A loess hilly coal mining subsidence area anti-seepage and leakage treatment method

Abstract

The present application relates to a kind of loess hilly coal mining collapse area anti-seepage treatment method, comprising the following steps: S01: coal seam mining surface crack grouting filling;Including: S011: numerical simulation predicts surface crack generation situation;S012: based on the length and width of surface crack measured by unmanned aerial vehicle remote sensing;S013: based on the depth of surface crack measured by ground penetrating radar;S014: surface crack is grouted and filled;S02: coal seam mining water flowing fractured zone grouting plugging;Including: S021: numerical simulation predicts water flowing fractured zone development height;S022: based on the development height of water flowing fractured zone measured by nano transient electromagnetic method;S023: determine the contact relationship of loess aquifer and water flowing fractured zone and carry out leakage analysis;S024: water flowing fractured zone is grouted and plugged;S03: grouting effect detection.The present application forms the integrated management technical framework system of "underground-ground" in loess hilly coal mining collapse area, realizes the organic integration of mine ecological geological environment protection and surface subsidence disaster prevention.

Description

Technical Field

[0001] This invention relates to the field of coal mining subsidence area management technology, and in particular to seepage prevention and plugging design for coal mining subsidence areas, specifically to a seepage prevention and plugging treatment method for coal mining subsidence areas in loess hills. Background Technology

[0002] Coal resources are a vital pillar of my country's economic development, and several coal energy production bases with reserves exceeding 100 million tons are concentrated in the ecologically fragile loess hilly region of northwestern my country. These mining areas are characterized by thick coal seams, shallow burial depth, high mining intensity, and significant topographic relief with thick loess overburden. Furthermore, the fragmented terrain of the loess hilly region, with its numerous U-shaped or V-shaped gullies, loose loess structure, high porosity, abundant vertical joints, and low tensile deformation resistance, causes severe surface damage during underground mining, resulting in numerous ground fissures. Additionally, the high development of water-conducting fracture zones after coal seam mining in this area leads to local connections with the surface, making the shallow, thick coal seams in the loess hilly region more susceptible to surface water and groundwater seepage.

[0003] Currently, numerical simulation methods are mainly used to predict the height of coal mining fissures and water-conducting fracture zones. Combined with the depth of aquifers and impermeable layers, the risk of surface water and shallow groundwater leakage is assessed, and finally, fly ash or coal gangue slurry is used for grouting and filling. However, this system has the following shortcomings:

[0004] (1) The characteristics of the loess hilly mining area were not fully considered when conducting the risk assessment of surface water and shallow groundwater leakage.

[0005] (2) There are problems of inaccurate measurement and unclear exploration in the process of grouting treatment of water-conducting fracture zones and surface cracks;

[0006] (3) There is no systematic anti-seepage and plugging technology applicable to coal mining subsidence areas in the Loess Hilly region. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the main purpose of this invention is to provide a method for seepage prevention and plugging treatment in the coal mining subsidence area of ​​loess hills, so as to simultaneously carry out seepage prevention and plugging design for surface cracks and water-conducting fissures in the loess hill mining area, thus forming an integrated "underground-above-ground" collaborative governance technology framework system for the coal mining subsidence area of ​​loess hills.

[0008] The technical solution of the present invention is as follows: A method for seepage prevention and plugging treatment in coal mining subsidence areas of loess hills, comprising the following steps: S01: Grouting and filling of surface cracks in coal seam mining; including: S011: Numerical simulation to predict the occurrence of surface cracks; S012: Measured length and width of surface cracks based on UAV remote sensing; S013: Measured depth of surface cracks based on ground penetrating radar; S014: Grouting and filling of surface cracks based on the measured length, width, and depth of the surface cracks; S02: Grouting and sealing of water-conducting fracture zones in coal seam mining; including: S021: Numerical simulation to predict the development height of water-conducting fracture zones; S022: Measured development height of water-conducting fracture zones based on nano-transient electromagnetic method; S023: Determining the contact relationship between the loess aquifer and the water-conducting fracture zone and performing seepage analysis; S024: Grouting and sealing of the water-conducting fracture zone based on the results of the seepage analysis; S03: Grouting effect detection.

[0009] The beneficial effects of this invention compared to the prior art are as follows: This invention proposes a method for seepage prevention and plugging treatment in coal mining subsidence areas in loess hills. This method combines numerical simulation prediction and field measurement to achieve accurate prediction of surface cracks and water-conducting fissure zones in shallow buried thick coal seam mining in loess hills. It has developed an integrated waterproofing and plugging technology for surface cracks and water-conducting fissure zones, forming an integrated "underground-above-ground" collaborative governance technology framework system for coal mining subsidence areas in loess hills, and realizing the organic integration of mine ecological geological environment protection and surface subsidence disaster prevention and control.

[0010] This invention is based on the unique topography of the Loess Hilly Region, combined with FLAC 3D Numerical simulation software, ground-penetrating radar, UAV remote sensing technology, and nano-transient electromagnetic method were used to predict the height of surface fissures and water-conducting fracture zones, as well as to determine the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fracture zone.

[0011] This invention determines whether the aquifer will leak based on the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fissure zone, identifies the location of the leakage point, and uses "loess-fly ash" grouting filling material to accurately fill and seal the surface cracks and water-conducting fissure zone.

[0012] This invention tests the grouting effect on surface cracks and water-conducting fissures. The test results prove that the seepage prevention and plugging method is effective and can effectively prevent the leakage of surface water and water in the loess aquifer. Attached Figure Description

[0013] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0014] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0015] Figure 1 This is a schematic flowchart illustrating a method for preventing seepage and plugging leaks in a coal mining subsidence area in loess hills, according to one embodiment of the present invention.

[0016] Figure 2 A schematic diagram of a computational model established for one embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the simulation results of mining at working face 4106 according to one embodiment of the present invention, wherein (a) is a distribution map of the plastic zone on the surface, (b) is a distribution map of the plastic zone in the vertical profile along the X-axis, (c) is a distribution map of the plastic zone in the vertical profile along the Y-axis, (d) is a contour map of the horizontal displacement of the surface, and (e) is a contour map of the inclined displacement of the surface.

[0018] Figure 4 This is a schematic diagram of the numerical simulation calculation results of the development height of the "two zones" in the 4106 working face according to one embodiment of the present invention, wherein (a) is the numerical simulation calculation result of the development height of the "two zones" after the first step of mining in the 4106 working face, and (b) is the numerical simulation calculation result of the development height of the "two zones" after the second step of mining in the 4106 working face.

[0019] Figure 5 This is a schematic diagram illustrating the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fracture zone according to one embodiment of the present invention. (a) is a contour map of the burial depth of the No. 4 coal roof in the 4106 working face, (b) is a contour map of the development height of the water-conducting fracture zone in the 4106 working face, and (c) is a distribution characteristic map of the water-conducting fracture zone and protective layer in the 4106 working face. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0021] It should be understood that the terms "comprising / including," "consisting of," or any other variations are intended to cover non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements includes not only those elements but may also include, where necessary, other elements not expressly listed, or elements inherent to such a product, apparatus, process, or method. Without further limitation, elements defined by the phrases "comprising / including," "consisting of," do not exclude the implementation of the invention in the following detailed description in conjunction with preferred embodiments.

[0022] See Figure 1 This invention proposes a method for preventing seepage and plugging leakage in coal mining subsidence areas in loess hills, comprising the following steps:

[0023] S01: Grouting and filling of surface fractures in coal seam mining; including:

[0024] S011: Numerical simulation to predict the occurrence of surface cracks;

[0025] S012: Length and width of surface cracks measured by UAV remote sensing;

[0026] S013: Depth of surface cracks measured by ground penetrating radar;

[0027] S014: Grouting is performed to fill the surface cracks based on the measured length, width and depth of the surface cracks;

[0028] S02: Grouting and sealing of water-conducting fracture zones in coal seam mining; including:

[0029] S021: Numerical simulation predicts the development height of water-conducting fracture zones;

[0030] S022: Measurement of water-conducting fracture zone development height based on nanotransient electromagnetic method;

[0031] S023: Determine the contact relationship between the loess aquifer and the water-conducting fracture zone and conduct leakage analysis;

[0032] S024: Grouting is performed to seal the water-conducting fracture zone based on the results of the leakage analysis;

[0033] S03: Grouting effect test.

[0034] It should be understood that there is no order of construction between S01 and S02. The grouting and sealing of the water-conducting fracture zone in the coal seam mining in S02 can be carried out first, and then the grouting and filling of the surface fractures in the coal seam mining in S01 can be carried out.

[0035] In S011, numerical simulation predictions of surface crack formation specifically include:

[0036] (1) Establishing a three-dimensional refined engineering geological model: First, the simulation range is determined based on the mining face and the maximum burial depth of the coal seam. The simulation range is required to extend outward from the working face and sufficiently cover the surrounding rock that may be deformed. Second, the rock strata elevation data of the study area are determined based on borehole exploration data, and combined with the simulation range in FLAC 3D A three-dimensional engineering geological model is established. Finally, the calculation boundary is determined for the three-dimensional engineering geological model. In actual coal mine excavation, the surrounding rock will not deform in all directions along the horizontal direction, so it is necessary to limit the model boundary.

[0037] (2) Selection of constitutive model: The selection of constitutive model is a key step in numerical simulation. FLAC 3D The system has 12 built-in constitutive models for soil and rock. When conducting simulations, it is necessary to select the appropriate model based on the actual engineering conditions and the applicable scope of each constitutive model, so that the model can reflect the main characteristics of the problem without being too complex.

[0038] (3) Determine the calculation parameters: Based on the physical and mechanical parameters of each rock layer in the study area and the collected experimental data, the calculation parameters such as elastic modulus E, Poisson's ratio μ, density ρ, internal friction angle φ and cohesive strength C are determined by a combination of indoor tests and engineering analogies.

[0039] (4) Predicting surface fractures in coal seam mining: Based on the mining continuity diagram of the coal mine, i.e., the mining process, determine the number and length of mining steps; use FLAC... 3D Numerical simulation software simulates the step-by-step mining of the working face; based on the surface plastic zone distribution map, the vertical profile plastic zone distribution map in the X-axis direction, and the vertical profile plastic zone distribution map in the Y-axis direction generated during the mining process, and combined with the probability integral method, the contour map of horizontal deformation in the dip and strike of the coal seam after each step of excavation is calculated, thereby obtaining the location, direction, length and height of the ground fissures.

[0040] In S012, the length and width of surface cracks measured by UAV remote sensing specifically include:

[0041] (1) Design the drone flight path;

[0042] (2) Data acquisition and preprocessing;

[0043] (3) Extract information on surface cracks.

[0044] UAV remote sensing has the advantages of low cost, high efficiency, high accuracy and high mobility. When identifying and investigating ground fissures, it can cover a wide area, be highly accurate and timely, and can accurately measure the length and width of ground fissures.

[0045] In some embodiments, designing a drone flight path includes: first selecting a drone based on the shape of the working face, the mining direction, and the actual surface conditions, combined with the location, direction, length, and height of the ground fissures obtained in S011;

[0046] Then determine the aerial photography area, altitude, heading, and the overlap rate between the lateral and heading directions; the altitude is determined as follows:

[0047] H = Gf / a (1)

[0048] In the formula, H is the relative flight altitude of the UAV, m; G is the ground resolution, m; f is the lens focal length, μm; and a is the lens pixel size.

[0049] In some embodiments, data acquisition and preprocessing include:

[0050] First, control the drone to fly along the designed route;

[0051] Then, the drone's radar antenna continuously transmits pulse signals to the coal mining subsidence area and receives and stores the returned signal information through the antenna.

[0052] Finally, the automated UAV remote sensing image intelligent software is used to perform image matching and connection on the acquired signal information, and to perform distortion correction, image matching and aerial triangulation on the images to generate digital products such as point cloud, DEM, DOM and DSM.

[0053] In some embodiments, extracting surface crack information includes: interpreting images in DEM, DOM, and DSM using ENVI to extract the number, length, and width of ground cracks measured by UAV remote sensing.

[0054] In S013, the depth of surface cracks measured by ground penetrating radar specifically includes:

[0055] (1) Set the ground-penetrating radar test parameters and arrange the survey lines;

[0056] (2) Data acquisition and processing;

[0057] (3) Read the depth information of surface cracks.

[0058] The basic principle of ground-penetrating radar (GPR) is to transmit high-frequency electromagnetic waves through a transmitting antenna. When the high-frequency electromagnetic waves encounter an interface with different dielectric constants, they generate reflected echoes. The cross-sectional scanning image of the medium is determined based on the time and form of the reflected echoes received by the receiving antenna.

[0059] In some embodiments, setting ground-penetrating radar test parameters and arranging survey lines includes: selecting a Canadian pulseEKKO professional ground-penetrating radar, determining the corresponding test method and setting the corresponding parameters based on the location, direction, length and height of the ground fissures obtained by combining the GPR of the ground-penetrating radar with S011, determining the survey line length and detection spacing along the direction perpendicular to the direction of the ground fissures, and arranging the observation lines using a measuring tape.

[0060] This invention preferably employs the transmitted wave single-line profiling method to measure surface cracks. The parameters that need to be set for this transmitted wave single-line profiling method include: frequency, time window, step size, sampling interval, and velocity.

[0061] In some embodiments, data acquisition and processing include: using ground-penetrating radar (GPR) to select the first wave for line scanning; after the scanning is completed, importing the file generated by the GPR into EKKO-VIFW professional software; and performing data editing, energy gain, digital filtering, and deconvolution processing on the raw data to obtain a clear profile.

[0062] In some embodiments, reading the depth information of surface cracks includes: firstly, extracting the relatively stable range of radar signal amplitude of the crack zone based on the processed profile, which is the surface crack zone; and then reading the longitudinal development morphology and depth information of the cracks.

[0063] This invention first uses FLAC 3D Numerical simulation software simulates and predicts the formation of surface cracks. Then, the length, width, and depth of the surface cracks are measured by UAV remote sensing and ground penetrating radar. This combination of prediction and measurement can obtain more accurate information about surface cracks and improve the efficiency and accuracy of grouting and filling.

[0064] In S014, the surface cracks are filled with grout based on the measured length, width, and depth, specifically including:

[0065] (1) Configure surface crack grouting materials; by analyzing the reinforcement mechanism of grouting filling slurry, and taking into account the fluidity, stability and strength of the stone body, select appropriate grouting filling materials and determine the slurry mix ratio.

[0066] (2) Design of grouting holes for surface fissures, specifically including:

[0067] 1) Determine the diameter of the grouting hole for surface fissures: According to the "Technical Specification for Waterproofing of Underground Engineering" (GB50108-2001), the borehole diameter should not be less than 40mm. Based on the predicted location, direction, length and height of the ground fissures obtained from S011, and the measured length, width and depth of the ground fissures and the characteristics of the stratum lithology obtained from S012 and S013, determine the specific diameter of the grouting hole.

[0068] 2) Determine the depth of grouting holes in surface fissures: Based on the depth of the fissures, combined with topography, lithology and other characteristics, determine the depth of the grouting holes.

[0069] 3) Determining the grouting volume for surface cracks: The control of the grouting volume is mainly based on the volume of the surface cracks, the porosity of the soil, and the empirical coefficient k value. The specific calculation formula is as follows:

[0070]

[0071] In the formula, Q is the grouting volume, m 3 ;γ w ρ is the gravitational density of water; H is the difference between the grouting pressure and the groundwater head; b is the fracture opening; μ g R is the dynamic viscosity of the grouting material, MPa·s; R is the diffusion radius of the grouting material, m; r c Let be the radius of the grouting pipe, in meters (m).

[0072] 4) Determine the grouting pressure: During the grouting process, when the stratum is very shallow, the grout will flow along the horizontal shear direction and cause grout to seep out at the surface. Therefore, the grouting pressure must meet the following requirements:

[0073] p=KH (3)

[0074] In the formula, P is the grouting pressure (MPa); K is the pressure adjustment coefficient; and H is the grouting depth (m).

[0075] 5) Determine the spacing of grouting holes: Determine the spacing of grouting holes based on the diffusion radius of the grouting material to ensure that the surface cracks can be filled with grout within their length.

[0076] The expression for the diffusion radius is:

[0077]

[0078] In the formula, R is the grout diffusion radius, cm; t is the grouting time, s; P2 is the pressure inside the grouting hole, Pa; P1 is the groundwater pressure inside the grouting fracture, Pa; b is the fracture width, cm; μ is the grout viscosity, Pa·s; and r is the grouting hole radius, cm.

[0079] In some embodiments, the spacing between grouting holes is generally equal to twice the grout diffusion radius.

[0080] In S021, the water-conducting fracture zone includes a collapse zone and a fracture zone, according to FLAC. 3D The calculation results of numerical simulation software are used to analyze the strain increment profile and displacement cloud map of the overlying strata of the coal seam at different mining stages. After mining is completed, the development depth of the water-conducting fracture zone is basically stable, and the development height of the water-conducting fracture zone is determined.

[0081] In S022, the nanotransient electromagnetic method involves applying a pulsed current to an ungrounded loop and measuring the change in the secondary field over time during the intervals of the primary field to locate various geological targets. In this step, the measured development height of water-conducting fracture zones based on the nanotransient electromagnetic method specifically includes:

[0082] (1) Set up survey lines and set acquisition parameters: The survey lines should be as perpendicular as possible to the stratigraphic direction or geological structure, and avoid areas with large electromagnetic interference.

[0083] This study selected the GDP-32 II Nano TEM system manufactured by Zonge Corporation of the United States. Through field tests, the control area was determined, a suitable measurement line layout and working device were selected, and the point spacing, basic line spacing, transmitting frame, receiving frame, transmission frequency, and number of superpositions were determined.

[0084] (2) Data acquisition and processing: The acquired raw data is organized and format converted, and noise is eliminated by filtering. The change of secondary field potential difference with time is converted into the change of resistivity with depth by time conversion and apparent resistivity inversion. Finally, the results are interpreted. The data collected in the whole area are used to draw the apparent resistivity cross-section of each survey line and the anomaly range is delineated. Then, the anomalies of each cross-section are displayed on the corresponding plan view.

[0085] (3) Analyze the exploration results: Based on the apparent resistivity profile, determine the electrical distribution characteristics of the underground geological body in the horizontal and vertical directions. Based on the shape, scale and variation characteristics of the apparent resistivity chromatogram, infer the distribution of the water-conducting fracture zone.

[0086] In S023, according to FLAC 3D The development height of the water-conducting fracture zone is determined by numerical simulation results and by the apparent resistivity profile obtained by nano-transient electromagnetic method. The final development height of the water-conducting fracture zone is then determined. The contact relationship between the two is determined by combining the burial depth of the loess aquifer, and the possibility of leakage in the loess aquifer is analyzed accordingly.

[0087] The present invention preferably uses FLAC 3D The contact relationship between the maximum value of the development height of the water-conducting fracture zone determined by numerical simulation results and the development height of the water-conducting fracture zone determined by the apparent resistivity profile obtained by nano-transient electromagnetic method and the loess aquifer was determined.

[0088] This invention first uses FLAC 3D Numerical simulation software is used to predict the development height of water-conducting fracture zones. Then, the development height of water-conducting fracture zones is measured by nano-transient electromagnetic method. The combination of prediction and measurement can obtain a more accurate development height of water-conducting fracture zones. The contact relationship between the development height of water-conducting fracture zones and loess aquifers can be determined by analyzing the development height of water-conducting fracture zones, and grouting can be carried out sequentially, which can improve the efficiency and accuracy of grouting and sealing.

[0089] In some embodiments, determining the contact relationship between the aquifer and the water-conducting fracture zone and performing leakage analysis includes:

[0090] (1) Determine whether the bottom plate of the loess aquifer is in contact with the top interface of the water-conducting fracture zone based on the development height of the water-conducting fracture zone and the burial depth of the loess aquifer.

[0091] (2) Based on the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fracture zone, and considering whether there is an impermeable layer between them, the following three situations are identified:

[0092] 1) When the bottom plate of the loess aquifer comes into contact with the top interface of the water-conducting fracture zone, leakage will occur;

[0093] 2) The bottom plate of the loess aquifer is not in contact with the top interface of the water-conducting fracture zone, and there is no waterproof layer at the top of the water-conducting fracture zone, which will cause leakage.

[0094] 3) The bottom plate of the loess aquifer is not in contact with the top interface of the water-conducting fracture zone, and there is a water-proof layer at the top of the water-conducting fracture zone, so there will be no leakage.

[0095] See Table 1 for details:

[0096] Table 1 Leakage Analysis Table

[0097]

[0098] In S024, the grouting and sealing of water-conducting fracture zones specifically includes:

[0099] (1) Determine the grouting range and grouting thickness of the water-conducting fracture zone: Based on the contact relationship between the water-conducting fracture zone and the bottom plate of the loess aquifer, and the leakage analysis of the loess aquifer, select the areas in the mining area where the above conditions 1) and 2) exist for grouting treatment.

[0100] (2) Preparation of grouting material for water-conducting fissures: The method of preparing the grouting material here is the same as the method of preparing the grouting material for surface fissures when grouting and filling surface fissures in S014. This invention will not be described in detail here.

[0101] (3) Design of grouting holes in water-conducting fracture zones: including:

[0102] 1) Selection of borehole location: The location of the borehole is determined based on the location of the underground roadway, the depth of the coal seam, and the surface drilling conditions, combined with the slurry and the separation space around the goaf.

[0103] 2) Selection of borehole diameter: The borehole diameter is determined based on the grouting volume per borehole and the daily grouting duration, combined with the lithology of the overlying soil and rock.

[0104] 3) Setting the drilling depth: In order to ensure that the filling grout does not flow down into the well, the final position of the borehole should be kept above the water-conducting fracture zone of the mining face. A maintenance zone thickness of about 5 times the coal seam mining height should be left, and the borehole should pass through each major delamination zone to ensure that the borehole has the ability to absorb grout and ensure the effect of grouting and reducing settlement.

[0105] 4) Setting the grouting pressure: To control the subsidence of the overlying key strata, the grouting pressure must be greater than the weight of the overlying strata. The formula for calculating the grouting pressure Pinjection is as follows:

[0106] P 注 -H1γ1≥P 地 -H1γ1=H1(γ-γ1) (4)

[0107] In the formula, P 注 The grouting filling pressure is measured in MPa; P 地 γ is the natural pressure of the formation above the grouting layer, MPa; H1 is the borehole depth from the surface to the grouting layer, m; γ is the overall specific gravity of the formation above the grouting layer, kg / m³. 3 γ1 is the specific gravity of the filling grouting material, kg / m³ 3 ;

[0108] 5) Setting the grouting volume per hole: The formula for calculating the grouting volume Q1 per hole is:

[0109]

[0110] In the formula, Q1 is the grouting volume per hole, m 3 S represents the treatment area of ​​a single hole, in meters. 2 h g The height of the void in the regular caving zone is given in meters (m), which is taken as 0.08m here; h k The height of the void in the irregular collapse zone is m, which is taken as 0.40m here; C is the compaction rate of the grouting material, which is taken as 0.85 here.

[0111] 6) Setting the spacing between adjacent boreholes: The spacing between adjacent boreholes is determined based on the diffusion distance of the grouting material, and must meet the following requirements:

[0112] L j ≤2k j R k (6)

[0113] In the formula, Lj The distance between adjacent grouting holes is in meters (m); k j For safety, a factor of 0.5 is typically used; R k Let be the diffusion radius of the grouting material, in meters (m).

[0114] In S03, the grouting effect test specifically includes:

[0115] (1) Detection of grouting effect of surface cracks: Based on the ground penetrating radar (GPR) to obtain the longitudinal development morphology and depth information of surface cracks after grouting, the morphology and depth information of surface cracks before grouting are compared to detect the grouting effect of surface cracks.

[0116] In this invention, the grouting effect of surface cracks is tested to further verify the results and ensure that grouting and filling the surface cracks based on the measured length, width and depth can effectively prevent surface water from seeping into the aquifer and avoid groundwater pollution.

[0117] (2) Detection of grouting effect of water-conducting fracture zone: Based on the nano-transient electromagnetic method, the morphology, scale and change characteristics of the apparent resistivity chromatogram of the water-conducting fracture zone after grouting are obtained, the distribution of the water-conducting fracture zone after grouting is inferred, and the morphology and scale of the water-conducting fracture zone before grouting are compared to detect the grouting effect of the water-conducting fracture zone.

[0118] In this invention, the grouting effect of the water-conducting fracture zone is tested, which serves as a further verification to ensure that grouting and sealing of the water-conducting fracture zone based on the leakage analysis results can effectively prevent groundwater from seeping into the coal mine roadway.

[0119] Engineering Examples

[0120] This invention takes the collapse area of ​​working face 4106 in Anjialing Mine 1 (4106-4112 working faces) as an example for seepage prevention and plugging design. The aquifers in this area are mainly composed of Ordovician limestone karst fissure aquifers, Taiyuan Formation sandstone fissure aquifers, Shanxi Formation sandstone fissure aquifers, Lower Shihezi Formation sandstone fissure aquifers, Upper Shihezi Formation sandstone fissure aquifers, and Quaternary pore aquifers.

[0121] The aquitard mainly includes the Benxi Formation aquitard of the Middle Carboniferous and the Pliocene aquitard of the Tertiary.

[0122] The specific design is as follows:

[0123] S011 specifically includes:

[0124] (1) Establish a three-dimensional refined engineering geological model

[0125] This study selects the 4106 working face of the No. 4 coal seam in Anjialing Mine No. 1 as the research object. The 4106-4112 working faces are 3780m long from east to west and 2412m wide from north to south (of which the 4106 working face is 1750m long and 330m wide), with a maximum coal seam burial depth of 390m. The east-west direction is set as the X-axis, the north-south direction as the Y-axis, and the elevation from low to high as the Z-axis. This model comprehensively considers the 4106-4112 working faces. The western boundary of the model is defined as 1000m westward from the western boundary of the 4108 working face, the eastern boundary of the model is defined as 1000m eastward from the eastern boundary of the 4108 working face, the northern boundary of the model is defined as 1000m northward from the northern boundary of the 4106 working face, and the southern boundary of the model is defined as 1000m southward from the southern boundary of the 4112 working face. The bottom calculation boundary is defined as 300m downward from the maximum coal seam burial depth. The model is 5780m long in the east-west direction, 4412m wide in the north-south direction, and 690m high.

[0126] The main strata simulated include: the Quaternary Holocene and Middle-Upper Pleistocene, the Tertiary Pliocene, the Permian Upper and Lower Shihezi Formation and Shanxi Formation, the Carboniferous Taiyuan Formation and Benxi Formation, and the Ordovician. Among them, the Taiyuan Formation is divided into 5 layers, corresponding to the top strata of coal seam 4, coal seam 4 (including the interlayer between 4-1 and 4-2), the strata between coal seam 4 and coal seam 9, coal seam 9, and the strata between coal seam 9 and the top boundary of the Ordovician.

[0127] The model was meshed into a hexahedral mesh using existing modeling and meshing software, resulting in a total of 262,574 elements and 285,852 nodes. The computational model is as follows: Figure 2 As shown. The calculation boundary is a displacement constraint boundary condition, with normal displacement constraints in the X and Y axes, and full constraint at the bottom of the Z axis. The gravitational acceleration in the model is taken as 9.80 m / s². 2 .

[0128] (2) Selecting a constitutive model

[0129] Generally, the total stress-strain curve of a rock mass under a certain confining pressure can be generalized into a typical total stress-strain curve of a rock mass based on the degree of deformation and failure of the rock mass. The Mohr-Coulomb model adopts the elastoplastic theory, which can describe the plastic deformation of soil and reflect the failure behavior of soil well.

[0130] The Mohr-Coulomb model is preferred for this project.

[0131] (3) Determine the calculation parameters

[0132] Based on the physical and mechanical parameters of the rock strata in the study area provided in the "Geological Report of Anjialing Mine No. 1 Production Shaft of Anjialing Open-pit Coal Mine, Pingshuo, Shanxi Province", and after collecting a large amount of experimental data in the Pingshuo area, the elastic modulus E, Poisson's ratio μ, unit weight γ, and internal friction were determined by combining indoor test results with engineering analogy. And calculation parameters such as cohesive strength c are detailed in Table 2.

[0133] Table 2 Calculation Parameters

[0134]

[0135] (4) Predicting surface fractures during coal seam mining

[0136] 1) According to the mining continuation diagram of the coal mine, the mining of the 4106 working face is divided into two steps. The mining time for each step is calculated based on the rainy season and the non-rainy season, with a mining advance rate of 200m / month. The 4106 working face is mined in two steps, corresponding to steps 1 and 2 of the overall process; the mining steps are detailed in Table 3.

[0137] Table 3. Excavation Time and Length Layout Table

[0138]

[0139] 2) After mining is completed, the depth of surface fissures is basically stable. Refer to the surface plastic zone distribution map generated during the mining of the 4106 working face for details. Figure 3 (a) shows the distribution of the plastic zone in the vertical cross-section along the X-axis. See also (see diagram for details). Figure 3 (b) shows the distribution of the plastic zone in the vertical cross-section along the Y-axis. See diagram (b) for details. Figure 3 (c) refers to the contour maps of horizontal and inclined displacement of the surface after the first and second steps of coal seam excavation, calculated using the probability integral method. See details in section (c). Figure 3 From (d) and (e), we can obtain the location, direction, length and height of the surface cracks after the completion of mining at working face 4106.

[0140] In S012, the length and width of surface cracks measured by UAV remote sensing specifically include:

[0141] (1) Designing UAV flight paths

[0142] Based on the shape of the 4106 working face, the mining direction and the actual surface conditions, combined with the information on the location, direction, length and width of the ground fissure obtained from the numerical simulation in S011, the DJI Phantom 4 Pro drone was selected to take aerial photos of the fissure. The flight height was determined to be 80m by formula (1), the flight direction was the direction of the working face, and the overlap rate between the side direction and the flight direction was 70% and 50% respectively.

[0143] (2) Data Acquisition and Preprocessing

[0144] The drone is controlled to fly along a set flight path. Pulse signals are continuously transmitted to the target through the radar antenna, and the antenna receives and stores the returned signal information.

[0145] Intelligent software for automated processing of UAV remote sensing images performs image matching and connection, distortion correction, image matching and aerial triangulation, and other processing to generate digital products such as point clouds, DEMs, DOMs and DSMs.

[0146] (3) Extracting surface fissure information

[0147] ENVI was used to interpret images from DEM, DOM, and DSM to extract information such as the number, length, and width of ground fissures.

[0148] In S013, the depth of surface cracks measured by ground penetrating radar specifically includes:

[0149] (1) Set the ground-penetrating radar test parameters and lay out the survey lines.

[0150] This project selected the Canadian Pulse EKKO professional ground-penetrating radar. Based on the location, direction, length, and height of the ground fissures obtained from the numerical simulation in S011, the transmission wave single-line profiling method was used to measure the fissures in the 4106 working face. Along the direction perpendicular to the fissure direction, the length of the measuring line was determined to be 20m, the detection interval was 0.4m, and a measuring tape was used to lay out the observation lines.

[0151] In this method, the frequency is set to 250MHz, the time window is 80ns (4.5m), the step size is 0.020m, the sampling interval is 400ps, and the sampling speed is 0.124m / ns.

[0152] (2) Data acquisition and processing

[0153] Select the first wave and start the survey line scan. After the scan is completed, import the file generated by GPR into the EKKO-VIFW professional software. After processing the raw data such as data editing, energy gain, digital filtering and deconvolution, extract the relatively stable range of radar signal amplitude in the crack zone of working face 4106 from the profile, thereby obtaining a clear profile.

[0154] (3) Read the depth information of surface cracks

[0155] Based on the processed profile, the relatively stable range of radar signal amplitude in the crack zone of working face 4106 was extracted, which is the surface crack zone, and the longitudinal development morphology and depth information of the cracks were read.

[0156] In S014, the grouting and filling of surface fissures specifically includes:

[0157] (1) Preparation of grouting material for surface cracks; This project analyzes the reinforcement mechanism of grouting filling material, and comprehensively considers the fluidity, stability and strength of the grout body, and selects loess-fly ash grouting filling material; The proportion range is determined as follows: grout concentration is 60% to 65%; loess-fly ash mass ratio is 1:1.5 to 1:3; auxiliary materials account for 30% to 33% of the solid material mass, and external additives account for 5% to 7% of the solid material mass.

[0158] In this embodiment, alkaline materials such as cement and lime are selected as auxiliary materials, and water glass is selected as an external additive. It is easy to understand that the solid material mentioned in this embodiment refers to the solid substances in the grouting material.

[0159] (2) Design of grouting holes for surface fissures, specifically including:

[0160] 1) Determine the diameter of the grouting hole for surface fissures: According to the "Technical Specification for Waterproofing of Underground Engineering" (GB50108-2001), the borehole diameter should not be less than 40mm. Based on the predicted location, direction, length and height of the ground fissures obtained from S011, and the measured length, width and depth of the ground fissures and the characteristics of the stratum lithology obtained from S012 and S013, determine the specific diameter of the grouting hole.

[0161] In this embodiment, the diameter of the grouting hole in the surface crack is 40mm.

[0162] 2) Determine the depth of grouting holes in surface fissures: Based on the depth of the fissures, combined with topography, lithology and other characteristics, determine the depth of the grouting holes.

[0163] In this embodiment, the depth of the grouting hole in the surface fissure is 4m.

[0164] 3) Determining the grouting volume for surface cracks: The control of the grouting volume is mainly based on the volume of the surface cracks, the porosity of the soil, and the empirical coefficient k value. The specific calculation formula is as follows:

[0165]

[0166] In the formula, Q is the grouting volume, m 3 ;γ w ρ is the gravitational density of water; H is the difference between the grouting pressure and the groundwater head; b is the fracture opening; μ g R is the dynamic viscosity of the grouting material, mPa·s; R is the diffusion radius of the grouting material, m; r c Let be the radius of the grouting pipe, in meters (m).

[0167] In this embodiment, the grouting volume for surface fissures is 7800 m³. 3 .

[0168] 4) Determine the grouting pressure: During the grouting process, when the stratum is very shallow, the grout will flow along the horizontal shear direction and cause grout to seep out at the surface. Therefore, the grouting pressure must meet the following requirements:

[0169] p=KH (3)

[0170] In the formula, P is the grouting pressure (MPa); K is the pressure adjustment coefficient; and H is the grouting depth (m).

[0171] In this embodiment, the grouting pressure is 0.8 MPa.

[0172] 5) Determine the spacing of grouting holes: Determine the spacing of grouting holes based on the diffusion radius of the grouting material to ensure that the surface cracks can be filled with grout within their length.

[0173] In this embodiment, the diffusion radius of the grouting material is 2.3m, so the spacing between grouting holes is 4.6m.

[0174] In S021, according to FLAC 3D The numerical simulation software calculation results are used to analyze the strain increment profile of the overlying strata of the coal seam at different mining stages. After mining is completed, the depth of the water-conducting fracture zone is basically stable. Based on the strain profile, such as... Figure 4 As shown, (a) and (b) are numerical simulation results of the development height of the "two zones" after the first and second mining steps of the 4106 working face, respectively. The maximum development height of the water-conducting fracture zone was finally determined to be 185m.

[0175] In S022, the measured height of the water-conducting fracture zone based on the nano-transient electromagnetic method specifically includes:

[0176] (1) Set up the survey line and set the acquisition parameters

[0177] This study selected the GDP-32 II Nano TEM manufactured by Zonge Systems, Inc. (USA), employing a center loop device. Field tests determined the control area to be 0.765 km². 2 The survey lines are arranged perpendicular to the strike of the strata, with a point spacing of 5m, a basic line spacing of 20m, a transmitting frame of 20m x 20m, a receiving frame of 5m x 5m, a transmitting frequency of 4Hz, and a superposition number of 6000.

[0178] (2) Data acquisition and processing

[0179] The acquired raw data is organized and format converted, and noise is eliminated by filtering. The change of secondary field potential difference with time is converted into the change of resistivity with depth by time conversion and apparent resistivity inversion. Finally, the results are interpreted. Apparent resistivity profiles of each survey line are drawn from the data collected in the whole area, and the anomaly range is delineated. Then, the anomalies of each profile are displayed on the corresponding plan view.

[0180] (3) Analyze the exploration results

[0181] Based on the apparent resistivity profile, the electrical distribution characteristics of the underground geological body in the horizontal and vertical directions were determined. Based on the morphology, scale, and variation characteristics of the apparent resistivity chromatogram, the development height of the water-conducting fracture zone was inferred to be 183.74m.

[0182] In S023, according to FLAC 3D The development height of the water-conducting fracture zone, determined by numerical simulation results and by the apparent resistivity profile obtained by nano-transient electromagnetic method, is ultimately determined to be 185m.

[0183] See Figure 5 According to the exploration results, the coal seam in working face 4106 is buried at a depth of approximately 120-290 mm, and the water-conducting fracture zone is developed to a height of approximately 185 m. Figure 5 (a) in the figure is a contour map of the burial depth of the roof of coal seam No. 4. Figure 5 (b) in the figure shows the height characteristics of the water-conducting fracture zone development at the working face. Figure 5 (c) in the figure shows the characteristic diagram after adding the development height of the water-conducting fracture zone to the thickness of the protective layer. It can be seen from the figure that the areas where the water-conducting fracture zone (including the protective layer) penetrates the aquitard of the Tertiary Jingle Formation are mainly distributed in two larger areas in the east and west. This indicates that there is direct contact between the bottom plate of the loess aquifer and the top interface of the water-conducting fracture zone.

[0184] Therefore, leakage will occur, and grouting is required to seal the water-conducting fissures in the 4106 working face.

[0185] In S024, the grouting and sealing of water-conducting fracture zones specifically includes:

[0186] (1) Determine the grouting range and grouting thickness of the water-conducting fracture zone: In this project, the grouting range of the water-conducting fracture zone is the planar development range of the water-conducting fracture zone, and the grouting thickness is the development height of the water-conducting fracture zone, i.e., 185m.

[0187] According to FLAC 3D Numerical simulation results and nano-transient electromagnetic method determined that the planar development range of the water-conducting fracture zone is 0 to 2430 m in the X-axis direction and within 310 m outside the working surface in the Y-axis direction.

[0188] (2) Preparation of grouting material for water-conducting fissures: The grouting material prepared here is the same as the surface fissure grouting material prepared in S014 when grouting and filling surface fissures.

[0189] (3) Design of grouting holes in water-conducting fracture zones: including:

[0190] 1) Selection of borehole location: The location of the borehole is determined based on the location of the underground roadway, the depth of the coal seam, and the surface drilling conditions, combined with the slurry and the separation space around the goaf.

[0191] 2) Selection of borehole diameter: The borehole diameter is determined based on the grouting volume per borehole and the daily grouting duration, combined with the lithology of the overlying soil and rock.

[0192] In this embodiment, the borehole diameter is 40mm.

[0193] 3) Setting the drilling depth: In order to ensure that the filling grout does not flow down into the well, the final position of the borehole should be kept above the water-conducting fracture zone of the mining face. A maintenance zone thickness of about 5 times the coal seam mining height should be left, and the borehole should pass through each major delamination zone to ensure that the borehole has the ability to absorb grout and ensure the effect of grouting and reducing settlement.

[0194] In this embodiment, the drilling depth is 255m.

[0195] 4) Setting the grouting pressure: To control the subsidence of the overlying key strata, the grouting pressure must be greater than the weight of the overlying strata. The formula for calculating the grouting pressure Pinjection is as follows:

[0196] P 注 -H1γ1≥P 地 -H1γ1=H1(γ-γ1) (4)

[0197] In the formula, P 注 The grouting filling pressure is measured in MPa; P 地 γ is the natural pressure of the formation above the grouting layer, MPa; H1 is the borehole depth from the surface to the grouting layer, m; γ is the overall specific gravity of the formation above the grouting layer, kg / m³. 3 γ1 is the specific gravity of the filling grouting material, kg / m³ 3 .

[0198] In this embodiment, the grouting pressure is 5 MPa.

[0199] 5) Setting the grouting volume per hole: The formula for calculating the grouting volume Q1 per hole is:

[0200]

[0201] In the formula, Q1 is the grouting volume per hole, m 3 S represents the treatment area of ​​a single hole, in meters. 2 h g The height of the void in the regular caving zone is given in meters (m), which is taken as 0.08m here; h k The height of the void in the irregular collapse zone is m, which is taken as 0.40m here; C is the compaction rate of the grouting material, which is taken as 0.85 here.

[0202] In this embodiment, the grouting volume per hole is 11m. 3 .

[0203] 6) Setting the spacing between adjacent boreholes: The spacing between adjacent boreholes is determined based on the diffusion distance of the grouting material, and must meet the following requirements:

[0204] L j ≤2k j R k (6)

[0205] In the formula, L j The distance between adjacent grouting holes is in meters (m); k j For safety, a factor of 0.5 is typically used; R k Let be the diffusion radius of the grouting material, in meters (m).

[0206] In this embodiment, the distance between adjacent boreholes is 5m.

[0207] Finally, the grouting effect of the surface cracks and the water-conducting fracture zone on the 4106 working face were tested to ensure that the grouting effect was good.

[0208] This invention proposes a comprehensive system for preventing and plugging seepage in coal mining subsidence areas, representing a novel method for this purpose in loess hilly coal mining subsidence zones. This method is based on the unique topography of the loess hilly region and incorporates FLAC (Fluorescent Alternative Coal Processing) technology. 3D Numerical simulation software, ground-penetrating radar, and UAV remote sensing technology enabled the prediction of the height of surface mining cracks and water-conducting fissures, as well as the determination of the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fissure. Based on this, it was determined whether the aquifer would leak, the location of the leakage point was identified, and grouting materials were used to fill and seal the surface cracks and water-conducting fissures.

[0209] This method enables accurate prediction of surface subsidence and ground fissures in shallow buried thick coal seam mining in the Loess Hilly Area. It has developed an integrated waterproofing and plugging technology for surface fissures and water-conducting fissures, and formed an integrated "underground-above-ground" collaborative governance technology framework for coal mining subsidence areas in the Loess Hilly Area. This has achieved the organic integration of mine ecological geological environment protection and surface subsidence disaster prevention and control.

[0210] It will be readily understood by those skilled in the art that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0211] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preventing seepage and plugging leakage in coal mining subsidence areas of loess hills, characterized in that, The steps include the following: S01: Grouting and filling of surface fractures in coal seam mining; including: S011: Numerical simulation to predict the occurrence of surface cracks; S012: Length and width of surface cracks measured by UAV remote sensing; S013: Depth of surface cracks measured by ground penetrating radar; S014: Grouting is performed to fill the surface cracks based on the measured length, width and depth of the surface cracks; S02: Grouting and sealing of water-conducting fracture zones in coal seam mining; including: S021: Numerical simulation predicts the development height of water-conducting fracture zones; S022: Measurement of water-conducting fracture zone development height based on nanotransient electromagnetic method; S023: Determine the contact relationship between the loess aquifer and the water-conducting fracture zone and conduct leakage analysis; S024: Grouting is performed to seal the water-conducting fracture zone based on the results of the leakage analysis; S03: Grouting effect inspection; among which... In S014, the grouting and filling of surface cracks specifically includes: (1) Preparation of surface crack grouting material: Select loess-fly ash grouting filling material and determine the following proportion range: grout concentration is 60% to 65%; loess-fly ash mass ratio is 1:1.5 to 1:3; auxiliary materials account for 30% to 33% of the solid material mass, and external additives account for 5% to 7% of the solid material mass; (2) Design grouting holes for surface cracks; including: 1) Determine the diameter of the grouting holes for surface cracks: the diameter shall not be less than 40 mm; 2) Determine the depth of grouting holes in surface fissures: Based on the fissure depth, combined with topography and lithological characteristics, determine the depth of grouting holes; 3) Determine the grouting volume for surface fissures: The formula for calculating the grouting volume Q is: （2） In the formula, Q is the grouting volume, m 3 ;γ w ρ is the gravitational density of water; H is the difference between the grouting pressure and the groundwater head; b is the fracture opening; μ g R is the dynamic viscosity of the grouting material, mPa•s; R is the diffusion radius of the grouting material, m; r c Let be the radius of the grouting pipe, in meters (m). 4) Determine the grouting pressure: The formula for calculating the grouting pressure P is: （3） In the formula, P is the grouting pressure (MPa); K is the pressure adjustment coefficient; and H is the grouting depth (m). 5) Determine the spacing of grouting holes: The spacing of grouting holes is determined based on the diffusion radius of the grouting material; In S023, the determination of the contact relationship between the loess aquifer and the water-conducting fracture zone and the leakage analysis include: (1) Determine whether the bottom plate of the loess aquifer is in contact with the top interface of the water-conducting fracture zone based on the development height of the water-conducting fracture zone and the burial depth of the loess aquifer. (2) Based on the contact relationship between the bottom plate of the loess aquifer and the top interface of the water-conducting fracture zone, and considering whether there is an impermeable layer between them, the following three situations are identified: 1) When the bottom plate of the loess aquifer comes into contact with the top interface of the water-conducting fracture zone, leakage will occur; 2) The bottom plate of the loess aquifer is not in contact with the top interface of the water-conducting fracture zone, and there is no waterproof layer at the top of the water-conducting fracture zone, which will cause leakage. 3) The bottom plate of the loess aquifer is not in contact with the top interface of the water-conducting fracture zone, and there is a water-proof layer at the top of the water-conducting fracture zone, so there will be no leakage. In S024, the grouting and sealing of the water-conducting fracture zone specifically includes: (1) Determine the grouting range and grouting thickness of the water-conducting fracture zone: The grouting range of the water-conducting fracture zone is the planar development range of the water-conducting fracture zone, and the grouting thickness is the development height of the water-conducting fracture zone; (2) Prepare grouting material for water-conducting fracture zones; (3) Design grouting holes in the water-conducting fracture zone; including: 1) Selection of borehole location: The location of the borehole is determined based on the location of the underground roadway, the depth of the coal seam, and the surface drilling conditions, combined with the slurry and the separation space around the goaf. 2) Selection of borehole diameter: The borehole diameter is determined based on the grouting volume per borehole and the daily grouting duration, combined with the lithology of the overlying soil and rock. 3) Setting the drilling depth: The final drilling position should be maintained above the water-conducting fracture zone of the mining face, with a maintenance zone thickness of 5 times the coal seam mining height, and the drilling should pass through each major delamination zone; 4) Setting the grouting pressure: Grouting pressure P 注 The calculation formula is: （4） In the formula, P 注 The grouting filling pressure is measured in MPa; P 地 γ is the natural pressure of the formation above the grouting layer, MPa; H1 is the borehole depth from the surface to the grouting layer, m; γ is the overall specific gravity of the formation above the grouting layer, kg / m³. 3 γ1 is the specific gravity of the filling grouting material, kg / m³ 3 ; 5) Setting the grouting volume per hole: The formula for calculating the grouting volume Q1 per hole is: （5） In the formula, Q1 is the grouting volume per hole, m 3 S represents the treatment area of ​​a single well, in meters. 2 h g The height of the void in the regular collapse zone, in meters (m); h k C represents the height of the voids in the irregular collapse zone, in meters; C represents the compaction rate of the grouting material. 6) Setting the spacing between adjacent boreholes: The spacing between adjacent boreholes is determined based on the diffusion distance of the grouting material, and must meet the following requirements: （6） In the formula, L j The distance between adjacent grouting holes is in meters (m); k j R is the safety factor; k Let be the diffusion radius of the grouting material, in meters (m).

2. The method for preventing seepage and plugging leakage in the coal mining subsidence area of ​​loess hills according to claim 1, characterized in that, In S011, the numerical simulation prediction of surface crack generation includes: Based on the mining continuation diagram of the coal mine, determine the number of mining steps and the step length; Using FLAC 3D Numerical simulation software simulates the step-by-step mining of the working face; Based on the surface plastic zone distribution map, the X-axis vertical profile plastic zone distribution map, and the Y-axis vertical profile plastic zone distribution map generated during the mining process, and combined with the probability integral method, the contour maps of horizontal deformation in the dip and strike of the coal seam after each step of excavation are calculated, thereby obtaining the location, direction, length, and height of the ground fissures.

3. The method for preventing seepage and plugging leakage in the coal mining subsidence area of ​​loess hills according to claim 1, characterized in that, In S012, the length and width of the surface cracks measured by UAV remote sensing specifically include: (1) Design the drone flight path; (2) Data acquisition and preprocessing; (3) Extract information on surface cracks.

4. The method for preventing seepage and plugging leakage in coal mining subsidence areas of loess hills according to claim 1, characterized in that, In S013, the depth of surface cracks measured by ground penetrating radar specifically includes: (1) Set the ground-penetrating radar test parameters and arrange the survey lines; (2) Data acquisition and processing; (3) Read the depth information of surface cracks.

5. The method for preventing seepage and plugging leakage in the coal mining subsidence area of ​​loess hills according to claim 4, characterized in that, The process of setting ground-penetrating radar test parameters and arranging survey lines includes: Surface cracks were measured using the transmitted wave single-line profiling method; the following parameters were set: frequency, time window, step size, sampling interval, and velocity. Based on the transmitted wave single-line profiling method, the length of the survey line and the detection spacing are determined along the direction perpendicular to the surface crack, and the observation lines are laid out using a measuring tape; and / or The data acquisition and processing include: The first wave of the ground-penetrating radar (GPR) was selected for line scanning. Import the data collected by the ground penetrating radar GPR into EKKO-VIEW, and perform data editing, energy gain, digital filtering and deconvolution processing on the raw data; Obtain a clear cross-sectional view; and / or The process of reading the depth information of surface cracks includes: Based on the processed profile, the radar signal of the fracture zone was extracted and identified as a surface fracture zone. Read the longitudinal development morphology and depth information of the crack.

6. The method for preventing seepage and plugging leakage in coal mining subsidence areas of loess hills according to claim 1, characterized in that, In S022, the measured height of the water-conducting fracture zone based on the nano-transient electromagnetic method includes: (1) Set up the measurement line and set the acquisition parameters: Using the nano transient electromagnetic system, determine the control area through field test, select the measurement line layout method and working device, and determine the point distance, basic line distance, transmitting frame, receiving frame, transmitting frequency and the number of suppression superpositions; (2) Data acquisition and processing: The change of the secondary field potential difference with time is converted into the change of resistivity with depth through time-depth conversion and apparent resistivity inversion. Finally, the results are interpreted. The data collected in the whole area are used to draw the apparent resistivity profile of each survey line and the anomaly range is delineated. Then, the anomalies of each profile are displayed on the corresponding plan view. (3) Analyze the exploration results: Based on the apparent resistivity profile, determine the electrical distribution characteristics of the underground geological body in the horizontal and vertical directions. Based on the shape, scale and variation characteristics of the apparent resistivity chromatogram, infer the distribution of the water-conducting fracture zone.

7. The method for preventing seepage and plugging leakage in coal mining subsidence areas of loess hills according to claim 1, characterized in that, In S03, the grouting effect detection specifically includes: (1) Detection of grouting effect of surface cracks: Based on the ground penetrating radar GPR, the longitudinal development morphology and depth information of surface cracks after grouting are obtained, and the morphology and depth information of surface cracks before grouting are compared to detect the grouting effect of surface cracks. (2) Detection of grouting effect of water-conducting fracture zone: Based on the nano-transient electromagnetic method, the morphology, scale and change characteristics of the apparent resistivity chromatogram of the water-conducting fracture zone after grouting are obtained, the distribution of the water-conducting fracture zone after grouting is inferred, and the morphology and scale of the water-conducting fracture zone before grouting are compared to detect the grouting effect of the water-conducting fracture zone.

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