A concrete internal three-dimensional imaging system and method

Abstract

The present invention provides a three-dimensional imaging system and method for the interior of concrete. When performing detection, firstly, two-dimensional imaging is performed on the concrete at a specified depth Z in the XY plane. By controlling the time difference of the excitation of each exciter, the Rayleigh waves emitted by each exciter reach a certain focal point at the same time. Each exciter is numbered and the excitation time is calculated. By translating the receiver signal and superimposing the signal, the degree of damage at the focal point is obtained. Repeating the above steps can obtain the damage matrix of any point, change the wavelength of the excitation wave, control the detection depth Z, and realize two-dimensional imaging of different depths of concrete, thereby generating three-dimensional imaging of the interior of concrete. This method can not only accurately locate the crack position in the concrete, but also locate the position of the internal aggregate steel bar, detect whether the internal reinforcement of the concrete is rusted, and whether the concrete cover or the surrounding soil is hollow, and the positioning and detection speed is fast.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and specifically relates to a concrete interior three-dimensional imaging system and method. Background Art

[0002] In recent years, with the development of large-scale infrastructure construction in my country, engineering quality accidents have occurred from time to time. Therefore, engineering quality inspection, especially non-destructive inspection of concrete structure engineering, has become more and more important, and the requirements for inspection have become higher and higher. The current non-destructive inspection methods for concrete engineering structures mainly include rebound method, radar method, impact echo method, P-wave velocity method and ultrasonic method. The rebound method is a commonly used non-destructive testing method for concrete, but the detection depth of this method is shallow, and it can only measure the average strength near the concrete surface, which cannot reflect the internal condition of the concrete. In addition, the rebound value is highly dispersed, and usually more than 16 valid rebound data are required for averaging, which has low operating efficiency. The radar method can accurately locate the internal defects of concrete, but it is greatly affected by the shielding of low-resistivity materials such as steel bars, especially when the density of steel bars is large, it is difficult to obtain the electromagnetic wave image behind the steel bars, and the radar cannot provide information on strength. The impact echo method can measure the internal defects of the structure and the thickness of the components, but its longitudinal resolution is low, and the detection accuracy is greatly affected by the steel bars and water content inside the structure. Although the ultrasonic penetration test can obtain the longitudinal wave velocity of the entire material, it cannot be applied to structures such as tunnel linings that cannot be penetrated. The P-wave velocity method can usually only measure the P-wave velocity of the concrete surface layer and cannot detect the internal structural condition of the concrete. Although the above-mentioned various concrete non-destructive testing methods have their own strengths, their common weakness is that they cannot detect the mechanical properties deep inside the concrete, which makes it difficult to meet the requirements of civil engineering non-destructive testing. Summary of the invention

[0003] The present invention provides a concrete interior three-dimensional imaging system and method, which are used to solve the technical problems raised in the background technology.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A three-dimensional imaging system inside concrete comprises: a concrete test block to be detected, an ultrasonic phased array, a connecting part and a detection device; the connecting part is a wedge block, a plurality of the wedge blocks are fixed to the bottom of the concrete test block to be detected, and the detection device is connected to the concrete test block to be detected through the wedge blocks; the ultrasonic phased array is fixed to the surface of the concrete test block to be detected, and comprises a plurality of transducers, the plurality of the transducers are arranged in a circular or cross shape, and each of the transducers excites or receives Rayleigh waves.

[0006] The detection device includes a signal generator, a test probe, a signal amplification module and an oscilloscope; the signal generator is used to generate an excitation signal to form an incident wave; a plurality of the test probes are fixed on the surface of the wedge block and connected to the signal generator and the oscilloscope through a wiring harness, and are used to transmit the incident wave to the surface of the concrete test block to be detected, form a vibration wave and output it to the oscilloscope; a plurality of the signal amplification modules are arranged between the signal generator and the test probe, and between the test probe and the oscilloscope, and are used to amplify the energy of the incident wave and the vibration wave; the oscilloscope is connected to the signal generator and the signal amplification module, and is used to display the incident wave and the vibration wave.

[0007] Furthermore, the signal amplification module includes a high-voltage amplifier and a voltage amplifier. The input end of the high-voltage amplifier is connected to the signal generator to amplify the energy of the incident wave; the input end of the voltage amplifier is connected to the test probe to amplify the energy of the vibration wave.

[0008] Furthermore, the test probe includes an excitation probe and a receiving probe; the excitation probe is connected to the output end of the high-voltage amplifier, and is used to transmit the incident wave to the surface of the concrete block to be tested; the receiving probe is connected to the input end of the voltage amplifier, and is used to receive the vibration wave after transmission in the concrete block to be tested.

[0009] Furthermore, the output ends of the signal generator, the high-voltage amplifier and the voltage amplifier are all connected to an oscilloscope, and the oscilloscope is used to display the incident wave generated by the signal generator, the incident wave amplified by the high-voltage amplifier and the vibration wave amplified by the voltage amplifier.

[0010] Furthermore, four wedge blocks are provided and fixed at the bottom of the concrete test block to be tested, and two excitation probes and two receiving probes are provided, which are arranged at intervals and fixed on the surface of the wedge block; a high-voltage amplifier is provided between each excitation probe and the signal generator, and a voltage amplifier is provided between each receiving probe and the oscilloscope.

[0011] Furthermore, the wedge block is an inclined wedge block, including an inclined wedge and a sliding block, the sliding block is fixed to the bottom of the concrete test block to be tested, the excitation probe and the receiving probe are both fixed to the surface of the inclined wedge, and the inclined wedge and the sliding block are used in combination.

[0012] A method for three-dimensional imaging of the interior of underwater concrete comprises the following steps:

[0013] S1. Place 24 transducers perpendicular to the surface of the underwater concrete block to be tested; 12 transducers excite Rayleigh waves and 12 transducers receive Rayleigh waves;

[0014] S2. The waveform of each transducer excitation signal is:

[0015]

[0016] Where N is the number of sine wave cycles, f is the excitation frequency, and t is time; adjust the excitation frequency f, and calculate the wavelength of the Rayleigh wave λ = c / f based on the known Rayleigh wave velocity c;

[0017] S3. For a point inside the concrete, calculate the coordinates (x, y, z); where z is the depth direction; the influence depth of the Rayleigh wave is mainly concentrated in the range of 1 / 3 wavelength, so the influence depth of the Rayleigh wave along the z direction is L = λ / 3;

[0018] At depth L, two-dimensional imaging is performed in the xy plane. By controlling the time difference of each excitation of the exciter, the Rayleigh waves emitted by each exciter reach the focal point (x0, y0) at the same time. The exciters are numbered from 1 to 12 in sequence. The time when the first exciter is excited is t0. The coordinates of the i-th exciter are (xi, yi), and the excitation time of the i-th exciter is t0+Δti. The calculation method of Δti is as follows:

[0019]

[0020] S4. Shift the received signals of the 12 receivers, the signal of the first receiver is not shifted, the signal of the i-th receiver is shifted by Δti, and the 12 shifted signals are superimposed to obtain the detection signal at (x0, y0, L); when there is a structure or damage at the focus point, a rebound wave will be caused, and the rebound wave will be in the same phase in each shifted signal. By superimposing the shifted signals, the echo caused by the damage can be amplified; otherwise, the received signal is noise, and the superposition of the shifted noise will not produce a significant amplification effect;

[0021] The maximum peak value of the superimposed detection signal is recorded as the damage degree D at (x0, y0, L);

[0022] S5. Change the focus point coordinates (x0, y0), and traverse all points of the concrete structure at a depth of L; change the excitation frequency f in S2, repeat steps S2-3, and obtain the damage degree matrix D (x0, y0, L) of any point inside the concrete, thereby generating a three-dimensional imaging diagram of the interior of the concrete.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a three-dimensional imaging system for the interior of concrete. The transducers are arranged in a circular or cross shape to facilitate the detection of cracks in various directions in concrete. Using Rayleigh waves, the particles vibrate in an elliptical shape. Rayleigh waves propagate far and have a large detection range. The device does not need to be set directly in the direction of the concrete. It can directly detect cracks inside the concrete in any direction, automatically generate a three-dimensional image, and is easy and quick to operate.

[0025] The present invention provides a method for three-dimensional imaging inside concrete. When performing detection, firstly, two-dimensional imaging is performed on the concrete at a specified depth Z in the XY plane. By controlling the time difference of the excitation of each exciter, the Rayleigh waves emitted by each exciter reach a certain focal point at the same time. Each exciter is numbered and the excitation time is calculated. By translating the receiver signal and superimposing the signal, the degree of damage at the focal point is obtained. The above steps can be repeated to obtain the damage matrix of any point, change the wavelength of the excitation wave, control the detection depth Z, and realize two-dimensional imaging of concrete at different depths, thereby generating three-dimensional imaging inside the concrete. When there is a structure at the focal point, a rebound wave will be caused, and the echo can be amplified by signal superposition. This method can not only accurately locate the crack position in the concrete, but also locate the position of the internal aggregate steel bars, detect whether the internal reinforcement of the concrete is rusted, and whether the concrete cover or the surrounding soil is hollow, and the positioning and detection speed is fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the circular arrangement diagram of transducers;

[0027] Figure 2 It is a diagram of the cross arrangement of transducers;

[0028] Figure 3 This is a schematic diagram of the impact depth of Rayleigh waves;

[0029] Figure 4 It is a schematic diagram of beam focusing point by point;

[0030] Figure 5 It is a schematic diagram of receiving and translating signals;

[0031] Figure 6 It is a schematic diagram of superimposed signals;

[0032] Figure 7 This is the structural diagram of the concrete internal three-dimensional imaging system;

[0033] In the figure, 1. concrete test block to be tested, 2. wedge block, 3. signal generator, 4-1. high voltage amplifier, 4-2. voltage amplifier, 5-1. excitation probe, 5-2. receiving probe, 6. oscilloscope. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] For examples, please refer to the attached Figure 7A three-dimensional imaging system for the interior of concrete includes: a concrete block to be tested 1, an ultrasonic phased array, a connection part, and a detection device. The connection part is a wedge block 2, and a plurality of wedge blocks 2 are fixed to the bottom of the concrete block to be tested 1. The detection device is connected to the concrete block to be tested 1 through the wedge blocks 2. The ultrasonic phased array is fixed to the surface of the concrete block to be tested, and includes a plurality of transducers, which are arranged in a circular or cross shape (such as Figure 1-2 As shown), each transducer excites Rayleigh waves or receives Rayleigh waves.

[0036] The detection device can detect cracks inside a concrete test block placed underwater or above water, and includes a signal generator 3, a test probe, a signal amplification module and an oscilloscope 6. The signal generator 3 is of the model Quantum 9520, and is used to generate an excitation signal to form an incident wave. A plurality of test probes are fixed on the surface of the wedge block 2, and are connected to the signal generator 3 and the oscilloscope 6 through wiring, and are used to transmit the incident wave to the surface of the concrete test block 1 to be detected, form a vibration wave and output it to the oscilloscope 6. A plurality of signal amplification modules are arranged between the signal generator 3 and the test probe, and between the test probe and the oscilloscope 6, and are used to amplify the energy of the incident wave and the vibration wave. The oscilloscope 6 is of the model Tektronix MSO64, and is connected to the signal generator 3 and the signal amplification module, and is used to display the incident wave and the vibration wave.

[0037] In the above structure, the signal amplification module includes a high-voltage amplifier 4-1 and a voltage amplifier 4-2, the model of the high-voltage amplifier 4-1 is MX200, and the model of the voltage amplifier 4-2 is PXPA3; the test probe includes an excitation probe 5-1 and a receiving probe 5-2, the model of the excitation probe 5-1 is Fuji AE1045SW, and the model of the receiving probe 5-2 is Fuji AE1045SW. The input end of the high-voltage amplifier 4-1 is connected to the signal generator 3, which is used to amplify the energy of the incident wave, and the excitation probe 5-1 is connected to the output end of the high-voltage amplifier 4-1, which is used to transmit the incident wave to the surface of the concrete test block 1 to be tested. The receiving probe 5-2 is connected to the input end of the voltage amplifier 4-2, which is used to receive the vibration wave transmitted in the concrete test block 1 to be tested. The output ends of the signal generator 3, the high-voltage amplifier 4-1 and the voltage amplifier 4-2 are all connected to the oscilloscope 6, which is used to display the incident wave generated by the signal generator 3, the incident wave amplified by the high-voltage amplifier 4-1 and the vibration wave amplified by the voltage amplifier 4-2.

[0038] In this embodiment, four wedges 2 are provided, fixed to the bottom of the concrete test block 1 to be tested, and two excitation probes 5-1 and receiving probes 5-2 are provided, arranged at intervals and fixed to the surface of the wedge 2. A high-voltage amplifier is provided between each excitation probe and the signal generator, and a voltage amplifier is provided between each receiving probe and the oscilloscope. The wedge 5 is an inclined wedge, including an inclined wedge and a slider, the slider is fixed to the bottom of the concrete test block 1 to be tested, the excitation probe 5-1 and the receiving probe 5-2 are fixed to the surface of the inclined wedge, and the inclined wedge and the slider are used in conjunction with each other.

[0039] A method for three-dimensional imaging of the interior of concrete includes the following steps:

[0040] S1. Place 24 transducers perpendicular to the surface of the underwater concrete block to be tested; among them, 12 transducers excite Rayleigh waves, and 12 transducers receive Rayleigh waves. The arrangement is alternating or random (e.g. Figure 1-2 shown).

[0041] S2. The waveform of each transducer excitation signal is:

[0042]

[0043] Where N is the number of sine wave cycles, f is the excitation frequency, and t is time; adjust the excitation frequency f, and calculate the wavelength of the Rayleigh wave λ = c / f based on the known Rayleigh wave velocity c. The excitation frequency f is adjusted in the signal generator, and the vibration frequency of the voltage is the excitation frequency.

[0044] S3. For a point inside the concrete, count the coordinates (x, y, z); where z is the depth direction; the depth of influence of Rayleigh waves is mainly concentrated in the range of 1 / 3 wavelength (such as Figure 3 As shown in the figure, the influence depth of the Rayleigh wave along the z direction is L = λ / 3. At the depth L, two-dimensional imaging in the xy plane is performed, and the Rayleigh waves emitted by each exciter are made to reach the focusing point (x0, y0) at the same time by controlling the time difference of the excitation of each exciter; Figure 4 Schematic diagram of beam focusing point by point.

[0045] The actuators are numbered from 1 to 12 in sequence. The time when the first actuator is excited is t0. The coordinates of the i-th actuator are (xi, yi). Then the time when the i-th actuator is excited is t0+Δti. Δti is calculated as follows:

[0046]

[0047] S4. Shift the received signals of the 12 receivers, the signal of the first receiver is not shifted, the signal of the i-th receiver is shifted by Δti, and the 12 shifted signals are superimposed to obtain the detection signal at (x0, y0, L); when there is a structure or damage at the focus point, it will cause a rebound wave, and the rebound wave will be in the same phase in each shifted signal. By superimposing the shifted signals, the echo caused by the damage can be amplified; otherwise, the received signal is noise, and the superposition of the shifted noise will not produce a significant amplification effect (such as Figure 5-6 shown).

[0048] The maximum peak value of the superimposed detection signal is recorded as the damage degree D at (x0, y0, L), thereby generating a three-dimensional image of the interior of the concrete.

[0049] S5. Change the focus point coordinates (x0, y0), and traverse all points of the concrete structure at a depth of L; change the excitation frequency f in S2, repeat steps S2-3, and obtain the damage degree matrix D (x0, y0, L) of any point inside the concrete.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for three-dimensional imaging of the interior of concrete, characterized in that: include: The system based on the method includes a concrete test block to be tested, an ultrasonic phased array, a connecting part and a testing device; The connecting part is a wedge block, and a plurality of the wedge blocks are fixed to the bottom of the concrete test block to be detected, and the detection device is connected to the concrete test block to be detected through the wedge block; the ultrasonic phased array is fixed to the surface of the concrete test block to be detected, and includes a plurality of transducers, and the plurality of the transducers are arranged in a circular or cross shape, and each of the transducers excites Rayleigh waves or receives Rayleigh waves; The detection device includes a signal generator, a test probe, a signal amplification module and an oscilloscope; the signal generator is used to generate an excitation signal to form an incident wave; a plurality of the test probes are fixed on the surface of the wedge block and connected to the signal generator and the oscilloscope through a cable, and are used to transmit the incident wave to the surface of the concrete test block to be detected, form a vibration wave and output it to the oscilloscope; a plurality of the signal amplification modules are arranged between the signal generator and the test probe, and between the test probe and the oscilloscope, and are used to amplify the energy of the incident wave and the vibration wave; the oscilloscope is connected to the signal generator and the signal amplification module, and is used to display the incident wave and the vibration wave; The method comprises the following steps: S1. Place 24 transducers perpendicular to the surface of the underwater concrete block to be tested; 12 transducers excite Rayleigh waves and 12 transducers receive Rayleigh waves; S2. The waveform of each transducer excitation signal is: Where N is the number of sine wave cycles, f is the excitation frequency, and t is time; adjust the excitation frequency f, and calculate the wavelength of the Rayleigh wave λ = c / f based on the known Rayleigh wave velocity c; S3. For a point inside the concrete, calculate the coordinates (x, y, z); where z is the depth direction; the influence depth of the Rayleigh wave is mainly concentrated in the range of 1 / 3 wavelength, so the influence depth of the Rayleigh wave along the z direction is L = λ / 3; At depth L, two-dimensional imaging is performed in the xy plane. By controlling the time difference of each excitation, the Rayleigh waves emitted by each exciter reach the focal point (x0, y0) at the same time. The exciters are numbered from 1 to 12 in sequence. The time when the first exciter is excited is t0, and the coordinates of the i-th exciter are (x i ,y i ), then the excitation time of the i-th actuator is t0+Δti; where Δt i The calculation method is as follows: S4. Shift the received signals of the 12 receivers. The signal of the first receiver is not shifted, and the signal of the i-th receiver is shifted by Δt. i , the 12 translated signals are superimposed to obtain the detection signal at (x0, y0, L); when there is a structure or damage at the focus point, it will cause a rebound wave, and the rebound wave will be in the same phase in each translated signal. By superimposing the translated signals, the echo caused by the damage can be amplified; The maximum peak value of the superimposed detection signal is recorded as the damage degree D at (x0, y0, L); S5. Change the focus point coordinates (x0, y0), and traverse all points of the concrete structure at a depth of L; change the excitation frequency f in S2, repeat steps S2-3, and obtain the damage degree matrix D (x0, y0, L) of any point inside the concrete, thereby generating a three-dimensional image of the interior of the concrete.

2. A method for three-dimensional imaging of the interior of concrete according to claim 1, characterized in that: The signal amplification module includes a high-voltage amplifier and a voltage amplifier. The input end of the high-voltage amplifier is connected to the signal generator to amplify the energy of the incident wave; the input end of the voltage amplifier is connected to the test probe to amplify the energy of the vibration wave.

3. A method for three-dimensional imaging of the interior of concrete according to claim 2, characterized in that: The test probe includes an excitation probe and a receiving probe; the excitation probe is connected to the output end of the high-voltage amplifier and is used to transmit the incident wave to the surface of the concrete test block to be tested; the receiving probe is connected to the input end of the voltage amplifier and is used to receive the vibration wave transmitted in the concrete test block to be tested.

4. A method for three-dimensional imaging of the interior of concrete according to claim 3, characterized in that: The output ends of the signal generator, the high-voltage amplifier and the voltage amplifier are all connected to an oscilloscope, and the oscilloscope is used to display the incident wave generated by the signal generator, the incident wave amplified by the high-voltage amplifier and the vibration wave amplified by the voltage amplifier.

5. A method for three-dimensional imaging of the interior of concrete according to claim 4, characterized in that: There are four wedge blocks fixed at the bottom of the concrete test block to be tested, and there are two excitation probes and two receiving probes, which are arranged at intervals and fixed on the surface of the wedge blocks; a high-voltage amplifier is provided between each excitation probe and the signal generator, and a voltage amplifier is provided between each receiving probe and the oscilloscope.

6. A method for three-dimensional imaging of the interior of concrete according to claim 5, characterized in that: The wedge block is an inclined wedge block, comprising an inclined wedge and a sliding block. The sliding block is fixed to the bottom of the concrete test block to be tested. The excitation probe and the receiving probe are both fixed to the surface of the inclined wedge. The inclined wedge and the sliding block are used in combination.

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