Method and system for exploring accumulated water at local low-lying points in goaf

Abstract

The invention discloses a method and a system for probing accumulated water at local low-lying points in a goaf, relates to the technical field of accumulated water probing, and solves the technical problem that misjudgment or missed judgment is easily caused due to limitation of only utilizing a mine transient electromagnetic method to detect an underground accumulated water area. The method comprises the following steps: acquiring resistivity abnormal region information of a goaf through a transient electromagnetic method; geological abnormal region information of the goaf is obtained through a radio wave perspective method; on the basis of the resistivity abnormal area information and the geological abnormal area information, water accumulation area information of the goaf is obtained, and the number of drill holes is determined according to the water accumulation area information; the water accumulation area and the water accumulation condition in the goaf can be more comprehensively explored by detecting the water accumulation area through the transient electromagnetic method and the radio wave perspective method, omission is avoided, and safety accidents caused by water accumulation in a mine can be prevented by timely and effective water drainage measures.

Description

Technical Field

[0001] The invention belongs to the field of water accumulation detection, and specifically relates to a method and system for detecting water accumulation at a local low-lying point in a goaf area. Background Art

[0002] In the energy storage and consumption structure, more than 90% of fossil energy is stored in the form of coal sources. The proportion of coal resources has long been around 70%. Although the Ministry of Energy has vigorously developed and researched the use of new energy, the proportion of energy structure will not change significantly for a long time in the future. However, the hydrogeological conditions of mines are extremely complex, and water accidents during coal mining are one of the important factors affecting mine safety production.

[0003] Traditionally, water detection under mining areas only uses mine transient electromagnetic method, which mainly uses the principle of electromagnetic induction to infer the structure and properties of underground media by emitting transient electromagnetic fields and observing their propagation and attenuation characteristics in underground media. In water detection, this method can detect information such as underground aquifers, water bodies, and the interface between water bodies and surrounding rocks. It has a certain accuracy in judging the location and range of water accumulation areas. However, when the conductivity of the water accumulation area is not much different from that of the surrounding rocks, the detection effect of this method may be affected, resulting in misjudgment or missed judgment; therefore, the present invention provides a method and system for detecting water accumulation in local low-lying points in goaf areas. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art; to this end, the present invention proposes a method and system for detecting water accumulation in local low-lying points in a goaf, which is used to solve the technical problem that only using mine transient electromagnetic method to detect water accumulation areas under mines has limitations, which can easily lead to misjudgment or missed judgment.

[0005] To achieve the above object, the first aspect of the present invention provides a method for detecting water accumulation at a local low-lying point in a goaf, comprising the following steps:

[0006] Step 1: Determine the scope of the goaf area based on the actual mining situation in the mining area;

[0007] Step 2: Determine the resistivity abnormal area of ​​the goaf by transient electromagnetic method and obtain the resistivity abnormal area information;

[0008] Step 3: Determine the geological anomaly area in the goaf through radio wave perspective method and obtain the geological anomaly area information;

[0009] Step 4: Based on the resistivity anomaly area information and the geological anomaly area information, obtain the water accumulation area information of the goaf, and determine the number of drill holes based on the water accumulation area information.

[0010] Preferably, the step of determining the resistivity abnormal area of ​​the goaf and obtaining the resistivity abnormal area information includes:

[0011] The coil is transmitted to the geological body to be detected with a preset current to collect a number of resistivity values ​​of each first detection point at different angles; wherein the first detection point is set at different angles of the return air chute and the auxiliary transport chute of the working face of the mining area;

[0012] Several resistivity values ​​are compared with the preset resistivity thresholds respectively. When the resistivity value is less than the preset resistivity threshold, the area detected by the corresponding first detection point is marked as a resistivity anomaly area, and the resistivity anomaly area information is obtained; otherwise, no operation is performed; wherein, the detection points all detect in the internal direction of the working face of the mining area, and the detection points are evenly set; detection at different angles includes detection in four directions: roof elevation angle of 15°, roof elevation angle of 30°, roof elevation angle of 45° and vertically upward.

[0013] The present invention can fully understand the geological conditions inside the working face of the mining area through detection in four directions: 15°, 30°, 45° and vertically upward. This multi-angle detection method helps to capture resistivity anomalies in different directions and depths, thereby improving the accuracy of detection. The uniform setting of detection points can ensure the continuity and consistency of detection results, avoiding detection blind spots or misjudgments caused by uneven distribution of detection points.

[0014] Preferably, the step of determining the geological anomaly area of ​​the goaf and obtaining the geological anomaly area information includes:

[0015] The electromagnetic wave transmitter of the preset frequency emits radio waves to the geological body to be detected; the electromagnetic wave field strength value of each second detection point is collected; wherein the second detection point is set in the return air chute and the auxiliary transport chute of the working face of the mining area;

[0016] The absorption coefficient value of each detection point is calculated, and the absorption coefficient value is compared with the preset absorption coefficient threshold. When the absorption coefficient value is greater than the preset absorption coefficient threshold, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly area information is obtained. Otherwise, no operation is performed.

[0017] Preferably, the collecting of the electromagnetic wave field strength value of each second detection point includes:

[0018] Control the transmission of detection signals from the return air chute to the auxiliary transport chute for reception, and then control the transmission of detection signals from the auxiliary transport chute to the return air chute for reception, and collect the electromagnetic wave field strength value of each second detection point by fixed-point method or synchronous method; wherein the transmitting point and the receiving point are respectively set at equal intervals.

[0019] The present invention can obtain more comprehensive information about geological bodies through a two-way detection method of transmitting in the return air chute and receiving in the auxiliary transport chute, and transmitting in the auxiliary transport chute and receiving in the return air chute. This two-way cross detection helps to eliminate the errors that may be caused by single-direction detection and improve the accuracy and reliability of the detection results; and the equidistant arrangement of the transmitting points and the receiving points can ensure the continuity and consistency of the detection results. The layout of the equally spaced detection points helps to capture the slight changes in the geological body, thereby more accurately identifying the geological anomaly area; by collecting the electromagnetic wave field strength values ​​of each detection point through the fixed-point method or the synchronous method, a large amount of data can be efficiently obtained, which not only improves the speed of data acquisition, but also reduces the complexity of manual operation, making the detection process more efficient.

[0020] Preferably, the collecting the electromagnetic wave field strength value of each second detection point by a fixed-point method or a synchronous method includes:

[0021] Fixed-point method: The transmitter is fixed, and the receiver moves along the return air chute or auxiliary transport chute at a fixed interval to collect the electromagnetic wave field strength value at each detection point;

[0022] Synchronous method: Move the transmitter and receiver synchronously in the same direction at the same distance in the return air chute and the auxiliary transport chute respectively, and collect the electromagnetic wave field strength value of each detection point.

[0023] Preferably, a resistivity distribution map is constructed by the resistivity values; and an absorption coefficient distribution map is constructed by the absorption coefficient values; wherein both the resistivity distribution map and the absorption coefficient distribution map correspond to each resistivity value and absorption coefficient value with a grayscale value.

[0024] Preferably, the resistivity distribution map and the absorption coefficient distribution map both correspond to each resistivity value and absorption coefficient value with a gray value, including:

[0025] Perform difference processing on the resistivity value and the preset resistivity threshold to obtain the resistivity difference; calculate the product of the resistivity difference and the preset grayscale value one to obtain the grayscale value corresponding to the resistivity value; when the grayscale value corresponding to the resistivity value is greater than the preset grayscale value, mark the area detected by the corresponding first detection point as a resistivity abnormal area, and obtain resistivity abnormality information; otherwise, do not perform any operation; wherein the grayscale value one is the preset grayscale value corresponding to the unit resistivity difference;

[0026] The absorption coefficient value is subjected to difference processing with the preset absorption coefficient threshold to obtain the absorption coefficient difference; the product of the absorption coefficient difference and the preset grayscale value two is calculated to obtain the grayscale value corresponding to the absorption coefficient; when the grayscale value corresponding to the absorption coefficient is greater than the preset grayscale value, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly information is obtained; otherwise, no operation is performed; wherein the grayscale value two is the preset grayscale value corresponding to the unit absorption coefficient difference.

[0027] The present invention can more intuitively recognize and understand the geological characteristics of the mining area by constructing resistivity distribution maps and absorption coefficient distribution maps, which are specifically reflected in the following aspects: the distribution maps can finely display the resistivity and absorption coefficient changes inside the geological body, including small differences and abnormal areas; the resistivity distribution map and the absorption coefficient distribution map can not only be displayed on a two-dimensional plane, but also can be visualized in three dimensions through technical means (such as three-dimensional modeling). This three-dimensional display method can more intuitively reflect the distribution characteristics of the geological body in three-dimensional space, which is helpful to understand the three-dimensional form of the geological structure.

[0028] Preferably, both the resistivity anomaly area and the geological anomaly area are waterlogged areas, and the resistivity anomaly area information and the geological anomaly area information both include the location and amount of waterlogged areas.

[0029] Preferably, determining the number of boreholes according to the waterlogged area information includes:

[0030] Obtain the diameter of the preset borehole, the preset water flow velocity and the preset drainage time; calculate the cross-sectional area of ​​the preset borehole based on the preset borehole diameter, and calculate the product of the cross-sectional area and the preset water flow velocity to obtain the drainage volume of a single borehole; calculate the product of the drainage volume of a single borehole and the preset drainage time, and obtain the drainage volume of a single borehole in the preset drainage time, which is marked as the total drainage volume of a single borehole; calculate the ratio of the water volume in the waterlogged area to the total drainage volume of a single borehole, and obtain the number of boreholes required for the waterlogged area.

[0031] The present invention calculates the drainage capacity of a single borehole by obtaining key physical parameters such as the borehole diameter, water flow velocity and drainage time; in addition, the influence of the drainage time is also taken into account to more comprehensively reflect the actual drainage capacity of the borehole and reasonably determine the number of boreholes. The optimized borehole design can ensure that each borehole can fully exert its drainage capacity and avoid waste of resources; at the same time, a reasonable borehole layout can also reduce interference between boreholes and improve the overall drainage effect.

[0032] Preferably, the second aspect of the present invention provides a local low-lying point water detection system in a goaf, comprising a resistivity detection module, a geological detection module and a determination module;

[0033] Resistivity detection module: used to obtain information on abnormal resistivity areas in goaf areas;

[0034] Geological detection module: used to obtain geological abnormal area information of goaf;

[0035] Judgment module: Based on the resistivity anomaly area information and the geological anomaly area information, the water accumulation area information of the goaf is obtained, and the number of drill holes is determined according to the water accumulation area information.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention detects the goaf by transient electromagnetic method and radio wave perspective method; the transient electromagnetic method can detect deeper underground structures and is suitable for large-area goafs of mines. The method can measure from multiple angles to obtain more comprehensive geological information and ensure accurate description of complex geological structures; the radio wave perspective method can provide higher resolution in a smaller range and is particularly suitable for detecting water accumulation in local low-lying points. Radio waves can penetrate rocks and soils of a certain thickness and are suitable for different types of geological media, especially under complex geological conditions. The two detection methods can detect water accumulation areas and water accumulation conditions in the goaf more comprehensively to avoid omissions; in addition, according to the detection results, the positions and numbers of drainage boreholes are reasonably arranged to ensure that each water accumulation point can be effectively treated, avoid unnecessary drilling construction, quickly drain the water, and reduce the impact of water accumulation in the mine on production; the present invention realizes accurate identification of water accumulation areas, and timely and effective drainage measures can prevent safety accidents caused by water accumulation in the mine, and ensure the life safety of miners and the normal production of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a schematic diagram of the process of the present invention;

[0040] Figure 2 This is a flowchart of the resistivity abnormal area analysis process of the present invention;

[0041] Figure 3 This is a flowchart of the geological anomaly zone analysis process of the present invention;

[0042] Figure 4 This is a system structure block diagram of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1The first embodiment of the present invention provides a method for detecting water accumulation in a local low-lying point in a goaf, comprising the following steps:

[0045] Step 1: Determine the scope of the goaf area according to the actual mining situation of the mining area; the goaf area refers to the mining area that has been mined;

[0046] See also Figure 2 ,Step 2: Determine the resistivity abnormal area of ​​the goaf area by transient electromagnetic method, and obtain the resistivity abnormal area information;

[0047] A number of first detection points are set at different angles of the return air chute and the auxiliary transport chute of the working face of the mining area, and a coil is emitted to the geological body to be detected with a preset current to collect a number of resistivity values ​​of each first detection point at different angles, and the several resistivity values ​​are compared with the preset resistivity threshold value. When the resistivity value is less than the preset resistivity threshold value, the area detected by the corresponding first detection point is marked as a resistivity anomaly area, and the resistivity anomaly area information is obtained; otherwise, no operation is performed; wherein, the first detection points all detect in the internal direction of the working face of the mining area, and the first detection points are evenly set; detection at different angles includes detection in four directions: roof elevation angle of 15°, roof elevation angle of 30°, roof elevation angle of 45° and vertically upward.

[0048] The resistivity anomaly area information includes the location and water accumulation of the resistivity anomaly area.

[0049] Specifically, a current transmitting coil with a certain waveform and intensity is transmitted to the mine in four directions: 15°, 30°, 45°, and vertically upward, thereby generating a primary magnetic field in the surrounding space. The primary magnetic field generates induced currents in the underground conductive rock ore body, and these induced currents decay over time. After the primary magnetic field disappears, the secondary electromagnetic field generated by the induced current is observed using a receiving coil or electrode, and the received secondary electromagnetic field data is collected and processed, including filtering, inversion, and other steps, to extract useful geological information;

[0050] Since water has good conductivity, the resistivity of water-containing areas will be relatively low; by processing and analyzing the received secondary electromagnetic field data, resistivity distribution images at different depths underground can be obtained. The low-resistivity areas in the image often correspond to water-containing structures, such as water accumulation areas in goafs.

[0051] Specifically, the resistivity value is subjected to difference processing with a preset resistivity threshold to obtain a resistivity difference; the product of the resistivity difference and a preset grayscale value 1 is calculated to obtain a grayscale value corresponding to the resistivity value; when the grayscale value corresponding to the resistivity value is greater than the preset grayscale value, the area detected by the corresponding first detection point is marked as a resistivity abnormal area, and resistivity abnormality information is obtained; otherwise, no operation is performed; wherein the grayscale value 1 is a preset grayscale value corresponding to a unit resistivity difference; and the grayscale value range is [0,255];

[0052] According to the resistivity distribution map, if the gray value of a certain area is larger, the color of the area in the resistivity distribution map will be brighter, that is, the waterlogged area. In addition, the three-dimensional inversion technology can be used to construct an underground three-dimensional resistivity model to more intuitively display the spatial distribution of the waterlogged area.

[0053] See also Figure 3 ,Step 3: Determine the geological anomaly area of ​​the goaf by radio wave perspective method and obtain the geological anomaly area information;

[0054] Specifically, a number of second detection points are set in the return air chute and auxiliary transport chute of the working face of the mining area, and radio waves are emitted to the geological body to be detected by an electromagnetic wave transmitter with a preset frequency; first, the waves are emitted in the return air chute and received in the auxiliary transport chute, and then, the waves are emitted in the auxiliary transport chute and received in the return air chute, and the electromagnetic wave field strength value of each second detection point is collected by a fixed-point method or a synchronous method; wherein the emitting points and the receiving points are set at equal intervals.

[0055] It should be noted that the fixed-point method is to fix the transmitter position, move the receiver along the return air chute or auxiliary transport chute at a fixed interval, and collect the electromagnetic wave field strength value of each second detection point;

[0056] The synchronization method is to move the transmitter and receiver synchronously in the same direction at the same interval in the return air chute and the auxiliary transport chute respectively, and collect the electromagnetic wave field strength values ​​of each second detection point.

[0057] The electromagnetic wave field strength value of each second detection point is collected, the absorption coefficient value of each detection point is calculated, and the absorption coefficient value is compared with the preset absorption coefficient threshold. When the absorption coefficient value is greater than the preset absorption coefficient threshold, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly area information is obtained. Otherwise, no operation is performed; wherein the geological information includes the location and water accumulation of the geological anomaly area.

[0058] The absorption coefficient α is calculated by the formula α=E / E0; wherein E is the electromagnetic wave field strength value actually measured at each second detection point, and E0 is the theoretical field strength value calculated according to the formula at each second detection point.

[0059] It should be noted that E0 is the field intensity of the electromagnetic wave after propagating in the medium, E0=Ein×P; wherein Ein is the field intensity of the incident electromagnetic wave; P is the transmission coefficient, P=(2×n1×cosθ1) / (n1×cosθ1+n2×cosθ2); n1 and n2 are the refractive indices of the incident medium and the transmission medium respectively, and θ1 and θ2 are the incident angle and the refraction angle respectively.

[0060] Since water has a strong ability to absorb electromagnetic waves, the absorption coefficient of the water-containing area will be relatively high; by processing the acquired absorption coefficient, an absorption coefficient distribution image can be obtained. The high absorption coefficient areas in the image often correspond to water-containing structures, that is, water accumulation areas.

[0061] Specifically, the absorption coefficient value is subjected to difference processing with a preset absorption coefficient threshold to obtain the absorption coefficient difference; the product of the absorption coefficient difference and the preset grayscale value two is calculated to obtain the grayscale value corresponding to the absorption coefficient; when the grayscale value corresponding to the absorption coefficient is greater than the preset grayscale value, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly information is obtained; otherwise, no operation is performed; wherein the grayscale value two is the preset grayscale value corresponding to the unit absorption coefficient difference.

[0062] According to the absorption coefficient distribution map, if the gray value of a certain area is larger, the color of the area in the resistivity distribution map will be brighter, that is, the waterlogged area. In addition, the three-dimensional inversion technology can be used to construct an underground three-dimensional absorption coefficient model to more intuitively display the spatial distribution of the waterlogged area.

[0063] Step 4: Based on the resistivity anomaly area information and the geological anomaly area information, obtain the water accumulation area information of the goaf, and determine the number of drill holes according to the water accumulation area information;

[0064] Both the resistivity anomaly areas and the geological anomaly areas are waterlogged areas.

[0065] Obtain the diameter of the preset borehole, the preset water flow velocity and the preset drainage time; calculate the cross-sectional area of ​​the preset borehole based on the preset borehole diameter, and calculate the product of the cross-sectional area and the preset water flow velocity to obtain the drainage volume of a single borehole; calculate the product of the drainage volume of a single borehole and the preset drainage time, and obtain the drainage volume of a single borehole in the preset drainage time, which is marked as the total drainage volume of a single borehole; calculate the ratio of the water volume in the waterlogged area to the total drainage volume of a single borehole, and obtain the number of boreholes required for the waterlogged area.

[0066] For example, suppose that a standard borehole has been preset with a diameter of R = 0.1 m and a water flow velocity of V = 2 m / s; where R and V are both positive integers;

[0067] Calculate the cross-sectional area: The cross-sectional area A of a standard borehole can be calculated by the following formula: A = π × (R / 2)^2; where π is the ratio of a circle to a circle (approximately equal to 3.14); Substituting R = 0.1 m into the formula, we get: A = π × (0.1 / 2)^2 = 0.00785 m2;

[0068] Calculation of drainage flow: The drainage flow Q of a single borehole is calculated by multiplying the cross-sectional area A and the water velocity V: Q = A × V. Substituting A = 0.00785 square meters and V = 2 meters per second into the formula, we get: Q = 0.00785 × 2 = 0.0157 cubic meters per second;

[0069] Calculate the number of boreholes in the waterlogged area: Assuming the water volume in the waterlogged area is 1000 cubic meters, calculate the number of boreholes required to achieve this drainage volume; and drain all the water in 1 hour; the drainage volume of each borehole in 1 hour is Q×t=0.0157×3600=56.52 cubic meters; therefore, the number of boreholes required in the waterlogged area is N=W / Q×t=1000 / 56.52≈17.7; where W is the water volume in the waterlogged area;

[0070] Since the number of boreholes must be an integer and needs to be rounded up, a waterlogged area requires at least 18 standard boreholes.

[0071] Transient electromagnetic method and radio wave perspective method have their own advantages and limitations when detecting waterlogged areas in mining areas. Transient electromagnetic method is sensitive to low-resistance bodies and can accurately determine the location and range of waterlogged areas, but it is sometimes difficult to solve specific problems due to the limitations of underground space and geophysical exploration methods. The radio wave perspective method can infer the existence of waterlogged areas by observing the attenuation of electromagnetic wave signals, but its positioning accuracy and water-richness judgment ability for abnormal bodies are relatively weak.

[0072] Therefore, the combination of transient electromagnetic method and radio wave perspective method for comprehensive detection can give full play to their respective advantages, verify and complement each other. This method can more comprehensively and accurately detect the water-covered area in the mining area, providing a strong guarantee for the safe production of coal mines.

[0073] See also Figure 4 , the second aspect of the present invention provides a local low-lying point water detection system in a goaf area, including a resistivity detection module, a geological detection module and a determination module;

[0074] Resistivity detection module: used to obtain information on abnormal resistivity areas in goaf areas;

[0075] Geological detection module: used to obtain geological abnormal area information of goaf;

[0076] Judgment module: Based on the resistivity anomaly area information and the geological anomaly area information, the water accumulation area information of the goaf is obtained, and the number of drill holes is determined according to the water accumulation area information.

[0077] Part of the data in the above formula is calculated by removing the dimension and taking its numerical value. The formula is a formula closest to the actual situation obtained by software simulation of a large amount of collected data; the preset parameters and preset thresholds in the formula are set by technical personnel in this field according to actual conditions or obtained through simulation of a large amount of data.

[0078] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A method for detecting water accumulation at local low-lying points in a goaf, characterized in that: The following steps are involved: Step 1: Determine the scope of the goaf area based on the actual mining situation in the mining area; Step 2: Determine the resistivity abnormal area of ​​the goaf by transient electromagnetic method and obtain the resistivity abnormal area information; Step 3: Determine the geological anomaly area in the goaf through radio wave perspective method and obtain the geological anomaly area information; Step 4: Based on the resistivity anomaly area information and the geological anomaly area information, obtain the water accumulation area information of the goaf, and determine the number of drill holes based on the water accumulation area information.

2. A method for detecting water accumulation at local low-lying points in a goaf according to claim 1, characterized in that: The step of determining the resistivity abnormal area of ​​the goaf and obtaining the resistivity abnormal area information includes: The coil is transmitted to the geological body to be detected with a preset current to collect a number of resistivity values ​​of each first detection point at different angles; wherein the first detection point is set at different angles of the return air chute and the auxiliary transport chute of the working face of the mining area; Several resistivity values ​​are compared with preset resistivity thresholds respectively. When the resistivity value is less than the preset resistivity threshold, the area detected by the corresponding first detection point is marked as a resistivity anomaly area, and the resistivity anomaly area information is obtained; otherwise, no operation is performed; wherein, the detection points all detect in the internal direction of the working face of the mining area, and the detection points are evenly set.

3. A method for detecting water accumulation at local low-lying points in a goaf according to claim 2, characterized in that: The step of determining the geological anomaly area of ​​the goaf and obtaining the geological anomaly area information includes: The electromagnetic wave transmitter of the preset frequency emits radio waves to the geological body to be detected; the electromagnetic wave field strength value of each second detection point is collected; wherein the second detection point is set in the return air chute and the auxiliary transport chute of the working face of the mining area; The absorption coefficient value of each detection point is calculated, and the absorption coefficient value is compared with the preset absorption coefficient threshold. When the absorption coefficient value is greater than the preset absorption coefficient threshold, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly area information is obtained. Otherwise, no operation is performed.

4. A method for detecting water accumulation at local low-lying points in a goaf according to claim 3, characterized in that: The collecting of electromagnetic wave field strength values ​​at each second detection point includes: Control the transmission of detection signals from the return air chute to the auxiliary transport chute for reception, and then control the transmission of detection signals from the auxiliary transport chute to the return air chute for reception, and collect the electromagnetic wave field strength value of each second detection point by fixed-point method or synchronous method; wherein the transmitting point and the receiving point are respectively set at equal intervals.

5. A method for detecting water accumulation at local low-lying points in a goaf according to claim 4, characterized in that: The collecting of the electromagnetic wave field strength value of each second detection point by a fixed-point method or a synchronous method includes: Fixed-point method: The transmitter is fixed, and the receiver moves along the return air chute or auxiliary transport chute at a fixed interval to collect the electromagnetic wave field strength value at each detection point; Synchronous method: Move the transmitter and receiver synchronously in the same direction at the same distance in the return air chute and the auxiliary transport chute respectively, and collect the electromagnetic wave field strength value of each detection point.

6. A method for detecting water accumulation at local low-lying points in a goaf according to claim 3, characterized in that: A resistivity distribution map is constructed by the resistivity values; and an absorption coefficient distribution map is constructed by the absorption coefficient values; wherein both the resistivity distribution map and the absorption coefficient distribution map correspond to each resistivity value and absorption coefficient value with a gray value.

7. A method for detecting water accumulation at local low-lying points in a goaf according to claim 6, characterized in that: The resistivity distribution map and the absorption coefficient distribution map both correspond to each resistivity value and absorption coefficient value with grayscale values, including: Perform difference processing on the resistivity value and the preset resistivity threshold to obtain the resistivity difference; calculate the product of the resistivity difference and the preset grayscale value one to obtain the grayscale value corresponding to the resistivity value; when the grayscale value corresponding to the resistivity value is greater than the preset grayscale value, mark the area detected by the corresponding first detection point as a resistivity abnormal area, and obtain resistivity abnormality information; otherwise, do not perform any operation; wherein the grayscale value one is the preset grayscale value corresponding to the unit resistivity difference; The absorption coefficient value is subjected to difference processing with the preset absorption coefficient threshold to obtain the absorption coefficient difference; the product of the absorption coefficient difference and the preset grayscale value two is calculated to obtain the grayscale value corresponding to the absorption coefficient; when the grayscale value corresponding to the absorption coefficient is greater than the preset grayscale value, the area detected by the corresponding second detection point is marked as a geological anomaly area, and the geological anomaly information is obtained; otherwise, no operation is performed; wherein the grayscale value two is the preset grayscale value corresponding to the unit absorption coefficient difference.

8. A method for detecting water accumulation at local low-lying points in a goaf according to claim 1, characterized in that: The resistivity anomaly area and the geological anomaly area are both waterlogged areas, and the resistivity anomaly area information and the geological anomaly area information both include the location and amount of waterlogged areas.

9. A method for detecting water accumulation at local low-lying points in a goaf according to claim 1, characterized in that: Determining the number of boreholes according to the waterlogged area information includes: Obtain the diameter of the preset borehole, the preset water flow velocity and the preset drainage time; calculate the cross-sectional area of ​​the preset borehole based on the preset borehole diameter, and calculate the product of the cross-sectional area and the preset water flow velocity to obtain the drainage volume of a single borehole; calculate the product of the drainage volume of a single borehole and the preset drainage time, and obtain the drainage volume of a single borehole in the preset drainage time, which is marked as the total drainage volume of a single borehole; calculate the ratio of the water volume in the waterlogged area to the total drainage volume of a single borehole, and obtain the number of boreholes required for the waterlogged area.

10. A system for detecting water accumulation at local low-lying points in a goaf, operating based on a method for detecting water accumulation at local low-lying points in a goaf as claimed in any one of claims 1 to 9, characterized in that: It includes resistivity detection module, geological detection module and determination module; Resistivity detection module: used to obtain information on abnormal resistivity areas in goaf areas; Geological detection module: used to obtain geological abnormal area information of goaf; Judgment module: Based on the resistivity anomaly area information and the geological anomaly area information, the water accumulation area information of the goaf is obtained, and the number of drill holes is determined according to the water accumulation area information.

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