CN114910490B - Microwave orthogonal polarization internal detection and three-dimensional reconstruction method for soil body cavity outside PE pipeline - Google Patents
Microwave orthogonal polarization internal detection and three-dimensional reconstruction method for soil body cavity outside PE pipeline Download PDFInfo
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- 239000002689 soil Substances 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000010287 polarization Effects 0.000 title claims abstract description 18
- 238000001514 detection method Methods 0.000 title abstract description 30
- 230000009466 transformation Effects 0.000 claims description 4
- 238000002592 echocardiography Methods 0.000 claims description 3
- 238000007689 inspection Methods 0.000 claims 1
- 239000004698 Polyethylene Substances 0.000 description 56
- 229920000573 polyethylene Polymers 0.000 description 51
- 125000005842 heteroatom Chemical group 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- -1 Polyethylene Polymers 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 1
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- 238000011895 specific detection Methods 0.000 description 1
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- 238000004381 surface treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G01N22/02—Investigating the presence of flaws
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
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Abstract
The invention discloses a microwave orthogonal polarization internal detection and three-dimensional reconstruction method for a soil body cavity outside a PE pipeline, which comprises the steps of placing a pair of microwave horn antennas connected to a vector network analyzer in the PE pipeline in a microwave orthogonal polarization mode, transmitting microwaves with stepped frequency from the PE pipeline by one microwave horn antenna to the outside of the PE pipeline, carrying out microwave detection on the soil body cavity outside the PE pipeline, receiving microwave reflection frequency domain signals by the other microwave horn antenna, converting the obtained microwave reflection frequency domain signals into microwave reflection time domain signals, further calculating the propagation speed of microwaves in mediums in each partial area, observing the distance time between two reflection peaks from the microwave reflection time domain signals, and obtaining distance information between two heterogeneous interfaces, thereby determining the thickness of PE pipe walls and the one-dimensional dimension of the soil body cavity in soil. The microwave detection scanning of circumferential multi-angle and axial positions is realized through the z-theta scanning device, and the three-dimensional reconstruction of the outer soil body cavity of the PE pipeline is realized.
Description
Technical Field
The invention belongs to the technical field of nondestructive testing, and relates to a microwave orthogonal polarization internal detection and three-dimensional reconstruction method for soil cavities outside buried PE pipelines.
Background
In the service process of a Polyethylene (PE) pipe, soil hollows are generated outside the buried PE pipe due to the factors such as earthquake action, rock and soil loosening and the like, and the soil hollows are one of the causes of damage such as pipe position deviation, pipe body local stress concentration, pipe wall thinning and the like, so that the structural integrity of the PE pipe is seriously endangered. Therefore, the method is very important to ensure the integrity and the safety of the PE pipeline and prevent the occurrence of safety accidents such as oil, gas and water leakage by timely finding out the outer soil body cavity of the PE pipeline and carrying out nondestructive quantitative evaluation on the outer soil body cavity.
The main nondestructive testing modes for buried pipelines at present comprise: eddy current detection, ultrasonic detection, infrared detection, etc. However, the method can not be effectively used for quantitative detection of the outer soil body cavity of the PE pipeline, and the main reason is as follows: (1) The eddy current detection is suitable for detecting metal materials, while polyethylene is a nonmetallic material, and the eddy current detection cannot be successfully implemented; (2) The ultrasonic detection needs good contact and surface treatment of a detected structure, and quantitative detection of soil hollows can not be carried out by the outer part or the inner part of the PE pipeline; (3) The infrared detection requires that the structural material has good heat conductivity, and the difficulty of quantitatively detecting the soil body cavity by the thermal radiation field through the PE pipe body or the rock-soil layer is great.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide the microwave orthogonal polarization internal detection and three-dimensional reconstruction method for the soil body cavity outside the buried PE pipeline, which can be used for rapidly and accurately detecting and quantitatively evaluating the three-dimensional size of the soil body cavity outside the buried PE pipeline and has important engineering application value.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a microwave orthogonal polarization internal detection and three-dimensional reconstruction method for a soil body cavity outside a PE pipeline comprises the following steps:
Step 1: setting up an experimental platform for evaluating the one-dimensional size of an outer soil body cavity of a PE pipeline, respectively connecting two ends of two coaxial cables with a vector network analyzer and a microwave horn antenna, arranging the two microwave horn antennas in the PE pipeline in a microwave orthogonal polarization mode, wherein the microwave orthogonal polarization arranging mode requires that long sides of apertures of the two microwave horn antennas are mutually perpendicular, and aperture centers of the two microwave horn antennas are symmetrical relative to a central axis of the PE pipeline, and fixing the two microwave horn antennas in a linear corner z-theta scanning device;
Step 2: the method for evaluating the one-dimensional size of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) A microwave horn antenna connected with a vector network analyzer through a coaxial cable radiates step frequency microwaves outwards from the interior of a PE pipe and receives reflected echoes by the other microwave horn antenna to obtain a microwave reflected frequency domain signal S 21;
2) Adding a Kaiser window to the microwave reflection frequency domain signal S 21 obtained in the step 2), converting the microwave reflection frequency domain signal S 21 into a microwave reflection time domain signal through Chirp-Z inverse transformation, observing the microwave reflection time domain signal, finding out each reflection peak in the microwave reflection time domain signal, adding one reflection peak in the time domain signal when one heterogeneous interface exists, if no soil cavity exists outside the PE pipeline, the number of the reflection peaks is two, namely an air-PE pipe heterogeneous interface reflection peak and a PE pipe-soil heterogeneous interface reflection peak, and if the soil cavity exists, the number of the reflection peaks is three, namely an air-PE pipe heterogeneous interface reflection peak, a PE pipe-soil cavity heterogeneous interface reflection peak and a soil cavity-soil heterogeneous interface reflection peak;
3) Determining the medium type between every two reflection peaks through the arrangement sequence of the interface corresponding to the interval between every two adjacent reflection peaks for the reflection peaks determined by observing the microwave reflection time domain signals in the step 2);
4) Determining that the time difference Deltat i,Δti between every two reflection peaks represents the time difference between the ith and the (i+1) th reflection peaks for the reflection peaks found by observing the microwave reflection time domain signal in step 2);
5) For the type of the medium determined in the step 2) and 3), the dielectric constant epsilon ri of the medium is matched with a microwave speed formula Calculating the microwave speed, v i represents the microwave speed of the medium between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface, and mu ri and epsilon ri respectively represent the relative magnetic conductivity and the relative dielectric constant of each layer of medium;
6) For Deltat i obtained in step 2) and v i obtained in step 5), the formula is given by Calculating the distance between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface;
7) Determining the one-dimensional size of the outer soil body cavity of the buried PE pipeline according to the distances from the ith layer of heterogeneous interface to the (i+1) th layer of heterogeneous interface at all axial positions and circumferential angles obtained in the step 2);
Step 3: the three-dimensional reconstruction of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) Scanning each axial position and each circumferential angle in the PE pipe through a z-theta scanning device;
2) Obtaining one-dimensional axial and circumferential dimensions of the outer soil body cavity of each scanning position from the scanning data obtained in the step 3) through the step 2 for each group of scanning data;
3) And 2) carrying out three-dimensional reconstruction of the outer soil body cavity of the PE pipeline by the axial and circumferential one-dimensional dimensions of the outer soil body cavity of each scanning position obtained in the step 2).
The microwave detection is a novel nondestructive detection technology which is provided by utilizing the characteristics of reflection, transmission and scattering of a heterogeneous interface when microwaves propagate in a dielectric material, and has the characteristics of wide detection spectrum, strong penetrating power, high sensitivity, non-contact, no need of couplant and the like, and meanwhile, the novel nondestructive detection technology has the advantages of high detection speed, small influence on environment, environmental protection and the like. In view of the above, the invention provides a novel method for realizing three-dimensional reconstruction of soil cavities outside buried PE pipelines through microwave orthogonal polarization detection. Compared with the prior art, the invention has the following advantages:
1. The invention provides a microwave orthogonal polarization internal detection and three-dimensional reconstruction method for a soil cavity outside a buried PE pipeline, which fills the blank of a nondestructive detection method in the field; the method has the advantages of simple operation, easy realization, small data volume and the like, and can be widely used for high-efficiency detection and three-dimensional reconstruction of the outer soil body cavity of the buried PE pipeline;
2. The microwave horn antenna is positioned in the PE pipe, and is not required to be close to the inner wall of the PE pipe, so that the application range of three-dimensional reconstruction of the outer soil body cavity of the PE pipe is greatly widened;
3. According to the method, the pair of microwave horn antennas is utilized, the microwave orthogonal polarization internal detection mode is combined, the mode of transmitting and receiving is adopted to collect data of the outer soil body cavity microwave detection of the PE pipeline, and the superposition influence of incident microwaves on reflected microwaves is effectively avoided.
Drawings
Fig. 1 is a schematic diagram of the measurement principle of the present invention.
Fig. 2 is a schematic diagram of a microwave horn antenna placement according to the present invention.
Fig. 3 is a schematic diagram of the placement of orthogonal polarizations of a microwave horn antenna according to the present invention.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
As shown in fig. 1, the detection principle of the method is as follows: according to the principle of microwave detection, namely according to the basic theory of microwave propagation, when incident waves are emitted from the microwave horn antenna 1, pass through the air 3 and the PE pipe 4 to reach an air-PE pipe heterogeneous interface, as the medium wave impedance at two sides of the heterogeneous interface is not matched, microwaves are reflected and transmitted at the heterogeneous interface, a part of energy is reflected back to the microwave horn antenna 2, a part of energy penetrates through the PE pipe 4 and the soil cavity 5 to reach the soil cavity-soil heterogeneous interface, again, as the medium wave impedance at two sides of the heterogeneous interface is not matched, reflection and transmission occur, a part of energy is reflected back to the microwave horn antenna 2, and a part of energy penetrates through the soil 6 to continue to propagate forwards. The determination of the outer soil body cavity size of the PE pipeline is realized by observing and processing the signals reflected back to the microwave horn antenna, so that the three-dimensional reconstruction is further carried out on the outer soil body cavity size.
The whole method comprises the following steps: the microwave horn antenna connected with the vector network analyzer is used for transmitting a microwave stepping frequency signal to scan from the inside to the outside of the PE pipe, receiving a microwave reflection frequency domain signal S 21, windowing the obtained frequency domain signal, converting the frequency domain signal into a microwave reflection time domain signal through inverse Chirp-Z transformation, analyzing the microwave reflection time domain signal, further calculating the propagation speed of microwaves in each medium through the known dielectric constants and magnetic conductivities of each medium in a propagation path, finding the distance time between two reflection peaks from the microwave reflection time domain signal, and multiplying the distance information between two heterogeneous interfaces through the microwave wave speed, thereby determining the one-dimensional size of soil body cavities in soil. The z-theta scanning device is used for scanning each axial depth and each circumferential angle, so that the three-dimensional information is determined, and the three-dimensional reconstruction of the soil body cavity outside the PE pipeline is realized.
The specific detection steps are as follows:
Step 1: building an experimental platform for evaluating one-dimensional dimensions of an outer soil body cavity of a PE pipeline: connecting two ends of two coaxial cables with a vector network analyzer and a microwave horn antenna respectively, placing the two microwave horn antennas in a PE tube in a microwave orthogonal polarization mode, wherein the microwave orthogonal polarization placing mode requires that long sides of apertures of the two microwave horn antennas are mutually perpendicular, aperture centers of the two microwave horn antennas are symmetrical relative to a central axis of the PE tube, and fixing the two microwave horn antennas in a linear angle z-theta scanning device;
Step 2: the method for evaluating the one-dimensional size of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) A microwave horn antenna connected with a vector network analyzer through a coaxial cable radiates step frequency microwaves outwards from the interior of a PE pipe and receives reflected echoes by the other microwave horn antenna to obtain a microwave reflected frequency domain signal S 21;
2) Adding a Kaiser window to the microwave reflection frequency domain signal S 21 obtained in the step 2), and converting the microwave reflection frequency domain signal S 21 into a microwave reflection time domain signal through Chirp-Z inverse transformation to observe the microwave reflection time domain signal, finding out each reflection peak in the microwave reflection time domain signal, wherein each reflection peak is provided with one hetero interface, one reflection peak is added in the time domain signal, if no soil cavity exists outside the PE pipeline, the number of reflection peaks is two (an air-PE pipe hetero interface reflection peak and a PE pipe-soil hetero interface reflection peak), and if the soil cavity exists, the number of reflection peaks is three (an air-PE pipe hetero interface reflection peak, a PE pipe-soil cavity hetero interface reflection peak and a soil cavity-soil hetero interface reflection peak);
3) Determining the medium type between every two reflection peaks through the arrangement sequence of the interface corresponding to the interval between every two adjacent reflection peaks for the reflection peaks determined by observing the microwave reflection time domain signals in the step 2);
4) Determining that the time difference Deltat i,Δti between every two reflection peaks represents the time difference between the ith and the (i+1) th reflection peaks for the reflection peaks found by observing the microwave reflection time domain signal in step 2);
5) For the type of the medium determined in the step 2) and 3), the dielectric constant epsilon ri of the medium is matched with a microwave speed formula Calculating the microwave speed, v i represents the microwave speed of the medium between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface, and mu ri and epsilon ri respectively represent the relative magnetic conductivity and the relative dielectric constant of each layer of medium;
6) For Deltat i obtained in step 2) and v i obtained in step 5), the formula is given by Calculating the distance between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface;
7) The distances from the i-th layer heterogeneous interface to the i+1-th layer heterogeneous interface at all axial positions and circumferential angles obtained in the step 2) can be used for determining the one-dimensional size of the outer soil body cavity of the buried PE pipeline;
Step 3: the three-dimensional reconstruction of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) Scanning each axial position and each circumferential angle in the PE pipe through a z-theta scanning device;
2) Obtaining one-dimensional axial and circumferential dimensions of the outer soil body cavity of each scanning position from the scanning data obtained in the step 3) through the step 2 for each group of scanning data;
3) And 2) carrying out three-dimensional reconstruction of the outer soil body cavity of the PE pipeline by the axial and circumferential one-dimensional dimensions of the outer soil body cavity of each scanning position obtained in the step 2).
Claims (1)
1. A microwave orthogonal polarization internal inspection and three-dimensional reconstruction method for a soil body cavity outside a PE pipeline is characterized by comprising the following steps of: the method comprises the following steps:
Step 1: setting up an experimental platform for evaluating the one-dimensional size of an outer soil body cavity of a PE pipeline, respectively connecting two ends of two coaxial cables with a vector network analyzer and a microwave horn antenna, arranging the two microwave horn antennas in the PE pipeline in a microwave orthogonal polarization mode, wherein the microwave orthogonal polarization arranging mode requires that long sides of apertures of the two microwave horn antennas are mutually perpendicular, and aperture centers of the two microwave horn antennas are symmetrical relative to a central axis of the PE pipeline, and fixing the two microwave horn antennas in a linear corner z-theta scanning device;
Step 2: the method for evaluating the one-dimensional size of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) A microwave horn antenna connected with a vector network analyzer through a coaxial cable radiates step frequency microwaves outwards from the interior of a PE pipe and receives reflected echoes by the other microwave horn antenna to obtain a microwave reflected frequency domain signal S 21;
2) Adding a Kaiser window to the microwave reflection frequency domain signal S 21 obtained in the step 2), converting the microwave reflection frequency domain signal S 21 into a microwave reflection time domain signal through Chirp-Z inverse transformation, observing the microwave reflection time domain signal, finding out each reflection peak in the microwave reflection time domain signal, adding one reflection peak in the time domain signal when one heterogeneous interface exists, if no soil cavity exists outside the PE pipeline, the number of the reflection peaks is two, namely an air-PE pipe heterogeneous interface reflection peak and a PE pipe-soil heterogeneous interface reflection peak, and if the soil cavity exists, the number of the reflection peaks is three, namely an air-PE pipe heterogeneous interface reflection peak, a PE pipe-soil cavity heterogeneous interface reflection peak and a soil cavity-soil heterogeneous interface reflection peak;
3) Determining the medium type between every two reflection peaks through the arrangement sequence of the interface corresponding to the interval between every two adjacent reflection peaks for the reflection peaks determined by observing the microwave reflection time domain signals in the step 2);
4) Determining that the time difference Deltat i,Δti between every two reflection peaks represents the time difference between the ith and the (i+1) th reflection peaks for the reflection peaks found by observing the microwave reflection time domain signal in step 2);
5) For the type of the medium determined in the step 2) and 3), the dielectric constant epsilon ri of the medium is matched with a microwave speed formula Calculating the microwave speed, v i represents the microwave speed of the medium between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface, and mu ri and epsilon ri respectively represent the relative magnetic conductivity and the relative dielectric constant of each layer of medium;
6) For Deltat i obtained in step 2) and v i obtained in step 5), the formula is given by Calculating the distance between the i-th layer heterogeneous interface and the i+1-th layer heterogeneous interface;
7) Determining the one-dimensional size of the outer soil body cavity of the buried PE pipeline according to the distances from the ith layer of heterogeneous interface to the (i+1) th layer of heterogeneous interface at all axial positions and circumferential angles obtained in the step 2);
Step 3: the three-dimensional reconstruction of the outer soil body cavity of the PE pipeline comprises the following specific steps:
1) Scanning each axial position and each circumferential angle in the PE pipe through a z-theta scanning device;
2) Obtaining one-dimensional axial and circumferential dimensions of the outer soil body cavity of each scanning position from the scanning data obtained in the step 3) through the step 2 for each group of scanning data;
3) And 2) carrying out three-dimensional reconstruction of the outer soil body cavity of the PE pipeline by the axial and circumferential one-dimensional dimensions of the outer soil body cavity of each scanning position obtained in the step 2).
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|---|---|---|---|---|
| US5933014A (en) * | 1994-11-23 | 1999-08-03 | Fraunhofer Gesellschaft Zur Foerderung | Process for detecting totally or partially hidden non-homogeneities by means of microwave radiation |
| JP3071226U (en) * | 2000-02-22 | 2000-08-29 | 孝 松永 | A device to detect the collapse of the inner wall of the tunnel |
| CN111175320A (en) * | 2020-01-08 | 2020-05-19 | 大连理工大学 | Concrete damage active detection method based on thermal ultrasonic |
| CN215574742U (en) * | 2021-08-26 | 2022-01-18 | 城安隧研(广州)科技有限公司 | Test platform for detecting defects of rear cavity of shield segment wall and underground pipeline |
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