On-site nondestructive testing and correcting method and device for concrete resistivity of one-way reinforced member

Abstract

The invention relates to a one-way reinforced member concrete resistivity field nondestructive testing correction method and device, and belongs to the field of reinforced concrete nondestructive testing. The reinforced concrete member to be detected is subjected to surface smoothing treatment, and reinforcing steel bars distributed in a single-direction and single-layer mode are arranged in the reinforced concrete member; wenner electrodes are installed on the surface, parallel to the unidirectional single-layer distributed steel bars, of the to-be-detected reinforced concrete member in the direction perpendicular to the axis of the steel bars, and the length, width and height of the member, the diameter of the steel bars, the thickness of a concrete protection layer and the distance between the electrodes are determined; and measuring the initial resistivity value of the concrete based on the Wenner technology, and correcting the initial resistivity value of the concrete through the size effect correction coefficient and the unidirectional distribution steel bar correction coefficient to obtain the corrected real resistivity. According to the method, the size effect and the correction coefficient under the influence of the one-way reinforcing steel bars are combined, and the quality of the concrete member containing the one-way distributed reinforcing steel bars can be more accurately controlled.

Description

Technical Field

[0001] The invention belongs to the field of nondestructive testing of reinforced concrete, and in particular relates to a method and a device for correcting on-site nondestructive testing of concrete resistivity of a unidirectional reinforced component. Background Art

[0002] Concrete resistivity is closely related to indicators such as steel bar corrosion, chloride ion permeability or crack presence. Therefore, on-site measurement of concrete resistivity is an important goal and provides new ideas for structural inspection and maintenance. However, its detection method is greatly affected by the distribution of steel bars, which often leads to a decrease in the accuracy of resistivity test results.

[0003] In view of the low detection accuracy of the current traditional resistivity detection methods, a test method suitable for reinforced concrete resistivity, Wenner technology, is proposed. Wenner technology has gradually become the first choice for laboratory and field resistivity detection because it can well avoid electrode polarization errors and has the advantages of non-destructiveness, safety, fast measurement and compact design.

[0004] For most reinforced concrete components, since the detection error generated when the Wenner electrode is perpendicular to the axis of the steel bar during detection is smaller than that in other directions, the detection direction of the Wenner electrode is generally perpendicular to the axis of the steel bar during detection.

[0005] However, since the use of Wenner technology is based on the assumption that the material is semi-infinite, isotropic and homogeneous, and there is a significant difference in resistivity between concrete and steel bars, due to the presence of steel bars, concrete no longer meets the assumptions of isotropic and homogeneous media. The current always flows through the path with the least resistance, making the current field unevenly distributed and even having current concentration. The presence of steel bars inside the concrete will cause deviations in the resistivity measurement results. The factors affecting the deviation mainly include the steel bar diameter and the thickness of the concrete protective layer, which will seriously affect the accuracy of the concrete resistivity measurement value, and further affect the judgment of the actual corrosion of reinforced concrete components, chloride ion penetration and crack development. When the Wenner electrode is installed parallel to the surface of the unidirectional single-layer distributed steel bars in a direction perpendicular to the steel bar axis, the resistivity obtained is closer to the true value of the resistivity than other detection directions. Therefore, when the Wenner technology is used for detection, it is generally preferred to install the Wenner electrode in a direction perpendicular to the steel bar axis. The resistivity measurement value of the reinforced concrete component is close to the actual value after adjustment. The average error of the unadjusted measurement is 26.75%, and the average error of the adjusted measurement is 1.51%

[0006] Therefore, the influence of the Wenner technique electrode being arranged perpendicular to the steel bar axis must be considered during the detection process in order to obtain reliable test results. Currently, there is no method for using the Wenner technique to detect the resistivity of concrete under the influence of unidirectionally distributed steel bars. Summary of the invention

[0007] The purpose of the present invention is to propose a method and device for nondestructive detection correction of concrete resistivity of one-way reinforced components, which is simple and convenient to operate. By determining the length, width and height of concrete, the diameter of steel bars in concrete, the thickness of concrete cover and the electrode spacing, the initial value of concrete resistivity is measured based on Wenner technology, and the corresponding size effect correction coefficient and one-way distribution steel bar correction coefficient are obtained by looking up the size effect resistivity correction coefficient table and the one-way distribution steel bar correction coefficient fitting formula. The corrected real resistivity is calculated according to the correction coefficient and the initial value of concrete resistivity, and the durability of reinforced concrete is grasped in real time.

[0008] The technical solution adopted by the present invention to solve the above technical problems is:

[0009] In a first aspect, the present invention proposes a method for correcting the on-site nondestructive detection of the resistivity of concrete of a one-way reinforced component, comprising:

[0010] The surface of the reinforced concrete component to be inspected is smoothed; the reinforced concrete component is provided with unidirectional single-layer steel bars;

[0011] Wenner electrodes are installed on the surface of the reinforced concrete component to be tested parallel to the unidirectional single-layer distributed steel bars and in a direction perpendicular to the steel bar axis. The length, width and height of the concrete component to be tested, as well as the diameter of the steel bars in the reinforced concrete component, the thickness of the concrete cover and the electrode spacing are determined and measured according to the installation surface and arrangement direction of the Wenner electrodes.

[0012] The initial value of concrete resistivity is measured based on the Wenner technique. The size effect correction coefficient and the unidirectional distribution steel bar correction coefficient are obtained by looking up the size effect resistivity correction coefficient table and the unidirectional distribution steel bar correction coefficient fitting formula. The corrected true resistivity is calculated based on the correction coefficient and the initial value of concrete resistivity.

[0013] Furthermore, when the initial value of the concrete resistivity is measured based on the Wenner technique, it is necessary to measure multiple times and take an average value.

[0014] Furthermore, conductive paste is applied to the contact point between the Wenner electrode and the surface of the reinforced concrete member to be detected.

[0015] Furthermore, the Wenner electrode is arranged in the central area of ​​the surface of the reinforced concrete component to be detected.

[0016] Furthermore, the axial direction of the steel bars in the inspected reinforced concrete component is regarded as the length direction of the component, the arrangement direction of the unidirectional single-layer steel bars is regarded as the width direction of the inspected reinforced concrete component, the direction perpendicular to the reinforced concrete surface where the Wenner electrodes are arranged is regarded as the height direction of the inspected concrete component, and the distance from the concrete surface where the Wenner electrodes are arranged to the upper surface of the unidirectional single-layer steel bars is regarded as the thickness of the protective layer of the inspected concrete.

[0017] Furthermore, the method for constructing the size effect resistivity correction coefficient table is:

[0018] Establish a concrete finite element model without steel bars and set the resistivity benchmark value of concrete components;

[0019] According to the orthogonal design of L / s:W / s:H / s from 4:1:1 to 10:10:10, the resistivity simulation values ​​under different size ratio designs were obtained through finite element analysis, and the size effect correction coefficient was introduced. The size effect correction coefficient was calculated according to the resistivity simulation value and the resistivity reference value, and the concrete resistivity correction coefficient table was constructed; where L, W, H, and s are the length, width, height and electrode spacing of the concrete component respectively;

[0020] The governing equations for the finite element model of concrete without reinforcement are as follows:

[0021]

[0022] The boundary conditions are:

[0023] n·J=0

[0024] Where ρ is the resistivity, V is the electric potential, n is the surface normal vector of the Wenner electrode installed on the concrete component, and J is the current density vector of the closed surface in the domain;

[0025] Considering that concrete material is homogeneous and isotropic,

[0026] Furthermore, when the size effect resistivity correction coefficient is obtained by looking up the concrete resistivity correction coefficient table, if the ratio between the size of the concrete component to be tested and the electrode spacing is a non-integer ratio, the size effect resistivity correction coefficient is calculated using trilinear interpolation; if the ratio between the concrete size and the electrode spacing exceeds 10:10:10, the size effect resistivity correction coefficient is 1.

[0027] Furthermore, the method for constructing the fitting formula of the unidirectional distribution steel bar correction coefficient is:

[0028] Establish a concrete finite element model with unidirectionally distributed steel bars and set the concrete resistivity benchmark value of reinforced concrete components;

[0029] According to the steel bar diameter d from the minimum value d min To the maximum value d max , the concrete cover thickness c is from the minimum value c min To the maximum value c max Orthogonal design was performed, and the resistivity simulation values ​​under different steel bar diameters and concrete cover thickness designs were obtained through finite element analysis. According to the relationship between the resistivity simulation values ​​and the resistivity reference values, a fitting formula for the steel bar correction coefficient was constructed.

[0030] The governing equations of the concrete finite element model containing unidirectionally distributed steel bars are as follows:

[0031]

[0032] The boundary conditions are:

[0033] n·J=0

[0034] Where ρ is the resistivity, V is the electric potential, n is the surface normal vector of the Wenner electrode installed on the reinforced concrete component to be tested, and J is the current density vector of the closed surface in the domain.

[0035] Furthermore, in a concrete member containing unidirectionally distributed steel bars, a steel bar correction coefficient fitting formula corresponds to a steel bar correction coefficient fitting formula, and the steel bar correction coefficient fitting formula is a relationship between the unidirectionally distributed steel bar correction coefficient and the concrete cover thickness and the electrode spacing.

[0036] Furthermore, it is preferred that the reinforced concrete member to be tested is a thin-walled or plate member with a rectangular parallelepiped structure. During the test, the appropriate Wenner electrode size, electrode spacing, current size, etc. are selected according to the on-site test object.

[0037] In a second aspect, the present invention proposes an on-site nondestructive detection and correction device for the resistivity of concrete of a one-way reinforced component, which is used to implement the above-mentioned detection and correction method.

[0038] The beneficial effects of the present invention are:

[0039] The present invention studies a method and device for nondestructive testing and correction of concrete resistivity of unidirectional reinforced components. The resistivity correction coefficient under the influence of size effect and the resistivity correction coefficient under the influence of steel bar are introduced into the Wenner technology to detect the resistivity of reinforced concrete with unidirectional single-layer distribution, so as to reduce the error and well grasp the durability of reinforced concrete components. It is a nondestructive testing method with the characteristics of convenience and speed, and overcomes the economic waste caused by traditional broken type testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the schematic diagram of Wenner technology;

[0041] Figure 2 This is a schematic diagram of the testing equipment;

[0042] Figure 3 This is a schematic diagram of reinforced concrete resistivity detection;

[0043] Figure 4 It is a schematic diagram of the finite element model of concrete containing unidirectionally distributed steel bars;

[0044] Figure 5 Schematic diagram of the concrete finite element model without steel bars. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs.

[0046] like Figure 1 As shown, a constant current source is used to pass a current I through electrodes 1 and 4, and an electric field will be generated in the reinforced concrete being tested. The potential difference V between electrodes 2 and 3 is measured. 23 , according to the Wenner technical theoretical formula, the resistivity ρ of reinforced concrete is calculated t .

[0047] Working principle of potential digital sensor: Wenner electrode is connected to potential digital sensor through wire to form a complete detection circuit. Current signal is input through electrode 1, flows through concrete and output through electrode 4 to form a working circuit. Potential difference between electrodes 2 and 3 is measured by potentiometer in the potential sensor. When the resistivity of concrete changes, the voltage difference measured by potentiometer is different under the same current, thus reflecting the change of resistivity of reinforced concrete.

[0048] like Figure 2 As shown, the selected Wenner electrode is connected to the potential sensor through a wire, and the potential sensor is connected to the single-chip microcomputer through an AD interface. The single-chip microcomputer controls the potential sensor to calculate and obtain the resistivity ρ t , and send the measured inductance value to the host computer through serial communication for display, and get ρ t value.

[0049] Before testing the resistivity of reinforced concrete, sandpaper should be used to smooth the surface to prevent the rough surface from affecting the measurement results. Figure 3As shown, apply conductive paste on the lower surface of the four electrodes so that they are in full contact with the reinforced concrete surface and are installed perpendicular to the axis of the steel bar. Place the Wenner electrode on the concrete surface and apply current. When the resistance value measured by the PC end has no obvious fluctuation, read and record the data. Repeat the above operation 3 times and take the average value to obtain the resistivity calculation value, and then complete one test.

[0050] The correction coefficient is obtained by finite element analysis. Since the size of reinforced concrete components is limited in actual concrete structures containing unidirectionally distributed steel bars, it is necessary to use the size effect correction coefficient and the steel bar correction coefficient in combination. Figure 4 The concrete finite element model with unidirectional reinforcement shown in Figure 5 The concrete finite element model without steel bars shown in the figure first takes the concrete finite element model with unidirectional distributed steel bars as an example, four Wenner electrodes (equally spaced) are arranged in the surface area of ​​the tested concrete component parallel to the unidirectional single-layer distributed steel bars in a direction perpendicular to the axis of the steel bars, and the height from the concrete surface to the upper surface of the steel bars is regarded as the thickness of the concrete protective layer. The concrete protective layer thickness of the tested component is denoted as c, the steel bar diameter is d, and the electrode spacing is s.

[0051] In the Wenner technique, two inner electrodes (numbered 2 and 3) measure the potential difference generated by the current applied between two outer electrodes (numbered 1 and 4), so the governing equations need to simulate the current and potential distribution within the domain. In the present invention, the current density vector J (A / m 2 ) is directly related to the electric field vector E (V / m) in the domain. The ratio of the two is defined as the conductivity σ (S / m) of the material according to Ohm's law, where σ is the reciprocal of the resistivity ρ (Ω·m) and the electric field vector E is the gradient of the electric potential V (V). Then:

[0052]

[0053] Since charge does not accumulate when the material is conducting, the law of conservation of current is satisfied, that is, the current flux entering the closed surface of the conducting material is equal to the current flux leaving the surface, then:

[0054]

[0055] Since the current flows only inside the material, all surfaces of the material can be considered as insulating and the boundary conditions satisfy the following equations:

[0056] n·J=0 (6)

[0057] Where: n is the material surface normal vector.

[0058] The design of the concrete finite element model without steel bars and the arrangement of electrodes are similar and will not be described in detail. In the control equations of the concrete finite element model without steel bars, the concrete material is considered to be uniform and isotropic.

[0059] This example explores the effects of concrete component size, protective layer thickness and steel bar diameter. A current of 1 mA is applied to electrode 1, the potential of electrode 4 is defined as zero, and the potential difference U between electrodes 2 and 3 is extracted. 23 , substitute into formula (7), and solve to obtain the resistivity simulation value ρ s , introduce the correction factor k 1 , k 2 (k 1 is the size effect correction factor, k 2 is the correction factor for unidirectionally distributed reinforcement), and the influence of the diameter of reinforcement and the thickness of concrete cover in reinforced concrete on the resistivity measured by the Wenner technique is analyzed.

[0060]

[0061] ρ=k 1 k 2 ρ s (8)

[0062] Where: ρ is the reference value of reinforced concrete resistivity (100Ω·m), ρ s is the resistivity simulation value, and I is the applied current, which is equal to 1mA.

[0063] In the concrete finite element model with unidirectional distributed steel bars, when analyzing different protective layer thicknesses, the protective layer thickness ranges from 20mm to 45mm. It can be found that as the thickness of the concrete protective layer increases, the resistivity value gradually increases. In the process of c changing from 20mm to 45mm, the resistivity value gradually increases and approaches the reference value of 100Ω·m. The correction coefficient k 2 From 2.51 to 1.28. This is because the thickness of the protective layer gradually increases, the distance between the steel bar and the electrode increases, and the thicker the protective layer, the more evenly the current can be distributed, so that the current passes through the concrete more evenly, which helps to avoid local current concentration. When the protective layer thickness c = 20mm, the current density of this section is mainly distributed inside the steel bar, and the current is mainly conducted through the steel bar; when the protective layer thickness c = 45mm, the current density distribution range of this section is wider and more uniform, which can better reflect the real resistivity of concrete, and thus is closer to the reference value.

[0064] When analyzing different steel bar diameters, the steel bar diameter range is 8 mm to 30 mm. When d changes from 8 mm to 20 mm, the resistivity value gradually increases to 65.42 Ω·m, and the correction coefficient k 2From 2.31 to 1.62; when d is greater than 20 mm, the resistivity value gradually decreases and the correction factor increases from 1.52 to 1.81.

[0065] The above simulation proves that the diameter of the steel bar and the thickness of the concrete cover have a great influence on the measurement results, revealing the mechanism of the influence of the steel bar on the resistivity measurement accuracy of the Wenner technology: the steel bar correction factor k under the combined influence of different concrete cover thicknesses and steel bar diameters is particularly important. Taking the concrete size of 320mm×200mm×160mm, the electrode spacing s is 40mm, the steel bar diameter d is 16mm, and the cover thickness c is 30mm as an example, under this model, the Wenner technology obtains a resistivity value of 75.14Ω·m. Since L / s, W / s, H / s=8:5:4, the size effect correction factor k is obtained. 1 is 0.895. The steel bar correction factor k given in this embodiment is 2 The corrected resistivity is 102.02Ω·m, and the deviation from the reference value is reduced from the uncorrected 24.86% to 2.22%, which shows a good correction effect. Because in actual engineering detection, the electrode spacing s is manually adjustable, considering the influence of aggregate particle size and the influence of electrode spacing on the correction factor, it is recommended that the electrode spacing of Wenner technology is fixed to 40mm in reinforced concrete detection. The correction coefficient is verified by taking the steel bar diameter d = 16mm and the protective layer thickness c = 20mm~40mm. It can be found that the resistivity simulation calculation values ​​of reinforced concrete with different protective layer thicknesses are close to the reference value after secondary adjustment. The unadjusted average error is 26.75%, and the adjusted average error is 1.51%. Therefore, in this embodiment, the electrode spacing of the Wenner technology is fixed to 40 mm. For the commonly used steel bar diameters in actual engineering applications, the steel bar diameters are 8 mm, 12 mm, 16 mm, 20 mm, 25 mm, and 30 mm. Under different protective layer thicknesses, the concrete resistivity measurement correction coefficient fitting formula considering the presence of steel bars is shown in the following table, where c is the thickness of the concrete cover.

[0066] Table 1 Correction coefficient k 2 expression

[0067]

[0068] In a concrete member containing unidirectionally distributed steel bars, a steel bar correction coefficient fitting formula corresponds to a steel bar correction coefficient fitting formula under any standard diameter. The steel bar correction coefficient fitting formula is a relationship between the unidirectionally distributed steel bar correction coefficient and the thickness of the concrete cover and the electrode spacing. The above quadratic equation fitting formula is preferred, that is:

[0069]

[0070] Where: k 2 is the correction coefficient of unidirectional distributed steel bars, c is the thickness of concrete cover, s is the electrode spacing, and A, B, and C are the fitting coefficients of the quadratic equation.

[0071] In the concrete finite element model without steel bars, when analyzing different cross-sectional sizes, the length L is fixed at 160 mm, the width W is changed, and the resistivity simulation value ρ is recorded at different W. s and correction factor k 1 The experiment found that when W changes from 40mm to 320mm, the resistivity simulation value ρ s Gradually decreases and approaches the reference value of 130Ω·m, the correction factor k 1 From 0.26 to 1.0, its growth rate decreases with the increase of W, and finally stabilizes at 0.91. This is because the length L is always 160mm. At this time, continuing to expand the cross-sectional size has little effect on the resistivity measurement. When W>200mm, k 1 Reaching above 0.90 means that the error between the resistivity simulation value and the reference value is less than 10%. This is because the surface potential distribution of the specimen changes with the size. In this experiment, the resistivity measurement error of concrete with different cross-sectional sizes is between 4.6% and 263.8%.

[0072] When analyzing different electrode spacings, the size of the concrete component being tested is fixed. The experiment found that when the electrode spacing s changes from 10mm to 100mm, the resistivity simulation value ρ s It dropped from 133Ω·m to 132Ω·m and then increased to 259Ω·m. The minimum value appeared at s=20mm, and then gradually increased, and the growth rate also continued to increase, and finally the deviation from the benchmark value reached 98%. This is because in Wenner technology, resistivity is defined as U 23 / I and 2πs. As the electrode spacing s increases, the ratio of potential difference to current U 23 / I gradually decreases, where s increases 10 times from 10mm to 100mm, and U 23 / I changes from 2126Ω to 411Ω, which is reduced to 1 / 5 of the original value. The increase of spacing s is greater than the decrease of the latter, which leads to the product of the two ρ s When the electrode spacing is small, the current is concentrated inside the cross-sectional area, but when the spacing is wide, the current inside the concrete cross-sectional area gradually diffuses to the edge of the concrete. As s continues to increase, the size effect becomes more significant, resulting in a greater deviation from the benchmark value. In this experiment, the measurement error of concrete resistivity with different electrode spacings is between 7.8% and 49.6%.

[0073] The experiment proved that when using the Wenner technique to measure resistivity, the concrete size and the electrode spacing have a great influence on the measurement results, revealing the mechanism of the size effect on the accuracy of resistivity measurement using the Wenner technique: when the cross-sectional size is larger, the potential gradient between the voltage measurement electrodes in the Wenner technique is smaller, resulting in a decrease in the resistivity measurement value; the larger the electrode spacing, the smaller the potential gradient between the measurement electrodes, but the decrease is significantly smaller than the increase in the electrode spacing, resulting in a gradual increase in the resistivity measurement value, and the current inside the concrete cross section gradually diffuses to the edge of the concrete, and the cross-sectional boundary gradually affects the current distribution inside the cross section, exacerbating the size effect. Therefore, the size effect correction coefficient k under the combined influence of different concrete sizes and electrode spacing is 1 It is particularly important. This embodiment normalizes the proportional relationship between the dimensions of concrete in all directions (L, W, H) and the electrode spacing s, and considers the new size effect through dimensionless parameters (L / s, W / s, H / s). According to the orthogonal design of L / s: W / s: H / s from 1:4:1 to 10:10:10, there are 700 groups of corresponding dimensions L, W, and H at each spacing, and the electrode spacings s discussed are 10mm, 30mm, 50mm, and 70mm respectively. Experimental research found that under the same size ratio, the correction coefficient k under different spacings s is 1 Shows good consistency, indicating that the correction factor k 1 It has nothing to do with the specific value of the spacing, but only depends on the proportional relationship between the concrete size and the spacing. Finally, based on the finite element results, the present invention established a size effect resistivity correction coefficient table, as shown in Table 2-1, Table 2-2, Table 2-3, and Table 2-4.

[0074] Table 2-1 L / s: W / s: H / s correction factor k 1 (1:4:1~3:5:10)

[0075]

[0076] Table 2-2 L / s: W / s: H / s correction factor k 1 (3:6:1~5:7:10)

[0077]

[0078] Table 2-3 L / s: W / s: H / s correction factor k 1 (5:8:1~7:9:10)

[0079]

[0080] Table 2-4 L / s: W / s: H / s correction factor k 1 (7:10:1~10:10:10)

[0081]

[0082]

[0083] After obtaining the above correction coefficient formula, the measured results can be corrected according to the above formulas (7)-(8).

[0084] The present invention only needs to measure or know the thickness of the concrete cover (c), the diameter of the steel bar to be measured (d) and the electrode spacing (s) to obtain the correction coefficient k of the unidirectionally distributed steel bar. 2 , combined with the size effect correction factor k 1 , the calculation results can be corrected to obtain more accurate results.

[0085] Based on the same inventive concept, a nondestructive detection and correction device for the resistivity of concrete of a one-way reinforced member is also provided in this embodiment. The device is used to implement the above-mentioned embodiment, and the descriptions that have been made will not be repeated. The terms "module" and the like used below can be a combination of software and / or hardware that can implement a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, it is also possible to implement them in hardware, or in a combination of software and hardware.

[0086] The detection and correction device comprises:

[0087] A concrete resistivity initial value measurement module, comprising a Wenner electrode, wherein the Wenner electrode is parallel to the surface of the unidirectional single-layer distributed steel bars of the reinforced concrete member to be detected and is installed in a direction perpendicular to the steel bar axis, and can measure the initial value of the concrete resistivity based on the Wenner technology;

[0088] A size effect correction module, which stores a size effect resistivity correction coefficient table, and searches for the size effect resistivity correction coefficient according to the proportional relationship between the size of the concrete component to be detected and the electrode spacing; the size effect resistivity correction coefficient table is established by constructing a concrete finite element model of steel bars and performing finite element analysis;

[0089] A one-way distribution steel bar correction module stores therein a one-way distribution steel bar correction coefficient fitting formula, and determines the formula according to the diameter of the steel bar in the concrete component to be detected, the thickness of the concrete cover, and the electrode spacing, and calculates the one-way distribution steel bar correction coefficient; the one-way distribution steel bar correction coefficient fitting formula is established by constructing a concrete finite element model containing unidirectional distribution steel bars and performing finite element analysis;

[0090] The concrete resistivity correction module is used to correct the initial value of concrete resistivity according to the size effect resistivity correction coefficient and the unidirectional distributed steel bar correction coefficient, and calculate the corrected true resistivity.

[0091] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment, and the implementation methods of the remaining modules will not be repeated here. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of the present invention. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0092] The embodiments of the apparatus of the present invention can be applied to any device with data processing capability, and the device with data processing capability can be a device such as a computer. The device embodiments can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, the processor of any device with data processing capability reads the corresponding computer program instructions in the non-volatile memory into the memory and runs them.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for correcting the resistivity of concrete in unidirectional reinforced components by nondestructive testing on site, characterized in that: include: The surface of the reinforced concrete component to be inspected is smoothed; the reinforced concrete component is provided with unidirectional single-layer steel bars; Wenner electrodes are installed on the surface of the reinforced concrete component to be tested parallel to the unidirectional single-layer distributed steel bars and in a direction perpendicular to the steel bar axis. The length, width and height of the concrete component to be tested, as well as the diameter of the steel bars in the reinforced concrete component, the thickness of the concrete cover and the electrode spacing are determined and measured according to the installation surface and arrangement direction of the Wenner electrodes. The initial value of concrete resistivity is measured based on the Wenner technique. The size effect correction coefficient and the unidirectional distribution steel bar correction coefficient are obtained by looking up the size effect resistivity correction coefficient table and the unidirectional distribution steel bar correction coefficient fitting formula. The corrected true resistivity is calculated based on the correction coefficient and the initial value of concrete resistivity.

2. The method for correcting the on-site nondestructive detection of the resistivity of concrete of one-way reinforced components according to claim 1 is characterized in that: When the initial value of the concrete resistivity is measured based on the Wenner technology, it is necessary to measure multiple times and take an average value, and a conductive paste needs to be applied to the contact point between the Wenner electrode and the surface of the reinforced concrete component to be detected.

3. The method for correcting the resistivity of concrete of one-way reinforced components in the field of nondestructive testing according to claim 1 is characterized in that: The Wenner electrode is arranged in the central area of ​​the surface of the reinforced concrete component to be detected.

4. The method for correcting the on-site nondestructive testing of the resistivity of concrete of one-way reinforced components according to claim 1 is characterized in that: The axial direction of the steel bars in the inspected reinforced concrete component is regarded as the length direction of the component, the arrangement direction of the unidirectional single-layer steel bars is regarded as the width direction of the inspected reinforced concrete component, the direction perpendicular to the reinforced concrete surface where the Wenner electrodes are arranged is regarded as the height direction of the inspected concrete component, and the distance from the concrete surface where the Wenner electrodes are arranged to the upper surface of the unidirectional single-layer steel bars is regarded as the thickness of the protective layer of the inspected concrete.

5. The method for correcting the on-site nondestructive testing of the resistivity of concrete of one-way reinforced components according to claim 1 or 4, characterized in that: The method for constructing the size effect resistivity correction coefficient table is: Establish a concrete finite element model without steel bars and set the resistivity benchmark value of concrete components; According to the orthogonal design of L / s:W / s:H / s from 1:4:1 to 10:10:10, the resistivity simulation values ​​under different size ratio designs were obtained through finite element analysis, the size effect correction coefficient was introduced, the size effect correction coefficient was calculated according to the resistivity simulation value and the resistivity reference value, and the concrete resistivity correction coefficient table was constructed; Where L, W, H, and s are the length, width, height, and electrode spacing of the concrete component, respectively; The governing equations for the finite element model of concrete without reinforcement are as follows: The boundary conditions are: n·J=0 Where ρ is the resistivity, V is the electric potential, n is the surface normal vector of the Wenner electrode installed on the concrete component, and J is the current density vector of the closed surface in the domain; Considering that concrete material is homogeneous and isotropic, 6. The method for correcting the on-site nondestructive testing of the resistivity of concrete of one-way reinforced components according to claim 5 is characterized in that: When the size effect correction coefficient is obtained by looking up the concrete resistivity correction coefficient table, if the ratio between the size of the concrete component to be tested and the electrode spacing is not an integer ratio, the size effect correction coefficient is calculated using trilinear interpolation; if the ratio between the concrete size and the electrode spacing exceeds 10: 10:10, the size effect correction factor is 1.

7. The method for correcting the on-site nondestructive testing of the resistivity of concrete of one-way reinforced components according to claim 1 or 4, characterized in that: The construction method of the unidirectional distribution steel bar correction coefficient fitting formula is: Establish a concrete finite element model with unidirectionally distributed steel bars and set the concrete resistivity benchmark value of reinforced concrete components; According to the steel bar diameter d from the minimum value d min To the maximum value d max , the concrete cover thickness c is from the minimum value c min To the maximum value c max Orthogonal design was performed, and the resistivity simulation values ​​under different steel bar diameters and concrete cover thickness designs were obtained through finite element analysis. According to the relationship between the resistivity simulation values ​​and the resistivity reference values, a fitting formula for the steel bar correction coefficient was constructed. The governing equations of the concrete finite element model containing unidirectionally distributed steel bars are as follows: The boundary conditions are: n·J=0 Where ρ is the resistivity, V is the electric potential, n is the surface normal vector of the Wenner electrode installed on the reinforced concrete component to be tested, and J is the current density vector of the closed surface in the domain.

8. The method for correcting the on-site nondestructive testing of the concrete resistivity of a one-way reinforced component according to claim 7, characterized in that: In a concrete component containing unidirectionally distributed steel bars, a steel bar correction coefficient fitting formula corresponds to a steel bar correction coefficient fitting formula under any standard diameter. The steel bar correction coefficient fitting formula is the relationship between the unidirectionally distributed steel bar correction coefficient and the concrete cover thickness and the electrode spacing. Where: k2 is the correction coefficient of unidirectional distributed steel bars, c is the thickness of the concrete cover, s is the electrode spacing, and A, B, and C are the fitting coefficients of the quadratic equation.

9. The method for correcting the on-site nondestructive testing of the resistivity of concrete of one-way reinforced components according to claim 1, characterized in that: The reinforced concrete component to be inspected is a thin-walled or plate component.

10. A non-destructive detection and correction device for concrete resistivity of one-way reinforced components, used to implement the method described in claim 1, characterized in that: The detection and correction device comprises: A concrete resistivity initial value measurement module, comprising a Wenner electrode, wherein the Wenner electrode is parallel to the surface of the unidirectional single-layer distributed steel bars of the reinforced concrete member to be detected and is installed in a direction perpendicular to the steel bar axis, and can measure the initial value of the concrete resistivity based on the Wenner technology; A size effect correction module, which stores a size effect resistivity correction coefficient table, and searches for the size effect resistivity correction coefficient according to the proportional relationship between the size of the concrete component to be detected and the electrode spacing; the size effect resistivity correction coefficient table is established by constructing a concrete finite element model of steel bars and performing finite element analysis; A one-way distribution steel bar correction module stores therein a one-way distribution steel bar correction coefficient fitting formula, and determines the formula according to the diameter of the steel bar in the concrete component to be detected, the thickness of the concrete cover, and the electrode spacing, and calculates the one-way distribution steel bar correction coefficient; the one-way distribution steel bar correction coefficient fitting formula is established by constructing a concrete finite element model containing unidirectional distribution steel bars and performing finite element analysis; The concrete resistivity correction module is used to correct the initial value of concrete resistivity according to the size effect resistivity correction coefficient and the unidirectional distributed steel bar correction coefficient, and calculate the corrected true resistivity.

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