CN113155949B - Combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of steel bar section and testing method thereof - Google Patents
Combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of steel bar section and testing method thereof Download PDFInfo
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Abstract
The combined magnetic sensor comprises a magnetic induction intensity monitoring unit and a data processing unit, wherein the magnetic induction intensity monitoring unit comprises a double-magnetic-circuit four-measuring-point built-in sensor for detecting the non-uniform corrosion condition of the section of the steel bar and a veneering type sensor for detecting the corrosion condition of the steel bar along the length direction, the double-magnetic-circuit four-measuring-point built-in sensor is built in a reinforced concrete test piece, and the veneering type sensor is externally attached to the surface of the reinforced concrete test piece. According to the invention, the non-uniform corrosion of the reinforcing steel bar is effectively measured in the non-uniform corrosion area of the reinforcing steel bar through the magnetic field, the non-uniform corrosion monitoring of the built-in sensor corresponding to the side of the reinforcing steel bar facing the protective layer and the side of the reinforcing steel bar facing away from the protective layer, and the corrosion condition monitoring of the facing sensor corresponding to the reinforcing steel bar along the length direction are realized, so that the principle is clear, the method is simple and convenient, the measuring speed is high, the part of the sensor can be repeatedly used, and the engineering applicability is strong and the stability is good.
Description
Technical Field
The invention relates to a nondestructive monitoring technology for steel bar corrosion in constructional engineering, in particular to a combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a section of a steel bar and a testing method thereof.
Background
The reinforced concrete structure combines the characteristics of steel bar tensile and concrete compressive, and since the reinforced concrete structure is applied to the field of civil engineering in the middle of 19 th century, the reinforced concrete structure has become one of the most widely applied structural forms in the world due to the characteristics of economical manufacturing cost, available local materials, low construction difficulty and the like. The loss caused by the durability failure of concrete is very great for a long time, which is far beyond the expectations of people, and how to improve the durability of the concrete in the service period has become a worldwide problem. And the steel bar is corroded most seriously in the reasons of the durability damage of the concrete, thereby attracting wide attention at home and abroad. Aiming at the research of steel bar corrosion detection in the construction engineering, a great deal of research is also carried out by the former.
At present, the detection method of the corrosion of the steel bar is divided into damage detection and nondestructive detection. The damage detection is carried out by breaking the concrete protection layer to take out the reinforcing steel bars, the result is accurate, but irreversible damage to the concrete structure can be caused, and the method is not applicable to the reinforced concrete structure in the service period. The nondestructive testing method is a hotspot of research at present, and mainly comprises a half-cell potential method, an acoustic emission technology and a magnetic field nondestructive testing method. The half-cell potential method is most commonly used, and the potential change is caused by the electrochemical reaction of the steel bar corrosion, so that the steel bar corrosion state is measured, but the accuracy is lower, the steel bar corrosion probability can only be judged qualitatively, and the corrosion condition cannot be quantified without unified judgment standard; the acoustic emission technology sensitively captures the release of microcrack expansion stress wave in concrete by measuring the acoustic wave propagation characteristic caused by the corrosion of the steel bar and can only qualitatively judge the corrosion occurrence probability according to the accumulated impact number and other parameters, so that the corrosion rate of the steel bar can not be quantitatively measured; the nondestructive testing method of the magnetic field can monitor the damage of the surface or the near surface of the steel bar under the condition of normal service of the concrete, and although the defect inside the steel bar can not be detected, compared with other methods which can not quantitatively detect the corrosion rate, the method has obvious improvement.
The system is named as an external steel bar corrosion nondestructive monitoring sensor based on an electromagnetic field principle and a testing method, chinese patent grant bulletin No. CN201910991189.8, grant bulletin No. 2020, no. 1 month and No. 3, and a magnetic field-based concrete steel bar corrosion nondestructive dynamic monitoring sensor and a magnetic field-based concrete, chinese patent application publication No. CN201811213216.0, publication bulletin No. 2019, no. 2 and No. 22, which utilize the magnetic field principle to perform nondestructive monitoring on steel bar corrosion. The external bayonet type magnetic sensor is provided based on the electromagnetic field principle, is simple and convenient to operate, can effectively detect the corrosion condition of a single detection steel bar at the corner of a reinforced concrete square column, and has a single detection object; the latter uses the static magnetic field principle to detect the corrosion rate of the steel bar, but the sensor related to the patent has the defects that: firstly, although three Hall sensors are arranged in the sensor, only the Hall sensors beside the steel bar clamping notch actually work; secondly, the Hall sensors are arranged in a single straight line direction, and the method cannot effectively monitor the change rule of the positions of the reinforcing steel bars; thirdly, the patent cannot effectively and quantitatively detect the non-uniform corrosion degree of the steel bars; fourthly, the magnetic core of the patent is further away from the steel bar notch by a certain distance, and the magnetic resistance of an air domain between the detection steel bar and the magnetic core can be increased; both are focused on the local corrosion of the steel bar, only the corrosion condition on the section of the steel bar is monitored, and the corrosion monitoring of the steel bar along the length direction is ignored.
The method is characterized in that the method is named as a device for detecting reinforcing steel bars in concrete and a method thereof, chinese patent application publication No. CN201911157575.3, the publication date is 2020, 2 and 25 days, and the method is named as a faced type reinforcing steel bar non-uniform corrosion monitoring sensor and testing method based on a magnetic field principle, chinese patent application publication No. CN112034034A, the publication date is 2020, 12 and 04 days, and the external scanning type nondestructive detection device and method are provided based on an electrostatic field principle and can detect the corrosion condition of reinforcing steel bars at a certain distance; the latter provides a monitoring sensor for rusting the steel bars in the existing reinforced concrete structure along the length direction based on the magnetic field principle; both can only detect the corrosion condition along length direction of the reinforcing bar facing to one side of the protective layer, and the non-uniform corrosion condition of the reinforcing bar can not be evaluated. And, both focus on the whole corrosion of reinforcing bar, only monitored the corrosion condition of reinforcing bar along length direction, and neglected the corrosion monitoring on the reinforcing bar cross-section.
The patent is entitled "a reinforcing bar corrosion electromagnetic field becomes response monitoring device", grant publication number CN208420791U, grant publication day is 22 days of 2019 1 month, but this patent utilizes hall element can real-time supervision reinforcing bar from rust to the whole corrosion process of the linear loss of quality, but can't quantitative monitoring reinforcing bar's inhomogeneous corrosion condition.
In actual construction engineering, a sensor and a test method for monitoring the local non-uniform corrosion condition of the section of the steel bar and the whole corrosion condition of the whole steel bar along the length direction still do not exist.
Therefore, the steel bar monitoring sensor which has the advantages of being capable of being from local corrosion to integral corrosion, clear in principle, simple and convenient in method, high in measuring speed, comprehensive in function, strong in engineering applicability, good in stability and the like is found, and has important significance in improving assessment and prediction of the corrosion degree of the steel bars.
Disclosure of Invention
In order to overcome the defects of the existing nondestructive monitoring technology for corrosion of the construction engineering reinforcing steel bar, the invention provides the combined magnetic sensor for monitoring the non-uniform corrosion and the axial corrosion of the section of the reinforcing steel bar, which has high stability, simple and convenient operation and strong engineering applicability, and the testing method thereof.
The technical scheme adopted for solving the technical problems is as follows:
The combined magnetic sensor for monitoring the non-uniform corrosion of the section of the steel bar and the corrosion along the axial direction comprises a magnetic induction intensity monitoring unit and a data processing unit, wherein the magnetic induction intensity monitoring unit comprises a double-magnetic-circuit four-measuring-point built-in sensor for detecting the non-uniform corrosion condition of the section of the steel bar and a veneering type sensor for detecting the corrosion condition of the steel bar along the length direction, the double-magnetic-circuit four-measuring-point built-in sensor is built in a reinforced concrete test piece and is fixed on a section to be detected of the steel bar to be detected through a plastic binding wire, and the veneering type sensor is externally attached to the surface of the reinforced concrete test piece;
The double-magnetic-circuit four-measuring-point built-in sensor comprises a left built-in sensor magnetic core, a right built-in sensor magnetic core, a built-in sensor permanent magnet, a first Hall sensor, a second Hall sensor, a third Hall sensor, a fourth Hall sensor and a built-in sensor packaging shell; the middle part of the upper end of the built-in sensor packaging shell is provided with a reinforcement bayonet used for clamping a reinforcement to be tested, the built-in sensor packaging shell comprises a built-in sensor inner shell and a built-in sensor outer shell packaging cover, a first Hall sensor placing groove, a second Hall sensor placing groove, a third Hall sensor placing groove, a fourth Hall sensor placing groove, a built-in sensor permanent magnet groove, a built-in sensor left magnetic core groove, a built-in sensor right magnetic core groove, a first cable bending space and a first wire hole, the first Hall sensor placing groove, the second Hall sensor placing groove, the third Hall sensor placing groove and the fourth Hall sensor placing groove are all arranged in the reinforcement bayonet, the built-in sensor permanent magnet groove is positioned between the built-in sensor left magnetic core groove and the built-in sensor right magnetic core groove, the first cable bending space is positioned below the built-in sensor permanent magnet groove, and the first wire hole is arranged at the bottom of the built-in sensor packaging shell and is communicated with the first cable bending space; the built-in sensor permanent magnet is connected with the left magnetic core and the right magnetic core of the built-in sensor at the same time, and is arranged in the built-in sensor permanent magnet groove, and the first Hall sensor, the second Hall sensor, the third Hall sensor and the fourth Hall sensor are symmetrically arranged by taking the center line of a steel bar bayonet as an axis, and are respectively arranged in the corresponding Hall sensor placing groove; the built-in sensor inner shell and the built-in sensor outer shell packaging cover are respectively provided with a first fixing hole and a second fixing hole;
The veneering sensor comprises a veneering sensor permanent magnet, a veneering sensor front magnetic core, a veneering sensor rear magnetic core, a veneering sensor packaging shell, a fifth Hall sensor and a sixth Hall sensor, wherein the veneering sensor packaging shell comprises a veneering sensor inner shell and a veneering sensor packaging cover, a fifth Hall sensor placing groove, a sixth Hall sensor placing groove, a veneering sensor front magnetic core placing groove, a veneering sensor rear magnetic core placing groove, a veneering sensor permanent magnet placing groove, a second cable bending space and a second wire hole, and the second wire hole is communicated with the second cable bending space; the veneering sensor permanent magnet is connected with the front magnetic core and the rear magnetic core of the veneering sensor at the same time and is arranged in the veneering sensor permanent magnet placing groove, the fifth Hall sensor and the sixth Hall sensor are arranged in a front-back symmetrical mode and are respectively arranged in the corresponding Hall sensor placing groove, and the inner shell of the veneering sensor and the packaging cover of the veneering sensor are respectively provided with a third fixing hole and a fourth fixing hole;
the data processing unit comprises a signal collector, a signal processor and a central controller, wherein the input end of the signal collector is electrically connected with the signal output end of the Hall sensor, the output end of the signal collector is electrically connected with the signal input end of the signal processor, and the signal output end of the signal processor is electrically connected with the port of the central controller.
Further, be equipped with first circuit pilot lamp between first hall sensor and second hall sensor and the signal acquisition ware, third hall sensor and fourth hall sensor and signal acquisition ware between be equipped with the second circuit pilot lamp, fifth hall sensor and sixth hall sensor and signal acquisition ware between be equipped with the third circuit pilot lamp.
Still further, the left magnetic core of the built-in sensor and the right magnetic core of the built-in sensor are E-shaped magnetic cores with two openings symmetrically arranged inwards, the upper end connecting line of the openings of the first pair of magnetic cores is overlapped with the tangent line of the top end of the steel bar to be tested, the openings of the second pair of magnetic cores are arranged into circular arcs, the bottom end connecting line is overlapped with the tangent line of the bottom end of the steel bar to be tested, and the openings of the third pair of magnetic cores are connected with the permanent magnet of the built-in sensor; the front magnetic core of the veneering sensor and the rear magnetic core of the veneering sensor are of symmetrical structures and are rectangular in section.
Still further, two fixed ends are arranged at the left end and the right end of the double-magnetic circuit four-measuring-point built-in sensor, the two fixed ends are respectively provided with a wire hole, a plastic binding wire is used for penetrating the wire holes, and the fixed ends are bound with the steel bars to be measured;
Furthermore, the built-in sensor permanent magnet and the veneering sensor permanent magnet are made of neodymium nickel boron, and the left magnetic core of the built-in sensor, the right magnetic core of the built-in sensor, the front magnetic core of the veneering sensor and the rear magnetic core of the veneering sensor are made of silicon steel; the built-in sensor packaging shell and the veneered sensor packaging shell are made of plastic materials.
A test method of a combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a section of a steel bar comprises the following steps: calculating the corrosion rate of the side of the steel bar to be measured facing the protective layer through the magnetic induction intensity values of the first Hall sensor and the second Hall sensor, calculating the corrosion rate of the side of the steel bar to be measured facing away from the protective layer through the magnetic induction intensity values of the third Hall sensor and the fourth Hall sensor, and comparing the corrosion rates of the two sides to analyze the non-uniform corrosion degree of the steel bar to be measured; and the rust rate of the steel bar along the length direction is calculated through the magnetic induction intensity values of the fifth Hall sensor and the sixth Hall sensor.
The method comprises the following specific steps:
firstly, preparing a reinforced concrete test piece before testing, wherein the process is as follows:
1.1, 8 HPB300 smooth round steel bars with set length and diameter are taken, 1 steel bar is used as a calibration steel bar, 7 steel bars are used as steel bars to be measured, the mass of the steel bars to be measured is respectively m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ, and the mass of the steel bars is calibrated m 0 and recorded;
1.2, the 5cm positions of the two ends of the calibration steel bar and the steel bar to be tested are coated with epoxy resin;
second, preparation before measurement is as follows:
2.1, respectively installing a first Hall sensor, a second Hall sensor, a third Hall sensor and a fourth Hall sensor in a first Hall sensor placing groove, a second Hall sensor placing groove, a third Hall sensor placing groove and a fourth Hall sensor placing groove of a built-in sensor packaging shell, installing a permanent magnet in a built-in sensor permanent magnet groove, bending a cable at a first cable bending space, externally connecting a circuit first indicator lamp, a circuit second indicator lamp and a signal collector through a first wire hole, finally connecting the built-in sensor inner shell and a packaging cover through a first fixing hole and a second fixing hole by using screws and nuts, and coating epoxy resin on all gaps for sealing;
2.2, respectively installing a fifth Hall sensor and a sixth Hall sensor in a fifth Hall sensor placing groove and a sixth Hall sensor placing groove of the veneered sensor packaging shell, installing a permanent magnet in a permanent magnet groove of the veneered sensor, bending a cable at a bending space of a second cable, externally connecting a third indicator lamp and a signal collector through a second wire hole, finally connecting the sensor with an inner shell of the veneered sensor and a packaging cover through a third fixing hole and a fourth fixing hole by using screws and nuts, and coating epoxy resin on all gaps for sealing;
2.3, controlling the acquisition frequency of the signal acquisition device through the central controller, testing the magnetic field, and ensuring that the magnetic induction intensity Gaussian values of the first Hall sensor, the second Hall sensor, the third Hall sensor and the fourth Hall sensor are the same; the magnetic induction intensity Gaussian values of the fifth Hall sensor and the sixth Hall sensor are the same;
2.4, mounting the built-in sensor on the steel bar to be tested, and fixing the left end and the right end of the built-in sensor by using plastic binding wires; placing the steel bar to be measured and the calibration steel bar in a mould, pouring and forming, and immersing the calibration reinforced concrete test piece and the reinforced concrete test piece to be measured in a standard salt concentration solution until the steel bar to be measured is saturated with salt, wherein the concentration of the standard sodium chloride solution is 0.1-2 mol/L;
2.5, packaging the veneering sensor through a veneering sensor packaging shell, and then placing the veneering sensor on a reinforced concrete test piece to be communicated with a magnetic circuit of the reinforced concrete to be tested;
Thirdly, calibrating and testing, wherein the process is as follows:
3.1, recording magnetic induction intensity data B 1Ⅰa,B2Ⅰa,B3Ⅰa,B4Ⅰa,B5Ⅰa,B6Ⅰa,B7Ⅰa of one side of a marked reinforcing steel bar facing the protective layer before corrosion under the monitoring of a built-in sensor of a reinforced concrete test piece with the mass of m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ; calibrating magnetic induction intensity data B 1Ⅰb,B2Ⅰb,B3Ⅰb,B4Ⅰb,B5Ⅰb,B6Ⅰb,B7Ⅰb of one side of the reinforcement back to the protective layer before rust;
3.2, recording magnetic induction intensity data B 1Ⅰc,B2Ⅰc,B3Ⅰc,B4Ⅰc,B5Ⅰc,B6Ⅰc,B7Ⅰc of the calibration reinforcing steel bar before rust on the reinforced concrete test piece with the mass of m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ under the monitoring of the veneering sensor;
3.3, realizing a simulation experiment of steel bar corrosion in a current acceleration corrosion mode, controlling the current density to be the same, and electrifying a reinforced concrete test piece corresponding to the mass m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ at equal intervals t 1,t2,t3,t4,t5,t6,t7;
3.3, recording magnetic induction intensity data B 1Ⅱa,B2Ⅱa,B3Ⅱa,B4Ⅱa,B5Ⅱa,B6Ⅱa,B7Ⅱa of the calibrated steel bar facing to one side of the protective layer under the monitoring of the built-in sensor after the reinforced concrete test piece is corroded; calibrating magnetic induction intensity data B 1Ⅱb,B2Ⅱb,B3Ⅱb,B4Ⅱb,B5Ⅱb,B6Ⅱb,B7Ⅱb of one side of the reinforcing steel bar, which is back to the protective layer, after corrosion;
3.4, recording magnetic induction intensity data B 1Ⅱc,B2Ⅱc,B3Ⅱc,B4Ⅱc,B5Ⅱc,B6Ⅱc,B7Ⅱc of the calibrated steel bar under monitoring of the veneering type sensor after the reinforced concrete test piece is corroded;
3.5, taking out the rusted steel bar, cutting off the parts coated with epoxy resin at the two ends, removing rust on the surface of the steel bar by using a rust remover, weighing, and recording the quality data of the steel bar as m 1Ⅱ,m2Ⅱ,m3Ⅱ,m4Ⅱ,m5Ⅱ,m6Ⅱ,m7Ⅱ;
3.4, calculating the mass change rate delta m 1,△m2,△m3,△m4,△m5,△m6,△m7 of the calibration steel bar respectively, wherein the calculation formulas are respectively shown in formulas (1) to (7);
3.5 respectively calculating the magnetic induction intensity change rate DeltaB 1a、△B2a、△B3a、△B4a、△B5a、△B6a、△B7a at the side of the reinforcing steel bar facing the protective layer and the magnetic induction intensity change rate DeltaB 1b、△B2b、△B3b、△B4b、△B5b、△B6b、△B7b at the side of the reinforcing steel bar facing away from the protective layer under the monitoring of the built-in sensor, wherein the calculation formulas are respectively shown in formulas (8) to (14);
3.6 calculating the change rate delta B 1c、△B2c、△B3c、△B4c、△B5c、△B6c、△B7c of the magnetic induction intensity of the steel bar under the monitoring of the veneering type sensor, wherein the calculation formulas are respectively shown in formulas (15) to (21);
3.6, respectively carrying out linear fitting on the relation between the mass change rate of the steel bar and the magnetic induction intensity change rate of the Hall sensors at the two sides under the monitoring of the built-in sensors to obtain a linear relation coefficient alpha a、αb; under the detection of the veneering sensor, performing linear fitting on the relation between the steel bar mass change rate and the magnetic induction intensity change rate of the Hall sensor to obtain a linear relation coefficient alpha c;
fourth, the procedure for the assay is as follows:
4.1, recording magnetic induction intensities B 0Ⅰa、B0Ⅰb、B0Ⅰc on two sides of the test piece to be tested before rusting;
4.2, placing the reinforced concrete to be tested in an environment which is easy to cause corrosion of the reinforced concrete, so as to promote the corrosion of the reinforced concrete;
4.3, placing the rusted test piece to be tested back to the original position, and recording the magnetic induction intensity B 0Ⅱa、B0Ⅱb、B0Ⅱc of the rusted steel bar;
4.4, the corrosion rate P of the reinforcing steel bar is calculated as formula (22);
Pa＝αa(B0Ιa-B0ΙΙa),Pb＝αb(B0Ιb-B0ΙΙb),Pc＝αc(B0Ιc-B0ΙΙc) (22)
Wherein, P a is the corrosion rate of reinforcing bar towards protective layer one side, P b is the corrosion rate of backing to protective layer one side, and P c is the corrosion rate of reinforcing bar under the monitoring of wainscot formula sensor.
4.4, Defining the non-uniform corrosion of the reinforcing steel bar as R, wherein the larger R is, the more serious the non-uniform corrosion of the reinforcing steel bar is, and the formula is (23);
R＝Pa/Pb (23)。
The beneficial effects of the invention are mainly shown in the following steps: the invention is based on a nondestructive testing method, utilizes a magnetic induction technology and adopts a unique and innovative built-in and veneered sensor testing method to realize the nondestructive monitoring of the non-uniform corrosion of the steel bar, calculates the corrosion rate and the non-uniform corrosion degree of the steel bar according to a theoretical formula, breaks through the limitations of the traditional testing method, such as the testing stability and the accuracy and the limitation that the non-uniform corrosion of the steel bar can not be detected, and realizes the testing of the corrosion rate of the steel bar of the reinforced concrete structure; the measured corrosion rate of the reinforced concrete structure can be applied to the evaluation of the current service performance and the prediction of the durability of the reinforced concrete structure; the external part of the veneered sensor can correspond to a plurality of inner magnetic cores to detect the non-uniform corrosion of the steel bars, and the built-in sensor has the advantages of clear principle, simple and convenient method, high measuring speed, repeated use of parts, good stability and the like, and can make up for the defects of the conventional method and equipment for measuring the corrosion rate of the steel bars.
Drawings
FIG. 1 is a schematic diagram of the working structure of the sensor of the present invention.
FIG. 2 is a schematic diagram of the working structure of the built-in sensor according to the present invention.
FIG. 3 is a three-dimensional schematic of the inner housing of the built-in sensor of the present invention.
Fig. 4 is a front view of a built-in sensor package cover according to the present invention.
Fig. 5 is a schematic diagram of a fixing manner of a built-in sensor in the present invention.
FIG. 6 is a schematic diagram of the working structure of the overlay sensor according to the present invention.
FIG. 7 is a three-dimensional schematic of a facing sensor inner housing according to the present invention.
FIG. 8 is a front view of a face-up sensor package cover in accordance with the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1 to 8, a combined magnetic sensor for monitoring non-uniform corrosion of a section of a steel bar and corrosion along an axial direction comprises a magnetic induction intensity monitoring unit and a data processing unit, wherein the magnetic induction intensity monitoring unit comprises a double-magnetic circuit four-measuring-point built-in sensor for detecting the non-uniform corrosion condition of the section of the steel bar and a veneering sensor for detecting the corrosion condition of the steel bar along the length direction.
The built-in sensor can monitor the non-uniform corrosion of the steel bars; is arranged in a reinforced concrete structure, and provides a new fixing mode of the sensor and the steel bars; the magnetic core is in an E-shaped special shape, so that the monitoring of four measuring points of the double magnetic circuits and the fixation of the permanent magnet can be effectively completed; the Hall sensors are symmetrically arranged in pairs, so that the corrosion conditions of the two sides of the reinforcing steel bar facing and facing away from the protective layer are accurately detected; the method is used for measuring the corrosion rate and the non-uniform corrosion degree of the steel bar, evaluating the corrosion condition of the steel bar and predicting the service life of the steel bar.
The veneering sensor can realize rust monitoring of the steel bars in the existing reinforced concrete structure along the length direction; the veneering sensor is externally attached to the surface of the reinforced concrete structure, namely, the magnetic core is externally arranged outside the reinforced concrete structure, the magnetic circuit passes through the corrosion area of the non-uniform corrosion steel bar, the non-uniform corrosion condition of the magnetic circuit passing through the length steel bar can be monitored, and the single detection steel bar corrosion condition in the middle of the reinforced concrete structure can be effectively judged by the Hall voltage obtained through the test; the method is used for measuring the corrosion rate of the steel bar, evaluating the corrosion degree of the steel bar and predicting the service life of the steel bar.
The method and the device are combined for use, so that the non-uniform local corrosion condition on the section of the reinforced bar can be monitored, and the overall corrosion condition of the reinforced bar along the length direction can be monitored, so that the problem that no effective method for measuring the corrosion condition of the reinforced bar of the reinforced concrete structure from local to whole is solved.
The working principle of the invention is as follows: the Hall voltage of the Hall sensor detection unit is sent to the signal processor; the signal processor collects and calculates and analyzes the data of the signal collector according to the set frequency, the collected data and the calculation result are stored in the central controller in real time, and the analysis calculation result is displayed in real time by the display.
Example 1a test method for a combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a steel bar section, taking as an example a 16mm diameter HPB300 plain round steel bar, comprises the steps of:
firstly, preparing a reinforced concrete test piece before testing, wherein the process is as follows:
1.1, 8 HPB300 smooth round steel bars with the length of 20cm and the diameter of 16mm are taken, 1 steel bar is taken as a calibration steel bar, 7 steel bars are taken as steel bars to be measured, the mass of the steel bars to be measured is respectively m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ, and the mass m 0 of the steel bars is calibrated and recorded;
1.2, the 5cm positions of the two ends of the calibration steel bar and the steel bar to be tested are coated with epoxy resin;
second, preparation before measurement is as follows:
2.1, a first Hall sensor 1-1, a second Hall sensor 9-2, a third Hall sensor 9-3 and a fourth Hall sensor 9-4 are respectively arranged in a first Hall sensor placing groove 9-1, a second Hall sensor 1-2, a third Hall sensor 1-3 and a fourth Hall sensor 1-4 of a built-in sensor packaging shell, a permanent magnet 4-1 is arranged in a built-in sensor permanent magnet groove 9-7, a cable is bent at a first cable bending space 9-10, a first circuit indicator lamp 8-1, a second circuit indicator lamp 8-2 and a signal collector 5 are externally connected through a first cable hole 9-11, finally, the sensors are connected with a built-in sensor inner shell and a packaging cover 9-12 through a first fixing hole 9-8 and a second fixing hole 9-9 by screws and nuts, and all gaps are coated with epoxy resin for sealing;
2.2, a fifth Hall sensor 1-5 and a sixth Hall sensor 1-6 are respectively installed in a fifth Hall sensor placing groove 10-1 and a sixth Hall sensor placing groove 10-2 of a veneered sensor packaging shell, a permanent magnet 4-2 is installed in a veneered sensor permanent magnet groove 10-5, a cable is bent at a second cable bending space 10-8, a third indicator lamp 8-3 and a signal collector 5 are externally connected through a second wire hole 10-9, finally, a sensor is connected with an inner shell of the veneered sensor and a packaging cover 10-10 through a third fixing hole 10-6 and a fourth fixing hole 10-7 by using screws and nuts, and all gaps are coated with epoxy resin for sealing;
2.3 controlling the acquisition frequency of the signal acquisition device 5 through the central controller 7, testing the magnetic field, and ensuring that the magnetic induction intensity Gaussian values of the first Hall sensor 1-1, the second Hall sensor 1-2, the third Hall sensor 1-3 and the fourth Hall sensor 1-4 are the same; the magnetic induction intensity Gaussian values of the fifth Hall sensor 1-5 and the sixth Hall sensor 1-6 are the same;
2.4, the built-in sensor is mounted on the steel bar 2 to be tested, and the left end 12-1 and the right end 12-2 are fixed by plastic binding wires. Placing the steel bar to be tested and the calibration steel bar in a mould and pouring and forming, wherein the raw materials of the concrete are as follows: cement is P.I and 525-grade portland cement, sand adopts river sand with a fineness modulus of 2.6, coarse aggregate adopts continuous graded broken stone (the maximum grain diameter is 25 mm), water adopts tap water, the effective section size of a casting test piece in a standard mould is 100mm multiplied by 100mm, the length of a reinforcing steel bar is 200mm, the protruding length of reinforcing steel bars on two sides is 50mm, the length of the test piece is 100mm, standard curing is performed in a curing room for 28d after casting molding, a standard reinforced concrete test piece and a reinforced concrete test piece to be tested are cast and molded, and are soaked in a standard salt concentration solution until saturated salt is formed, wherein the concentration of the standard sodium chloride solution is 0.1-2 mol/L;
2.5, packaging the veneering sensor through a veneering sensor packaging shell, and then placing the veneering sensor on a reinforced concrete test piece to be communicated with a magnetic circuit of the reinforced concrete to be tested;
Thirdly, calibrating and testing, wherein the process is as follows:
3.1, recording magnetic induction intensity data B 1Ⅰa,B2Ⅰa,B3Ⅰa,B4Ⅰa,B5Ⅰa,B6Ⅰa,B7Ⅰa of one side of the calibrating reinforcement facing the protective layer before rust under the monitoring of a built-in sensor of the reinforced concrete test piece 11 corresponding to the mass m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ; calibrating magnetic induction intensity data B 1Ⅰb,B2Ⅰb,B3Ⅰb,B4Ⅰb,B5Ⅰb,B6Ⅰb,B7Ⅰb of one side of the reinforcement back to the protective layer before rust;
3.2, recording magnetic induction intensity data B 1Ⅰc,B2Ⅰc,B3Ⅰc,B4Ⅰc,B5Ⅰc,B6Ⅰc,B7Ⅰc of the calibration reinforcing steel bar before rust on the reinforced concrete test piece with the mass of m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ under the monitoring of the veneering sensor;
3.3, realizing a simulation experiment of steel bar corrosion in a current acceleration corrosion mode, controlling the current density to be the same, and electrifying a reinforced concrete test piece corresponding to the mass m 1Ⅰ,m2Ⅰ,m3Ⅰ,m4Ⅰ,m5Ⅰ,m6Ⅰ,m7Ⅰ at equal intervals for 1 day, 2 days, 3 days, 4 days, 5 days, 6 days and 7 days;
3.3, recording magnetic induction intensity data B 1Ⅱa,B2Ⅱa,B3Ⅱa,B4Ⅱa,B5Ⅱa,B6Ⅱa,B7Ⅱa of the calibrated steel bar facing to one side of the protective layer under the monitoring of the built-in sensor after the reinforced concrete test piece is corroded; calibrating magnetic induction intensity data B 1Ⅱb,B2Ⅱb,B3Ⅱb,B4Ⅱb,B5Ⅱb,B6Ⅱb,B7Ⅱb of one side of the reinforcing steel bar, which is back to the protective layer, after corrosion;
3.4, recording magnetic induction intensity data B 1Ⅱc,B2Ⅱc,B3Ⅱc,B4Ⅱc,B5Ⅱc,B6Ⅱc,B7Ⅱc of the calibrated steel bar under monitoring of the veneering type sensor after the reinforced concrete test piece is corroded;
3.5, taking out the rusted steel bar, cutting off the parts coated with epoxy resin at the two ends, removing rust on the surface of the steel bar by using a rust remover, weighing, and recording the quality data of the steel bar as m 1Ⅱ,m2Ⅱ,m3Ⅱ,m4Ⅱ,m5Ⅱ,m6Ⅱ,m7Ⅱ;
3.4, calculating the mass change rate delta m 1,△m2,△m3,△m4,△m5,△m6,△m7 of the calibration steel bar respectively, wherein the calculation formulas are respectively shown in formulas (1) to (7);
3.5 respectively calculating the magnetic induction intensity change rate DeltaB 1a、△B2a、△B3a、△B4a、△B5a、△B6a、△B7a at the side of the reinforcing steel bar facing the protective layer and the magnetic induction intensity change rate DeltaB 1b、△B2b、△B3b、△B4b、△B5b、△B6b、△B7b at the side of the reinforcing steel bar facing away from the protective layer under the monitoring of the built-in sensor, wherein the calculation formulas are respectively shown in formulas (8) to (14);
3.6 calculating the change rate delta B 1c、△B2c、△B3c、△B4c、△B5c、△B6c、△B7c of the magnetic induction intensity of the steel bar under the monitoring of the veneering type sensor, wherein the calculation formulas are respectively shown in formulas (15) to (21);
3.6, respectively carrying out linear fitting on the relation between the mass change rate of the steel bar and the magnetic induction intensity change rate of the Hall sensors at the two sides under the monitoring of the built-in sensors to obtain a linear relation coefficient alpha a、αb; under the detection of the veneering sensor, performing linear fitting on the relation between the steel bar mass change rate and the magnetic induction intensity change rate of the Hall sensor to obtain a linear relation coefficient alpha c;
fourth, the procedure for the assay is as follows:
4.1, before the rust of the test piece to be tested is recorded, the magnetic induction intensity B 0Ⅰa、B0Ⅰb at the lower two sides of the test piece to be tested is monitored by the built-in sensor, and the magnetic induction intensity B 0Ⅰc is monitored by the veneered sensor;
4.2, placing the reinforced concrete to be tested in an environment which is easy to cause corrosion of the reinforced concrete, so as to promote the corrosion of the reinforced concrete;
4.3, placing the rusted test piece to be tested back to the original position, and recording the magnetic induction intensity B 0Ⅱa、B0Ⅱb on the two lower sides monitored by the built-in sensor and the magnetic induction intensity B 0Ⅱc monitored by the veneered sensor after the steel bar is rusted;
4.4, the corrosion rate P of the reinforcing steel bar is calculated as formula (22);
Pa＝αa(B0Ιa-B0ΙΙa),Pb＝αb(B0Ιb-B0ΙΙb),Pc＝αc(B0Ιc-B0ΙΙc) (22)
Wherein, P a is the corrosion rate of reinforcing bar towards protective layer one side, P b is the corrosion rate of backing to protective layer one side, and P c is the corrosion rate of reinforcing bar under the monitoring of wainscot formula sensor.
4.4, Defining the non-uniform corrosion of the reinforcing steel bar as R, wherein the larger R is, the more serious the non-uniform corrosion of the reinforcing steel bar is, and the formula is (23);
R＝Pa/Pb (23)。
The double-magnetic-circuit four-measuring-point built-in sensor comprises a left built-in sensor magnetic core 3-2, a right built-in sensor magnetic core 3-1, a built-in sensor permanent magnet 4-1, a first Hall sensor 1-1, a second Hall sensor 1-2, a third Hall sensor 1-3, a fourth Hall sensor 1-4 and a built-in sensor packaging shell 9; the middle part of the upper end of the built-in sensor packaging shell is provided with a reinforcement bayonet used for clamping reinforcement to be tested, the built-in sensor packaging shell 9 comprises a built-in sensor inner shell and a built-in sensor outer shell packaging cover 9-12, the built-in sensor inner shell is provided with a first Hall sensor placing groove 9-1, a second Hall sensor placing groove 9-2, a third Hall sensor placing groove 9-3, a fourth Hall sensor placing groove 9-4, a built-in sensor left magnetic core groove 9-5, a built-in sensor right magnetic core groove 9-6, a built-in sensor permanent magnet groove 9-7, a first cable bending space 9-10 and a first cable bending space 9-11, the first Hall sensor placing groove 9-1, the second Hall sensor placing groove 9-2, the third Hall sensor placing groove 9-3, the fourth Hall sensor placing groove 9-4 are all arranged in the bayonet, the built-in sensor permanent magnet groove 9-7 is positioned between the built-in sensor left magnetic core groove 9-5 and the built-in sensor right magnetic core groove 9-10, and the cable bending space 9-11 is arranged below the built-in sensor right magnetic core groove 9-5, and the built-in sensor permanent magnet groove 9-10 is arranged at the bottom of the first cable bending space 9-10; the inner shell of the built-in sensor and the packaging cover 9-12 of the outer shell of the built-in sensor are respectively provided with a first fixing hole 9-8 and a second fixing hole 9-9; the built-in sensor permanent magnet 4-1 is connected with the left built-in sensor magnetic core 3-2 and the right built-in sensor magnetic core 3-1; the first Hall sensor 1-1 and the second Hall sensor 1-2 and the third Hall sensor 1-3 and the fourth Hall sensor 1-4 are symmetrically arranged by taking the center line of a steel bar bayonet as an axis, and are respectively and correspondingly arranged in Hall sensor placement grooves of the built-in sensor packaging shell according to numbers; two fixed ends 12-1 and 12-2 are arranged at the left end and the right end of the built-in sensor, wire holes are respectively arranged at the two fixed ends, and a plastic binding wire can be used for penetrating the wire holes and binding the fixed ends with the steel bars 2 to be tested so as to fix the sensor integrally.
The veneered sensor comprises a veneered sensor fifth Hall sensor 1-5, a sixth Hall sensor 1-6, a veneered sensor front magnetic core 3-3, a veneered sensor rear magnetic core 3-4, a veneered sensor permanent magnet 4-2 and a veneered sensor packaging shell 10; the veneered sensor packaging outer shell 10 comprises a veneered sensor inner shell and a veneered sensor packaging cover 10-10; the inner shell of the veneered sensor is provided with a fifth Hall sensor placing groove 10-1, a sixth Hall sensor placing groove 10-2, a front magnetic core placing groove 10-3 of the veneered sensor, a rear magnetic core placing groove 10-4 of the veneered sensor, a permanent magnet placing groove 10-5 of the veneered sensor, a second cable bending space 10-8 and a second wire hole 10-9; the inner shell of the veneered sensor and the packaging cover 10-10 of the veneered sensor are respectively provided with a third fixing hole 10-6 and a fourth fixing hole 10-7;
The data processing unit comprises a signal collector 5, a signal processor 6 and a central controller 7, wherein the input end of the signal collector 5 is electrically connected with the signal output end of the Hall sensor, the output end of the signal collector 5 is electrically connected with the signal input end of the signal processor 6, and the signal output end of the signal processor 6 is electrically connected with the port of the central controller 7.
Further, in the built-in sensor, the first Hall sensor 1-1, the second Hall sensor 1-2, the third Hall sensor 1-3 and the fourth Hall sensor 1-4 are symmetrically arranged; in the veneered sensor, the fifth Hall sensor 1-5 and the sixth Hall sensor are symmetrically arranged 1-6.
The left magnetic core 3-2 of the built-in sensor and the right magnetic core 3-1 of the built-in sensor are E-shaped magnetic cores with two openings symmetrically arranged inwards. The upper end connecting line of the first pair of magnetic core openings coincides with the tangent line at the top end of the steel bar 2 to be tested, the second pair of magnetic core openings are arranged into circular arcs, the bottom end connecting line coincides with the tangent line at the bottom end of the steel bar 2 to be tested, the third pair of magnetic core openings are connected with the built-in sensor permanent magnet 4-1, the magnetic induction lines following the principle of 'shortest path' can be ensured to penetrate through the rust area to the greatest extent, and great difference of medium relative magnetic permeability exists in the magnetic field area. The steel bars with different sizes can be clamped according to the changing of the opening distance of the magnetic core; the front magnetic core 3-3 of the veneered sensor and the rear magnetic core 3-4 of the veneered sensor are of symmetrical structures and are rectangular in section.
The magnetic cores of the built-in sensor and the veneering sensor are made of silicon steel.
The permanent magnets of the built-in sensor and the veneered sensor are made of neodymium nickel boron (Nd 2Fe14 B).
The sensor packaging shells of the built-in sensor and the veneering sensor are made of plastic materials.
The signal collector 5 of the built-in sensor is respectively provided with a first indicating lamp 8-1 and a second indicating lamp 8-2. The first indicator light 8-1 and the second indicator light 8-2 of the built-in sensor respectively prompt whether the two circuits in the signal collector 5 work normally. A third circuit indicator lamp 8-3 is arranged between the signal collector 5 of the veneering sensor and the fifth Hall sensor 1-5 and between the signal collector of the veneering sensor and the sixth Hall sensor 1-6, and the third indicator lamp 8-3 prompts whether the circuit works normally or not.
The built-in sensor packaging shell and the built-in sensor packaging cover 9-12 comprise a first fixing hole 9-8 and a second fixing hole 9-9; the veneered sensor packaging shell and the sensor packaging cover comprise a third fixing hole 10-6 and a fourth fixing hole 10-7 which are threaded holes, and are connected through bolts by corresponding bolts and nuts during installation. The screw and the nut are made of brass, so that the magnetic field is prevented from being disturbed.
The built-in sensor is built in the reinforced concrete test piece 11 and is fixed on a section to be tested of the reinforced bar to be tested through a plastic binding wire; the veneering sensor is externally attached to the reinforced concrete test piece 11.
The permanent magnets of the built-in sensor and the veneered sensor are all required to be placed in a magnetic insulation environment after being detected together with the magnetic core, so that the influence of demagnetization of the permanent magnets on detection precision is avoided.
The built-in sensor is built in the reinforced concrete test piece 11, so that real-time dynamic monitoring is realized. The concrete can also protect the sensor from external disturbance, so that the measurement accuracy is ensured.
The first Hall sensor 1-1, the second Hall sensor 1-2, the third Hall sensor 1-3 and the fourth Hall sensor 1-4 of the built-in sensor are symmetrically arranged in pairs by taking the center line of a reinforcing steel bar bayonet as an axis; the fifth Hall sensor 1-5 and the sixth Hall sensor 1-6 of the veneered sensor are symmetrically arranged by taking the central line of a bayonet as an axis.
As an improvement, a fixing mode of the magnetic sensor is designed, two fixing ends 12-1 and 12-2 are arranged at the left end and the right end of the built-in sensor, wire holes are respectively formed, a plastic binding wire is used for penetrating through the wire holes and binding the fixing ends with steel bars, so that the sensor is integrally fixed, and the phenomenon that the dislocation occurs and the test effect is influenced is avoided.
The veneering sensor can monitor the non-uniform corrosion of the reinforcing steel bars, and can be used repeatedly and used for flow monitoring.
The built-in sensor and the veneered sensor packaging shell both contain circuit board connecting cable bending spaces, namely a first cable bending space 9-10 and a second cable bending space 10-8, so as to ensure that a circuit can be effectively bent; the first wire hole 9-11 and the second wire hole 10-9 are respectively arranged to ensure that the line effectively connects the intensity monitoring unit with the data processing unit.
The data processing unit of the built-in sensor can be realized by utilizing the existing mature technology, and mainly comprises the steps of controlling working current of a coil, measuring magnetic induction intensity values of a first Hall sensor 1-1 and a second Hall sensor 1-2 so as to calculate corrosion rate of one side of a steel bar 2 to be measured facing a protective layer, measuring magnetic induction intensity values of a third Hall sensor 1-3 and a fourth Hall sensor 1-4 so as to calculate corrosion rate of one side of the steel bar 2 facing away from the protective layer, and comparing the corrosion rates of two sides so as to analyze non-uniform corrosion degree of the steel bar 2 to be measured; the data processing unit of the veneering sensor and the related control circuit thereof can be realized by utilizing the prior mature technology and mainly comprises the steps of measuring the magnetic induction intensity values of the fifth Hall sensor 1-5 and the sixth Hall sensor 1-6 so as to calculate the corrosion rate of the reinforcing steel bars along the length direction. The magnetic induction intensity measuring system and the data processing system complete data storage, post-processing and real-time display through the signal processor 6 and the central controller 7.
Example 2 identical test RC beams (800 mm×100mm×150 mm) were prepared, with a2 Φ16 HPB300 plain round bar at the bottom as a longitudinal bar, with 2 Φ10 bars standing up, Φ6@100 stirrups, and a protective layer thickness of 20mm. The cement adopts P.I 42.5 cement; the fine aggregate adopts river sand with the fineness modulus of 2.5-2.6 mm, and the mud content is not more than 1.5%; the coarse aggregate adopts broken limestone with continuous grading of 5-20 mm; the water is purified water. Table 1 shows the concrete mix ratio.
Before pouring, fixing the 4 built-in magnetic sensors with 16mm bayonet sizes at the middle-span positions of each longitudinal rib of each test RC beam by using plastic tie wires respectively, and ensuring that the sensors cannot move.
TABLE 1 concrete mix ratio
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And (5) standard curing for 28 days in a curing room after casting and molding. After curing, the initial magnetic induction intensity values of the 4 magnetic sensors are recorded. And using a face-mounted sensor to detect the magnetic induction intensity value from the support to the steel bar in the span.
Concentrated loads of 30kN were applied to the midspan of each of the 2 test beams, and after the application, the sides were coated with epoxy resin, and only the upper and lower surfaces of 100mm×800mm were used as the penetration surfaces of chloride ions. All the loaded components were then placed in a multi-functional test box simulating the climatic environment of tidal range chloride, and the readings of each sensor were monitored in real time. From the test data, the change rate of the magnetic field intensity on the side facing the protective layer is larger than that on the side facing away from the protective layer, which indicates that the reinforcing steel bar is suffering from non-uniform corrosion. And taking out the rusted RC beam from the test box, detecting the magnetic induction intensity value of the rusted steel bars from the support to the span by using a veneered sensor, and calculating the magnetic induction intensity change rate by combining the magnetic induction intensity value before rusting.
And analyzing data, namely comprehensively analyzing the non-uniform corrosion of the steel bars on the section and the corrosion condition of the steel bars along the length direction to obtain the corrosion condition of the steel bars from local to whole.
In specific implementation, the invention does not limit the specific device model, as long as the components can complete the functions.
Finally, it should be noted that the specific examples listed above for the new configuration of concrete for the measurement laboratory are not limiting of the invention. The process and method of sampling reinforced concrete structures from existing projects of embedded built-in sensors are completely consistent and will not be described in detail herein.
The embodiments of the present invention described herein are merely examples of implementation forms of the inventive concept, and the scope of protection of the present invention should not be construed as being limited to the specific forms set forth in the embodiments, but also equivalent technical means as will occur to those skilled in the art based on the inventive concept.
Claims (5)
1. The utility model provides a joint magnetic sensor of inhomogeneous corrosion of monitoring reinforcing bar cross-section and along axial corrosion which characterized in that: the device comprises a magnetic induction intensity monitoring unit and a data processing unit, wherein the magnetic induction intensity monitoring unit comprises a double-magnetic circuit four-measuring-point built-in sensor for detecting the non-uniform corrosion condition of the section of a steel bar and a veneering type sensor for detecting the corrosion condition of the steel bar along the length direction, the double-magnetic circuit four-measuring-point built-in sensor is built in a reinforced concrete test piece and is fixed on a section to be detected of the steel bar through a plastic binding wire, and the veneering type sensor is externally attached to the surface of the reinforced concrete test piece;
The double-magnetic-circuit four-measuring-point built-in sensor comprises a left built-in sensor magnetic core, a right built-in sensor magnetic core, a built-in sensor permanent magnet, a first Hall sensor, a second Hall sensor, a third Hall sensor, a fourth Hall sensor and a built-in sensor packaging shell; the middle part of the upper end of the built-in sensor packaging shell is provided with a reinforcement bayonet used for clamping a reinforcement to be tested, the built-in sensor packaging shell comprises a built-in sensor inner shell and a built-in sensor outer shell packaging cover, a first Hall sensor placing groove, a second Hall sensor placing groove, a third Hall sensor placing groove, a fourth Hall sensor placing groove, a built-in sensor permanent magnet groove, a built-in sensor left magnetic core groove, a built-in sensor right magnetic core groove, a first cable bending space and a first wire hole, the first Hall sensor placing groove, the second Hall sensor placing groove, the third Hall sensor placing groove and the fourth Hall sensor placing groove are all arranged in the reinforcement bayonet, the built-in sensor permanent magnet groove is positioned between the built-in sensor left magnetic core groove and the built-in sensor right magnetic core groove, the first cable bending space is positioned below the built-in sensor permanent magnet groove, and the first wire hole is arranged at the bottom of the built-in sensor packaging shell and is communicated with the first cable bending space; the built-in sensor permanent magnet is connected with the left magnetic core and the right magnetic core of the built-in sensor at the same time, and is arranged in the built-in sensor permanent magnet groove, and the first Hall sensor, the second Hall sensor, the third Hall sensor and the fourth Hall sensor are symmetrically arranged by taking the center line of a steel bar bayonet as an axis, and are respectively arranged in the corresponding Hall sensor placing groove; the built-in sensor inner shell and the built-in sensor outer shell packaging cover are respectively provided with a first fixing hole and a second fixing hole;
The veneering sensor comprises a veneering sensor permanent magnet, a veneering sensor front magnetic core, a veneering sensor rear magnetic core, a veneering sensor packaging shell, a fifth Hall sensor and a sixth Hall sensor, wherein the veneering sensor packaging shell comprises a veneering sensor inner shell and a veneering sensor packaging cover, a fifth Hall sensor placing groove, a sixth Hall sensor placing groove, a veneering sensor front magnetic core placing groove, a veneering sensor rear magnetic core placing groove, a veneering sensor permanent magnet placing groove, a second cable bending space and a second wire hole, and the second wire hole is communicated with the second cable bending space; the veneering sensor permanent magnet is connected with the front magnetic core and the rear magnetic core of the veneering sensor at the same time and is arranged in the veneering sensor permanent magnet placing groove, the fifth Hall sensor and the sixth Hall sensor are arranged in a front-back symmetrical mode and are respectively arranged in the corresponding Hall sensor placing groove, and the inner shell of the veneering sensor and the packaging cover of the veneering sensor are respectively provided with a third fixing hole and a fourth fixing hole;
The data processing unit comprises a signal collector, a signal processor and a central controller, wherein the input end of the signal collector is electrically connected with the signal output end of the Hall sensor, the output end of the signal collector is electrically connected with the signal input end of the signal processor, and the signal output end of the signal processor is electrically connected with the port of the central controller;
The left magnetic core of the built-in sensor and the right magnetic core of the built-in sensor are E-shaped magnetic cores with two openings symmetrically arranged inwards, the upper end connecting lines of the openings of the first pair of magnetic cores coincide with the tangent line of the top end of the steel bar to be tested, the openings of the second pair of magnetic cores are arranged into circular arcs, the bottom end connecting lines coincide with the tangent line of the bottom end of the steel bar to be tested, and the openings of the third pair of magnetic cores are connected with the permanent magnets of the built-in sensor; the front magnetic core of the veneering sensor and the rear magnetic core of the veneering sensor are of symmetrical structures and are rectangular in section;
Calculating the corrosion rate of the side of the steel bar to be measured facing the protective layer through the magnetic induction intensity values of the first Hall sensor and the second Hall sensor, calculating the corrosion rate of the side of the steel bar to be measured facing away from the protective layer through the magnetic induction intensity values of the third Hall sensor and the fourth Hall sensor, and comparing the corrosion rates of the two sides to analyze the non-uniform corrosion degree of the steel bar to be measured; and the rust rate of the steel bar along the length direction is calculated through the magnetic induction intensity values of the fifth Hall sensor and the sixth Hall sensor.
2. The joint magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a rebar cross-section of claim 1, wherein: the first Hall sensor, the second Hall sensor and the signal collector are provided with a first circuit indicator lamp therebetween, the third Hall sensor, the fourth Hall sensor and the signal collector are provided with a second circuit indicator lamp therebetween, and the fifth Hall sensor, the sixth Hall sensor and the signal collector are provided with a third circuit indicator lamp therebetween.
3. A combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a rebar cross-section as in claim 1 or 2, wherein: two fixed ends are arranged at the left end and the right end of the double-magnetic-circuit four-measuring-point built-in sensor, wire holes are respectively formed in the two fixed ends, a plastic binding wire penetrates through the wire holes, and the fixed ends are bound with the steel bars to be measured.
4. A combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a rebar cross-section as in claim 1 or 2, wherein: the built-in sensor permanent magnet and the veneering sensor permanent magnet are made of neodymium nickel boron, and the left magnetic core of the built-in sensor, the right magnetic core of the built-in sensor, the front magnetic core of the veneering sensor and the rear magnetic core of the veneering sensor are made of silicon steel; the built-in sensor packaging shell and the veneered sensor packaging shell are made of plastic materials.
5. A test method based on the combined magnetic sensor for monitoring non-uniform corrosion and axial corrosion of a section of steel bar according to claim 1, wherein: the method comprises the following steps: calculating the corrosion rate of the side of the steel bar to be measured facing the protective layer through the magnetic induction intensity values of the first Hall sensor and the second Hall sensor, calculating the corrosion rate of the side of the steel bar to be measured facing away from the protective layer through the magnetic induction intensity values of the third Hall sensor and the fourth Hall sensor, and comparing the corrosion rates of the two sides to analyze the non-uniform corrosion degree of the steel bar to be measured; and the rust rate of the steel bar along the length direction is calculated through the magnetic induction intensity values of the fifth Hall sensor and the sixth Hall sensor.
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