two categories of methods: destructive testing and non-destructive testing. In contrast, non-destructive testing methods that do not damage the structure have been widely used. Among various non-destructive testing methods such as sound, light, heat, electricity, and magnetism, the spontaneous magnetic leakage technique has relatively comprehensive advantages in detecting steel bar corrosion. The steel bar corrosion detection method based on spontaneous magnetic leakage does not require pre-embedded sensors, is simple and convenient to operate, and has low costs. Currently, a spontaneous magnetic leakage non-destructive evaluation technique for the corrosion rate of the steel bar cross-section has been developed, which can achieve a quantitative estimation of the steel bar corrosion rate. However, such techniques are currently only applicable to stress-free bare steel bars. The existing spontaneous magnetic leakage detection techniques for bare steel bar corrosion cannot consider the interference caused by the stress change of the steel bars and are difficult to accurately estimate the corrosion rate of steel bars in existing concrete structures.

[0004] Therefore, proposing a magnetic evaluation method for the corrosion rate of steel bars in concrete structures to eliminate stress interference to solve the difficulties existing in the prior art is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a magnetic evaluation method for the corrosion rate of steel bars in concrete structures to eliminate stress interference, which greatly improves the existing spontaneous magnetic leakage evaluation method for the corrosion rate of bare steel bars, can quantitatively correct the interference of stress changes, and realizes a high-precision estimation of the corrosion rate of steel bars inside concrete structures.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A magnetic evaluation method for the corrosion rate of steel bars in concrete structures to eliminate stress interference includes:

[0008] S1. Scanning the spontaneous magnetic field intensity of the steel bars before and after the corrosion of the concrete structure, and calculating the change information of the spontaneous magnetic field of the corroded steel bars;

[0009] S2. Determining the corrosion type of the steel bars in the concrete structure according to the change information of the spontaneous magnetic field of the corroded steel bars;

[0010] S3. Calculate the change rate of the magnetization intensity of the steel bars in the concrete structure caused by the stress change before and after the corrosion of the concrete structure;

[0011] S4. Calculate the quantitative index of the spontaneous leakage magnetic field according to the corrosion type of the steel bars in the concrete structure;

[0012] S5. Modify the quantitative index of the spontaneous leakage magnetic field according to the corrosion type of the steel bars in the concrete structure and the change rate of the magnetization intensity of the steel bars in the concrete structure;

[0013] S6. Calculate the evaluation value of the corrosion rate of the steel bars in the concrete structure after eliminating the stress interference.

[0014] For the above method, optionally, the information on the change of the spontaneous leakage magnetic field of the corroded steel bars obtained in S1 is specifically as follows:

[0015] S101. Determine the spontaneous leakage magnetic scanning path and scan to obtain the data of the spontaneous leakage magnetic field intensity of the steel bars in the concrete structure in the non-corroded state;

[0016] S102. Keep the path unchanged and scan to obtain the data of the spontaneous leakage magnetic field intensity of the steel bars in the concrete structure in the corroded state;

[0017] S103. Calculate the information on the change of the spontaneous leakage magnetic field of the corroded steel bars:

[0018]

[0019] In the formula, B zx and B zz are the tangential component and the normal component of the spontaneous leakage magnetic field, B bx and B bz are the tangential component and the normal component of the spontaneous leakage magnetic field of the steel bars in the concrete structure in the non-corroded state, B cx and B cz are the tangential component and the normal component of the spontaneous leakage magnetic field of the steel bars in the concrete structure in the corroded state.

[0020] For the above method, optionally, the corrosion type of the steel bars in the concrete structure determined in S2 is specifically as follows:

[0021] S201. Draw a curve according to the sequence values of the tangential component B zx or the normal component B zz of the spontaneous leakage magnetic field;

[0022] S202. Measure the width of the non-zero value region of the curve of the tangential component B zx or the normal component B zz , and the measured value is the corrosion width of the steel bars;

[0023] If the corrosion width of the steel bars is greater than 30 cm, it is the overall corrosion type, otherwise it is the local corrosion type.

[0024] In the above method, optionally, in S3, the change rate of the magnetization intensity of the steel bars in the concrete structure is calculated as follows:

[0025] S301. Select a partially uncorroded area adjacent to the steel bar corrosion area as the magnetic calibration area;

[0026] S302. Calculate the average spontaneous leakage magnetic field intensity B of the steel bars in the magnetic calibration area in the uncorroded state bu-av and the average spontaneous leakage magnetic field intensity B in the corroded state cu-av ;

[0027] S303. Calculate the change rate of the magnetization intensity of the steel bars:

[0028]

[0029] In the formula, MR is the change rate of the magnetization intensity of the steel bars considering the interference of the steel bar stress change.

[0030] In the above method, optionally, in S4, the quantization index of the spontaneous leakage magnetic field is calculated as follows:

[0031] S401. When the steel bar is of the overall corrosion type, calculate the quantization index of the spontaneous leakage magnetic field:

[0032]

[0033] In the formula, I se is the quantization index of the spontaneous leakage magnetic field of the overall corroded steel bar, B zx is the tangential component of the spontaneous leakage magnetic field in the overall corroded area, B b-av is the average spontaneous leakage magnetic field intensity in the corroded area of the steel bar in the uncorroded state;

[0034] S402. When the steel bar is of the local corrosion type, calculate the quantization index of the spontaneous leakage magnetic field:

[0035]

[0036] In the formula, I sl is the quantization index of the spontaneous leakage magnetic field of the local corroded steel bar, ΔB zz is the peak-valley difference value of the normal component of the spontaneous leakage magnetic field in the local corroded area, B bx-av is the average value of the initial tangential component of the spontaneous leakage magnetic field in the corroded area of the steel bar in the uncorroded state.

[0037] In the above method, optionally, in S5, the quantization index of the spontaneous leakage magnetic field is corrected as follows:

[0038] S501. Calculate the correction ratio R of the quantization index of the spontaneous leakage magnetic field considering stress interference according to the steel bar corrosion type:

[0039] R = m·MR

[0040] Wherein, m is a correction parameter, and its value is obtained through experiments. For the local corrosion type, m takes 0.6, and for the overall corrosion type, m takes 2.5. MR is the change rate of the magnetization intensity of the steel bar considering the interference of the steel bar stress change;

[0041] S502. For the local corrosion type, calculate the corrected spontaneous leakage magnetic field quantization change index:

[0042]

[0043] Wherein, I slm is the corrected spontaneous leakage magnetic field quantization index;

[0044] S503. For the overall corrosion type, calculate the corrected spontaneous leakage magnetic field quantization change index:

[0045]

[0046] Wherein, I sem is the corrected spontaneous leakage magnetic field quantization index, and η is the corrosion rate of the steel bar cross-section.

[0047] For the above method, optionally, in S6, when calculating the evaluation value of the corrosion rate of the steel bars in the concrete structure after eliminating the stress interference, specifically:

[0048] S601. For the local corrosion type, determine the likelihood function characterizing the correlation between the spontaneous magnetic leakage index and the corrosion rate:

[0049]

[0050] Wherein, W(·) is the Weibull distribution function, h is the distance between the sensor and the surface of the steel bar during the spontaneous magnetic leakage scanning, the unit is mm, and η is the corrosion rate of the steel bar cross-section;

[0051] S602. For the overall corrosion type, determine the likelihood function characterizing the correlation between the spontaneous magnetic leakage index and the corrosion rate:

[0052] f(I sem η) = W(I sem ; 0.74·η + 0.13, 240·η 4.86 + 3.69)

[0053] Wherein, W(·) is the Weibull distribution function, and η is the corrosion rate of the steel bar cross-section;

[0054] S603. Calculate the probabilistic quantitative estimation result π(η|I) of the steel bar corrosion rate:

[0055]

[0056] Where η is the corrosion rate of the steel bar cross-section, and I represents I slm or I sem , π(η) is the prior distribution of η, Θ is the parameter space, which is the value range of η;

[0057] S604. For the local corrosion type, directly calculate the point estimate of the corrosion rate of the steel bar cross-section with a preset confidence level according to π(η|I);

[0058] S605. For the overall corrosion type, calculate the point estimate of the corrosion rate of the overall corroded steel bar cross-section according to π(η|I);

[0059] S606. According to the point estimate of the corrosion rate of the overall corroded steel bar cross-section and S503, calculate the new corrected spontaneous magnetic leakage quantization index I sem ;

[0060] S607. According to the new corrected spontaneous magnetic leakage quantization index I sem , S602, S603, S605 and S606, perform cyclic update calculations until the difference between the I sem obtained from two adjacent calculations is less than 0.01;

[0061] S608: According to the I sem obtained from the last cyclic update, S602, S603 and S605, obtain the point estimate of the corrosion rate of the steel bar cross-section with a preset confidence level.

[0062] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a magnetic evaluation method for the corrosion rate of steel bars in concrete structures to eliminate stress interference, and has the following beneficial effects: The present invention can quantitatively correct the stress change interference and achieve high-precision estimation of the corrosion rate of internal steel bars in existing concrete structures; By using a micro-magnetic sensing device to scan the surface of the concrete structure to obtain the spontaneous magnetic field change information before and after the corrosion of the internal steel bars, there is no need to embed sensors, and rapid, accurate and non-destructive detection of the corrosion rate of steel bars in existing concrete structures can be realized; The present invention does not rely on long-term monitoring, does not cause any damage to the concrete structure, does not have any impact on the service performance of the concrete structure, and is simple and convenient to operate, low in cost, high in precision and stable in effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0064] Figure 1Flow chart of a magnetic evaluation method for the corrosion rate of steel bars in a concrete structure to eliminate stress interference provided by the present invention;

[0065] Figure 2 Schematic diagram of the specific implementation work of a magnetic evaluation method for the corrosion rate of steel bars in a concrete structure to eliminate stress interference provided by the present invention;

[0066] Explanation of reference numerals:

[0067] 1 is a displacement meter step counter; 2 is a micro-magnetic sensor; 3 is a magnetic field scanning path; 4 is a steel bar; 5 is the steel bar corrosion area; 6 is concrete. Specific implementation manner

[0068] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0069] In this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or sequence between these entities or operations. The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0070] Refer to Figure 1 As shown, the present invention discloses a magnetic evaluation method for the corrosion rate of steel bars in a concrete structure to eliminate stress interference, including:

[0071] S1. Scan the spontaneous leakage magnetic field intensity of the steel bars before and after corrosion of the concrete structure, and calculate the change information of the spontaneous leakage magnetic field of the corroded steel bars;

[0072] S2. Determine the corrosion type of the steel bars in the concrete structure according to the change information of the spontaneous leakage magnetic field of the corroded steel bars;

[0073] S3. Calculate the change rate of the magnetization intensity of the steel bars in the concrete structure caused by the stress change before and after corrosion of the concrete structure;

[0074] S4. Calculate the quantization index of the spontaneous leakage magnetic field according to the corrosion type of the steel bars in the concrete structure;

[0075] S5. Modify the quantization index of the spontaneous leakage magnetic field according to the corrosion type of the steel bars in the concrete structure and the change rate of the magnetization intensity of the steel bars in the concrete structure;

[0076] S6. Calculate the evaluation value of the corrosion rate of the steel bars in the concrete structure after eliminating the stress interference.

[0077] Furthermore, the information on the change in the spontaneous leakage magnetic field of the corroded steel bars obtained in S1 is specifically as follows:

[0078] S101. Determine the scanning path of the spontaneous leakage magnetic field, and scan to obtain the data of the spontaneous leakage magnetic field intensity of the steel bars in the concrete structure in the non-corroded state;

[0079] S102. Keep the path unchanged, and scan to obtain the data of the spontaneous leakage magnetic field intensity of the steel bars in the concrete structure in the corroded state;

[0080] S103. Calculate the information on the change in the spontaneous leakage magnetic field of the corroded steel bars:

[0081]

[0082] In the formula, B zx and B zz are the tangential component and the normal component of the spontaneous leakage magnetic field, B bx and B bz are the tangential component and the normal component of the spontaneous leakage magnetic field of the steel bars in the concrete structure in the non-corroded state, B cx and B cz are the tangential component and the normal component of the spontaneous leakage magnetic field of the steel bars in the concrete structure in the corroded state.

[0083] Furthermore, the corrosion type of the steel bars in the concrete structure determined in S2 is specifically as follows:

[0084] S201. Draw a curve according to the sequence values of the tangential component B zx or the normal component B zz of the spontaneous leakage magnetic field;

[0085] S202. Measure the width of the non-zero value region of the curve of the tangential component B zx or the normal component B zz , and the measured value is the corrosion width of the steel bars;

[0086] S203. If the corrosion width of the steel bars is greater than 30 cm, it is the overall corrosion type, otherwise it is the local corrosion type.

[0087] Furthermore, the change rate of the magnetization intensity of the steel bars in the concrete structure calculated in S3 is specifically as follows:

[0088] S301. Select a part of the uncorroded area adjacent to the corroded area of the steel bar as the magnetic calibration area;

[0089] S302. Calculate the average spontaneous leakage magnetic field intensity B of the steel bar in the magnetic calibration area in the uncorroded state bu-av and the average spontaneous leakage magnetic field intensity B cu-av ;

[0090] S303. Calculate the change rate of the magnetization intensity of the steel bar:

[0091]

[0092] In the formula, MR is the change rate of the magnetization intensity of the steel bar considering the interference of the stress change of the steel bar.

[0093] Furthermore, in S4, calculate the quantization index of the spontaneous leakage magnetic field, specifically:

[0094] S401. When the steel bar is of the overall corrosion type, calculate the quantization index of the spontaneous leakage magnetic field:

[0095]

[0096] In the formula, I se is the quantization index of the spontaneous leakage magnetic field of the overall corroded steel bar, B zx is the tangential component of the spontaneous leakage magnetic field in the overall corroded area, B b-av is the average spontaneous leakage magnetic field intensity in the corroded area of the steel bar in the uncorroded state;

[0097] S402. When the steel bar is of the local corrosion type, calculate the quantization index of the spontaneous leakage magnetic field:

[0098]

[0099] In the formula, I sl is the quantization index of the spontaneous leakage magnetic field of the locally corroded steel bar, ΔB zz is the peak-valley difference of the normal component of the spontaneous leakage magnetic field in the local corroded area, B bx-av is the average value of the initial tangential component of the spontaneous leakage magnetic field in the corroded area of the steel bar in the uncorroded state.

[0100] Furthermore, in S5, correct the quantization index of the spontaneous leakage magnetic field, specifically:

[0101] S501. Calculate the correction ratio R of the quantization index of the spontaneous leakage magnetic field considering stress interference according to the corrosion type of the steel bar:

[0102] R = m·MR

[0103] Wherein, m is a correction parameter, and its value is obtained through experiments. For local corrosion type, m takes 0.6, and for overall corrosion type, m takes 2.5. MR is the change rate of the magnetization intensity of the steel bar considering the interference of the steel bar stress change;

[0104] S502. For the local corrosion type, calculate the corrected spontaneous magnetic leakage field quantization change index:

[0105]

[0106] Wherein, I slm is the corrected spontaneous magnetic leakage field quantization index;

[0107] S503. For the overall corrosion type, calculate the corrected spontaneous magnetic leakage field quantization change index:

[0108]

[0109] Wherein, I sem is the corrected spontaneous magnetic leakage field quantization index, η is the corrosion rate of the steel bar cross-section, and the initial value of η is 0.

[0110] Furthermore, in S6, calculate the evaluation value of the corrosion rate of the steel bar in the concrete structure after eliminating the stress interference, specifically:

[0111] S601. For the local corrosion type, determine the likelihood function that characterizes the correlation between the spontaneous magnetic leakage index and the corrosion rate:

[0112]

[0113] Wherein, W(·) is the Weibull distribution function, h is the distance between the sensor and the surface of the steel bar during the spontaneous magnetic leakage scanning, the unit is mm, and η is the corrosion rate of the steel bar cross-section;

[0114] S602. For the overall corrosion type, determine the likelihood function that characterizes the correlation between the spontaneous magnetic leakage index and the corrosion rate:

[0115] f(I sem |η) = W(I sem ; 0.74·η + 0.13, 240·η 4.86 + 3.69)

[0116] Wherein, W(·) is the Weibull distribution function, and η is the corrosion rate of the steel bar cross-section;

[0117] S603. Calculate the probabilistic quantitative estimation result π(η|I) of the steel bar corrosion rate:

[0118]

[0119] Wherein, η is the corrosion rate of the steel bar cross-section, and I represents I slm or Isem , π(η) is the prior distribution of η, Θ is the parameter space, and is the value range of η;

[0120] S604. For the local corrosion type, directly calculate the point estimate of the corrosion rate of the steel bar cross-section with a preset confidence level according to π(η|I);

[0121] S605. For the overall corrosion type, calculate the point estimate of the corrosion rate of the overall corroded steel bar cross-section according to π(η|I);

[0122] S606. According to the point estimate of the corrosion rate of the overall corroded steel bar cross-section and S503, calculate the new corrected spontaneous magnetic leakage quantization index I sem ;

[0123] S607. According to the new corrected spontaneous magnetic leakage quantization index I sem , S602, S603, S605 and S606, perform cyclic update calculations until the difference between the Is obtained from two adjacent calculations sem is less than 0.01;

[0124] S608: According to the I sem obtained from the last cyclic update, S602, S603 and S605, obtain the point estimate of the corrosion rate of the steel bar cross-section with a preset confidence level.

[0125] In a specific embodiment, as shown in reference Figure 2 , when the steel bar corrosion area 5 does not appear, use the displacement sensor 1 and the magnetic sensor 2 to scan along the scanning path 3 on the surface of the concrete 6 to obtain the spontaneous magnetic field intensity data at different positions on the scanning path 3 of the non-corroded concrete structure; after the steel bar corrosion area 5 appears, use the displacement sensor 1 and the magnetic sensor 2 to scan along the scanning path 3 on the surface of the concrete 6 again to obtain the spontaneous magnetic field intensity data at different positions on the scanning path 3 of the corroded concrete structure; then, subtract the spontaneous magnetic field intensity data at the corresponding positions on the scanning path 3 of the corroded concrete structure from the spontaneous magnetic field intensity data at different positions on the scanning path 3 of the corroded concrete structure one by one to calculate the spatial magnetic field change information of the corroded steel bar; draw a curve according to the spatial magnetic field change information of the corroded steel bar, measure the width of the non-zero abnormal change area of the curve. For example, if the measured width value is less than 30 cm, the steel bar corrosion area 5 is determined to be locally corroded; select the part of the concrete structure scanning path 3 corresponding to the non-corroded area 4 of the steel bar as the calibration area for the non-corroded steel bar, obtain the average value of the spontaneous magnetic field intensity data scanned before and after the corrosion of the concrete structure in this calibration area, and then calculate the magnetization intensity change rate MR caused by the stress change of the concrete structure before and after corrosion; if the steel bar is locally corroded, then calculate the value of the spontaneous magnetic field quantization index I of the corrosion area 5 sl, and take the correction parameter m as 0.6; calculate the correction ratio R of the spontaneous leakage magnetic field quantization index considering stress interference and correct I according to R sl After that, the corrected value of the spontaneous leakage magnetic field quantization index I is obtained slm ; Based on I slm and S6, the point estimate value of the corrosion rate of the local corrosion section of the steel bar with a preset confidence level is obtained

[0126] Each embodiment in this specification is described in a progressive manner. For the same or similar parts between the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, reference can be made to the partial description of the method embodiment. The systems and system embodiments described above are only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work

[0127] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can 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 will be accorded the widest scope consistent with the principles and novel features disclosed herein

Claims

1. A magnetic evaluation method for steel bar corrosion rate of concrete structure eliminating stress interference, characterized in that: include: S1. Scan the spontaneous leakage magnetic field intensity of the steel bars before and after corrosion of the concrete structure, and calculate the spontaneous leakage magnetic field variation information of the corroded steel bars; S2, determining the type of steel bar corrosion in the concrete structure according to the spontaneous leakage magnetic field variation information of the corroded steel bar; S3. Calculate the change rate of the magnetic strength of the steel bars of the concrete structure caused by the stress change before and after the corrosion of the concrete structure; S4. Calculate the quantitative index of spontaneous leakage magnetic field according to the type of steel bar corrosion in concrete structure; S5. Modify the quantitative index of spontaneous leakage magnetic field according to the type of steel bar corrosion in concrete structure and the rate of change of magnetization intensity of steel bar in concrete structure; S6. Calculate the estimated value of steel corrosion rate of concrete structure after eliminating stress interference.

2. According to a method for magnetic assessment of steel bar corrosion rate of concrete structure eliminating stress interference according to claim 1, it is characterized in that: The spontaneous leakage magnetic field variation information of the corroded steel bar is obtained in S1, specifically: S101, determining a spontaneous magnetic leakage scanning path, scanning and obtaining the spontaneous magnetic leakage magnetic field intensity data of the steel bars in a state where the concrete structure is not corroded; S102, the path remains unchanged, scanning to obtain the spontaneous leakage magnetic field intensity data of the steel bars in the corroded state of the concrete structure; S103, calculate the spontaneous leakage magnetic field variable information of the corroded steel bar: In the formula, B zx and B zz are the tangential and normal components of the spontaneous leakage magnetic field, B bx and B bz is the tangential and normal components of the spontaneous leakage magnetic field of the steel bar in the uncorroded concrete structure, B cx and B cz It is the tangential component and normal component of the spontaneous leakage magnetic field of the steel bar under the corrosion state of the concrete structure.

3. According to a method for magnetic assessment of steel bar corrosion rate of concrete structure eliminating stress interference according to claim 2, it is characterized in that: S2 determines the type of steel corrosion in concrete structures, specifically: S201, according to the tangential component B of the spontaneous leakage magnetic field zx Or normal component B zz Draw a curve with the sequence value of S202, measure tangential component B zx Or normal component B zz The width of the non-zero area of ​​the curve, the measured value is the width of the steel bar corrosion; S203: If the steel bar corrosion width is greater than 30cm, it is the overall corrosion type; otherwise, it is the local corrosion type.

4. According to the method for magnetic assessment of steel bar corrosion rate of concrete structure eliminating stress interference according to claim 1, it is characterized in that: The change rate of the magnetization intensity of the steel bars in the concrete structure is calculated in S3, specifically: S301, selecting a portion of the non-corroded area adjacent to the steel bar corroded area as a magnetic calibration area; S302, calculate the average spontaneous leakage magnetic field strength B of the steel bars in the magnetic calibration area in the uncorroded state bu-av and the average spontaneous leakage magnetic field strength B in the rusted state cu-av ; S303. Calculate the rate of change of the magnetization strength of the steel bar: Where MR is the rate of change of steel bar magnetization intensity taking into account the interference of steel bar stress change.

5. According to the method for magnetic evaluation of steel bar corrosion rate of concrete structure eliminating stress interference according to claim 1, it is characterized in that: The quantitative index of spontaneous leakage magnetic field is calculated in S4, specifically: S401. When the steel bar is of overall corrosion type, calculate the quantitative index of spontaneous leakage magnetic field: In the formula, I se It is a quantitative index of spontaneous leakage magnetic field of the overall corroded steel bar. zx is the tangential component of the spontaneous leakage magnetic field in the overall corrosion area, B b-av It is the average spontaneous leakage magnetic field intensity in the steel bar corrosion area in the uncorroded state; S402. When the steel bar is partially corroded, calculate the quantitative index of spontaneous leakage magnetic field: In the formula, I sl It is a quantitative index of spontaneous leakage magnetic field of locally corroded steel bars, ΔB zz is the peak-to-valley difference of the normal component of the spontaneous leakage magnetic field in the local corrosion area, B bx-av It is the average value of the tangential component of the initial spontaneous leakage magnetic field in the steel bar corrosion area in the uncorroded state.

6. A magnetic assessment method for steel bar corrosion rate of concrete structure eliminating stress interference according to claim 5, characterized in that: The quantitative index of the modified spontaneous leakage magnetic field in S5 is as follows: S501. Calculate the correction ratio R of the spontaneous leakage magnetic field quantitative index considering stress interference according to the type of steel bar corrosion: R=m·MR Where m is a correction parameter, the value of which is obtained through experiments. The local corrosion type m is 0.6, the overall corrosion type m is 2.5, and MR is the rate of change of the magnetization intensity of the steel bar considering the interference of the stress change of the steel bar. S502. For local corrosion types, calculate and modify the quantitative variable index of spontaneous leakage magnetic field: In the formula, I slm It is a quantitative index of corrected spontaneous leakage magnetic field; S503. For the overall corrosion type, calculate and modify the quantitative variable index of the spontaneous leakage magnetic field: In the formula, I sem It is a quantitative index of modified spontaneous leakage magnetic field, and η is the corrosion rate of steel bar section.

7. A magnetic evaluation method for steel bar corrosion rate of concrete structure eliminating stress interference according to claim 6, characterized in that: The evaluation value of the steel corrosion rate of the concrete structure that eliminates stress interference is calculated in S6, specifically: S601. For the local corrosion type, determine the likelihood function that characterizes the correlation between the spontaneous magnetic flux leakage index and the corrosion rate: Where W(·) is the Weibull distribution function, h is the distance between the sensor and the steel bar surface during spontaneous magnetic flux leakage scanning, in mm, and η is the corrosion rate of the steel bar section; S602. For the overall corrosion type, determine the likelihood function that characterizes the correlation between the spontaneous magnetic flux leakage index and the corrosion rate: f(I sem η)=W(I sem ; 0.74·h+0.13,240·h 4.86 +3.69) Where W(·) is the Weibull distribution function, η is the corrosion rate of the steel bar section; S603, calculate the probabilistic quantitative estimation result π(η|I) of the steel bar corrosion rate: Where η is the corrosion rate of the steel bar section, I represents I slm or I sem , π(η) is the prior distribution of η, Θ is the parameter space, which is the range of η; S604. For local corrosion types, directly calculate the point estimate of the corrosion rate of the steel bar section with a preset confidence level according to π(η|I); S605. For the overall corrosion type, a point estimate of the corrosion rate of the overall corroded steel bar section is calculated according to π(η|I); S606: Based on the estimated value of the corrosion rate of the entire corroded steel bar section and S503, a new modified spontaneous magnetic leakage quantitative index I is calculated. sem ; S607, according to the new modified spontaneous magnetic leakage quantitative index I sem , S602, S603, S605 and S606, cyclically update the calculation until the I obtained by two consecutive calculations is sem The difference is less than 0.01; S608: Update the I obtained from the last cycle sem , S602, S603 and S605, to obtain a point estimate of the corrosion rate of the steel section with a preset confidence level.

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