Cement concrete internal defect detection device and method based on ultrasonic technology

Abstract

The invention relates to a cement concrete internal defect detection device and method based on an ultrasonic technology, and belongs to the technical field of ultrasonic detection. Comprising a model processing terminal which is preset with multiple processing stages; the scanner is in communication connection with the model processing terminal, and the model processing terminal performs first-level grid division and second-level grid division on the basis of data acquired by the scanner; the ultrasonic detector is used for detecting defects in the concrete; the core drilling machine is used for coring and sampling the defects; the positioning support is provided with a positioning table, the positioning table slides relative to the positioning support, the scanner, the ultrasonic detector and the core drilling machine are detachably installed on the positioning table, and the positioning support is used for controlling the ultrasonic detector and the core drilling machine to conduct detection at a first-stage collection point and a second-stage collection point. The method is used for solving the technical problems that in the prior art, auxiliary positioning and to-be-detected surface pretreatment are needed, the number of process steps is large, and the machining efficiency is low.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic testing technology, and specifically relates to a device and method for detecting internal defects in cement concrete based on ultrasonic technology. Background Technology

[0002] In the flaw detection process of bridges and pavements, it is necessary to detect and treat defects inside the concrete. During the inspection process of bridge and pavement slabs, the position of the reinforcing bars needs to be marked first, and then the detection position needs to be marked using auxiliary tools. Since there are many types of flaws in the areas to be detected and the concrete surface is not smooth, it is necessary to actively fill and fill with coupling agent. When measuring defects, the transducer installation position needs to be mapped according to the arrangement of the reinforcing bars. Finally, the voids and non-compact points in the concrete are collected accordingly.

[0003] Patent CN213715126U discloses a portable ultrasonic concrete detector, relating to the technical field of equipment for construction engineering. This utility model includes a detector body with detection head assemblies electrically connected to the middle of both sides of the body. Each detection head assembly includes a main detection head, a secondary detection head, a conductive tube, and a conductive rod. The conductive tubes on both sides of the detector body are threadedly and electrically connected to the conductive rod connected to the outer middle of the connector. The main detection head is electrically connected to one end of a connecting wire on one side of the detector body. Protective components are connected to both sides and the rear middle of the detector body. These protective components include L-shaped side plates, a first cover plate, and a second cover plate. The L-shaped side plates are connected to the middle of both sides of the detector body, and the first and second cover plates are connected to the upper and lower ends of the rear middle of the detector body. A pull handle is connected to the middle of the inner end of the L-shaped side plate.

[0004] The existing technology has at least the following problems in its use:

[0005] When using general-purpose portable ultrasonic testing instruments to detect concrete structures on-site, auxiliary positioning and pretreatment of the surface to be tested are required. Existing technologies involve many steps and reduce processing efficiency. Summary of the Invention

[0006] This invention provides a device and method for detecting internal defects in cement concrete based on ultrasonic technology. It addresses the technical problem that existing technologies using general-purpose portable ultrasonic testing instruments require auxiliary positioning and pretreatment of the surface to be tested during on-site detection of concrete structures, resulting in numerous steps and reduced processing efficiency.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] An ultrasonic-based device for detecting internal defects in cement concrete includes: a model processing terminal with multiple processing stages, used to collect information to be detected; a scanner, communicatively connected to the model processing terminal, used to spatially locate the reinforcing bars inside the concrete and measure the dimensions of the structure to be detected, the model processing terminal dividing the data collected by the scanner into primary and secondary grids to form corresponding primary and secondary acquisition points; an ultrasonic testing instrument, communicatively connected to the model processing terminal, used to detect defects inside the concrete at the primary and secondary acquisition points; a core drill, communicatively connected to the model processing terminal, used to extract core samples from the defects; and a positioning bracket with a first driving direction and a second driving direction, a positioning platform mounted on the positioning bracket, the positioning platform sliding relative to the positioning bracket, the scanner, the ultrasonic testing instrument, and the core drill detachably mounted on the positioning platform, the positioning bracket communicatively connected to the model processing terminal, used to control the ultrasonic testing instrument and the core drill to perform detection at the primary and secondary acquisition points.

[0009] Furthermore, the scanner includes: an electromagnetic rebar scanning unit for outputting the three-dimensional coordinates and diameter parameters of the rebar; and a three-dimensional laser scanning unit for acquiring a three-dimensional surface model of the concrete structure to be inspected, so as to determine the length, width, and thickness of the structure.

[0010] Furthermore, the model processing terminal is pre-set with a rebar avoidance algorithm and a mesh generation module. The rebar avoidance algorithm calculates the minimum distance between the sampling point and the edge of the rebar based on the rebar coordinates output by the electromagnetic rebar scanning unit.

[0011] An internal defect detection method includes the following steps: Step S1: Preprocessing and model building, controlling the scanner to scan the concrete structure to be inspected, the electromagnetic rebar scanning unit to collect the three-dimensional coordinates (x, y, z) and diameter parameters of the rebar, the three-dimensional laser scanning unit to collect the structural dimensions (Lx, Ly, Lz), the model processing terminal to receive the scan data and generate a rebar-structure associated three-dimensional model; Step S2: Primary mesh generation and initial inspection, the model processing terminal calls the rebar avoidance algorithm, calculates the primary sampling interval according to the formula, and generates rebar-avoiding primary sampling points; controlling the positioning bracket to drive the ultrasonic detector along the X / Y axis linear module, and sequentially collects the sound velocity (v), amplitude (A), and frequency (f) parameters at each primary sampling point; Step S3: Suspicious area marking, setting thresholds for each parameter according to process requirements, and marking the detected sound... Thresholds are set for velocity and amplitude, and four types of defects are preset: voids or honeycombs are defined as Class A defects, structural cracks as Class B defects, density defects as Class C defects, and joint surface defects as Class D defects. Step S4: Secondary mesh generation and fine inspection. The model processing terminal expands the suspicious area to form a secondary detection zone. The grid where the secondary acquisition point is located is determined by 1 / 5 to 1 / 3 of the defect size. The control positioning bracket drives the ultrasonic detector to scan at the secondary acquisition point to generate a defect scanning image and calibrate the defect size and type. Step S5: Tertiary verification and report generation. If the secondary detection defect information exceeds the standard, the core drilling machine is installed and the control positioning bracket is switched to take a core at the defect center for verification. The model processing terminal integrates the tertiary data, updates the 3D model, and outputs a detection report containing defect coordinates, type, and treatment suggestions.

[0012] Further, step S2 includes the following steps: Step S2.1, the first-level sampling grid spacing D1 must simultaneously satisfy the following constraints: Constraint 1: detect the smallest defect; Constraint 2: adapt to the transducer wavelength; Constraint 3: cover the thickness of the component. The three constraints are defined by the following formulas:

[0013] D1=min(2d min ,3λ,H / 5);

[0014] Constraint 1 is 2d min The spacing should be ≤2 times the minimum defect size to ensure that the defect is covered by at least one sampling point;

[0015] Constraint 2 is 3λ, and the spacing is ≤3 times the wavelength to avoid signal distortion caused by sound wave diffraction;

[0016] Constraint 3 is H / 5, and the spacing is ≤ 1 / 5 of the component thickness to ensure that the detection direction covers the entire thickness;

[0017] Step S2.2: Within the component inspection plane, divide the area into uniform grids according to D1. Set the starting coordinates of the inspection plane and compensate the component edges by 50mm to avoid edge effects. Step S2.3: Adjust the reinforcement avoidance. Remove sampling points that overlap with the reinforcement. For each initially divided sampling point, calculate its horizontal distance from all reinforcements. If a sampling point enters the reinforcement influence zone, remove that point and add a new sampling point in its adjacent position. Step S2.4: Initial inspection and invalid point removal. Use an ultrasonic testing instrument to collect information from each primary sampling point, excluding component boundaries and hole areas. If a sampling point is located outside the component boundary or the corresponding position is a reserved hole, it is marked as an invalid point and will not be inspected.

[0018] Further, step S3 includes the following steps: Step S3.1, Preprocessing of detection parameters: The model processing terminal calls the detection ambient temperature (t) collected by the environmental sensor to perform temperature compensation on the sound velocity (v) collected in the first stage. The compensation formula is V t =V 20 ×[1+0.015×(t-20)], where V 20 The standard sound velocity of concrete at 20℃ is used, and the amplitude (A) is calibrated to eliminate coupling differences at different acquisition points; Step S3.2, setting the threshold range for four types of defects and verifying the preset parameters:

[0019] The threshold range for Class A defects is: V t <0.85V std And A<A std -25dB;

[0020] The threshold range for Class B defects is: acoustic time difference Δt between cross-slit and non-cross-slit defects > 150 μs and amplitude reduction ≥ 30%;

[0021] The threshold range for Class C defects is: V t <0.95V std And the frequency drift is greater than 3kHz;

[0022] The threshold range for Class D defects is: combined with a surface acoustic time difference > 20 μs and an amplitude reduction ≥ 40%;

[0023] Where V std A std The values ​​represent the average sound velocity and amplitude in the normal concrete area.

[0024] Step S3.3: Based on the data collected in step S2.4 and the data preliminarily processed in step S3.1, the defects are judged and marked by type; Step S3.4: Suspicious area is defined. The model processing terminal counts the number of consecutively marked defect points. When there are ≥3 consecutive defect points, the area where the group of defect points is located is marked as a suspicious area by extending 20mm in all directions. The area category is marked according to the defect type with the highest proportion in the area.

[0025] Further, step S4 includes the following steps: Step S4.1, determination of the secondary detection area; Step S4.2, further division of the secondary grid and arrangement of secondary sampling points; Step S4.3, high-precision ultrasonic scanning, the model processing terminal sends the coordinate sequence of secondary acquisition points to the positioning bracket, controls the positioning stage to move along the X / Y axis linear module, synchronously switches the ultrasonic detector to phased array mode, increases the sampling frequency to twice the preset value of the primary acquisition point, and increases the gain by 10dB-15dB; the scanning mode is adjusted for different defect types, B-type defects are collected by scanning along the defect direction and scanning perpendicular to the defect direction, and A-type, C-type, and D-type defects are sampled by fixed-point grid scanning, and the position is fed back in real time by the grating ruler displacement sensor of the positioning bracket during the scanning process; the model processing terminal receives the secondary sampling points; Step S4.4, defect size and type calibration, the primary preliminary judgment result is compared with the secondary imaging result and integrated. If the secondary result is consistent with the primary result, the precise size of the defect is updated. If they are inconsistent, the defect type is corrected and the corresponding defect evaluation standard is rematched; defects in the secondary detection area that exceed the specification limit are marked.

[0026] This invention provides a device and method for detecting internal defects in cement concrete based on ultrasonic technology, with the following advantages:

[0027] By dividing the grid into primary and secondary grids, rapid defect localization is achieved using the primary grid, while the secondary grid enables concentrated defect segmentation and detailed defect capture, thereby improving detection efficiency and accuracy.

[0028] Defects are verified by core drilling using a positioning bracket and positioning table-assisted scanner and ultrasonic testing instrument sampling, and a core drilling machine to check for defects.

[0029] By optimizing the grid division algorithm and using internal preset schemes for line drawing and positioning, the process of manual mapping and positioning is reduced, thereby improving detection efficiency, positioning accuracy, and the precision of detection points. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating a method for detecting internal defects in cement concrete based on ultrasonic technology, provided in an embodiment of the present invention. Detailed Implementation

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0033] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to welding, bolting, or riveting; they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] Example:

[0037] An ultrasonic-based device for detecting internal defects in cement concrete includes: a model processing terminal with multiple processing stages, used to collect information to be detected; a scanner, communicatively connected to the model processing terminal, used to locate the spatial position of reinforcing bars inside the concrete and measure the dimensions of the structure to be detected, the model processing terminal dividing the data collected by the scanner into primary and secondary grids to form corresponding primary and secondary acquisition points; an ultrasonic detector, communicatively connected to the model processing terminal, used to detect internal defects in the concrete at the primary and secondary acquisition points; a core drill, communicatively connected to the model processing terminal, used to extract core samples from the defects; and a positioning bracket with a first driving direction and a second driving direction, a positioning platform mounted on the positioning bracket, the positioning platform sliding relative to the positioning bracket, the scanner, the ultrasonic detector, and the core drill detachably mounted on the positioning platform, the positioning bracket communicatively connected to the model processing terminal, used to control the ultrasonic detector and the core drill to perform detection at the primary and secondary acquisition points.

[0038] In this embodiment, the model processing terminal uses an industrial-grade laptop computer, pre-installed with BIM modeling software and customized detection algorithm programs. The multi-level processing stages are implemented through modular software design, and it can receive data transmitted from components such as scanners and ultrasonic testing instruments in real time. The scanner is a combination of a ZBL-R630 electromagnetic rebar scanner and a FaroFocusS70 3D laser scanner. The core drilling machine is an HZ-200 type concrete core drilling machine, which is fixed by a magnetic base on the positioning platform. The positioning bracket adopts an aluminum profile splicing structure, with the first driving direction being the X-axis and the second driving direction being the Y-axis. It is driven by a linear module, which is equipped with a servo motor and a grating ruler displacement sensor. At least four magnetic positioning seats are arranged on the positioning platform. The scanner, ultrasonic testing instrument, and core drilling machine are connected to the positioning seats through quick-release connectors. The motion control commands of the positioning bracket are communicated by the model processing terminal through a bus.

[0039] Furthermore, the scanner includes: an electromagnetic rebar scanning unit for outputting the three-dimensional coordinates and diameter parameters of the rebar; and a three-dimensional laser scanning unit for acquiring a three-dimensional surface model of the concrete structure to be inspected, in order to determine the length, width, and thickness of the structure.

[0040] In this embodiment, the electromagnetic rebar scanning unit has a built-in dual-coil detection module that identifies the position of the rebar through the principle of electromagnetic induction. When working, it needs to be in close contact with the concrete surface. The scanning path is driven by the positioning bracket, and the step size is set to be less than the minimum spacing of the rebar to avoid missed detection. The output three-dimensional coordinates (x, y, z) of the rebar are imported into the BIM software of the model processing terminal for subsequent mesh generation.

[0041] Furthermore, the model processing terminal is pre-loaded with a rebar avoidance algorithm and a mesh generation module. The rebar avoidance algorithm calculates the minimum distance between the sampling point and the edge of the rebar based on the rebar coordinates output by the electromagnetic rebar scanning unit.

[0042] In this embodiment, the core of the rebar avoidance algorithm is the Euclidean distance calculation formula:

[0043] Where (x) p y p (x) represents the sampling point, and its planar coordinates are (x, y). r y rThe coordinates of the center plane of the rebar are shown in the image. The algorithm's preset safe distance for avoiding rebar varies depending on the component type: the avoidance distance for load-bearing structures must be greater than or equal to 30mm, and the avoidance distance for non-load-bearing structures must be greater than or equal to 20mm. When the calculated minimum distance is less than the safe distance, the algorithm automatically marks the sampling point as a "point to be avoided" and offsets it by D1 / 2 along the vertical length of the rebar at its adjacent position, where D1 is the first-level sampling interval, to generate a new sampling point, ensuring that the grid coverage rate after avoidance is ≥95%. The grid generation module has two built-in subroutines: a first-level grid generation subroutine and a second-level grid generation subroutine. The first-level grid generation subroutine calls the following formula:

[0044] D1=min(2d min ,3λ,H / 5);

[0045] Where d min =λ / 2, where λ is the ultrasonic wave length, and V is the standard sound velocity at 20℃. 20 =4500m / s, transducer frequency f=50kHz, calculated λ=90mm, therefore dmin=45mm, 3λ=270mm, H is the component thickness, specifically in a 200mm thick floor slab, H / 5=40mm, finally D1 takes the minimum value of 40mm; the secondary mesh generation subroutine automatically calls different formulas according to the defect type, as follows:

[0046] Type A defects (void defects) are represented by D² = max(D² - π / 2). def / 3, 10mm);

[0047] Type B defects (structural crack defects) are represented by D2 = max(ω). def / 5, 5mm);

[0048] Type C defects (density defects) are represented by D² = max(D² + π ... def / 3, 15mm);

[0049] Type D defects (structural defects) are represented by D2 = max(h def / 3, 8mm);

[0050] The module also supports manual adjustment of mesh parameters, and the completed mesh is displayed in the BIM model as a colored point cloud.

[0051] Furthermore, the method includes the following steps: Step S1: Preprocessing and model building, controlling the scanner to scan the concrete structure to be inspected, the electromagnetic rebar scanning unit acquiring the three-dimensional coordinates (x, y, z) and diameter parameters of the rebar, and the three-dimensional laser scanning unit acquiring the structural dimensions (L). x L y L zStep S2: First-level mesh generation and initial inspection. The model processing terminal calls the rebar avoidance algorithm, calculates the first-level sampling interval according to the formula, and generates rebar-avoidance type first-level acquisition points. The positioning bracket drives the ultrasonic detector along the X / Y axis linear module to collect sound velocity (v), amplitude (A), and frequency (f) parameters at each first-level acquisition point in sequence. Step S3: Suspicious area marking. According to the process requirements, the threshold values ​​of each parameter are set. The threshold values ​​of the detected sound velocity and amplitude are set, and four types of defects are preset. Specifically, voids or honeycombs are defined as Class A defects, structural cracks are defined as Class B defects, and dense... Solidity defects are defined as Class C defects, and bonding surface defects are defined as Class D defects; Step S4: Secondary mesh generation and fine inspection, the model processing terminal expands the suspicious area to form a secondary inspection area, and the mesh where the secondary acquisition point is located is determined by 1 / 5-1 / 3 of the defect size; the control positioning bracket drives the ultrasonic detector to scan at the secondary acquisition point, generate defect scanning images, and calibrate the defect size and type; Step S5: Tertiary verification and report generation, if the secondary inspection defect information exceeds the standard, the core drilling machine is installed and the control positioning bracket is switched to take cores at the defect center for verification; the model processing terminal integrates the tertiary data, updates the 3D model, and outputs an inspection report containing defect coordinates, type, and treatment suggestions.

[0052] In this embodiment, the data comparison and processing in step S5 are based on existing technology, so they will not be described in detail.

[0053] Further, step S2 includes the following steps: Step S2.1, the first-level sampling grid spacing D1 must simultaneously satisfy the following constraints: Constraint 1: detect the smallest defect; Constraint 2: adapt to the transducer wavelength; Constraint 3: cover the thickness of the component. The three constraints are defined by the following formulas:

[0054] ;

[0055] Constraint 1 is 2d min The spacing should be ≤2 times the minimum defect size to ensure that the defect is covered by at least one sampling point;

[0056] Constraint 2 is 3λ, and the spacing is ≤3 times the wavelength to avoid signal distortion caused by sound wave diffraction;

[0057] Constraint 3 is H / 5, and the spacing is ≤ 1 / 5 of the component thickness to ensure that the detection direction covers the entire thickness;

[0058] Step S2.2: Within the component inspection plane, divide the area into uniform grids according to D1. Set the starting coordinates of the inspection plane and compensate the component edges by 50mm to avoid edge effects. Step S2.3: Adjust the reinforcement avoidance. Remove sampling points that overlap with the reinforcement. For each initially divided sampling point, calculate its horizontal distance from all reinforcements. If a sampling point enters the reinforcement influence zone, remove that point and add a new sampling point in its adjacent position. Step S2.4: Initial inspection and invalid point removal. Use an ultrasonic testing instrument to collect information from each primary sampling point, excluding component boundaries and hole areas. If a sampling point is located outside the component boundary or the corresponding position is a reserved hole, it is marked as an invalid point and will not be inspected.

[0059] In this embodiment, the three-dimensional dimensions (length / width / thickness) of the component are obtained by a 3D laser scanner with an accuracy ≤1mm / m, corresponding to Lx / Ly / Lz; R i (x) i y i , z i r i Let be the parameters of the i-th rebar, where the center coordinates of the rebar are (x...). i y i , z i ), radius r i Obtained by a rebar scanner;

[0060] d min The minimum detectable defect size for the transducer is d. min =λ / 2, where λ is the length of the ultrasonic wave, and v is taken as the standard sound velocity at 20℃. 20 =4500m / s, transducer frequency f=50kHz, λ=4500 / 50000=0.09m, longitudinal wave in concrete λ=v / f, v is the speed of sound, f is the transducer frequency;

[0061] H represents the thickness value of the cross section being detected in the 3D model, corresponding to the thickness of the component in the detection direction.

[0062] Further, step S3 includes the following steps: Step S3.1: Preprocessing of detection parameters. The model processing terminal calls the detection ambient temperature (t) collected by the environmental sensor to perform temperature compensation on the sound velocity (v) collected in the first stage. The compensation formula is V t =V 20 ×[1+0.015×(t-20)], where V 20 The standard sound velocity of concrete at 20℃ is used, and the amplitude (A) is calibrated to eliminate coupling differences at different acquisition points; Step S3.2: Setting the threshold range for four types of defects and verifying the preset parameters.

[0063] The threshold range for Class A defects is: V t <0.85Vstd And A<A std -25dB;

[0064] The threshold range for Class B defects is: acoustic time difference Δt between cross-slit and non-cross-slit defects > 150 μs and amplitude reduction ≥ 30%;

[0065] The threshold range for Class C defects is: V t <0.95V std And the frequency drift is greater than 3kHz;

[0066] The threshold range for Class D defects is: combined with a surface acoustic time difference > 20 μs and an amplitude reduction ≥ 40%;

[0067] Where V std A std The values ​​represent the average sound velocity and amplitude in the normal concrete area.

[0068] Step S3.3: Based on the data collected in step S2.4 and the data preliminarily processed in step S3.1, the defects are judged and marked by type; Step S3.4: Suspicious area is defined. The model processing terminal counts the number of consecutively marked defect points. When there are ≥3 consecutive defect points, the area where the group of defect points is located is marked as a suspicious area by extending 20mm in all directions. The area category is marked according to the defect type with the highest proportion in the area.

[0069] In this embodiment, data is collected in the component detection plane, which is preset to be the xy plane. A uniform grid is divided according to D1, and the coordinates of the sampling points (x, y, ...) are... j y j Calculation formula:

[0070] x j =x start +j×D1( j=0, 1, 2, .... , n x -1);

[0071] y j =y start +k×D1( k=0, 1, 2, .... , n y -1);

[0072] x start / y start To detect the starting coordinates of the plane, and to compensate the edge of the component by 50mm to avoid edge effects;

[0073] n x =(Lx-100mm) / D1 The final value is rounded up, representing the preset number of sampling points in the x-direction, n. y =(Ly-100mm) / D1 The final value is rounded up, representing the preset number of sampling points in the y-direction;

[0074] Parameter input: Import component 3D dimensions (L) x L y L z ), Reinforcing steel parameter R i Transducer parameters (f), safety distance for rib protection S safe ;

[0075] Basic spacing calculation: Calculate D1 according to the formula. If D1 < 30mm (minimum practical spacing), then take D1 = 30mm; Initial grid division: Generate a uniform grid sampling point set;

[0076] P init ={( x j y j )};

[0077] Rebar avoidance screening: Calculate the distance between each point and the rebar, remove points within the affected area, add new points, and obtain the rebar avoidance grid;

[0078] Invalid points are removed to obtain the final set of primary sampling points, which in turn generates the movement trajectory of the automatic traction device, ensuring the highest detection efficiency.

[0079] Further, step S4 includes the following steps: Step S4.1, determination of the secondary detection area; Step S4.2, further division of the secondary grid and arrangement of secondary sampling points; Step S4.3, high-precision ultrasonic scanning, the model processing terminal sends the coordinate sequence of secondary acquisition points to the positioning bracket, controls the positioning stage to move along the X / Y axis linear module, synchronously switches the ultrasonic detector to phased array mode, increases the sampling frequency to twice the preset value of the primary acquisition point, and increases the gain by 10dB-15dB; the scanning mode is adjusted for different defect types, B-type defects are collected by scanning along the defect direction and scanning perpendicular to the defect direction, and A-type, C-type, and D-type defects are sampled by fixed-point grid scanning, and the position is fed back in real time by the grating ruler displacement sensor of the positioning bracket during the scanning process; the model processing terminal receives the secondary sampling points; Step S4.4, defect size and type calibration, the primary preliminary judgment result is compared with the secondary imaging result and integrated. If the secondary result is consistent with the primary result, the precise size of the defect is updated. If they are inconsistent, the defect type is corrected and the corresponding defect evaluation standard is rematched; defects in the secondary detection area that exceed the specification limit are marked.

[0080] In this embodiment, based on the defect type (A / B / C / D) of the primary sampling marker, the proportional conversion ratio is calculated according to the corresponding defect size, ranging from 1 / 5 to 1 / 3, to determine D2, as shown in the following formula:

[0081] Type A defects (void defects) are represented by D² = max(D² - π / 2). def / 3, 10mm);

[0082] Type B defects (structural crack defects) are represented by D2 = max(ω). def / 5, 5mm);

[0083] Type C defects (density defects) are represented by D² = max(D² + π ... def / 3, 15mm);

[0084] Type D defects (structural defects) are represented by D2 = max(h def / 3, 8mm);

[0085] The suspected area is expanded and aligned with the mesh (to adapt to the defect direction). To avoid missing defect edges, the first-level suspected area A is... sus Expanding outwards by 2×D2, we obtain the secondary detection region A. sec :

[0086] A sec =(x min -2D2,x max +2D2, y min -2D2,y max +2D2);

[0087] If the initial direction angle of the defect is θ def If the angle is ≠ 0°, then rotate the grid by θ. def This aligns the mesh orientation with the defect direction, reduces sampling point redundancy, and rotates the sampling point coordinates (x... m ′,y m ')formula:

[0088] x m =x0 + m × D2 × cosθ def -n×D2×sinθ def ;

[0089] y m =y0+m×D2×sinθ def +n×D2×cosθ def ;

[0090] (x0, y0): A sec Starting coordinates of the bottom left corner;

[0091] m = 0, 1, ..., n m -1 is the row index of the rotated grid;

[0092] n = 0, 1, ..., nn-1 are the column indices of the rotated grid;

[0093] Finally, secondary reinforcement avoidance and adjustment are performed to eliminate or offset points within the reinforcement influence zone, resulting in a secondary sampling point set. Scanning mode selection: Class B cracks: cross-scanning is used, scanning once in the defect direction and once in the perpendicular direction; Class A, C, and D defects: full sampling scan within the preset grid is used to generate corresponding scan images; Parameter setting optimization: the ultrasonic testing instrument gain is increased by 10-15dB, and the sampling frequency is increased to twice that of the first level to improve data accuracy.

[0094] In summary, by using a positioning bracket and positioning platform to assist in sampling by a scanner and ultrasonic testing instrument, and by using a core drilling machine to verify defects; by using hierarchical grid division and multi-device collaborative control, the efficiency of concrete defect detection and the accuracy of defect location are improved; by using a rebar avoidance algorithm and high-precision drive of the positioning bracket, the interference rate is reduced; by dividing into primary and secondary grids, the primary grid enables rapid defect location and the secondary grid enables centralized division and detailed capture of defects, as well as the preset of defect types, thereby improving detection efficiency and accuracy.

[0095] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for detecting internal defects in cement concrete based on ultrasonic technology, characterized in that, include: The model processing terminal has multiple processing stages and is used to collect information to be detected. The scanner is communicatively connected to the model processing terminal, and the scanner is used to locate the spatial position of the steel bars inside the concrete and to measure the size of the structure to be inspected. The model processing terminal divides the data collected by the scanner into primary and secondary grids to form corresponding primary and secondary acquisition points. An ultrasonic testing instrument, which is connected to the model processing terminal, is used to detect defects inside the concrete at the primary acquisition point and the secondary acquisition point. A core drilling machine, which is communicatively connected to the model processing terminal, is used to sample cores from defects; The positioning bracket has a first driving direction and a second driving direction. A positioning platform is provided on the positioning bracket. The positioning platform slides relative to the positioning bracket. The scanner, the ultrasonic detector, and the core drill are detachably mounted on the positioning platform. The positioning bracket is communicatively connected to the model processing terminal and is used to control the ultrasonic detector and the core drill to perform detection at the primary acquisition point and the secondary acquisition point.

2. The device for detecting internal defects in cement concrete based on ultrasonic technology according to claim 1, characterized in that, The scanner includes: The electromagnetic rebar scanning unit is used to output the three-dimensional coordinates and diameter parameters of the rebar. The three-dimensional laser scanning unit is used to acquire a three-dimensional surface model of the concrete structure to be inspected, so as to determine the length, width and thickness of the structure.

3. The device for detecting internal defects in cement concrete based on ultrasonic technology according to claim 2, characterized in that, The model processing terminal is pre-set with a rebar avoidance algorithm and a mesh generation module. The rebar avoidance algorithm calculates the minimum distance between the sampling point and the edge of the rebar based on the rebar coordinates output by the electromagnetic rebar scanning unit.

4. A method for detecting internal defects, characterized in that, The method of the ultrasonic-based cement concrete internal defect detection device according to claim 3 includes the following steps: Step S1: Preprocessing and model building. The scanner is controlled to scan the concrete structure to be inspected. The electromagnetic rebar scanning unit collects the three-dimensional coordinates (x, y, z) and diameter parameters of the rebar. The three-dimensional laser scanning unit collects the structural dimensions (Lx, Ly, Lz). The model processing terminal receives the scanning data and generates a rebar-structure associated three-dimensional model. Step S2: First-level mesh generation and initial inspection. The model processing terminal calls the rebar avoidance algorithm to calculate the first-level sampling interval according to the formula and generate rebar-avoiding first-level acquisition points. The positioning bracket drives the ultrasonic detector along the X / Y axis linear module to collect sound velocity (v), amplitude (A), and frequency (f) parameters at each first-level acquisition point in sequence. Step S3: Suspicious area marking. Based on process requirements, threshold values ​​for each parameter are set. Threshold values ​​are set for the sound velocity and amplitude of the detection. Four types of defects are preset: voids or honeycombs are defined as Class A defects, structural cracks are defined as Class B defects, density defects are defined as Class C defects, and bonding surface defects are defined as Class D defects. Step S4: Secondary mesh generation and fine inspection. The model processing terminal expands the suspicious area to form a secondary inspection area. The mesh where the secondary acquisition point is located is determined by 1 / 5 to 1 / 3 of the defect size. The positioning bracket drives the ultrasonic detector to scan at the secondary acquisition point to generate a defect scanning image and calibrate the defect size and type. Step S5: Level 3 verification and report generation. If the level 2 defect information exceeds the standard, install the core drilling machine and switch the control positioning bracket to take core samples at the defect center for verification. The model processing terminal integrates the level 3 data, updates the 3D model, and outputs an inspection report containing defect coordinates, type, and processing suggestions.

5. The method for detecting internal defects according to claim 4, characterized in that, Step S2 includes the following steps: Step S2.1: The first-level sampling grid spacing D1 must simultaneously satisfy the following constraints: Constraint 1: detect the smallest defect; Constraint 2: adapt to the transducer wavelength; Constraint 3: cover the thickness of the component. The formulas for these three constraints are as follows: D1=min(2d min ,3λ,H / 5) Constraint 1 is 2d min The spacing should be ≤2 times the minimum defect size to ensure that the defect is covered by at least one sampling point; Constraint 2 is 3λ, and the spacing is ≤3 times the wavelength to avoid signal distortion caused by sound wave diffraction; Constraint 3 is H / 5, and the spacing is ≤ 1 / 5 of the component thickness to ensure that the detection direction covers the entire thickness; Step S2.2: Divide the component into a uniform grid according to D1 within the component inspection plane, set the starting coordinates of the inspection plane, and compensate the component edge by 50mm to avoid edge effects; Step S2.3: Adjust the reinforcement avoidance. Remove the sampling points that overlap with the reinforcement. For each initially divided sampling point, calculate its horizontal distance from all reinforcements. If the sampling point enters the reinforcement influence zone, remove the point and add a new sampling point at its adjacent position. Step S2.4, Initial inspection and invalid point removal: Use an ultrasonic testing instrument to collect information from each primary sampling point, excluding component boundaries and hole areas. If a sampling point is located outside the component boundary, or the corresponding position is a reserved hole, it is marked as an invalid point and will not be tested.

6. The method for detecting internal defects according to claim 5, characterized in that, Step S3 includes the following steps: Step S3.1: Preprocessing of detection parameters. The model processing terminal calls the ambient temperature (t) collected by the environmental sensor to perform temperature compensation on the sound velocity (v) collected in the first stage. The compensation formula is V t =V 20 ×[1+0.015×(t-20)], where V 20 The standard sound velocity of concrete at 20℃ was used, and the amplitude (A) was calibrated to eliminate coupling differences at different acquisition points. Step S3.2: Setting the threshold range for four types of defects and verifying preset parameters; The threshold range for Class A defects is: V t <0.85V std And A<A std -25dB; The threshold range for Class B defects is: acoustic time difference Δt between cross-slit and non-cross-slit defects > 150 μs and amplitude reduction ≥ 30%; The threshold range for Class C defects is: V t <0.95V std And the frequency drift is greater than 3kHz; The threshold range for Class D defects is: combined with a surface acoustic time difference > 20 μs and an amplitude reduction ≥ 40%; Where V std A std The average sound velocity and wave amplitude in the normal concrete area; Step S3.3: Based on the data collected in step S2.4 and the data preliminarily processed in step S3.1, determine and mark the type of defects; Step S3.4: Defining suspicious areas. The model processing terminal counts the number of consecutively marked defect points. When there are ≥3 consecutive defect points, it is marked as a defect area. The defect area is then extended 20mm outwards to mark suspicious areas, and the area category is labeled according to the defect type with the highest proportion in the area.

7. The method for detecting internal defects according to claim 6, characterized in that, Step S4 includes the following steps: Step S4.1: Determining the secondary detection area; Step S4.2: Further subdivision of the secondary grid and arrangement of secondary sampling points; Step S4.3: High-precision ultrasonic scanning. The model processing terminal sends the coordinate sequence of the secondary acquisition points to the positioning bracket, controls the positioning stage to move along the X / Y axis linear module, and simultaneously switches the ultrasonic detector to phased array mode. The sampling frequency is increased to twice the preset value of the primary acquisition points, and the gain is increased by 10dB-15dB. The scanning mode is adjusted according to different defect types. For Class B defects, scanning along the defect direction and scanning perpendicular to the defect direction are used for acquisition. For Class A, Class C, and Class D defects, fixed-point grid scanning sampling is used. During the scanning process, the position is fed back in real time by the grating ruler displacement sensor of the positioning bracket. The model processing terminal receives the secondary sampling points. Step S4.4, Defect size and type calibration: Integrate the preliminary judgment results of the first level with the imaging results of the second level. If the second level results are consistent with the first level results, update the precise size of the defect. If they are inconsistent, correct the defect type and re-match the corresponding defect evaluation criteria; mark the defects in the second level detection area that exceed the specification limits.

Images