Method and device for quantitatively characterizing mining-induced fractures of overlying strata

Abstract

The invention discloses an overlying strata mining-induced fracture quantitative characterization method and device. The method comprises the following steps: acquiring an overlying strata mining-induced fracture image in an excavation time step in a similar model; performing image processing on the overlying strata mining-induced fissure image to obtain a corresponding fissure binary image and a fissure skeleton image; based on the fracture binary image and the fracture skeleton image, determining a fracture quantitative characterization index corresponding to the overlying strata mining-induced fracture in the similar model; and based on the quantitative characterization index of the fracture, performing quantitative characterization on the mining-induced fracture of the overburden strata. According to the method, quantitative characterization is carried out on the overlying strata mining-induced fracture based on the fracture quantitative characterization index, so that the overall condition of the mining-induced fracture in the overlying strata is comprehensively analyzed and evaluated, a test result is conveniently subjected to standardized characterization, and powerful support is provided for solving related problems of mining engineering.

Description

Technical Field

[0001] The invention relates to the technical field of underground mining, and in particular to a method and a device for quantitatively characterizing mining-induced cracks in overburden rocks. Background Art

[0002] After underground coal seam mining, the overlying rock strata will sink and break, forming mining fissures in the rock strata. Among them, mining fissures are the main flow channels for coal mine gas, groundwater and filling slurry. In addition, studying the spatial distribution, geometric characteristics and topological structure of mining fissures is of great significance for coal and gas co-mining, mine water hazard prevention and control, and surface subsidence control. For example, using the seepage channels formed by mining fissures to depressurize coal seam gas is a key step in achieving coal and gas co-mining and eliminating gas disaster risks.

[0003] In the prior art, the distribution characteristics of mining fractures can be studied by field observation methods and laboratory similar model test methods. Among them, mining fractures exist in the underground rock mass of coal mines. Due to the limited space and complex environment of coal mines, the observation process of field observation methods is complicated, the cycle is long, and the cost is high. In addition, only the distribution and development characteristics of fractures near the drilling point can be obtained, and the overall distribution of mining fractures in the overburden cannot be fully analyzed and evaluated.

[0004] In addition, the similarity model test method is based on the similarity theory, and uses rock-like materials to construct multiple groups of rock layers with different properties, simulating the spatial structure of the real underground overburden, and visually reproducing the delamination, fracture, collapse and spatial distribution of mining fissures in the underground rock layer of the coal mine in the laboratory through the step-by-step excavation of the coal seam. However, in the characterization of the spatial distribution, geometric characteristics and topological structure of mining fissures, qualitative description is still used, and there is a lack of quantitative characterization methods and means, which has led to a vague understanding of the characteristics of mining fissures in existing research, hindering the quantitative analysis and in-depth research of mining engineering problems such as gas extraction design, water-conducting fissure evaluation, and grouting filling control. For example, when describing the inclination of the fissure, the expressions "horizontal fissure" and "vertical fissure" are usually used, without clarifying the exact angle of the fissure. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To this end, the present invention proposes a method for quantitative characterization of overburden mining fractures, which can determine the fracture quantitative characterization indicators corresponding to the overburden mining fractures in the similar model based on the fracture binary image and the fracture skeleton image corresponding to the overburden mining fracture image, and quantitatively characterize the overburden mining fractures based on the fracture quantitative characterization indicators, so as to comprehensively analyze and evaluate the overall situation of the mining fractures in the overburden, facilitate the standardized characterization of the test results, and provide strong support for solving related problems in mining engineering.

[0007] Another object of the present invention is to provide a device for quantitatively characterizing mining-induced cracks in overburden rocks.

[0008] To achieve the above-mentioned purpose, the present invention provides a method for quantitatively characterizing mining-induced fractures in overburden strata, the method comprising:

[0009] Obtain the mining crack images of overburden rocks at the time of excavation in similar models;

[0010] Performing image processing on the overburden mining crack image to obtain a corresponding crack binary image and a crack skeleton image;

[0011] Based on the fracture binary map and the fracture skeleton map, determining the fracture quantitative characterization index corresponding to the overburden mining fracture in the similarity model;

[0012] Based on the crack quantitative characterization index, the mining-induced cracks in the overburden strata are quantitatively characterized.

[0013] The method for quantitatively characterizing overburden mining cracks in the embodiment of the present invention may also have the following additional technical features:

[0014] In one embodiment of the present invention, the determining of the fracture quantitative characterization index corresponding to the overburden mining fracture in the similarity model based on the fracture binary map and the fracture skeleton map includes:

[0015] Based on the fracture binary map, determining the fracture network fractal dimension corresponding to the overburden mining fracture;

[0016] Based on the fracture skeleton diagram, the fracture density, and / or fracture inclination, and / or fracture length, and / or fracture spacing, and / or fracture network connectivity corresponding to the overburden mining fractures are determined.

[0017] In one embodiment of the present invention, determining the fracture network fractal dimension corresponding to the overburden mining fracture based on the fracture binary map includes:

[0018] Determine the calculation order and the first box side length corresponding to the crack binary image;

[0019] Based on the side length of the first box, counting the number of first boxes covering the crack in the crack binary image;

[0020] The side length of the first box is updated to obtain the side length of the second box, and based on the side length of the second box, the number of second boxes covering the crack in the crack binary image is counted;

[0021] Repeat the above steps until the calculation order is reached, perform linear fitting based on the side length of the first box, the number of the first boxes, the side length of the second box and the number of the second boxes, and determine the slope of the fitting line in the fitting result as the fractal dimension of the fracture network corresponding to the overburden mining fracture.

[0022] In one embodiment of the present invention, determining the fracture density corresponding to the overburden mining fracture based on the fracture skeleton diagram includes:

[0023] Determine the measurement window size corresponding to the crack skeleton image;

[0024] Determine the number of independent cracks in the measurement window, and determine the crack density at a central pixel point corresponding to the measurement window based on the number of independent cracks;

[0025] Repeat the above steps until all measurement windows in the crack skeleton map are traversed to obtain the crack density at each central measurement pixel point;

[0026] Based on the crack density at each central pixel point, a crack density map corresponding to the overburden mining cracks is drawn.

[0027] In one embodiment of the present invention, determining the fracture inclination angle corresponding to the overburden mining fracture based on the fracture skeleton diagram includes:

[0028] determining independent fractures in the fracture skeleton map;

[0029] Extracting coordinates of all pixel points in the independent crack;

[0030] Decomposing or linearly fitting the coordinates of the independent fractures to calculate the corresponding fracture inclination angles;

[0031] Repeat the above steps until all independent fractures in the fracture skeleton diagram are traversed to obtain the fracture inclination angle of each independent fracture;

[0032] Based on the fracture inclination angle of each independent fracture, a fracture inclination angle distribution map corresponding to the overburden mining fracture is drawn.

[0033] In one embodiment of the present invention, determining the crack length corresponding to the overburden mining crack based on the crack skeleton diagram includes:

[0034] determining independent fractures in the fracture skeleton map;

[0035] Calculating the crack length of the independent crack according to the connectivity relationship of the crack pixels in the independent crack;

[0036] Repeat the above steps until all independent cracks in the crack skeleton graph are traversed to obtain the crack length of each independent crack;

[0037] Based on the crack length of each independent crack, a crack length distribution map corresponding to the overburden mining cracks is drawn.

[0038] In one embodiment of the present invention, determining the fracture spacing corresponding to the overburden mining fracture based on the fracture skeleton diagram includes:

[0039] Determine, according to the fracture inclination angle of each independent fracture in the fracture skeleton diagram, a nearly horizontal fracture that meets a preset range of fracture inclination angles;

[0040] Determine a pixel point in the near-horizontal fissure, and calculate the distance between the pixel point and the adjacent horizontal fissure below;

[0041] Repeat the above steps until all nearly horizontal cracks in the crack skeleton diagram are traversed to obtain the crack spacing of nearly horizontal cracks;

[0042] Based on the crack length of each independent crack, a crack spacing distribution map corresponding to the overburden mining cracks is drawn.

[0043] In one embodiment of the present invention, determining the connectivity of the fracture network corresponding to the overburden mining fracture based on the fracture skeleton diagram includes:

[0044] Determining independent cracks in the crack skeleton graph, and determining corresponding nodes based on the independent cracks;

[0045] According to the preset rules, determine the node coordination number of the node;

[0046] Repeat the above steps until all the nodes are traversed to obtain the node coordination number of each node;

[0047] Based on the node coordination number of each node, a fracture network connectivity distribution map corresponding to the overburden mining fractures is drawn.

[0048] In one embodiment of the present invention, the quantitative characterization of overburden mining cracks based on the crack quantitative characterization index includes:

[0049] Obtain the target scenario where analysis of overburden mining cracks is required;

[0050] The target scene is quantitatively analyzed based on the indicator result corresponding to the crack quantitative characterization indicator, and the quantitative analysis result is output.

[0051] Another aspect of the present invention provides a device for quantitatively characterizing overburden mining cracks, the device comprising:

[0052] An acquisition module is used to acquire the overburden mining crack image at the excavation time step in a similar model;

[0053] A processing module, used for performing image processing on the overburden mining crack image to obtain a corresponding crack binary image and a crack skeleton image;

[0054] A determination module, used to determine the crack quantitative characterization index corresponding to the overburden mining crack in the similarity model based on the crack binary map and the crack skeleton map;

[0055] The characterization module is used to quantitatively characterize the overburden mining cracks based on the crack quantitative characterization index.

[0056] The method and device for quantitative characterization of overburden mining fractures in the embodiments of the present invention can determine the fracture quantitative characterization indicators corresponding to the overburden mining fractures in the similar model based on the fracture binary map and fracture skeleton map corresponding to the overburden mining fracture image, and quantitatively characterize the overburden mining fractures based on the fracture quantitative characterization indicators, thereby comprehensively analyzing and evaluating the overall situation of the mining fractures in the overburden, facilitating the standardized characterization of the test results, and providing strong support for solving problems related to mining engineering.

[0057] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0059] Figure 1 is a flow chart of a method for quantitatively characterizing overburden mining cracks according to an embodiment of the present invention;

[0060] Figure 2 is a schematic diagram of calculating the fractal dimension of a fracture network according to an embodiment of the present invention;

[0061] Figure 3 is a schematic diagram of calculating crack density according to an embodiment of the present invention;

[0062] Figure 4 is a schematic diagram of calculating the fracture inclination according to an embodiment of the present invention;

[0063] Figure 5 is a schematic diagram of calculating crack length according to an embodiment of the present invention;

[0064] Figure 6 is a schematic diagram of calculating the crack spacing according to an embodiment of the present invention;

[0065] Figure 7 is a schematic diagram of calculating fracture network connectivity according to one embodiment of the present invention;

[0066] Figure 8 It is a structural diagram of a device for quantitatively characterizing overburden mining fractures according to another embodiment of the present invention. DETAILED DESCRIPTION

[0067] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0068] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0069] The following describes a method and device for quantitatively characterizing overburden mining fractures according to an embodiment of the present invention with reference to the accompanying drawings.

[0070] Figure 1 It is a flow chart of a method for quantitatively characterizing overburden mining fractures according to an embodiment of the present invention.

[0071] like Figure 1 As shown, the method may include the following steps:

[0072] Step 101, obtaining an image of mining-induced cracks in the overburden strata during excavation in a similar model.

[0073] In one embodiment of the present invention, the similar model is a model of the area to be excavated. Also, in one embodiment of the present invention, after the similar model is determined, the coal seam can be excavated according to the designed step size, and the overburden mining crack image at the excavation step in the similar model can be obtained.

[0074] Step 102, performing image processing on the overburden mining crack image to obtain a corresponding crack binary image and crack skeleton image.

[0075] In one embodiment of the present invention, after obtaining the overburden mining fracture image through the above steps, the overburden mining fracture image can be processed to obtain a corresponding fracture binary image and a fracture skeleton image.

[0076] In one embodiment of the present invention, the method of performing image processing on the overburden mining crack image to obtain the corresponding crack binary image and crack skeleton image may include the following steps:

[0077] Step 1021, performing image processing on the overburden mining crack image to obtain a crack binary image containing the cracks;

[0078] Step 1022, skeletonization is performed on the fracture binary image to obtain a fracture skeleton image containing fracture network geometric information and topological structure.

[0079] In one embodiment of the present invention, image filtering, contrast enhancement and threshold segmentation may be performed on the overburden mining crack image to obtain a crack binary image containing cracks, so as to complete the extraction of cracks in the overburden mining image.

[0080] Step 103, based on the fracture binary map and the fracture skeleton map, determine the fracture quantitative characterization index corresponding to the overburden mining fracture in the similar model.

[0081] In one embodiment of the present invention, after obtaining the fracture binary map and fracture skeleton map through the above steps, the fracture quantitative characterization index corresponding to the overburden mining fracture in the similar model can be determined based on the fracture binary map and fracture skeleton map.

[0082] Specifically, in one embodiment of the present invention, the method for determining the fracture quantitative characterization index corresponding to the overburden mining fracture in the similar model based on the fracture binary image and the fracture skeleton image may include the following steps:

[0083] Step 1031, based on the fracture binary map, determining the fracture network fractal dimension corresponding to the overburden mining fracture;

[0084] Step 1032, based on the fracture skeleton diagram, determine the fracture density, and / or fracture inclination, and / or fracture length, and / or fracture spacing, and / or fracture network connectivity corresponding to the overburden mining fractures.

[0085] In one embodiment of the present invention, the method for determining the fractal dimension of the fracture network corresponding to the overburden mining fracture based on the fracture binary map may include the following steps:

[0086] Step 10311, determining the calculation order and the first box side length corresponding to the crack binary image;

[0087] Step 10312, based on the side length of the first box, counting the number of first boxes covering the crack in the crack binary image;

[0088] Step 10313, updating the side length of the first box to obtain the side length of the second box, and based on the side length of the second box, counting the number of second boxes covering the crack in the crack binary map;

[0089] Step 10314, repeat the above steps until the calculation order is reached, perform linear fitting based on the side length of the first box, the number of the first boxes, the side length of the second box and the number of the second boxes, and determine the slope of the fitting line in the fitting result as the fractal dimension of the fracture network corresponding to the overburden mining fracture.

[0090] In one embodiment of the present invention, before determining the fracture network fractal dimension corresponding to the fracture binary image, the calculation order and the first box side length corresponding to the fracture binary image may be determined as needed. For example, the calculation order may be 5.

[0091] And, in one embodiment of the present invention, after obtaining the box side length and the number of boxes corresponding to each calculation order through the above steps, decomposition or linear fitting can be performed according to the box side length and the number of boxes corresponding to each calculation order, and the slope of the fitting line in the fitting result is determined as the fractal dimension of the fracture network corresponding to the overburden mining fracture through the first formula, wherein the first formula is:

[0092]

[0093] Among them, D B is the fractal dimension of the crack network, δ is the side length of the box, N δ is the number of sides of the box and F is the fractal object to be studied.

[0094] For example, in one embodiment of the present invention, Figure 2 A schematic diagram of calculating the fractal dimension of a fracture network provided by an embodiment of the present invention. In a two-dimensional graph, a uniformly distributed square grid can be used to cover the fractal object, and the number of boxes required to cover the fractal object can be counted to determine the fractal dimension of a fractal object F. Figure 2 As shown, (a) is the grid when the box is covered at the kth step, (b) is the grid when the box is covered at the k+1th step, and (c) is the grid when the box is covered at the k+2th step. The side length and number of boxes corresponding to each step are decomposed or linearly fitted (such as Figure 2 In (d), the fractal dimension of the fracture network corresponding to the mining-induced fractures in the overburden rock is obtained.

[0095] Furthermore, in one embodiment of the present invention, the method for determining the fracture density corresponding to the overburden mining fracture based on the fracture skeleton diagram may include the following steps:

[0096] Step 1, determine the measurement window size corresponding to the crack skeleton image;

[0097] Step 2: determining the number of independent cracks in the measurement window, and determining the crack density at the central measurement pixel point corresponding to the measurement window based on the number of independent cracks;

[0098] Step 3, repeat the above steps until all measurement windows in the crack skeleton map are traversed to obtain the crack density at each central measurement pixel point;

[0099] Step 4: Based on the crack density at each central pixel point, draw a crack density map corresponding to the overburden mining cracks.

[0100] In one embodiment of the present invention, the definition of fracture density is the number of internal fractures per unit area. The area with a larger fracture density in the overburden is generally more broken, with lower rock strength and higher permeability. Based on this, the fracture density can be determined by measuring the window.

[0101] And, in one embodiment of the present invention, the size of the measurement window corresponding to the crack skeleton image can be determined as needed. In one embodiment of the present invention, before determining the number of independent cracks in the measurement window, each independent crack in the crack skeleton image can be identified and numbered one by one, each independent crack corresponds to a number, and the number value is assigned to the pixel at the corresponding crack position in the image.

[0102] Further, in one embodiment of the present invention, after determining the size of the measurement window, the number of independent cracks in the measurement window centered on the measured pixel point can be determined by counting the number of different numbers in the measurement window, and the crack density at the central measurement pixel point corresponding to the measurement window can be determined by a second formula, wherein the second formula is:

[0103]

[0104] Among them, ρ f (x, y) is the crack density at the pixel with coordinates (x, y) in the crack skeleton map, N f (x, y) is the number of cracks in the measurement window centered on the measured pixel, and S represents the area of ​​the measurement window.

[0105] For example, in one embodiment of the present invention, Figure 3 A schematic diagram of calculating crack density provided by an embodiment of the present invention. Figure 3 As shown, (a) is the independent crack distribution and the measurement window position, (b) is the independent crack distribution and the central measured pixel point in the measurement window, and (c) is the crack density map.

[0106] Further, in one embodiment of the present invention, the method for determining the fracture inclination angle corresponding to the overburden mining fracture based on the fracture skeleton diagram may include the following steps:

[0107] Step a, determining independent cracks in the crack skeleton map;

[0108] Step b, extracting the coordinates of all pixels in the independent cracks;

[0109] Step c, decomposing or linearly fitting the coordinates of the independent fractures to calculate the corresponding fracture inclination angles;

[0110] Step d, repeat the above steps until all independent cracks in the crack skeleton diagram are traversed to obtain the crack inclination angle of each independent crack;

[0111] Step e: based on the fracture inclination angle of each independent fracture, draw a fracture inclination angle distribution map corresponding to the overburden mining fracture.

[0112] In one embodiment of the present invention, the fracture dip is the angle between the fracture and the horizontal line, which can reflect the rotation characteristics of the overburden after breaking. In one embodiment of the present invention, the horizontal axis to the right can be defined as 0°, and the dip increases in the counterclockwise direction along the horizontal axis.

[0113] In one embodiment of the present invention, after extracting the coordinates of all pixel points in the independent crack, the direction vector of the crack can be obtained by SVD decomposition or linear fitting. The corresponding crack inclination angle is calculated by the third formula, where the third formula is:

[0114]

[0115] Among them, θ f is the crack inclination angle, n y and n x are the vertical and horizontal components of the crack direction vector, respectively.

[0116] For example, in one embodiment of the present invention, Figure 4 A schematic diagram of calculating the crack inclination angle provided by an embodiment of the present invention. Figure 4 As shown, (a) is the spatial distribution of crack inclination, and (b) is the crack inclination distribution diagram.

[0117] Further, in one embodiment of the present invention, the above-mentioned determination of the crack length corresponding to the overburden mining crack based on the crack skeleton diagram includes:

[0118] Step 1: determine the independent cracks in the crack skeleton diagram;

[0119] Step 2: Calculate the crack length of the independent crack through the connectivity relationship of the crack pixels in the independent crack;

[0120] Step 3, repeat the above steps until all independent cracks in the crack skeleton diagram are traversed to obtain the crack length of each independent crack;

[0121] Step 4: Based on the length of each independent crack, draw a crack length distribution map corresponding to the overburden mining cracks.

[0122] In one embodiment of the present invention, after determining the independent cracks in the crack skeleton graph, the crack length of the independent crack can be calculated by using the point-by-point accumulation method according to the connectivity of the crack pixels in the independent crack.

[0123] Specifically, in one embodiment of the present invention, Figure 5 A schematic diagram of calculating crack length provided by an embodiment of the present invention. Figure 5 As shown in Figure 1, (a) is the principle diagram for calculating the crack length. Starting from one end of an independent crack, the connection relationship of the crack pixels is checked. If the pixels are diagonally connected, the crack length is accumulated. pixels; if the pixel connection relationship is horizontal or vertical, the crack length is accumulated by 1 pixel.

[0124] In one embodiment of the present invention, the connection relationship of the pixels in the independent cracks is identified one by one in the crack skeleton graph, and the connection relationship is accumulated and summed according to the above rules to obtain the length of a crack.

[0125] And, in one embodiment of the present invention, after obtaining the crack length of each independent crack through the above steps, a crack length distribution diagram corresponding to the overburden mining crack can be drawn as follows: Figure 5 (b) as shown.

[0126] Further, in one embodiment of the present invention, the method for determining the fracture spacing corresponding to the overburden mining fracture based on the fracture skeleton diagram may include the following steps:

[0127] Step S1, determining a nearly horizontal fracture that meets a preset range of fracture inclination angles according to the fracture inclination angle of each independent fracture in the fracture skeleton diagram;

[0128] Step S2, determining a pixel point in a near horizontal crack, and calculating the distance between the pixel point and the adjacent horizontal crack below;

[0129] Step S3, repeat the above steps until all the nearly horizontal cracks in the crack skeleton graph are traversed to obtain the crack spacing of the nearly horizontal cracks;

[0130] Step S4, based on the crack length of each independent crack, draw a crack spacing distribution map corresponding to the overburden mining cracks.

[0131] In one embodiment of the present invention, the fracture spacing can be defined as the distance between two adjacent nearly horizontal parallel fractures, which can be used to evaluate the thickness of the rock formation. In one embodiment of the present invention, the nearly horizontal fractures that meet the preset range of fracture inclination can be determined according to the fracture inclination of each independent fracture in the fracture skeleton diagram, that is, the independent fractures that meet the preset range of fracture inclination are determined as nearly horizontal fractures, wherein the preset range of fracture inclination can be set by experiment or experience, for example, the preset range of fracture inclination is (0-, 30°) and (150, 180°).

[0132] And, in one embodiment of the present invention, after determining the near-horizontal crack through the above steps, the pixel point in the near-horizontal crack can be determined, and the spacing with the adjacent horizontal crack at the lower position can be calculated using the fourth formula at the pixel point, wherein the fourth formula is:

[0133]

[0134] Where d is the distance between the cracks, L is the length of the vertical line between the cracks, is the average of the inclination angles of the two fractures.

[0135] Specifically, in one embodiment of the present invention, the above Figure 6 A schematic diagram of calculating the crack spacing provided by an embodiment of the present invention. Figure 6 (a) is the principle diagram for calculating the crack spacing, as shown in Figure 6 As shown in (a), a pixel point A of a near-horizontal crack 1 is selected, and a near-horizontal crack 2 adjacent to the crack is searched downward from point A, the intersection point B of the vertical line and the near-horizontal crack 2 is located, the length L of the line segment AB is obtained, and the crack spacing d at this point is calculated using the fourth formula above.

[0136] And, in one embodiment of the present invention, after the crack length of each independent crack is obtained through the above steps, a crack spacing distribution map corresponding to the overburden mining cracks can be drawn according to the crack length of each independent crack, such as Figure 6 (b) as shown.

[0137] Further, in one embodiment of the present invention, the method for determining the connectivity of the fracture network corresponding to the overburden mining fracture based on the fracture skeleton diagram may include the following steps:

[0138] Step 10321, determining independent cracks in the crack skeleton graph, and determining corresponding nodes based on the independent cracks;

[0139] Step 10322, determining the node coordination number of the node according to a preset rule;

[0140] Step 10323, repeat the above steps until all nodes are traversed to obtain the node coordination number of each node;

[0141] Step 10324, based on the node coordination number of each node, draw a fracture network connectivity distribution map corresponding to the overburden mining fractures.

[0142] In one embodiment of the present invention, the connectivity of the fracture network is an important parameter for evaluating the permeability of the overburden rock, which can be evaluated by the node coordination number, wherein the node coordination number refers to the number of independent fractures connected to the node.

[0143] In one embodiment of the present invention, after determining the independent cracks in the crack skeleton diagram and determining the corresponding nodes based on the independent cracks, the nodes and independent cracks can be numbered respectively, and then the crack nodes can be analyzed point by point to count the number of independent cracks connected to the crack nodes.

[0144] For example, in one embodiment of the present invention, Figure 7 A schematic diagram of calculating the connectivity of a fracture network provided by an embodiment of the present invention. Figure 7 (a) is a schematic diagram for calculating the connectivity of the fracture network. Figure 7 As shown in (a), the node color corresponds to the node coordination number. And, in one embodiment of the present invention, the type of the crack can be determined according to the coordination numbers corresponding to the two endpoints of the crack. Specifically, in one embodiment of the present invention, if a crack has an endpoint with a coordination number of 1 and the other endpoint has a coordination number greater than 1, then the crack is a branch end crack of the crack network; if the coordination numbers of both endpoints of a crack are greater than 1, then the crack is a trunk crack of the crack network; if the coordination numbers of both endpoints of a crack are equal to 1, then the crack is a separate crack that is not connected to other cracks.

[0145] Further, in one embodiment of the present invention, after obtaining the node coordination number of each node through the above steps, a fracture network connectivity distribution map corresponding to the overburden mining fracture can be drawn based on the node coordination number of each node, such as Figure 7 (b) In one embodiment of the present invention, after drawing the fracture network connectivity distribution map, the main fractures with larger node coordination numbers in the fractures can be determined as the key channels for controlling fluid seepage through the fracture network connectivity distribution map.

[0146] Step 104, based on the crack quantitative characterization index, quantitatively characterize the overburden mining cracks.

[0147] In one embodiment of the present invention, after the fracture quantitative characterization index is obtained through the above steps, the overburden mining fractures can be quantitatively characterized based on the fracture quantitative characterization index.

[0148] Specifically, in one embodiment of the present invention, the method for quantitatively characterizing overburden mining cracks based on the crack quantitative characterization index may include the following steps:

[0149] Step 1041, obtaining a target scene for analyzing overburden mining cracks;

[0150] Step 1042 , quantitatively analyzing the target scene based on the index result corresponding to the crack quantitative characterization index, and outputting the quantitative analysis result.

[0151] Among them, in one embodiment of the present invention, all of the above-mentioned fracture quantitative characterization indicators have relatively clear physical meanings. By using a single indicator or combining multiple indicators, target scenarios involving overburden mining fracture characteristics in coal mining can be analyzed and guided.

[0152] For example, in one embodiment of the present invention, the fracture inclination angle can be applied to the quantitative classification of mining fractures; the integrity of the overburden fractured rock blocks is defined in combination with the fracture length and the fracture spacing, which can be used to identify key rock layers such as thick and hard rock layers that affect the overburden movement and fracture process; the fractal dimension of overburden mining fractures is used to quantitatively describe the complexity of the overburden mining fracture network at different spatial positions, which can be used to guide the quantitative division of the overburden "three horizontal zones" and "three vertical zones". Compared with the traditional qualitative description method of mining fractures based on similar model tests, the fracture quantitative characterization index can be more accurate and scientific, with better quantifiability, which is convenient for the standardized characterization of test results and provides strong support for solving mining engineering related problems.

[0153] In one embodiment of the present invention, the target scenario may include at least one of the following:

[0154] Overburden damage;

[0155] Permeability;

[0156] Overburden rock rotation state;

[0157] Thickness of overlying rock layers;

[0158] Integrity of overburden;

[0159] Overburden permeability;

[0160] Classification of overburden fractures;

[0161] Identification of key layers;

[0162] The “three horizontal zones” and “three vertical zones” division;

[0163] Identification of water inrush risk areas.

[0164] And, in one embodiment of the present invention, after acquiring the target scene, the target scene can be quantitatively analyzed based on the index result corresponding to the crack quantitative characterization index, and the quantitative analysis result can be output. In one embodiment of the present invention, different target scenes correspond to different crack quantitative characterization indexes.

[0165] Specifically, in one embodiment of the present invention, Table 1 is a correspondence table of a target scene and corresponding crack quantitative characterization indicators proposed in an embodiment of the present invention.

[0166] Table 1

[0167]

[0168] The quantitative characterization method for overburden mining fractures in an embodiment of the present invention determines the fracture quantitative characterization indicators corresponding to the overburden mining fractures in a similar model based on the fracture binary map and the fracture skeleton map corresponding to the overburden mining fracture image, and quantitatively characterizes the overburden mining fractures based on the fracture quantitative characterization indicators, thereby being able to comprehensively analyze and evaluate the overall situation of the mining fractures in the overburden, facilitating the standardized characterization of the test results, and providing strong support for solving problems related to mining engineering.

[0169] Figure 8 1 is a schematic structural diagram of a device 10 for quantitatively characterizing overburden mining fractures according to an embodiment of the present invention.

[0170] like Figure 8 As shown, the device may include:

[0171] An acquisition module 801 is used to acquire an image of overburden mining cracks at the time of excavation in a similar model;

[0172] Processing module 802, used to perform image processing on the overburden mining crack image to obtain the corresponding crack binary image and crack skeleton image;

[0173] A determination module 803 is used to determine the fracture quantitative characterization index corresponding to the overburden mining fracture in the similar model based on the fracture binary map and the fracture skeleton map;

[0174] The characterization module 804 is used to quantitatively characterize the mining-induced fractures in the overburden strata based on the fracture quantitative characterization index.

[0175] In one embodiment of the present disclosure, the processing module 802 is specifically configured to:

[0176] Based on the fracture binary map, the fractal dimension of the fracture network corresponding to the mining fractures in the overburden rock is determined;

[0177] Based on the fracture skeleton diagram, the fracture density, and / or fracture inclination, and / or fracture length, and / or fracture spacing, and / or fracture network connectivity corresponding to the overburden mining fractures are determined.

[0178] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0179] Determine the calculation order and the first box side length corresponding to the crack binary image;

[0180] Based on the side length of the first box, the number of first boxes covering the crack in the crack binary image is counted;

[0181] The side length of the first box is updated to obtain the side length of the second box, and based on the side length of the second box, the number of second boxes covering the crack in the crack binary image is counted;

[0182] Repeat the above steps until the calculation order is reached, perform linear fitting based on the side length of the first box, the number of the first boxes, the side length of the second box and the number of the second boxes, and determine the slope of the fitting line in the fitting result as the fractal dimension of the fracture network corresponding to the overburden mining fracture.

[0183] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0184] Determine the measurement window size corresponding to the crack skeleton image;

[0185] Determine the number of independent cracks in the measurement window, and determine the crack density at the central measurement pixel point corresponding to the measurement window based on the number of independent cracks;

[0186] Repeat the above steps until all measurement windows in the crack skeleton map are traversed to obtain the crack density at each central measurement pixel point;

[0187] Based on the crack density at each central pixel point, a crack density map corresponding to the mining cracks in the overburden is drawn.

[0188] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0189] Identify individual fractures in the fracture skeleton map;

[0190] Extract the coordinates of all pixels in independent cracks;

[0191] Decompose or linearly fit the coordinates of independent fractures and calculate the corresponding fracture inclination angles;

[0192] Repeat the above steps until all independent fractures in the fracture skeleton diagram are traversed to obtain the fracture inclination angle of each independent fracture;

[0193] Based on the fracture inclination of each independent fracture, a fracture inclination distribution map corresponding to the overburden mining fractures is drawn.

[0194] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0195] Identify individual fractures in the fracture skeleton map;

[0196] The crack length of the independent crack is calculated through the connectivity relationship of the crack pixels in the independent crack;

[0197] Repeat the above steps until all independent cracks in the crack skeleton graph are traversed to obtain the crack length of each independent crack;

[0198] Based on the length of each independent crack, a crack length distribution map corresponding to the overburden mining cracks is drawn.

[0199] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0200] According to the fracture inclination angle of each independent fracture in the fracture skeleton diagram, a nearly horizontal fracture that meets a preset fracture inclination angle range is determined;

[0201] Determine the pixel point in the near horizontal crack, and calculate the distance between the pixel point and the adjacent horizontal crack below;

[0202] Repeat the above steps until all nearly horizontal cracks in the crack skeleton diagram are traversed to obtain the crack spacing of nearly horizontal cracks;

[0203] Based on the length of each independent fracture, a fracture spacing distribution map corresponding to the overburden mining fractures is drawn.

[0204] In one embodiment of the present disclosure, the processing module 802 is further configured to:

[0205] Determine independent fractures in the fracture skeleton graph, and determine corresponding nodes based on the independent fractures;

[0206] According to the preset rules, determine the node coordination number of the node;

[0207] Repeat the above steps until all nodes are traversed to obtain the node coordination number of each node;

[0208] Based on the node coordination number of each node, the fracture network connectivity distribution map corresponding to the overburden mining fractures is drawn.

[0209] In one embodiment of the present disclosure, the characterization module 804 is further used to:

[0210] Obtain the target scenario where analysis of overburden mining cracks is required;

[0211] The target scene is quantitatively analyzed based on the indicator results corresponding to the crack quantitative characterization indicators, and the quantitative analysis results are output.

[0212] The device for quantitative characterization of overburden mining fractures in an embodiment of the present invention determines the fracture quantitative characterization indicators corresponding to the overburden mining fractures in a similar model based on the fracture binary map and the fracture skeleton map corresponding to the overburden mining fracture image, and quantitatively characterizes the overburden mining fractures based on the fracture quantitative characterization indicators, thereby being able to comprehensively analyze and evaluate the overall situation of the mining fractures in the overburden, facilitating the standardized characterization of the test results, and providing strong support for solving problems related to mining engineering.

[0213] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0214] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A method for quantitative characterization of mining-induced fractures in overburden strata, characterized in that: The method comprises: Obtain the mining crack images of overburden rocks at the time of excavation in similar models; Performing image processing on the overburden mining crack image to obtain a corresponding crack binary image and a crack skeleton image; Based on the fracture binary map and the fracture skeleton map, determining the fracture quantitative characterization index corresponding to the overburden mining fracture in the similarity model; Based on the crack quantitative characterization index, the mining-induced cracks in the overburden strata are quantitatively characterized.

2. The method according to claim 1, characterized in that The method of determining the fracture quantitative characterization index corresponding to the overburden mining fracture in the similarity model based on the fracture binary map and the fracture skeleton map includes: Based on the fracture binary map, determining the fracture network fractal dimension corresponding to the overburden mining fracture; Based on the fracture skeleton diagram, the fracture density, and / or fracture inclination, and / or fracture length, and / or fracture spacing, and / or fracture network connectivity corresponding to the overburden mining fractures are determined.

3. The method according to claim 2, characterized in that The determining, based on the fracture binary map, the fracture network fractal dimension corresponding to the overburden mining fractures comprises: Determine the calculation order and the first box side length corresponding to the crack binary image; Based on the side length of the first box, counting the number of first boxes covering the crack in the crack binary image; The side length of the first box is updated to obtain the side length of the second box, and based on the side length of the second box, the number of second boxes covering the crack in the crack binary image is counted; Repeat the above steps until the calculation order is reached, perform linear fitting based on the side length of the first box, the number of the first boxes, the side length of the second box and the number of the second boxes, and determine the slope of the fitting line in the fitting result as the fractal dimension of the fracture network corresponding to the overburden mining fracture.

4. The method according to claim 2, characterized in that: The determining, based on the fracture skeleton diagram, the fracture density corresponding to the overburden mining fractures comprises: Determine the measurement window size corresponding to the crack skeleton image; Determine the number of independent cracks in the measurement window, and determine the crack density at a central pixel point corresponding to the measurement window based on the number of independent cracks; Repeat the above steps until all measurement windows in the crack skeleton map are traversed to obtain the crack density at each central measurement pixel point; Based on the crack density at each central pixel point, a crack density map corresponding to the overburden mining cracks is drawn.

5. The method according to claim 2, characterized in that: The determining, based on the fracture skeleton diagram, the fracture inclination angle corresponding to the overburden mining fracture comprises: determining independent fractures in the fracture skeleton map; Extracting coordinates of all pixel points in the independent crack; Decomposing or linearly fitting the coordinates of the independent fractures to calculate the corresponding fracture inclination angles; Repeat the above steps until all independent fractures in the fracture skeleton diagram are traversed to obtain the fracture inclination angle of each independent fracture; Based on the fracture inclination angle of each independent fracture, a fracture inclination angle distribution map corresponding to the overburden mining fracture is drawn.

6. The method according to claim 2, characterized in that The determining, based on the fracture skeleton diagram, the fracture length corresponding to the overburden mining fracture comprises: determining independent fractures in the fracture skeleton map; Calculating the crack length of the independent crack according to the connectivity relationship of the crack pixels in the independent crack; Repeat the above steps until all independent cracks in the crack skeleton graph are traversed to obtain the crack length of each independent crack; Based on the crack length of each independent crack, a crack length distribution map corresponding to the overburden mining cracks is drawn.

7. The method according to claim 5, characterized in that Determining the fracture spacing corresponding to the overburden mining fractures based on the fracture skeleton diagram includes: Determine, according to the fracture inclination angle of each independent fracture in the fracture skeleton diagram, a nearly horizontal fracture that meets a preset range of fracture inclination angles; Determine a pixel point in the near-horizontal fissure, and calculate the distance between the pixel point and the adjacent horizontal fissure below; Repeat the above steps until all nearly horizontal cracks in the crack skeleton diagram are traversed to obtain the crack spacing of nearly horizontal cracks; Based on the crack length of each independent crack, a crack spacing distribution map corresponding to the overburden mining cracks is drawn.

8. The method according to claim 2, characterized in that: Determining the fracture network connectivity corresponding to the overburden mining fractures based on the fracture skeleton diagram includes: Determining independent cracks in the crack skeleton graph, and determining corresponding nodes based on the independent cracks; According to the preset rules, determine the node coordination number of the node; Repeat the above steps until all the nodes are traversed to obtain the node coordination number of each node; Based on the node coordination number of each node, a fracture network connectivity distribution map corresponding to the overburden mining fractures is drawn.

9. The method according to claim 1, characterized in that: The method of quantitatively characterizing the mining-induced cracks in the overburden strata based on the crack quantitative characterization index includes: Obtain the target scenario where analysis of overburden mining cracks is required; The target scene is quantitatively analyzed based on the indicator result corresponding to the crack quantitative characterization indicator, and the quantitative analysis result is output.

10. A device for quantitative characterization of overburden mining cracks, characterized in that: The device comprises: An acquisition module is used to acquire the overburden mining crack image at the excavation time step in a similar model; A processing module, used for performing image processing on the overburden mining crack image to obtain a corresponding crack binary image and a crack skeleton image; A determination module, used to determine the crack quantitative characterization index corresponding to the overburden mining crack in the similarity model based on the crack binary map and the crack skeleton map; The characterization module is used to quantitatively characterize the overburden mining cracks based on the crack quantitative characterization index.

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