A method for predicting the range of ground movement induced by underground metal mining

Abstract

The present invention designs a method for predicting the range of surface movement induced by underground metal mining. First, a three-dimensional geological model of the underground ore body and a three-dimensional refined calculation model are constructed; the safety level of surface structures is determined; the theoretical value of surface deformation is calculated using a probability integral method; then, the rock quality of each rock group is graded and evaluated using multiple rock quality evaluation methods such as RQD, RMR, and GSI; the rock mechanical parameters are determined using the Hock-Brown criterion; the ore body mining simulation is performed using the refined calculation model, and the effects of different safety pillar thicknesses, segment heights, and inter-panel pillar widths on rock layer and surface movement and damage induced by ore body mining are analyzed. The inclination, curvature, and horizontal deformation of each surface point are calculated and contour maps are drawn. The boundaries of the surface movement range are selected, the surface movement range is predicted, and the maximum movement range allowed by the safety level of surface structures is compared to confirm whether the mining method is reasonable. The method avoids casualties and property losses caused by surface movement and collapse.

Description

Technical Field

[0001] The present invention belongs to the technical field of mining, and in particular relates to a method for predicting the range of surface movement induced by underground metal mining. Background Art

[0002] With the development of society and the economy, and the growth of industrial demand, mining pressure is gradually increasing. Existing mining capacity can no longer meet the increased demand for mineral resources. Mine mining is gradually moving to deeper strata or complex geological conditions, making development more difficult and causing more serious damage to the ecological environment in mining areas. Ground pressure disasters caused by underground mining activities seriously endanger the safety of underground shafts and equipment. The collapse of goafs formed by ore production causes strata movement and ground subsidence, ultimately causing surface subsidence and deformation, the collapse of houses and buildings, and the destruction of farmland, even threatening human life and property safety.

[0003] Numerous scholars have conducted extensive research on coal mining subsidence, achieving fruitful results. Unlike coal mines, metal mines are generally formed by magma intrusion, metamorphism, and mineralization. Ore bodies often exhibit irregular morphology and are mostly located in mountainous areas with complex geological structures. The mechanical properties and deformation characteristics of the geological bodies are anisotropic. Iron ore mining, in particular, requires comprehensive consideration of ore body occurrence, ore grade, and mining costs. Caving is generally used for mining. Therefore, the rock movement and ground subsidence mechanisms caused by metal mining differ from those of coal mining. However, research on ground subsidence caused by metal mining is relatively limited compared to coal mining. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention designs a method for predicting the range of surface movement induced by underground metal mining; it can intuitively show the impact of each step of underground mining on surface stability, and provide a more scientific reference basis for mine safety production.

[0005] A method for predicting the range of ground movement induced by underground metal mining, comprising the following steps:

[0006] Step 1: Use drone scanning to determine the topography, landforms, vegetation, and distribution of various buildings in the mining area, and obtain 3D visualization data of the mining area; build a drillhole database; establish a 3D network 3D solid model and a 3D refined calculation model that includes the mining area surface, tunnels, faults, and ore bodies, and obtain the lithologic distribution of the underground mining area, the relationship between the ore body and the surrounding rock, and the distribution of faults in the mining area;

[0007] Step 1-1: Use drones to determine the topography, landforms, vegetation, and distribution of various buildings and structures in the mining area, obtain 3D visualization point cloud data of the mining area, and implement drone oblique photography modeling of the mining area;

[0008] Step 1-2: Based on the geological profile and drilling exploration data, organize the project number, drilling coordinates, maximum hole depth, trajectory type, depth, azimuth, inclination, RMR value, RQD value of each borehole, organize the positioning table, inclinometer table, RMR table and RQD table, select the "Drilling - New Database" function in the 3DMine software, import the above tables, and establish a drilling database;

[0009] Steps 1-3: Based on the current topographic map of the mining area, extract and assign three-dimensional values ​​to contour lines and elevation points. Use the constraint line creation function of 3DMine software to create a DTM and establish a three-dimensional surface model of the mining area. Based on the drilling data and exploration line profiles in the mining area exploration report, extract the boundary lines between different rock masses and determine the spatial posture and position of the rock masses. Based on the development system diagram, extract the boundary lines of the rail transport platform, return air shaft, inclined shaft and drainage well at different elevations, determine the spatial posture and position of the development system at different elevations, and complete the construction of the 3DMine three-dimensional solid model.

[0010] Steps 1-4: Create a cube model in Rhino based on the dimensions of the mining area. Cut it using the point cloud data obtained in step 1-1 to obtain an initial model with surface morphology. Based on the exploration lines, geological longitudinal sections, and geological cross sections in the mining area exploration report, extract the boundaries of faults, surrounding rock, interbedded rock, and ore groups, and determine their spatial posture and spatial position. In Rhino, connect the cross-sectional lines of a certain surrounding rock or interbedded rock, and use the "lofting" function to construct solid surfaces for cutting. Based on the basic principle of "from large to small, from outside to inside", use Boolean operations to cut the initial model in sequence, completing the construction of the Rhino 3D refined calculation model and 3D mesh model of the mining area.

[0011] Step 2: Exploring the mining area, collecting information on the location, height, and building type of surface buildings, and then determining the protection level of surface structures according to regulations;

[0012] Step 3: Calculate the surface deformation value using the probability integral method; determine whether the surface structures exceed the maximum inclination and horizontal deformation values ​​of the protection level of the area; and take appropriate mining measures to achieve the goal and requirements of safe mining of the ore body under the building;

[0013] Step 3-1: Cut the 3Dmine three-dimensional solid model created in step 1 into blocks with a side length of a; and export the block coordinates x, y, z and side length data; a is selected according to the size of the model;

[0014] Step 3-2: Determine the surface subsidence coefficient η and horizontal movement coefficient b based on actual measurement data of the mining area z , the main influencing angle tangent tanβ, the mining impact propagation angle θ and the inflection point offset s;

[0015] Step 3-3, calculate the inclination i, curvature k, and horizontal deformation U of each block using the following formula;

[0016]

[0017]

[0018]

[0019] Where W0 is the maximum surface subsidence value, W0 = mηcosα, m is the mining thickness of the ore body, η is the settlement coefficient, and α is the inclination angle of the ore layer; r z is the main impact radius;

[0020] Step 3-4, obtaining an isovalue curve diagram based on the inclination, curvature and horizontal deformation values ​​of each block obtained in step 3-3;

[0021] Step 4: Use a deep learning-based intelligent recognition system to perform RQD identification on the core photos obtained during exploration to obtain accurate RQD values ​​for rock mass quality indicators. Parameters for calculating rock engineering quality are obtained based on the borehole description, and the corresponding weights of various rock mass mechanical parameters are calculated using the rock quality parameters. Three rock mass quality evaluation methods, RQD, RMR, and GSI, are used to evaluate the rock quality of each rock group, obtaining comprehensive and accurate rock mass quality classification results.

[0022] Step 4-1: Determine the uniaxial compressive strength (UCS) of dry rock by comparing it with indoor uniaxial compressive tests and standard specifications;

[0023] Step 4-2: For boreholes with core data, use the deep learning-based intelligent core RQD identification system to import core photos, identify core lengths, obtain core RQD values, and assign corresponding weights. For boreholes without core data, based on the borehole description itself, appropriate weights are assigned according to the text description of the degree of fragmentation and structural surface conditions.

[0024] Step 4-3: Calculate the structural surface spacing J using the RQD value s , the relationship between the two is:

[0025]

[0026] Step 4-4: Reduce the structural surface conditions involved in the drilling description accordingly to determine the structural surface condition weights;

[0027] Steps 4-5: Determine groundwater conditions and weights based on the lithology and elevation of the aquifer locations in the hydrogeological report;

[0028] Step 4-6: rock mass parameters J of jointed rock mass v (Number of joints / m 3 ) Determine the geological strength index (GSI) of jointed rock mass;

[0029] Step 4-7: Determine the rock mass class corresponding to the RQD classification method based on the RQD value obtained in step 4-2; determine the rock mass class corresponding to the RMR classification method based on the values ​​obtained in steps 4-1 and 4-5; determine the rock mass class corresponding to the GSI classification method based on the value obtained in step 4-6;

[0030] Step 5: Determine various rock mass strength indices and mechanical parameters using the Hoek-Brown strength criterion based on the uniaxial compressive strength of the complete rock blocks, the Hoek-Brown constant of the complete rock blocks, and the geological strength index (GSI) of the rock mass.

[0031] Step 5-1: Obtain the uniaxial compressive strength σ of the complete rock blocks constituting the rock mass based on the results of the indoor uniaxial compressive test. ci ;

[0032] Step 5-2: Obtain the Hoek-Brown constant m of the complete rock blocks that make up the rock mass based on the rock mass type i ;

[0033] Step 5-3: Calculate the material constant m based on the geological strength index (GSI) of the rock mass, the evaluation of the rock mass structure, ore rock state, and the quality of the rock mass discontinuity during comprehensive exploration, and the disturbance parameter D considering the blasting effect and stress release. b , s, α, the calculation formula is as follows:

[0034]

[0035]

[0036]

[0037] Among them, m b is the Hoek-Brown constant of the rock mass; m i is the Hoek-Brown constant of the complete rock blocks that make up the rock mass; GSI is the geological strength index of the rock mass; D is the coefficient of the degree of disturbance of the rock mass caused by blasting or stress release;

[0038] Step 5-4: Calculate the uniaxial compressive strength σ of various rock masses according to the Hoek-Brown strength criterion c , tensile strength σ t , elastic modulus E m , friction angle φ, cohesion c:

[0039] σ c=σ ci s α

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] Step 6: Use the three-dimensional refined calculation model obtained in Step 1 to simulate ore body mining, analyze the effects of different safety pillar thicknesses, segment heights, and inter-panel pillar widths on rock and surface movement and damage caused by ore body mining, calculate the inclination, curvature, and horizontal deformation of each surface point, and draw contour maps. Select the boundaries of the surface movement range, thereby predicting the surface movement range and comparing it with the maximum movement range allowed by the safety level of surface structures to confirm whether the mining method is reasonable;

[0046] Step 6-1. Determine the working conditions based on the thickness of the safety pillars, the height of the sections, and the width of the pillars between the panels. Use "lofting" to construct the cutting solid surface of the section line. Based on the basic principle of "from large to small, from outside to inside", use Boolean operations to cut and mesh the 3D refined calculation model in sequence. Check and handle mesh errors, select the appropriate size to output the mesh file. Select the size based on the model size and the desired accuracy.

[0047] Step 6-2: Import the mesh file into Flac3D, group and rename the zones according to the divided surrounding rock, fault, and ore body, and assign the 3D refined calculation model to the Mohr-Coulomb model; assign values ​​to the rock mass mechanical parameters calculated in step 5 according to different zone groups; balance the initial in-situ stress of the Mohr-Coulomb model; reset the displacement and velocity of the Mohr-Coulomb model to zero; and perform excavation and backfilling solutions according to different working conditions;

[0048] Step 6-3: Use the finite difference method to simulate underground metal mine ore body mining; after the simulation is completed, the spatial position coordinates and displacements of the nodes in the x, y, and z directions of the surface of the different working condition models are output as a text file; the inclination, curvature, and horizontal deformation of each surface point are calculated using the method in step 3;

[0049] Step 6-4: Use the displacement contour creation tool to draw contour maps of the ground surface's tilt, curvature, and horizontal deformation to predict the range of ground movement.

[0050] Step 6-5: Compare the maximum movement range allowed by the safety level of the surface structures in step 2 to confirm whether the mining method is safe and reasonable.

[0051] Beneficial technical effects of the present invention:

[0052] (1) The present invention is used to predict the scope of ground movement induced by underground metal mining, and the deformation and damage state of the ground surface at different mining stages can be determined, providing a basis for safe production and avoiding casualties and property losses caused by ground movement and collapse;

[0053] (2) Based on the prediction results of the scope of surface movement induced by underground metal mining, the degree to which adjacent structures and facilities are affected by mining is determined, providing a basis for determining the scope and time of relocation, and providing a reference for the reasonable layout of planned ground facilities such as production, office and living facilities;

[0054] (3) The present invention establishes a 3Dmine three-dimensional geological database based on the drilling information from the field survey, and manages the engineering positioning data, inclinometric data, lithologic information, etc. of the drilling hole in the database, realizes the comprehensive query, combination, extraction and calculation of the data, and performs real-time data entry, modification and update. At the same time, it can query and display the drilling data in three dimensions, thereby obtaining the spatial variability mechanical parameters of the rock mass, which are then used as basic data for subsequent geological modeling work; the RQD intelligent recognition system independently developed by the team is used to analyze the drilling sampling photos to obtain more realistic classification results and rock mass mechanical parameters.

[0055] (4) The method of the present invention proposes a method for predicting the range of surface movement induced by mining underground metal mines using the simulated backfill mining method. The mine is equivalent to a rock mass model, the rock mass is classified and relevant parameters are calculated, and then Flac3D is used to analyze the surface movement law and predict the damage range, thereby realizing a three-dimensional numerical simulation prediction of the range of surface movement induced by mining underground metal mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a distribution map of underground mine ore bodies according to a specific embodiment of the present invention;

[0057] Figure 2 Schematic diagram of a large-diameter deep hole subsequent filling method according to a specific embodiment of the present invention, wherein 1 is a middle section roadway along the vein; 2 is a segmented footwall along the vein trunk line; 3 is a segmented hanging wall along the vein trunk line; 4 is a panel area connecting road; 5 is a ore-exiting through the vein; 6 is a trench roadway; 7 is a ore-exiting access road; 8 is a ore-exiting through the vein; 9 is a stope chute; 10 is a top-cut roadway; 11 is a cutting shaft; 12 is a top-cut connecting roadway; 13 is a top-cutting along the vein roadway;

[0058] Figure 3 It is a 3Dmine three-dimensional geological model according to a specific embodiment of the present invention;

[0059] Figure 4 3D refined computational model of a specific embodiment of the present invention, (a) is a front view, (b) is a right side view, (c) is a top view, and (d) is a 3D diagram;

[0060] Figure 5 1 is a surface deformation parameter map of a Zhonggan ditch based on the probability integral method according to a specific embodiment of the present invention, wherein (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0061] Figure 6 is a numerical model grid model of a specific embodiment of the present invention;

[0062] Figure 7 1 is the surface deformation result of Scheme 1 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0063] Figure 8 1 is the surface deformation result of Scheme 2 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0064] Figure 9 1 is the surface deformation result of Scheme 3 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0065] Figure 10 1 is the surface deformation result of Scheme 4 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0066] Figure 11 1 is the surface deformation result of Scheme 5 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0067] Figure 12 1 is the surface deformation result of Scheme 6 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0068] Figure 13 1 is the surface deformation result of Scheme 7 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0069] Figure 14 1 is the surface deformation result of Scheme 8 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0070] Figure 15 1 is the surface deformation result of Scheme 9 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0071] Figure 16 10 is the surface deformation result of the scheme 10 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0072] Figure 17 1 is the surface deformation result of Scheme 11 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0073] Figure 18 12 is the surface deformation result of Scheme 12 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0074] Figure 19 13 is the surface deformation result of the scheme 13 of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0075] Figure 20 14 is the surface deformation result of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0076] Figure 21 15 is the surface deformation result of the embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0077] Figure 22 16 is the surface deformation result of the specific embodiment of the present invention, (a) is the tilt contour line, (b) is the curvature contour line, and (c) is the surface deformation contour line;

[0078] Figure 23 This is a flow chart of a method for predicting the range of ground movement induced by underground metal mining according to a specific embodiment of the present invention;

[0079] Figure 24 It is a flow chart of three-dimensional modeling of an underground metal mining area according to a specific embodiment of the present invention;

[0080] Figure 25 This is a flow chart of the probability integral method for calculating the theoretical value of surface deformation according to a specific embodiment of the present invention;

[0081] Figure 26 is a flow chart of rock mass quality evaluation according to a specific embodiment of the present invention;

[0082] Figure 27 is a flow chart for determining rock mass mechanical parameters according to a specific embodiment of the present invention;

[0083] Figure 28 It is a flow chart of ore body mining simulation according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0084] The present invention is described in detail below with reference to the accompanying drawings and examples.

[0085] Taking the underground mining of Zhonggangou vanadium-titanium magnetite as an example, the method for predicting the range of surface movement induced by underground metal mining is explained in detail.

[0086] The geological background of this underground mine: The ore-bearing basic-ultramafic rock mass in the Zhonggangou vanadium-titanium magnetite ore deposit is a basin with an uneven floor. Later faults and syenite dissected the rocks into three rock bodies: the southwest (W), northeast (N), and east (E). The main ore body (the southwest ore body) occurs at elevations between 350 and 1,280 meters and is buried at depths of 150 to 1,100 meters. The southwest ore body is mostly multi-layered, with dips between 40° and 47°, single-layer thicknesses ranging from 23 to 118 meters, and interbedded rock thicknesses of 8 to 22 meters. The eastern ore body is single-layered, with dips between 68° and 74° and thicknesses ranging from 13 to 73 meters. The ore types are primarily pyroxenite, with olivine pyroxenite to a lesser extent, and gabbro to a lesser extent. The rock quality is Grade III, indicating medium rock quality and medium rock integrity. Most of the rocks on the roof of the ore-bearing rock mass are from the Tertiary Xigeda Formation, which has poor diagenesis, low hardness and low mechanical strength. The ore structure is mainly inclusive structure, mosaic structure and sponge iron structure; the structure is mainly medium impregnation structure, followed by sparse impregnation structure and dense impregnation structure, with a small amount of banded structure, dense block structure, flow structure and mottled structure, as shown in the attached figure. Figure 1 The hydrogeological conditions of the ore deposit are of medium complexity, the engineering geological conditions of the mining area are medium, the geological environment conditions of the mining area are poor, and the development and utilization conditions of the mining area belong to the complex mining technical conditions type (Ⅲ3) with environmental geological problems as the main problem.

[0087] Mining background of this underground mine: The mining method is large diameter deep hole open field followed by filling method, as shown in the attached Figure 2 As shown. The designed middle section height is 200m, with a subsection height of 45m. The first phase will mine the ore body above the 880m elevation, the second phase will mine the ore body between the 480m and 880m elevations, and the third phase will mine the ore body below the 480m elevation. The southwest ore group is divided into four middle sections: 1080m, 880m, 680m, the 480m middle section, and below 480m; the eastern ore body is divided into three middle sections: 1280m, 1080m, and the 880m middle section.

[0088] There are 16 plans divided according to the mining method, see Table 1.

[0089] Table 1 Specific conditions of various schemes

[0090] plan Working conditions 1 The height of the inter-plate pillar is 15m, the height of the segment is 45m, and the thickness of the safety pillar is 45m 2 The height of the inter-plate pillar is 15m, the height of the segment is 45m, and the thickness of the safety pillar is 60m. 3 The height of the inter-plate pillar is 15m, the height of the segment is 45m, and the thickness of the safety pillar is 75m. 4 The height of the inter-plate pillar is 15m, the height of the segment is 60m, and the thickness of the safety pillar is 45m. 5 The height of the inter-plate pillar is 15m, the height of the segment is 60m, and the thickness of the safety pillar is 60m. 6 The height of the inter-plate pillar is 15m, the height of the segment is 60m, and the thickness of the safety pillar is 75m. 7 The height of the inter-plate pillar is 18m, the height of the segment is 45m, and the thickness of the safety pillar is 45m. 8 The height of the inter-plate pillar is 18m, the height of the segment is 45m, and the thickness of the safety pillar is 60m. 9 The height of the inter-plate pillar is 18m, the height of the segment is 45m, and the thickness of the safety pillar is 75m. 10 The height of the inter-plate pillar is 18m, the height of the segment is 60m, and the thickness of the safety pillar is 45m. 11 The height of the inter-plate pillar is 18m, the height of the segment is 60m, and the thickness of the safety pillar is 60m. 12 The height of the inter-plate pillar is 18m, the height of the segment is 60m, and the thickness of the safety pillar is 75m. 13 The interval pillar is 25m, the segment height is 60m, and the thickness of the safety pillar is 40m 14 The interval pillar is 25m, the segment height is 60m, and the thickness of the safety pillar is 45m 15 The interval pillar is 30m, the segment height is 60m, and the thickness of the safety pillar is 40m 16 The interval pillar is 30m, the segment height is 60m, and the thickness of the safety pillar is 45m

[0091] Underground metal mining can induce surface subsidence and land collapse in mined-out areas, destroying vast tracts of forestland, farmland, and other land resources, as well as important transportation routes and residential buildings, and seriously threatening the safety of life and property near mining areas. Simulating the mechanical behavior of surface collapse during ore mining, from its inception to its active phase and finally to its decay phase, and accurately predicting its onset in both time and space, are challenging prediction techniques.

[0092] A method for predicting the extent of ground movement induced by underground metal mining, such as Figure 23 As shown, the specific steps include:

[0093] Step 1: Use drone scanning to determine the topography, landforms, vegetation, and distribution of various structures in the mining area, and obtain real-life 3D visualization data of the mining area; build a drilling database; establish a 3D Mine 3D solid model and a 3D refined calculation model that includes the mining area surface, tunnels, faults, and ore bodies, and obtain the lithologic distribution of underground mining areas, the relationship between ore bodies and surrounding rocks, and the distribution of faults in the mining area; Figure 24 As shown;

[0094] Step 1-1: Use a Matrice 300RTK aircraft equipped with a PSDK 102S oblique camera to conduct drone oblique photogrammetry to collect surface structure parameter data, realistically reflecting the appearance, location, height, and other attributes of the features. Combined with the PC application software, DJI Map, surface modeling of the Zhonggangou vanadium-titanium magnetite mine was achieved.

[0095] Step 1-2: Based on the geological profile and drilling exploration data, organize the project number, drilling coordinates, maximum hole depth, trajectory type, depth, azimuth, inclination, RMR value, RQD value of each borehole, organize the positioning table, inclinometer table, RMR table and RQD table, select the "Drilling - New Database" function in the 3DMine software, import the above tables, and establish a drilling database;

[0096] Steps 1-3: Based on the current topographic map of the mining area, extract and assign three-dimensional values ​​to the contour lines and elevation points, use the constraint line creation DTM function of 3DMine software to establish a three-dimensional surface model of the mining area; based on the drilling data and exploration line profile of the mining area exploration report, extract the boundary lines between different rock masses and determine the spatial posture and position of the rock masses; based on the development system diagram, extract the boundary lines of the rail transport track, return air shaft, inclined shaft and drainage well at different elevations, determine the spatial posture and position of the development system at different elevations, and complete the construction of the 3DMine three-dimensional solid model, as shown in the attached figure. Figure 3 As shown;

[0097] Steps 1-4: Create a cube model in Rhino based on the size of the mining area, and cut it according to the point cloud data obtained in step 1-1 to obtain an initial model with surface morphology; extract the boundary lines of faults, surrounding rocks, interbedded rocks, and ore groups based on the exploration lines, geological longitudinal sections, and geological cross sections in the mining area exploration report, and determine their spatial posture and spatial position; in Rhino software, connect the cross-section lines of a certain surrounding rock or interbedded rock, and use the "lofting" function to construct a solid surface for cutting; according to the basic principle of "from large to small, from outside to inside", use Boolean operations to cut the initial model in sequence to complete the Rhino 3D refined calculation model of the mining area (see attached). Figure 4 Construction of the shown and three-dimensional mesh model;

[0098] Step 2: Exploring the mining area, collecting information on the location, height, and building type of surface buildings (structures), and then determining the surface building protection level based on the "Classification of Building Protection Levels in Mining Areas," "Classification of Roads in Mining Areas," and "Relationship between Building Damage and Surface Deformation" standards.

[0099] According to mining theory, surface deformation caused by underground mining does not exceed the permissible deformation of surface structures, and in principle, these structures will not be damaged. Based on the actual situation at the Zhonggangou vanadium-titanium magnetite mine, this study analyzed the impact of underground mining operations on surface safety. Based on the surface deformation values, the authors discussed whether the disturbance damage to various structures was within the allowable range specified in the corresponding regulations, thereby determining the rationality of the mining operations.

[0100] Step 3: Calculate the surface deformation value using the probability integral method; Figure 25 As shown, it is determined whether the surface structure exceeds the maximum inclination and horizontal deformation value of the protection level of the area; so that corresponding mining measures can be taken to achieve the goal and requirements of safe mining of the ore body under the building;

[0101] Step 3-1: Cut the 3Dmine 3D solid model created in step 1 into blocks with a side length of 10; and export the block coordinates x, y, z and side length data;

[0102] Step 3-2: Determine the surface subsidence coefficient η and horizontal movement coefficient b based on actual measurement data of the mining area z , the main influencing angle tangent tanβ, the mining impact propagation angle θ and the inflection point offset s;

[0103] Step 3-3, calculate the inclination i, curvature k, and horizontal deformation U of each block using the following formula;

[0104]

[0105]

[0106]

[0107] Where W0 is the maximum surface subsidence value, W0 = mηcosα, m is the mining thickness of the ore body, η is the settlement coefficient, and α is the inclination angle of the ore layer; r z is the main impact radius;

[0108] Step 3-4: Use Matlab to program and calculate, and get the isovalue curve graph; Figure 5 , (a) is the contour map of surface tilt, (b) is the contour map of surface curvature, and (c) is the contour map of surface horizontal deformation.

[0109] Step 4: Evaluate the engineering rock mass quality of various types of rock mass. This step is the premise and basis for reducing and determining all engineering rock mass mechanical parameters, that is, through some simple and easy-to-measure indicators of the rock mass, link the engineering geological conditions and rock mass mechanical properties and parameters, and draw lessons from the successes and failures of existing engineering design, construction and treatment to classify the rock mass. Through classification, the quality of various types of engineering rock mass can be summarized, and possible rock mass mechanical problems can be predicted, providing parameters and basis for engineering design, support lining, and construction method selection. The present invention uses a variety of rock mass quality evaluation methods such as RQD, RMR, GSI, etc. to evaluate the rock mass quality of each rock group. Figure 26 The specific steps are as follows:

[0110] Step 4-1: Determine the uniaxial compressive strength (UCS) of dry rock by comparing it with indoor uniaxial compressive tests and standard specifications;

[0111] Step 4-2: The RQD value reflects the degree to which the rock mass is cut by various structural planes. Because the indicator is clearly defined, can be obtained incidentally during the drilling process, and is a quantitative indicator, it is highly useful for overall mine design and the design of roadway support systems. For boreholes with core data, the core RQD data is obtained using a deep learning-based intelligent core RQD identification system. For boreholes without core data, the core description itself is used to assign appropriate weights based on the textual description of the degree of fragmentation and structural plane conditions.

[0112] Step 4-3: Calculate J by RQD s (Spatial spacing), the calculation formula is:

[0113]

[0114] Step 4-4: Reduce the structural surface conditions such as weathering, faulting, continuity, opening, and smoothness in the borehole description accordingly, taking the structural surface conditions and weathering degree into consideration to determine the structural surface conditions;

[0115] Steps 4-5: Determine groundwater conditions and weights based on the lithology and elevation of the aquifer locations in the hydrogeological report;

[0116] Step 4-6: rock mass parameters J of jointed rock mass v (Number of joints / m 3 ) Determine the geological strength index (GSI) of jointed rock mass.

[0117] Step 4-7: According to steps 4-1 to 4-6, the classification results of the three classification methods are obtained, as shown in Table 2.

[0118] Table 2 Rock mass quality classification results;

[0119]

[0120]

[0121] Step 5: Use the Hoek-Brown criterion to determine the rock mass mechanical parameters, such as Figure 27 The specific steps are as follows:

[0122] Step 5-1: Obtain the uniaxial compressive strength σ of the complete rock blocks constituting the rock mass through indoor tests ci ;

[0123] Step 5-2: Obtain the Hoek-Brown constant m of the complete rock blocks that make up the rock mass based on the rock mass type i , see Table 3;

[0124] Table 3. Rock mass Hoek-Brown constants;

[0125] Lithology <![CDATA[Hoek-Brown constant m i > Lithology <![CDATA[Hoek-Brown constant m i > pyroxenite 25 Gabbro 25 Xigeda Formation mudstone 4 Syenite 25 Pyroxene syenite mixed rock 25 Iron-bearing peridotite 17 Xigeda Formation sandstone 17 diabase 17 pyroxene ore 25 metamorphic sandstone 17 Gabbro 25 Dolomitic marble 7 olivine 25

[0126] Step 5-3: Calculate the material constant m based on the geological strength index GSI of the rock mass, the rock mass structure, the ore rock state, the quality of the rock mass discontinuity surface, and the disturbance parameter D considering the blasting effect and stress release. b , s, α, the calculation formula is as follows:

[0127]

[0128]

[0129]

[0130] Step 5-4: Calculate the uniaxial compressive strength σ of the rock mass c , tensile strength σ t , elastic modulus E m , friction angle φ, cohesion c, the calculation formula is as follows:

[0131] σ c =σ ci s α

[0132]

[0133]

[0134]

[0135]

[0136]

[0137] The calculation results are shown in Table 4.

[0138] Table 4 Calculation results of rock mass mechanical parameters;

[0139] rock type Tensile strength (MPa) Elastic modulus (GPa) Friction angle (°) Cohesion (MPa) pyroxenite 0.81 12.28 43.07 2.85 Xigeda Formation mudstone 0.02 0.11 13.56 0.02 Pyroxene syenite mixed rock 0.71 25.46 53.14 2.90 Xigeda Formation sandstone 0.10 0.40 23.25 0.20 pyroxene ore 1.20 12.38 43.86 3.90 Gabbro 0.68 6.52 46.03 1.06 olivine 0.86 11.47 37.35 3.42 Gabbro 0.46 5.88 42.75 1.66 Syenite 0.45 7.59 42.21 2.13 Iron-bearing peridotite 0.79 15.47 44.84 2.16 diabase 0.74 21.72 47.17 2.46 metamorphic sandstone 0.89 14.51 45.10 2.61 Dolomitic marble 1.12 33.13 42.52 3.26

[0140] Step 6: Use the three-dimensional refined calculation model obtained in step 1 to simulate ore mining, analyze the effects of different safety pillar thicknesses, segment heights, and inter-panel pillar widths on rock and surface movement and damage caused by ore mining, calculate the inclination, curvature, and horizontal deformation of each surface point, and draw contour maps. Select the boundaries of the surface movement range, thereby predicting the surface movement range and comparing it with the maximum movement range allowed by the safety level of surface structures to confirm whether the mining method is reasonable; Figure 28 As shown;

[0141] Step 6-1. Use lofting in the Rhino 3D model, cut from large to small and from outside to inside, merge non-popular, use NURBS for preliminary mesh division and mesh error check, use the griddle plug-in to display mesh self-intersection, duplicate faces, exposed edges and other errors, process mesh errors until there are no mesh errors, select the appropriate size for mesh output, as shown in the attached figure. Figure 6 shown.

[0142] Step 6-2: Import the mesh file f3grid output in step 1 into the finite element calculation software flac3D. Rename the corresponding zone groups in the flac3D model based on the already divided solid blocks, such as the surrounding rock, fault, and ore body. Fix the bottom, front, back, and left and right sides of the calculation model, and assign the constitutive model of the entire calculation model to the Mohr-Coulomb model. Utilize the various parameters of the surrounding rock and ore body obtained from the above calculations and assign values ​​according to the different zone groups. Calculate until the unbalanced force reaches 1e-5, and the initial in-situ stress equilibrium of the model is considered complete. Reset the displacement and velocity of the model, and perform excavation and backfilling according to different working conditions. Solve the same model, and when the unbalanced force reaches 1e-5, the excavation or backfilling is considered complete.

[0143] Step 6-3: Based on the results of the rock mass mechanics parameter calculations and the refined three-dimensional computational model, the finite difference method is used to simulate underground metal mine mining. After the simulation is completed, the spatial position coordinates and displacements of the nodes on the surface of the different working conditions are output to a text file using the developed FISH language. The inclination, curvature, and horizontal deformation of each surface point are calculated using the method in Step 3.

[0144] Step 6-4: Use the displacement contour creation tool to draw contour maps of the surface's tilt, curvature, and horizontal deformation;

[0145] Step 6-5: Compare the maximum movement range allowed by the safety level of the surface structures in step 2 to confirm whether the mining method is safe and reasonable.

[0146] Using the above-mentioned three-dimensional refined calculation model and rock mass parameters, a numerical simulation of large-diameter deep-hole open-field and subsequent filling mining of Zhonggangou vanadium-titanium magnetite was carried out according to the mining steps, and the surface movement and damage conditions during the mining process were obtained. Figure 7-Figure 22 The surface deformation results after mining are completed according to Schemes 1 to 16 respectively.

[0147] Increasing the size of the intermediate pillars has a better effect on controlling surface deformation, and their control effect on surface deformation is stronger than that of the safety pillar thickness. When the safety pillar thickness is 45m and the segment height is 60m, when the intermediate pillar size is increased to 25m, deformation in small areas of the Hongfa and Boda tailings ponds exceeds the regulatory requirements, and the plastic zone has not yet developed to the surface, indicating relatively good surrounding rock stability. When the inter-panel pillar width is increased to 30m, the deformation of surface structures meets the regulatory requirements. Furthermore, it is feasible to reduce the safety pillar thickness to 40m.

[0148] Similarly, increasing the thickness of the safety pillars also offers the feasibility of reducing the size of the inter-pillars. When the safety pillar thickness was increased to 75m, the segment height reached 45m, and the inter-pillar width reached 18m, deformation in small areas of the Hongfa and Boda tailings ponds exceeded regulatory requirements, and the plastic zone of the surrounding rock was also relatively small. However, the safety pillars and inter-pillars between the panels require enhanced monitoring and management.

[0149] Considering surface deformation and surrounding rock stability, the thickness of the safety pillars should be set at least 45m, and the inter-panel pillars should be set at least 20m during the later design phase. From an economic and safety perspective, the recommended solution is: a safety pillar thickness of 45m, inter-panel pillars of 30m, and a segment height of 60m.

Claims

1. A method for predicting the range of ground movement induced by underground metal mining, characterized in that: The specific steps include: Step 1: Use drone scanning to determine the topography, landforms, vegetation, and distribution of various buildings in the mining area, and obtain 3D visualization data of the mining area. Build a drillhole database. Develop a 3D Mine 3D solid model and a 3D refined calculation model that includes the mining area's surface, tunnels, faults, and ore bodies. This will determine the lithologic distribution of the underground mining area, the relationship between the ore body and surrounding rock, and the distribution of faults in the mining area. Step 2: Exploring the mining area, collecting information on the location, height, and building type of surface buildings, and then determining the protection level of surface structures according to regulations; Step 3: Calculate the surface deformation value using the probability integral method; determine whether the surface structures exceed the maximum inclination and horizontal deformation values ​​of the mining area protection level; and take appropriate mining measures; Step 4: Use a deep learning-based intelligent recognition system to perform RQD recognition on the core photos obtained during exploration to obtain accurate RQD values ​​for rock mass quality indicators. Parameters for calculating rock engineering quality are obtained based on the borehole description, and the corresponding weights of various rock mass mechanical parameters are calculated using the rock quality parameters. The rock mass quality evaluation methods of RQD, RMR and GSI were used to evaluate the rock mass quality of each rock group and obtain the rock mass quality classification results; Step 4-1: Determine the uniaxial compressive strength (UCS) of dry rock by comparing it with indoor uniaxial compressive tests and standard specifications; Step 4-2: For boreholes with core data, use the deep learning-based intelligent core RQD identification system to import core photos, identify core lengths, obtain core RQD values, and assign corresponding weights. For boreholes without core data, based on the borehole description itself, appropriate weights are assigned according to the text description of the degree of fragmentation and structural surface conditions. Step 4-3: Calculate the structural surface spacing using the RQD value , the relationship between the two is: ； Step 4-4: Reduce the structural surface conditions involved in the drilling description accordingly to determine the structural surface condition weights; Steps 4-5: Determine groundwater conditions and weights based on the lithology and elevation of the aquifer locations in the hydrogeological report; Step 4-6: rock mass parameters of jointed rock mass (Number of joints / m 3 ) Determine the geological strength index (GSI) of jointed rock mass; Step 4-7: Determine the rock mass class corresponding to the RQD classification method based on the RQD value obtained in step 4-2; determine the rock mass class corresponding to the RMR classification method based on the values ​​obtained in steps 4-1 and 4-5; determine the rock mass class corresponding to the GSI classification method based on the value obtained in step 4-6; Step 5: Determine various rock mass strength indices and mechanical parameters using the Hoek-Brown strength criterion based on the uniaxial compressive strength of the complete rock blocks, the Hoek-Brown constant of the complete rock blocks, and the geological strength index (GSI) of the rock mass. Step 6. Use the three-dimensional refined calculation model obtained in step 1 to simulate ore mining, analyze the effects of different safety pillar thicknesses, segment heights, and inter-panel pillar widths on rock and surface movement and damage caused by ore mining, calculate the inclination, curvature, and horizontal deformation of each surface point and draw contour maps, select the boundaries of the surface movement range, and thus predict the surface movement range and compare it with the maximum movement range allowed by the safety level of surface structures to confirm whether the mining method is reasonable.

2. The method for predicting the range of ground movement induced by underground metal mining according to claim 1, characterized in that: Step 1 is as follows: Step 1-1: Use drones to determine the topography, landforms, vegetation, and distribution of various buildings and structures in the mining area, obtain 3D visualization point cloud data of the mining area, and implement drone oblique photography modeling of the mining area; Step 1-2: Based on the geological profile and drilling exploration data, organize the project number, drilling coordinates, maximum hole depth, trajectory type, depth, azimuth, inclination, RMR value, RQD value of each borehole, organize the positioning table, inclinometer table, RMR table, and RQD table. Select the "Drilling - New Database" function in the 3DMine software, import the organized drillhole data, and establish a drillhole database. Steps 1-3: Based on the current topographic map of the mining area, extract and assign three-dimensional values ​​to contour lines and elevation points. Use the constraint line creation function of 3DMine software to create a DTM and establish a three-dimensional surface model of the mining area. Based on the drilling data and exploration line profiles in the mining area exploration report, extract the boundary lines between different rock masses and determine the spatial posture and position of the rock masses. Based on the development system diagram, extract the boundary lines of the rail transport platform, return air shaft, inclined shaft and drainage well at different elevations, determine the spatial posture and position of the development system at different elevations, and complete the construction of the 3DMine three-dimensional solid model. Steps 1-4: Create a cube model in Rhino based on the mining area dimensions and cut it using the point cloud data obtained in step 1-1 to obtain an initial model with surface morphology. Based on the exploration lines, geological longitudinal sections, and geological cross sections in the mining area exploration report, extract the boundaries of faults, surrounding rock, interbedded rock, and ore groups to determine their spatial posture and position. In Rhino, connect the cross-sectional lines of a certain surrounding rock or interbedded rock and use the "lofting" function to construct a solid surface for cutting. Based on the basic principle of "from large to small, from outside to inside," use Boolean operations to cut the initial model in sequence to complete the construction of the Rhino 3D refined calculation model and 3D mesh model of the mining area.

3. The method for predicting the range of ground movement induced by underground metal mining according to claim 1, characterized in that: Step 3 is as follows: Step 3-1: Cut the 3Dmine three-dimensional solid model created in step 1 into blocks with a side length of a; and export the block coordinates x, y, z and side length data; a is selected according to the size of the model; Step 3-2: Determine the surface subsidence coefficient based on actual measurement data of the mining area , horizontal shift coefficient , the main influence angle tangent , mining impact propagation angle and inflection point offset ; Step 3-3. Calculate the inclination of each block , curvature , horizontal deformation , the formula is as follows; ； ； ； Where W0 is the maximum surface subsidence value, W0=mηcosα, m is the mining thickness of the ore body, η is the settlement coefficient, and α is the inclination angle of the ore layer; r z is the main impact radius; Step 3-4: Obtain an isovalue curve diagram based on the inclination, curvature and horizontal deformation values ​​of each block obtained in step 3-3.

4. The method for predicting the range of ground movement induced by underground metal mining according to claim 1, characterized in that: Step 5 is as follows: Step 5-1: Obtain the uniaxial compressive strength of the complete rock blocks that make up the rock mass based on the results of the indoor uniaxial compressive test ; Step 5-2: Obtain the Hoek-Brown constant of the complete rock blocks that make up the rock mass based on the rock mass type ; Step 5-3: Calculate the material constant based on the geological strength index (GSI) of the rock mass, the evaluation of the rock mass structure, ore rock state, and the quality of the rock mass discontinuity during comprehensive exploration, and the disturbance parameter D considering the blasting effect and stress release. 、 、 , the calculation formula is as follows: ； ； ； Among them, m b is the Hoek-Brown constant of the rock mass; m i is the Hoek-Brown constant of the complete rock blocks that make up the rock mass; GSI is the geological strength index of the rock mass; D is the coefficient of the degree of disturbance of the rock mass caused by blasting or stress release; Step 5-4: Calculate the uniaxial compressive strength of various rock masses according to the Hoek-Brown strength criterion ,tensile strength , elastic modulus , friction angle , cohesion : ； ； ， ； ， ； ； 。 5. The method for predicting the range of ground movement induced by underground metal mining according to claim 1, characterized in that: Step 6 is as follows: Step 6-1. Determine the working conditions based on the thickness, segment height, and width of the pillars between different panels. Use "Lofting" to construct the cutting solid surface of the cross-section line. Based on the basic principle of "from large to small, from outside to inside", use Boolean operations to cut and mesh the 3D refined calculation model in sequence. Check and handle mesh errors, and select the size to output the mesh file. Step 6-2: Import the mesh file into Flac3D, group and rename the zones according to the divided surrounding rock, fault, and ore body, and assign the 3D refined calculation model to the Mohr-Coulomb model; assign values ​​to the rock mass mechanical parameters calculated in step 5 according to different zone groups; and balance the initial in-situ stress of the Mohr-Coulomb model; Reset the displacement and velocity of the Mohr-Coulomb model to zero; perform excavation and backfilling solutions according to different working conditions; Step 6-3: Use the finite difference method to simulate underground metal mine ore body mining; after the simulation is completed, the spatial position coordinates and displacements of the nodes in the x, y, and z directions of the surface of the different working condition models are output as a text file; the inclination, curvature, and horizontal deformation of each surface point are calculated using the method in step 3; Step 6-4: Use the displacement contour creation tool to draw contour maps of the ground surface's tilt, curvature, and horizontal deformation to predict the range of ground movement. Step 6-5: Compare the maximum movement range allowed by the safety level of the surface structures in step 2 to confirm whether the mining method is safe and reasonable.

6. A method for predicting the range of ground movement induced by underground metal mining according to claim 5, characterized in that: Step 6 selects the size based on the model size and the accuracy you want to achieve.

Images