CN112462432A - High-precision detection method and device for coal field fire area cavity - Google Patents
High-precision detection method and device for coal field fire area cavity Download PDFInfo
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Abstract
The invention relates to the technical field of coal field fire zone cavity detection, in particular to a high-precision coal field fire zone cavity detection method and device. The former includes a setting electrode; acquiring detection data of element points corresponding to the detection points corresponding to the measurement electrodes under the ground, and performing data processing on the detection data; and performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity. According to the invention, the measuring electrodes are added on the basis of a monopole dipole sounding method, the polar distance between the measuring electrodes is unchanged, the first power supply electrode which is continuously changed during detection automatically detects deep physical property abnormity, meanwhile, multiple overlapping measurement is realized on the physical property abnormity, the detection element points are uniformly distributed, the full coverage on the whole section of the coal field fire area is realized, the element data is not reduced due to the increase of the detection depth, and further, the determination precision of the cavity of the coal field fire area is not influenced.
Description
Technical Field
The invention relates to the technical field of coal field fire zone cavity detection, in particular to a high-precision coal field fire zone cavity detection method and device.
Background
China is one of the most serious countries in the coal field fire area in the world, and because the occurrence of the coal field fire area causes or aggravates economic losses caused by other natural disasters, the economic losses cannot be estimated, so that the research of coal field fire area investigation is comprehensively and systematically deeply developed by means of modern scientific technology and multi-discipline cross-department joint customs.
The coal burning not only loses a large amount of precious coal resources, but also seriously pollutes the atmospheric environment. The investment and efficiency of the fire management project mainly depend on the detection precision of the coal fire in the early stage. At present, the domestic geophysical prospecting method has various means, and the existing high-density direct current method is used for exploring hidden holes and coal seam goafs of underground rock bodies, determining the vertical extension and inclination of faults and cracks and determining the existing position of underground water. When the depth is continuously increased by using a high-density direct current method, the electrode distance is also continuously increased, the geological element data are more rare, the resolution ratio is reduced therewith, the physical property abnormity with a small deep range is difficult to identify, the electrode distance and the point distance are often encrypted for improving the resolution ratio, the length of a measuring line is prolonged, the detection precision is improved, the field workload is multiplied therewith, and the working efficiency is greatly reduced.
Disclosure of Invention
The invention provides a high-precision detection method and device for coal field fire zone cavities, overcomes the defects of the prior art, and can effectively solve the problems that the resolution and the recognition degree are reduced and deep cavities are difficult to recognize along with the increase of the detection depth in the high-density direct current method for detecting the coal field fire zone cavities.
One of the technical schemes of the invention is realized by the following measures: a high-precision detection method for cavities in a coal field fire area comprises the following steps:
arranging a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
when different first power supply electrodes supply power, the detection data of the element points corresponding to the detection points of the measuring electrodes under the ground are obtained, and data processing is carried out on the detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface, and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
and performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
The following is further optimization or/and improvement of the technical scheme of the invention:
when the above-mentioned different first power supply electrode supplies power, the detection data of the corresponding element point of probe point under ground of each measuring electrode to carry out data processing to a plurality of detection data includes:
according to the detection depth, acquiring detection data of corresponding element points of corresponding detection points under the ground when different first power supply electrodes supply power to the measuring electrodes, wherein the detection data comprise element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the apparent resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
and forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical exponential amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data subjected to mathematical exponential amplification.
The above-mentioned according to the detection degree of depth, obtain each measuring electrode when different first power supply electrode supplies power, correspond the detection data of the corresponding element point of probe point under the ground, include:
determining that the grounding resistances of all the electrodes meet the detection requirement;
selecting a corresponding first power supply electrode according to the detection depth, using different first power supply electrodes to supply power, acquiring the power supply voltage and the measurement current of a corresponding element point of a detection point where a certain measurement electrode is located, and circularly acquiring the power supply voltage and the measurement current of the corresponding element point of the detection point where each measurement electrode is located when different first power supply electrodes supply power;
and outputting detection data of each element point, wherein the detection data comprises the horizontal position of the element point, the corresponding depth of the element point, and the apparent resistivity value of the element point is obtained through the supply voltage and the measurement current of the element point.
The establishing of the geophysical model comprises the following steps:
carrying out primary screening on the detection data, and eliminating a maximum value and a minimum value;
carrying out weighted average on apparent resistivity values of the detection data;
and determining the rock stratum distribution and the rock stratum resistance value of the fire area of the coal field to be detected, and establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging.
The secondary screening of the detection data after the performance includes:
carrying out weighted average on apparent resistivity values in the primarily screened detection data;
setting a threshold value according to the weighted average result;
and screening out the detection data with the absolute value of the apparent resistivity value larger than the threshold value to complete secondary screening.
The analyzing the cavity position according to the apparent resistivity contour profile comprises the following steps:
determining an apparent resistivity value anomaly threshold;
determining an apparent resistivity value abnormal area in an apparent resistivity contour profile;
and comparing the apparent resistivity value with an abnormal apparent resistivity value threshold, and if the apparent resistivity value is larger than the abnormal apparent resistivity value threshold, determining the position as the position of the hole.
The second technical scheme of the invention is realized by the following measures: a coal field fire zone cavity high accuracy detection device includes:
the electrode setting unit is used for setting a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
the detection data acquisition and processing unit is used for acquiring detection data of element points corresponding to detection points under the ground corresponding to each measuring electrode when different first power supply electrodes supply power, and processing data of the detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface, and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
and the drawing and analyzing unit is used for performing two-dimensional inversion on the processed detection data, drawing a profile of the apparent resistivity isoline of the fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
The following is further optimization or/and improvement of the technical scheme of the invention:
the detection data acquiring and processing unit includes:
the detection data acquisition unit is used for acquiring detection data of corresponding element points of the corresponding detection points under the ground when the different first power supply electrodes supply power according to the detection depth, wherein the detection data comprises element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
the model establishing unit is used for establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
and the data deduction unit is used for forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical index amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data amplified by the mathematical index.
The invention adds measuring electrodes on the basis of a monopole dipole depth measurement method, the polar distance between the measuring electrodes is unchanged, all the electrodes are well laid at one time, the first power supply electrode which is continuously changed during detection automatically detects deep physical property abnormity, simultaneously realizes multiple overlapping measurement on the physical property abnormity, and corresponding element points are arranged vertically below each detection point according to the increasing depth, so that the element points are uniformly distributed, the full coverage of the whole section of a coal field fire area is realized, the element data is not reduced due to the increase of the detection depth, and further the determination precision of a cavity of the coal field fire area is not influenced, the section of the coal field fire area detected by the invention is rectangular in distribution, and the two ends of the section have no blind areas, thereby solving the problems that the inverted triangle section detected by the existing high-density direct current method, the deep parts at the two ends of the section are blind areas, and the blind areas are often reduced in the field operation, the length of the measuring line is artificially prolonged and is often multiplied, so that the working capacity of field operation is multiplied, and the field operation capacity is effectively reduced on the basis of ensuring the detection precision. Meanwhile, after a plurality of detection data of the coal field fire area to be detected when different first power supply electrodes supply power are obtained, the detection data corresponding to the surface electrical property unevenness caused by the power supply current are removed, and the detection data corresponding to the underground electrical property abnormal body are screened and amplified in a data processing mode, so that the ground resistance inconsistency, the terrain interference and the electric field interference caused by the power supply electrodes due to the surface electrical property unevenness can be effectively avoided, and the abnormality is amplified, so that the coal field fire area cavity is accurately judged in the apparent resistivity contour sectional view.
Drawings
FIG. 1 is a flowchart of a detection method according to embodiment 1 of the present invention.
Fig. 2 is a schematic view of the electrode arrangement of example 1 of the present invention.
FIG. 3 is a flowchart of a detection method according to embodiment 2 of the present invention.
FIG. 4 is a flowchart of the geophysical model building in embodiment 2 of the present invention.
FIG. 5 is a flowchart of a detection method according to embodiment 3 of the present invention.
Fig. 6 is a schematic diagram of detection in embodiment 3 of the present invention.
FIG. 7 is a schematic structural view of an apparatus according to embodiment 4 of the present invention.
Fig. 8 is a schematic structural diagram of a detection data acquiring and processing unit in embodiment 4 of the present invention.
Detailed Description
The present invention is not limited by the following examples, and specific embodiments may be determined according to the technical solutions and practical situations of the present invention.
The invention is further described with reference to the following examples and figures:
s101, arranging a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
s102, acquiring detection data of element points corresponding to detection points of each measuring electrode under the ground when different first power supply electrodes supply power, and performing data processing on a plurality of detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
s103, performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
The invention discloses a high-precision detection method for coal field fire zone holes, which is characterized in that measuring electrodes are added on the basis of a monopole dipole sounding method, the polar distance between the measuring electrodes is unchanged, all the electrodes are arranged at one time, a first power supply electrode is continuously changed during detection, deep physical property abnormity is automatically detected, multiple overlapping measurement is realized for the physical property abnormity, corresponding element points are arranged vertically below each detection point according to the increasing of the depth, the element points are uniformly distributed, the whole section of the coal field fire zone is fully covered, the reduction of element data due to the increase of the detection depth is avoided, the determination precision of the coal field fire zone holes is not influenced, the section of the detected coal field fire zone is in rectangular distribution, the two ends of the section are free of blind areas, the problem that the existing high-density direct current method detects inverted triangle sections, and the two ends of the section are blind areas, in the field actual operation, the length of the measuring line is usually increased in multiples in order to reduce the blind area and artificially prolong the length of the measuring line, so that the workload of the field operation is increased in multiples, and the field operation amount is effectively reduced on the basis of ensuring the detection precision.
According to the method, after a plurality of detection data of the coal field fire area to be detected when different first power supply electrodes supply power are obtained, through data processing modes such as eliminating the detection data corresponding to the surface electrical property nonuniformity caused by the power supply current, screening and amplifying the detection data corresponding to the underground electrical anomaly, the ground resistance inconsistency, the terrain interference and the electric field interference caused by the power supply electrodes due to the surface electrical nonuniformity can be effectively avoided, and therefore the coal field fire area cavity is accurately judged in the apparent resistivity contour sectional view.
In step S101 of the above technical solution, the second power supply electrode is an infinite electrode, and is generally arranged in a direction perpendicular to the measuring line, and the distance at infinity can be 8 to 10 times the length of the measuring line (the length of the measuring line is a length measured by a straight line where a plurality of detection points need to be arranged in a fire area of the coal field to be measured). The measuring electrode is divided into an electrode M and an electrode N, the polar distance between the electrode M and the electrode N is fixed, and the electrode M and the electrode N are respectively arranged on a detection point.
For example, if the length of the measuring line is 80 meters, the depth of probing is 120 meters, the distance between probing points is 5 meters, the distance between first power supply electrodes is 20 meters, and the electrode distance between measuring electrodes is 10 meters, as shown in fig. 2, there are 17 probing points, 5 first power supply electrodes (a 1, a2, A3, a4, and a5, respectively), and the second power supply electrode is arranged 640 meters perpendicular to the measuring line.
In the above technical solution, the detection data output in step S102 is in dat format, where X is a horizontal position of the element point, Y is a corresponding depth of the element point, and Z is an apparent resistivity value of the element point.
In step S103 of the above technical solution, selecting domestic GEORES3D three-dimensional high-density electrical method software or germany cscs three-dimensional high-density electrical method software, performing two-dimensional inversion with terrain correction on the processed probe data, drawing a profile of a resistivity contour line by sufer mapping software to obtain dat result data, and analyzing the cavity position according to the profile of the resistivity contour line, specifically as follows:
1. determining an apparent resistivity value anomaly threshold (which may be typically set at 3000 Ω);
2. determining an apparent resistivity value abnormal area in an apparent resistivity contour profile;
3. and comparing the apparent resistivity value with an abnormal apparent resistivity value threshold, and if the apparent resistivity value is larger than the abnormal apparent resistivity value threshold, determining the position as the position of the hole.
Embodiment 2, as shown in fig. 3, discloses a method for detecting a cavity in a coal field fire zone with high accuracy, which includes:
s201, arranging a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
s202, acquiring detection data of corresponding element points of corresponding detection points under the ground when different first power supply electrodes supply power according to the detection depth, wherein the detection data comprise element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
s203, establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
s204, forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical exponential amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data amplified by the mathematical exponential;
s205, performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
In the above technical solution, a geophysical model is established according to the formation distribution, the formation resistance value and the weighted average apparent resistivity value through step S203, as shown in fig. 4, which includes
S2031, primary screening is carried out on the detection data, and a maximum value and a minimum value are removed;
s2032, carrying out weighted average on apparent resistivity values of the element points corresponding to the detection points;
s2033, determining the rock stratum distribution and the rock stratum resistance value of the fire area of the coal field to be measured, and establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the weighted average apparent resistivity value.
Since the absolute value of the extreme values in the detection data is generally more than 30 times greater than the median of the original data, and the extreme values are caused by the inconsistency of the ground resistance, the topographic interference and the electric field interference of the power supply electrode due to the non-uniform electrical property of the earth surface, the detection data can be distinguished and removed by a similarity method in step S2031, so that the abnormality reflected by the cavity of the coal field fire area is distinguished from the abnormality reflected by the non-uniform electrical property of the earth surface.
In step S2032, the apparent resistivity values of the element points corresponding to the detection points are weighted and averaged, an apparent resistivity value interval is determined by analogy, then an interval in which the apparent resistivity value of each element point is located is determined, and the ratio of each apparent resistivity value interval is determined.
In the step S2033, the rock stratum distribution of the fire area of the coal field to be measured needs to be determined by combining geological data to determine the geological condition in the detection area, for example, the rock stratum of a certain fire area is sandstone, the fourth series covering layer is pebble layer, coal layer, etc., then the distribution condition of each rock stratum is determined according to the geological structure, a geophysical model is established according to the rock stratum distribution, the rock stratum resistance value and the weighted average apparent resistivity value, and the establishment of the geophysical model is completed by using the existing software according to the rock stratum distribution, the rock stratum resistance value and the weighted average apparent resistivity value, so that the description is omitted.
In step S204 of the above technical solution, the geophysical model and the primarily screened detection data may be subjected to forward modeling through an arithmetic progression to make the apparent resistivity value of the detection data closer to the actual apparent resistivity value of the formation, and then the secondarily screened detection data is subjected to mathematical exponential amplification, where the amplified anomaly is the abnormal prominent range of the later-stage imaging.
Wherein, carry out secondary screening to the survey data after the primary screening, include:
1. acquiring forward-acting detection data in a specific area, and carrying out weighted average on apparent resistivity values of the forward-acting detection data; after forward modeling, the detection data judges the area where the cavity possibly appears and the type of the cavity according to the resistivity value, so that a specific area is found;
2. setting a threshold value according to the result of the weighted average, namely multiplying the result of the weighted average by a set percentage; for example, if the range of the coal seam is a specific region, and the result obtained by weighted average in the range of the coal seam is 130 Ω, the threshold is 130 Ω × 50%;
3. and screening out the detection data with the absolute value of the apparent resistivity value larger than the threshold value to complete secondary screening.
Embodiment 3, as shown in fig. 5, discloses a method for detecting a cavity in a coal field fire zone with high accuracy, which includes:
s301, arranging a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
s302, determining that the grounding resistances of all electrodes meet the detection requirement;
s303, selecting a corresponding first power supply electrode according to the detection depth, using different first power supply electrodes to supply power, acquiring the power supply voltage and the measurement current of an element point corresponding to the detection point where a certain measurement electrode is located, and circularly acquiring the power supply voltage and the measurement current of the element point corresponding to the detection point where each measurement electrode is located when different first power supply electrodes supply power;
s304, outputting detection data of each element point, wherein the detection data comprise element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points, and the apparent resistivity values of the element points are obtained through the power supply voltage and the measurement current of the element points;
s305, establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the apparent resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
s306, forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical exponential amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data amplified by the mathematical exponential;
s307, performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
In step S302 of the above technical solution, since the magnitude of the ground resistance has a large influence on the collected detection data, if the ground resistance is too large, much interference is caused to the collected detection data and the analysis of the later data, and therefore the ground resistance should be smaller than a set value (the set value may be 2K Ω). The commonly used direct current electrical method instruments have the detection function of the ground resistance, the commonly selected direct current electrical method instruments include a DYJJ-2 type multifunctional digital electrical method instrument produced by Pentium geological instruments of Chongqing, an AGI multifunctional digital electrical method instrument of America and the like, the direct current electrical method instruments are connected with a first power supply electrode and a second power supply electrode through external jacks of the instruments, the ground resistance of the second power supply electrode and all electrodes is automatically detected, the electrodes with the ground resistance larger than 2K omega are screened out, the electrodes with the ground resistance smaller than 2K omega are processed through manual watering, grouting and other modes, the electrodes are processed through multiple times of detection and multiple times of manual processing, the data acquisition work can be carried out when all the electrodes meet the detection requirements, the electrodes which do not reach the detection requirements after the multiple times of manual processing can be shielded manually, namely the electrodes do not participate in power supply and measurement.
In step S303 of the above technical solution, the power supply voltage and the measurement current of the elemental point can be obtained by a power supply system of a high-density resistivity method, where the power supply system includes a first power supply electrode, a second power supply electrode, a power supply electrode switch, and a 440V dc circuit, and the power supply voltage and the measurement current of the elemental point can be obtained by the measurement electrode switch.
In step S303 of the above technical solution, as shown in fig. 6, a corresponding first power supply electrode is selected according to a detection depth, different first power supply electrodes are used for supplying power, and a power supply voltage and a measurement current of an element point corresponding to a detection point where a certain measurement electrode is located are obtained. The distance between each first supply electrode and the measuring electrode here determines the depth of investigation.
For example, if the detection depth is 80 meters, the first power supply electrodes are spaced by 20 meters, the electrodes adjacent to the measurement electrodes are selected to supply power, the first power supply electrodes within the range of 80 meters are selected step by step to supply power, the first power supply electrodes which are 80 meters away from the current measurement electrode are selected farthest to supply power, and when each first power supply electrode supplies power, the power supply voltage and the measurement current of the essential point corresponding to the detection point where the measurement electrode is located are obtained, so that 5 groups of detection results can be obtained; data acquisition is performed in the same manner for adjacent measurement electrodes in turn.
In step S304, the apparent resistivity value of the element point is obtained according to Δ U/I, where Δ U is the potential difference and I is the measurement current.
Embodiment 4, as shown in fig. 7, discloses a high-precision detection device for a cavity in a coal field fire zone, which includes:
the electrode setting unit is used for setting a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging a measuring electrode at each detection point, wherein the polar distance between each pair of measuring electrodes is the same;
the detection data acquisition and processing unit is used for acquiring detection data of element points corresponding to detection points under the ground corresponding to each measuring electrode when different first power supply electrodes supply power, and processing data of the detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface, and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
and the drawing and analyzing unit is used for performing two-dimensional inversion on the processed detection data, drawing a profile of the apparent resistivity isoline of the fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
In the above embodiment, the detection data acquiring and processing unit further includes:
as shown in fig. 8, the detection data acquiring and processing unit includes:
the detection data acquisition unit is used for acquiring detection data of corresponding element points of the corresponding detection points under the ground when the different first power supply electrodes supply power according to the detection depth, wherein the detection data comprises element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
the model establishing unit is used for establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
and the data deduction unit is used for forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical index amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data amplified by the mathematical index.
The above technical features constitute the best embodiment of the present invention, which has strong adaptability and best implementation effect, and unnecessary technical features can be increased or decreased according to actual needs to meet the requirements of different situations.
Claims (10)
1. A high-precision detection method for cavities in a coal field fire area is characterized by comprising the following steps:
arranging a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
when different first power supply electrodes supply power, the detection data of the element points corresponding to the detection points of the measuring electrodes under the ground are obtained, and data processing is carried out on the detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
and performing two-dimensional inversion on the processed detection data, drawing a profile of an apparent resistivity contour line of a fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
2. The method for detecting the coal field fire zone cavity with high precision according to claim 1, wherein when different first power supply electrodes are powered on, each measuring electrode corresponds to detection data of an element point of a detection point corresponding to the underground, and data processing is performed on the detection data, and the method comprises the following steps:
according to the detection depth, acquiring detection data of corresponding element points of corresponding detection points under the ground when different first power supply electrodes supply power to the measuring electrodes, wherein the detection data comprise element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the apparent resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
and forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical exponential amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data subjected to mathematical exponential amplification.
3. The method for detecting the cavity in the coal field fire zone with high precision according to claim 2, wherein the obtaining of the detection data of the corresponding element point of the detection point under the ground when each measuring electrode supplies power to different first power supply electrodes according to the detection depth comprises:
determining that the grounding resistances of all the electrodes meet the detection requirement;
selecting a corresponding first power supply electrode according to the detection depth, using different first power supply electrodes to supply power, acquiring the power supply voltage and the measurement current of a corresponding element point of a detection point where a certain measurement electrode is located, and circularly acquiring the power supply voltage and the measurement current of the corresponding element point of the detection point where each measurement electrode is located when different first power supply electrodes supply power;
and outputting detection data of each element point, wherein the detection data comprises the horizontal position of the element point, the corresponding depth of the element point, and the apparent resistivity value of the element point is obtained through the supply voltage and the measurement current of the element point.
4. The method for detecting the cavities in the coal field fire zone with high precision as claimed in claim 2 or 3, wherein the establishing of the geophysical model comprises the following steps:
carrying out primary screening on the detection data, and eliminating a maximum value and a minimum value;
carrying out weighted average on apparent resistivity values of the detection data;
and determining the rock stratum distribution and the rock stratum resistance value of the fire area of the coal field to be detected, and establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging.
5. The method for detecting the cavity in the coal field fire zone with high precision as claimed in claim 2 or 3, wherein the secondary screening of the calculated detection data comprises:
carrying out weighted average on apparent resistivity values in the primarily screened detection data;
setting a threshold value according to the weighted average result;
and screening out the detection data with the absolute value of the apparent resistivity value larger than the threshold value to complete secondary screening.
6. The method for detecting the cavity in the coal field fire zone with high precision as claimed in claim 4, wherein the secondary screening of the calculated detection data comprises:
carrying out weighted average on apparent resistivity values in the primarily screened detection data;
setting a threshold value according to the weighted average result;
and screening out the detection data with the absolute value of the apparent resistivity value larger than the threshold value to complete secondary screening.
7. The method for detecting the coal field fire zone cavity with high precision as claimed in any one of claims 1, 2, 3 or 6, wherein the analyzing the cavity position according to the apparent resistivity contour profile comprises:
determining an apparent resistivity value anomaly threshold;
determining an apparent resistivity value abnormal area in an apparent resistivity contour profile;
and comparing the apparent resistivity value with an abnormal apparent resistivity value threshold, and if the apparent resistivity value is larger than the abnormal apparent resistivity value threshold, determining the position as the position of the hole.
8. The method for detecting the coal field fire zone cavity with high precision as claimed in any one of claims 4 or 5, wherein the analyzing the cavity position according to the apparent resistivity contour profile comprises:
determining an apparent resistivity value anomaly threshold;
determining an apparent resistivity value abnormal area in an apparent resistivity contour profile;
and comparing the apparent resistivity value with an abnormal apparent resistivity value threshold, and if the apparent resistivity value is larger than the abnormal apparent resistivity value threshold, determining the position as the position of the hole.
9. A high-precision detection device for cavities in fire areas of coal fields is characterized by comprising
The electrode setting unit is used for setting a plurality of detection points at equal intervals along a straight line in a fire area of a coal field to be detected; arranging first power supply electrodes at a plurality of detection points, wherein the distances between adjacent first power supply electrodes are the same; disposing a second feeding electrode at infinity; arranging measuring electrodes at the detection points, wherein the polar distances of the measuring electrodes are the same;
the detection data acquisition and processing unit is used for acquiring detection data of element points corresponding to detection points under the ground corresponding to each measuring electrode when different first power supply electrodes supply power, and processing data of the detection data; the data processing comprises the steps of eliminating the detection data influenced by the uneven electrical property of the earth surface, and screening and amplifying the detection data corresponding to the underground electrical abnormal body;
and the drawing and analyzing unit is used for performing two-dimensional inversion on the processed detection data, drawing a profile of the apparent resistivity isoline of the fire zone of the coal field to be detected according to the two-dimensional inverted detection data, and analyzing the position of the cavity.
10. The coal field fire zone cavity high-precision detection device according to any one of claim 9, wherein the detection data acquisition and processing unit comprises:
the detection data acquisition unit is used for acquiring detection data of corresponding element points of the corresponding detection points under the ground when the different first power supply electrodes supply power according to the detection depth, wherein the detection data comprises element point horizontal positions, element point corresponding depths and apparent resistivity values of the element points;
the model establishing unit is used for establishing a geophysical model according to the rock stratum distribution, the rock stratum resistance value and the visual resistivity value after weighted averaging; wherein, the apparent resistivity value after weighted average is obtained by performing primary screening on the detection data and performing weighted average on the apparent resistivity value of the detection data after primary screening;
and the data deduction unit is used for forward modeling the primarily screened detection data according to the geophysical model, secondarily screening the forward screened detection data, performing mathematical index amplification on the secondarily screened detection data, and combining the detection data obtained by forward modeling and the detection data amplified by the mathematical index.
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