CN105676000A - Transmission-type CT ground penetrating radar-based measurement method for measuring soil relative dielectric constant - Google Patents
Transmission-type CT ground penetrating radar-based measurement method for measuring soil relative dielectric constant Download PDFInfo
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- CN105676000A CN105676000A CN201610011854.9A CN201610011854A CN105676000A CN 105676000 A CN105676000 A CN 105676000A CN 201610011854 A CN201610011854 A CN 201610011854A CN 105676000 A CN105676000 A CN 105676000A
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- 239000002689 soil Substances 0.000 title claims abstract description 18
- 230000000149 penetrating effect Effects 0.000 title abstract description 4
- 238000000691 measurement method Methods 0.000 title abstract 2
- 238000012937 correction Methods 0.000 claims abstract description 4
- 238000003556 assay Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 abstract description 7
- 238000004806 packaging method and process Methods 0.000 abstract 1
- 238000001514 detection method Methods 0.000 description 13
- 238000002474 experimental method Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004587 chromatography analysis Methods 0.000 description 2
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- 230000001427 coherent effect Effects 0.000 description 1
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- 230000005288 electromagnetic effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2617—Measuring dielectric properties, e.g. constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/12—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with electromagnetic waves
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Abstract
The invention discloses a transmission-type CT ground penetrating radar-based measurement method for measuring the soil relative dielectric constant. The method comprises the steps of respectively packaging a transmitting system and a receiving system in different housings, wherein the transmitting system comprises a transmitting antenna and the receiving system comprises a receiving antenna; collecting the data of electromagnetic waves in the air; selecting a first arrival as a take-off point; obtaining different antenna distances and the corresponding first take-off time; calculating the theoretical travel time of electromagnetic waves in the in air; calculating the average take-off time based on the first take-off time and the theoretical travel time; obtaining the second take-off time of the electromagnetic waves in a medium of a predetermined thickness; adopting the average take-off time as a zero line correction value to correct the second take-off time; calculating the propagation velocity of the electromagnetic waves in the medium according to the thickness and the corrected second take-off time; and calculating a relative dielectric constant according to the propagation velocities of the electromagnetic waves in the medium and in the air. According to the technical scheme of the invention, the relative dielectric constant of the medium can be accurately calculated.
Description
Technical field
The present invention relates to ground penetrating radar exploration field, be specifically related to a kind of transmission-type CT GPR assay method to soil relative dielectric constant.
Background technology
Ground penetrating radar exploration is that (frequency range is 10 by launching high-frequency impulse electromagnetic wave6-109Hz) science of underground objects detection is carried out. GPR has the features such as simple to operate, detection accuracy is high, not damaged, picking rate are fast, is current engineering detecting and the most commonly used technical method of prospecting, and the application in Geotechnical Engineering is also increasingly extensive. The detection method of current GPR is mainly based on reflection profile method. Fig. 1 is the detection principle of reflective GPR, reflection detection is the transmitting antenna of radar and reception antenna is all positioned over measured medium surface, by launching high-frequency wideband electromagnetic impulse signal in medium, and receiver media has the process of the electromagnetic wave signal realization detection that electrical property difference place is reflected back.
But, due to underground medium distribution and qualitative complexity, reflective GPR is difficult to accurately distinguish the layer position information of each medium in data inversion process; And take-off time cannot be determined accurately, thus high-frequency impulse electromagnetic wave spread speed in media as well cannot accurately be calculated, the relative dielectric constant of detection medium therefore cannot be calculated.
Summary of the invention
In view of this, the present invention proposes a kind of transmission-type CT GPR assay method to soil relative dielectric constant, recoverable electromagnetic wave take-off time in media as well, calculates electromagnetic wave spread speed in media as well, thus accurately calculating the relative dielectric constant of soil.
The present invention provides a kind of transmission-type CT GPR assay method to soil relative dielectric constant, wherein, comprise the following steps: S101, the emission system of GPR is individually enclosed in different housings from reception system, emission system includes transmitting antenna, and reception system includes reception antenna;S102, the form placed in opposite directions by two antennas concentrically line in atmosphere gathers electromagnetic wave data, choose electromagnetic wave first arrival as ski-jump, obtain transmitting antenna and the variant antenna distance of reception antenna and the first corresponding take-off time thereof, electromagnetic wave aerial theoretical hourage is calculated according to antenna distance, by the first take-off time and electromagnetic wave aerial theoretical hourage, after correspondence is subtracted each other and average to calculate average take-off time; S103, measured medium is carried out concentrically line and the CT that places in opposite directions surveys work, obtain the electromagnetic wave the second take-off time in predetermined dielectric thickness, second take-off time is corrected as zero line corrected value by the average take-off time calculated before, calculates electromagnetic wave spread speed completely in media as well according to the second take-off time after thickness and correction; S104, calculates relative dielectric constant according to electromagnetic wave spread speed in medium and air.
Preferably, antenna distance is 0-200cm.
Preferably, just most there is the phase place of same feature.
Preferably, just most zero phase or 1/4 wavelength or 1/2 wavelength.
Preferably, coaxial cable for high frequency is adopted to be connected between transmitting antenna with reception antenna.
Preferably, the second take-off time is the take-off time of single track waveform.
Relative dielectric constant defining method provided by the invention is by being individually enclosed in different housings by emission system from reception system, obtain the average take-off time in air and correct the take-off time in actual measurement medium, can accurately draw electromagnetic wave spread speed in media as well, thus accurately calculating the relative dielectric constant of medium, overcoming conventional reflective GPR can not the defect of accurate calculation medium relative dielectric constant.
Accompanying drawing explanation
Fig. 1 is the detection principle schematic diagram of reflective GPR.
Fig. 2 is the flow chart of the relative dielectric constant assay method of the embodiment of the present invention.
Fig. 3 is that the air of the different antennae distance of the embodiment of the present invention is to drawing experiment schematic diagram.
Fig. 4 is the soil model detection schematic diagram of the transmission CT formula GPR of the embodiment of the present invention.
Fig. 5 is the air of the different antennae distance of the embodiment of the present invention Gpr Data figure to drawing experiment.
Fig. 6 is the Gpr Data single track information display figure of the embodiment of the present invention.
Fig. 7 is the single track radar waveform figure that the GPR of the embodiment of the present invention is first arrival time with first time positive crest.
Fig. 8 is soil media transmission-type CT antenna measured section and the single track information retrieval figure of one embodiment of the invention.
Detailed description of the invention
Below in conjunction with accompanying drawing and specific embodiment, technical scheme is described in detail.
Fig. 2 illustrates the flow chart of the relative dielectric constant defining method of the present invention, and it comprises the following steps:
S101, is individually enclosed in different housings by the emission system of GPR from reception system, and emission system includes transmitting antenna, and reception system includes reception antenna;
Based on GR (GeologyRadar, GPR) series GPR 750MHz antenna, emission system and reception system are separated, transmitting antenna radiating surface is individually enclosed in different housings with transmitter module, reception antenna radiating surface with receiver module, and reach the shielding electromagnetic effect of interference by filling absorbing material in housing, it is transformed into transmission CT (ChromatographicTechnique, chromatographic technique) formula GPR. Use coaxial cable for high frequency as signal synchronous transfer line between transmitting antenna and reception antenna.Two antennas are powered respectively, and designs data power interface and be connected with main frame.
Wherein, the relative distance of two antennas arbitrarily can regulate in preset range, such as 0-200cm. For convenience of operation, it is possible to two housings are separately mounted on support, for instance two housings are separately mounted to the bottom at support two ends. The shape of support is not specifically limited, to facilitate emission system and reception system to use.
S102, the form placed in opposite directions by two antennas concentrically line in atmosphere gathers electromagnetic wave data, choose electromagnetic wave first arrival as ski-jump, obtain transmitting antenna and the variant antenna distance of reception antenna and the first corresponding take-off time thereof, electromagnetic wave aerial theoretical hourage is calculated according to antenna distance, by the first take-off time and electromagnetic wave aerial theoretical hourage, after correspondence is subtracted each other and average to calculate average take-off time; Wherein, in this area, seismic wave wavefront arrives certain observation station, and in observation station, cymoscope detects that the moment of particle vibration is called the first arrival time of ripple, is called for short first arrival.
Using transmission CT formula GPR to carry out air to drawing experiment, two antenna conllinear are staggered relatively with predetermined spacing, and such as 0cm, 40cm, 80cm, 120cm, 160cm and 200cm place, as shown in Figure 3 and Figure 4, wherein T is emission system, and R is reception system.
Air, to drawing experiment to refer in atmosphere by staggered relatively for two antennas and move with equivalent interval, carries out continuous Coherent Noise in GPR Record collection. By choosing first arrival as ski-jump, and read respectively two antennas at different distances time the first take-off time, as at a distance of 40cm time, the first take-off time is t02. First arrival can have the phase place of same feature according to waveform selection, such as the zero phase of signal, 1/4 wavelength, 1/2 wavelength etc.
After choosing first arrival, read air to drawing variant antenna distance d in experiment1, d2……dnAnd the take-off time t of correspondence01, t02……t0nAnd electromagnetic theoretical hourage t1, t2……tn. Different antennae distance electromagnetic wave aerial theoretical hourage is t1-t01, t2-t02……tn-t0n, wherein, t1=d1/ c, t2=d2/c……tn=dn/ c, c are the aerial spread speed of electromagnetic wave, c=3 × 108M/s. Then travel in air take-off average time is tair=[(t1-t01)+(t2-t02)+……+(tn-t0n)]/n, tairFor the electromagnetic wave average take-off time in atmosphere calculated according to same first arrival.
As shown in Figure 5, at air to drawing in experiment, when the two antennas respectively 40cm of relative distance in atmosphere, 80cm, 120cm and 160cm place, take-off time display situation on radar cross-section is read from first positive crest location (i.e. 1/4 wavelength), and by reading the first take-off time value t at this place0i(i=1,2,3,4) calculate travelling take-off t average time in airair。
S103, measured medium is carried out concentrically line and the CT that places in opposite directions surveys work, obtain the electromagnetic wave the second take-off time in predetermined dielectric thickness, second take-off time is corrected as zero line corrected value by the average take-off time calculated before, calculates electromagnetic wave spread speed completely in media as well according to the second take-off time after thickness and correction; As shown in Figure 6, in embodiments of the present invention, in predetermined dielectric thickness, electromagnetic wave penetrates what measured medium was formed radar cross-section the corresponding single track shape information figure reading the second take-off time with the first positive crest location (i.e. 1/4 wavelength place).
With average take-off time tairAs the zero line corrected value of actual measurement soil radar data, radar data is carried out single track waveform extracting.In actual measurement single track Wave data, with average take-off time tairInitial time t as actual measurement soil data transmission0. It is analyzed further according to the single track waveform in detection data, reads through the take-off time t after thickness d soil mediaa, then calculate electromagnetic wave spread speed v in soil.
To multiple single track information batch processings, electromagnetic wave the mean propagation velocity v in media as well can also be calculatedOn average. The computing formula propagating velocity of wave is:
Wherein, v is electromagnetic wave spread speed in soil, and d is the dielectric thickness of electromagnetic wave traverse, taFor electromagnetic wave spread speed in soil, t0For initial time.
S104, calculates relative dielectric constant according to electromagnetic wave spread speed in medium and air.
Relative dielectric constant can be calculated according to following formula,
Wherein, v is electromagnetic wave spread speed in soil, and c is the aerial spread speed of electromagnetic wave, c=3 × 108m/s。
In a particular embodiment, corresponding numerical parameter can be substituted into the relative dielectric constant that can calculate medium in the formula in S104. Fig. 7 is air to the single track information drawn in each phase data read with the first positive crest (1/4 wavelength place) for take-off time in experiment and actual detection work, and the reading position of the first take-off time of correspondence and the second take-off time. Wherein, front 6 roads are from left to right followed successively by the air reading position to drawing antenna distance respectively 0cm in experiment, 40cm, 80cm, the first take-off time that 120cm, 160cm and 200cm are corresponding, three roads next are the reading position of the second take-off time that actual detection work surface is corresponding, the reading position of the first take-off time and the second take-off time is placed on same scale, with the error of the take-off time reading position that reduction causes due to scale difference, improve the degree of accuracy of calculation medium relative dielectric constant. Fig. 8 is in inventive embodiments, radar cross-section during for different water cut soil transmission detection and the take-off time single track information of correspondence thereof, and wherein, in figure, the position of arrow indication is the reading position of the second take-off time.
On the basis of above-described embodiment, it is also possible to calculate electromagnetic wave the mean propagation velocity v in media as wellOn average, thus obtaining average relative DIELECTRIC CONSTANT εOn average。
The present invention is by being individually enclosed in different housings by emission system from reception system, obtain the average take-off time in air and correct the take-off time in actual measurement medium, can accurately draw electromagnetic wave spread speed in media as well, thus accurately calculating the relative dielectric constant of medium, overcoming conventional reflective GPR can not the defect of accurate calculation medium relative dielectric constant.
Above, in conjunction with specific embodiments technical scheme being described in detail, described specific embodiment is adapted to assist in the thought understanding the present invention. Derivation and modification that those skilled in the art make on the basis of the specific embodiment of the invention fall within scope.
Claims (6)
1. the transmission-type CT GPR assay method to soil relative dielectric constant, it is characterised in that comprise the following steps:
S101, is individually enclosed in different housings by the emission system of GPR from reception system, and emission system includes transmitting antenna, and reception system includes reception antenna;
S102, the form placed in opposite directions by two antennas concentrically line in atmosphere gathers electromagnetic wave data, choose electromagnetic wave first arrival as ski-jump, obtain transmitting antenna and the variant antenna distance of reception antenna and the first corresponding take-off time thereof, electromagnetic wave aerial theoretical hourage is calculated according to antenna distance, by the first take-off time and electromagnetic wave aerial theoretical hourage, after correspondence is subtracted each other and average to calculate average take-off time;
S103, measured medium is carried out concentrically line and the CT that places in opposite directions surveys work, obtain the electromagnetic wave the second take-off time in predetermined dielectric thickness, second take-off time is corrected as zero line corrected value by the average take-off time calculated before, calculates electromagnetic wave spread speed completely in media as well according to the second take-off time after thickness and correction;
S104, calculates relative dielectric constant according to electromagnetic wave spread speed in medium and air.
2. assay method as claimed in claim 1, it is characterised in that antenna distance is 0-200cm.
3. assay method as claimed in claim 1, it is characterised in that just most there is the phase place of same feature.
4. assay method as claimed in claim 3, it is characterised in that just most zero phase or 1/4 wavelength or 1/2 wavelength.
5. assay method as claimed in claim 1, it is characterised in that adopt coaxial cable for high frequency to be connected between transmitting antenna with reception antenna.
6. assay method as claimed in claim 1, it is characterised in that the second take-off time is the take-off time of single track waveform.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990143A (en) * | 2017-02-16 | 2017-07-28 | 北京市道路工程质量监督站 | A kind of measuring method and system of asphalt dielectric constant |
| CN110161495A (en) * | 2019-05-23 | 2019-08-23 | 中国地质大学（北京） | A kind of soil effective soil layer thickness determines method and system |
| CN111387087A (en) * | 2020-04-10 | 2020-07-10 | 林心 | Automatic egg hatching degree detection system |
| CN111387088A (en) * | 2020-04-10 | 2020-07-10 | 林心 | Egg hatching degree detection method based on image processing |
| CN112526618A (en) * | 2020-11-19 | 2021-03-19 | 中国电波传播研究所（中国电子科技集团公司第二十二研究所） | Ionized layer tomography measuring instrument based on multi-band multi-constellation satellite signals and observation method thereof |
| CN113238199A (en) * | 2021-04-08 | 2021-08-10 | 中国科学院国家天文台 | Method and device for calculating dielectric constant, electronic equipment and storage medium |
| CN113884550A (en) * | 2021-09-09 | 2022-01-04 | 水利部交通运输部国家能源局南京水利科学研究院 | Method for measuring dielectric constant of soil body/concrete in field layering manner and application thereof |
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2016
- 2016-01-08 CN CN201610011854.9A patent/CN105676000A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990143A (en) * | 2017-02-16 | 2017-07-28 | 北京市道路工程质量监督站 | A kind of measuring method and system of asphalt dielectric constant |
| CN106990143B (en) * | 2017-02-16 | 2019-12-06 | 北京市道路工程质量监督站 | Method and system for measuring dielectric constant of asphalt mixture |
| CN110161495A (en) * | 2019-05-23 | 2019-08-23 | 中国地质大学（北京） | A kind of soil effective soil layer thickness determines method and system |
| CN110161495B (en) * | 2019-05-23 | 2020-07-28 | 中国地质大学（北京） | Method and system for determining thickness of effective soil layer of soil |
| CN111387087A (en) * | 2020-04-10 | 2020-07-10 | 林心 | Automatic egg hatching degree detection system |
| CN111387088A (en) * | 2020-04-10 | 2020-07-10 | 林心 | Egg hatching degree detection method based on image processing |
| CN112526618A (en) * | 2020-11-19 | 2021-03-19 | 中国电波传播研究所（中国电子科技集团公司第二十二研究所） | Ionized layer tomography measuring instrument based on multi-band multi-constellation satellite signals and observation method thereof |
| CN113238199A (en) * | 2021-04-08 | 2021-08-10 | 中国科学院国家天文台 | Method and device for calculating dielectric constant, electronic equipment and storage medium |
| CN113238199B (en) * | 2021-04-08 | 2023-05-05 | 中国科学院国家天文台 | Method and device for calculating dielectric constant, electronic equipment and storage medium |
| CN113884550A (en) * | 2021-09-09 | 2022-01-04 | 水利部交通运输部国家能源局南京水利科学研究院 | Method for measuring dielectric constant of soil body/concrete in field layering manner and application thereof |
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