CN210243850U - Shallow buried non-metallic object detection system - Google Patents
Shallow buried non-metallic object detection system Download PDFInfo
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- CN210243850U CN210243850U CN201921220801.3U CN201921220801U CN210243850U CN 210243850 U CN210243850 U CN 210243850U CN 201921220801 U CN201921220801 U CN 201921220801U CN 210243850 U CN210243850 U CN 210243850U
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Abstract
The utility model discloses a shallow layer buries ground non-metallic object detection system, the system includes: the sound wave transmitting assembly, the sound wave receiving assembly and the spectrum analyzer; the sound wave transmitting component is used for transmitting two sound source/vibration source signals with different frequencies; the sound wave receiving assembly is used for receiving signals, amplifying and filtering the signals and then sending the signals to the spectrum analyzer; the spectrum analyzer is used for carrying out fast Fourier transform on the collected signals, drawing a spectrogram of the signals, detecting whether sum frequency or difference frequency signals exist in the spectrogram of the signals except for the frequencies of two sound sources/vibration sources, and if the sum frequency or difference frequency signals exist, the buried object is a non-metal object, so that the detection of the buried non-metal object is realized. The utility model discloses a nonmetal object is discerned through the acoustic characteristic difference of material to the system, has easy and simple to handle, low cost, easy to carry out, does not receive the advantage that weather and soil moisture influence.
Description
Technical Field
The utility model relates to a geophysical prospecting technical field, in particular to shallow layer buries ground non-metallic object detection system.
Background
A shallow buried non-metallic object is a non-metallic object buried under the ground within 1 meter, and is also called a flexible object because its flexibility is much greater than that of a rigid object such as metal or rock. With the progress of science and technology, the physical and chemical properties of many non-metal materials have a great leap, and because of the advantages of low cost, light weight, no toxicity, corrosion resistance, easy processing, manufacturing and maintenance, etc., the non-metal materials can gradually replace metal materials in some fields, such as non-metal water and gas supply pipelines in municipal construction, non-metal pressure vessels in petrochemical and pharmaceutical industries, non-metal mines and bombs in military, etc.
In the field of conventional geophysical prospecting technology, since the target object to be detected is mainly a metal product, researchers have developed many detection methods based on the electrical and magnetic principles, but these conventional methods have unsatisfactory effects in detecting non-metal objects due to the characteristics of non-metal materials that are not (weakly) conductive and not (weakly) conductive.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome above-mentioned technical defect, to the shallow layer bury ground non-metallic object, provided an acoustics detection system and method based on nonlinear resonance effect. Because the acoustic characteristics (characteristic impedance) of the non-metal object are greatly different from soil, metal objects and rocks, the influence of interference objects in the soil can be effectively avoided, and the detection accuracy of the non-metal object is higher.
In order to achieve the above object, the utility model provides a shallow layer buries ground non-metallic object detection system, the system includes: the sound wave transmitting assembly, the sound wave receiving assembly and the spectrum analyzer;
the sound wave transmitting component is used for transmitting two sound source/vibration source signals with different frequencies;
the sound wave receiving assembly is used for receiving signals, amplifying and filtering the signals and then sending the signals to the spectrum analyzer;
the spectrum analyzer is used for carrying out fast Fourier transform on the collected signals, drawing a spectrogram of the signals, detecting whether sum frequency or difference frequency signals exist in the spectrogram of the signals except for the frequencies of two sound sources/vibration sources, and if the sum frequency or difference frequency signals exist, the buried object is a non-metal object, so that the detection of the buried non-metal object is realized.
As an improvement of the above system, the acoustic wave emitting assembly comprises 2 acoustic sources, each acoustic source emitting an acoustic wave signal having a different frequency; the sound source includes: a signal generator, a power amplifier and a loudspeaker;
the signal generator generates an excitation signal required by detection, wherein the excitation signal is single-frequency excitation, random excitation or frequency sweep excitation with the frequency range lower than 2000 Hz;
the power amplifier adopts a power amplifier with adjustable amplification factor to amplify the power of the excitation signal generated by the signal generator;
the loudspeaker converts the electric signal output by the power amplifier into a ground excitation signal and radiates excitation energy into soil.
As an improvement of the above system, the acoustic wave emitting assembly comprises 2 vibration sources, each vibration source emitting a vibration signal with a different frequency; the vibration source comprises: the device comprises a signal generator, a power amplifier and a vibration exciter;
the signal generator generates an excitation signal required by detection, wherein the excitation signal is single-frequency excitation, random excitation or frequency sweep excitation with the frequency range lower than 2000 Hz;
the power amplifier adopts a power amplifier with adjustable amplification factor to amplify the power of the excitation signal generated by the signal generator;
the vibration exciter converts an electric signal output by the power amplifier into a ground excitation signal and radiates excitation energy into soil.
As an improvement of the above system, the acoustic wave receiving unit includes: the device comprises a sensor array, a preamplifier, a filter and a signal acquisition card;
the sensor array is an array formed by a plurality of sensors and used for converting the sound wave signal/vibration signal into an electric signal;
the preamplifier is used for amplifying the electric signal;
the analog filter is used for filtering the amplified electric signal;
and the signal acquisition card is used for converting the filtered analog electric signal into a digital electric signal and outputting the digital electric signal to the spectrum analyzer.
As an improvement to the above system, the sensor is a geophone, accelerometer or vibrometer.
As an improvement of the system, the number of channels of the signal acquisition card is not less than the number of sensors in the sensor array.
As an improvement of the system, the signal sampling frequency of the signal acquisition card is 3-5 times of the sensor frequency.
The utility model has the advantages that:
1. the system of the utility model identifies the non-metallic object through the acoustic characteristic difference of the material, and has the advantages of simple operation, low cost, easy implementation and no influence of weather and soil humidity;
2. the utility model discloses a nonlinear resonance effect that the system adopted can effectively avoid interferents such as metal, rock to the influence of probing result, has very strong pertinence, can greatly improve and survey the accuracy.
Drawings
FIG. 1 is a schematic diagram of detection of shallow buried non-metallic objects;
fig. 2(a) is a soil-buried object steady state diagram;
fig. 2(b) is a view showing a state in which the soil-buried object is compressed;
fig. 2(c) is a drawing of a soil-buried object in tension;
FIG. 3 is a non-linear equivalent model of a soil-buried non-metallic object;
FIG. 4(a) is a schematic diagram of the frequency spectrum of a detection signal without an object;
FIG. 4(b) is a schematic diagram of the frequency spectrum of the probing signal of the rigid body;
FIG. 4(c) is a schematic diagram of the frequency spectrum of the detection signal of the non-metallic object;
fig. 5 is the utility model discloses a bury ground non-metallic object detection system schematic diagram.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
The principle of the utility model is that: a schematic diagram of detection of shallow buried non-metallic objects based on non-linear resonance effect is shown in fig. 1. The ground is excited by adopting a double sound source or a vibration source (or a single sound source or a vibration source capable of simultaneously transmitting two excitation signals), when no object is buried under the ground surface, the sound waves are gradually attenuated in the process of propagating to the deep part of the soil, and only the excitation source signals and interference noise signals can be detected on the ground surface, so that the similarity of the frequency components of the received signals and the excitation source signals is very high, and only the attenuation to a certain degree exists in the amplitude. When buried objects exist under the earth surface, the soil-buried objects can be regarded as a forced vibration system, when sound waves coupled into the soil are transmitted to the surface of the objects, firstly, strong reflection or scattering phenomena can occur at the interface of the soil-buried objects due to large acoustic impedance difference between the buried objects and the soil; secondly, under the action of sound pressure, a system formed by the soil and the buried object can resonate, so that the intensity of echo reflected by the target object is increased; thirdly, due to the great flexibility of the non-metallic object, a non-linear effect can occur under the action of the sound pressure, and the non-linear effect can change the frequency components of the sound wave, so that the sum frequency (or difference frequency) modulation is actually carried out on two sound wave signals. The signal modulated by the buried object is reflected and transmitted back to the earth surface, the echo signal is picked up through a sensor array arranged on the earth surface, then the acquired signal is subjected to Fast Fourier Transform (FFT), a frequency spectrogram of the signal is drawn, and whether the buried non-metal object exists in the detection area can be judged by comparing the signal components in the frequency spectrogram with the frequency components of the excitation source signal.
The nonlinear effect of forced vibration of soil-buried objects is: when the system is not subjected to external force, the system is stableA constant state, as shown in FIG. 2 (a); when the soil is acted by external force, two processes of compression and stretching exist, and because the nonmetal object has larger flexibility, the soil extrudes the nonmetal object to cause deformation in the compression process, and the interface between the nonmetal object and the nonmetal object is tightly combined, as shown in fig. 2 (b); during the stretching process, the soil and the non-metal object have different flexibility, resulting in a certain separation at the interface between the two, as shown in fig. 2 (c). The equivalent mechanical model for the compression and stretching phases is shown in FIG. 3, where k is1，k2Representing the stiffness of the soil and buried objects, respectively.
The nonlinear effect modulates the sound wave signal of the soil-buried non-metallic object interface to generate a new sum frequency or difference frequency signal, as shown in formula (1):
f＝mf1±nf2(m, n are natural numbers) (1)
Fig. 4(a), 4(b) and 4(c) show the frequency spectrum diagrams of the detection signals when there is no buried object, the buried object is a rigid body (such as metal or rock) and the buried object is a non-metal respectively. The detection of the buried non-metallic object can be realized through the frequency component analysis in the spectrogram.
As shown in fig. 5, the utility model provides a shallow layer buries ground non-metallic object detection system, detection system mainly includes the three: the system comprises a sound wave transmitting part, a sound wave receiving part and a signal processing part, wherein the signal transmitting part adopts 2 sound sources/vibration sources to respectively transmit signals with different frequency components (or adopts a single sound source/vibration source capable of simultaneously transmitting 2 excitation signals), and the system specifically comprises the following steps: signal generators 1 and 2, power amplifiers 1 and 2, speakers (vibration exciters) 1 and 2; the signal receiving section includes: the sensor array (the sensor adopts vibration measuring instruments such as a geophone, an accelerometer or a vibrometer), a preamplifier, a filter and a signal acquisition card; the signal analyzing section includes: and a spectrum analyzer.
(1) Signal generator
The signal generator of any waveform is used to generate the excitation signal required for detection, and generally, a single-frequency excitation, a random excitation or a frequency-sweep excitation with a frequency range lower than 2000Hz is used, wherein the signals of the signal generators 1 and 2 need to have a certain frequency component difference.
(2) Power amplifier
The power amplifier with adjustable amplification factor is adopted to amplify the power of the modulation signal generated by the signal generator, so that the penetration depth of the sound wave in the soil is increased, and the specific amplification factor in practical application is determined according to soil parameters (such as looseness, humidity and the like).
(4) Loudspeaker (vibration exciter)
The speaker (exciter) functions to convert an electric signal into a ground excitation signal and radiate excitation energy into the soil. The loudspeaker is non-contact with the ground, and has the advantage of not damaging the vegetation and infrastructure of the ground, but the acoustic coupling efficiency is relatively low, and therefore the detection depth is limited. If the object is buried deeply, a contact type vibration exciter can be adopted, so that the vibration exciter is directly and mechanically connected with the soil, and the sound energy can be transmitted into the soil to a greater extent.
(5) Sensor array
The sensor adopts instruments for measuring vibration such as a geophone, an accelerometer or a vibrometer and the like to convert vibration signals into electric signals. In theory, only a single sensor can be used for measurement, but in order to improve the reliability of the detection system, a plurality of sensors are generally used to form an array.
(6) Preamplifier and filter
The sound wave signals reflected back to the earth surface by the buried object are relatively weak in attenuation through soil, noise signals are mixed in, in order to improve the signal to noise ratio, a preamplifier needs to be adopted to amplify the signals, then an analog filter is adopted to filter the signals, and the signal processing and analysis in the later period are facilitated.
(7) Signal collecting card
The signal acquisition card converts the analog electric signals into digital electric signals, the number of channels of the acquisition card is not less than the number of sensors in the sensor array, and the signal sampling frequency is generally 3-5 times of the sensor frequency.
(8) Spectrum analyzer
Spectrum analyzerThe method comprises performing fast Fourier transform on the collected signal to obtain a spectrogram of the signal, analyzing frequency components of the signal, and searching for a frequency f except for the excitation source1And f2Besides, whether a sum frequency signal or a difference frequency signal exists in the signal spectrogram or not can be used for detecting the buried non-metallic object.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art will understand that modifications and equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and all of them shall fall within the scope of the claims of the present invention.
Claims (7)
1. A shallow buried non-metallic object detection system, the system comprising: the sound wave transmitting assembly, the sound wave receiving assembly and the spectrum analyzer;
the sound wave transmitting component is used for transmitting two sound source/vibration source signals with different frequencies;
the sound wave receiving assembly is used for receiving signals, amplifying and filtering the signals and then sending the signals to the spectrum analyzer;
the spectrum analyzer is used for carrying out fast Fourier transform on the collected signals, drawing a spectrogram of the signals, detecting whether sum frequency or difference frequency signals exist in the spectrogram of the signals except for the frequencies of two sound sources/vibration sources, and if the sum frequency or difference frequency signals exist, the buried object is a non-metal object, so that the detection of the buried non-metal object is realized.
2. The shallow buried non-metallic object detection system of claim 1, wherein said acoustic emission assembly includes 2 acoustic sources, each acoustic source emitting an acoustic signal having a different frequency; the sound source includes: a signal generator, a power amplifier and a loudspeaker;
the signal generator generates an excitation signal required by detection, wherein the excitation signal is single-frequency excitation, random excitation or frequency sweep excitation with the frequency range lower than 2000 Hz;
the power amplifier adopts a power amplifier with adjustable amplification factor to amplify the power of the excitation signal generated by the signal generator;
the loudspeaker converts the electric signal output by the power amplifier into a ground excitation signal and radiates excitation energy into soil.
3. The shallow buried non-metallic object detection system of claim 1 wherein the acoustic transmission assembly includes 2 vibration sources, each vibration source transmitting a vibration signal having a different frequency; the vibration source comprises: the device comprises a signal generator, a power amplifier and a vibration exciter;
the signal generator generates an excitation signal required by detection, wherein the excitation signal is single-frequency excitation, random excitation or frequency sweep excitation with the frequency range lower than 2000 Hz;
the power amplifier adopts a power amplifier with adjustable amplification factor to amplify the power of the excitation signal generated by the signal generator;
the vibration exciter converts an electric signal output by the power amplifier into a ground excitation signal and radiates excitation energy into soil.
4. A shallow buried non-metallic object detection system as claimed in claim 2 or 3 wherein said acoustic wave receiving assembly includes: the device comprises a sensor array, a preamplifier, an analog filter and a signal acquisition card;
the sensor array is an array formed by a plurality of sensors and used for converting the sound wave signal/vibration signal into an electric signal;
the preamplifier is used for amplifying the electric signal;
the analog filter is used for filtering the amplified electric signal;
and the signal acquisition card is used for converting the filtered analog electric signal into a digital electric signal and outputting the digital electric signal to the spectrum analyzer.
5. The system of claim 4, wherein the sensor is a geophone, an accelerometer or a vibrometer.
6. The system for detecting the shallow buried nonmetallic object of claim 4, wherein the number of channels of the signal acquisition card is not less than the number of sensors in the sensor array.
7. The system for detecting the shallow buried non-metallic object according to claim 4, wherein the signal sampling frequency of the signal acquisition card is 3-5 times of the sensor frequency.
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| CN201921220801.3U CN210243850U (en) | 2019-07-31 | 2019-07-31 | Shallow buried non-metallic object detection system |
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| CN201921220801.3U CN210243850U (en) | 2019-07-31 | 2019-07-31 | Shallow buried non-metallic object detection system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110346829A (en) * | 2019-07-31 | 2019-10-18 | 中国科学院声学研究所 | A kind of buried non-metallic object detection system of shallow-layer |
| CN113759358A (en) * | 2021-09-08 | 2021-12-07 | 苏州捷杰传感技术有限公司 | Detection method and system for buried pipeline |
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2019
- 2019-07-31 CN CN201921220801.3U patent/CN210243850U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110346829A (en) * | 2019-07-31 | 2019-10-18 | 中国科学院声学研究所 | A kind of buried non-metallic object detection system of shallow-layer |
| CN113759358A (en) * | 2021-09-08 | 2021-12-07 | 苏州捷杰传感技术有限公司 | Detection method and system for buried pipeline |
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