A method for accurate grouting of gangue filling slurry in layers and stages

Abstract

The present invention discloses a method for accurate grouting of gangue filling slurry in layers and stages for mining, and belongs to the technical field of grouting and filling in mining areas. First, a field survey is carried out to monitor the distribution of voids in the overburden after coal seam mining in multiple different areas of the mining area, and the void distribution characteristics of the delamination area, collapse zone, and fracture zone of the typical mining area are obtained. A layered grouting method of filling slurry with different particle size ranges is adopted for different blocks, and then a discrete element numerical simulation method is used to obtain the spatiotemporal evolution characteristics of the porosity of the mining overburden for a staged grouting method, and finally the grouting amount is accurately controlled according to the flow and diffusion characteristics of the gangue slurry. By dividing the overburden strata after mining into blocks, slurries with different particle size gradations are preferably selected for filling according to the void characteristics of different layers, and the grouting layer, timing, and grouting amount are accurately grasped according to the spatiotemporal evolution characteristics of the overburden voids, the grouting efficiency can be effectively improved, and the filling and surface deformation control effects can be ensured.

Description

Technical Field

[0001] The invention relates to a method for accurate grouting of gangue filling slurry in layers and stages for mining, belonging to the technical field of grouting filling in mining areas. Background Art

[0002] The mining of coal resources is often accompanied by the output of solid waste products such as coal gangue, which brings many problems to society and the environment. After coal is mined, the overlying rock strata move and break, resulting in surface deformation and damage to buildings. Gangue disposal and surface deformation control have increasingly become difficult problems that need to be solved in the protection of the ecological environment in mining areas. Gangue grouting filling technology can achieve the dual goals of gangue disposal and surface deformation control by making gangue into slurry and injecting it into the well. At present, gangue grouting filling technology usually requires ball milling or screening of gangue to obtain slurry with good conveying performance to fill the entire post-mining space, which increases the filling cost and restricts the improvement of filling effect. In view of the current urgent need for gangue solid waste disposal and surface deformation control, it is of great significance to develop precise grouting filling methods based on the characteristics of overburden pores. Summary of the invention

[0003] Technical problem: In view of the shortcomings of the existing technology, a method for precise grouting of mining gangue filling slurry in layers and stages is provided, which can determine the preferred slurry indicators in different areas, as well as the optimal grouting layer, grouting timing and grouting amount according to the void distribution characteristics and spatiotemporal evolution laws of the overlying rock strata, so that the overlying rock strata can be grouted and filled in time when a small degree of deformation occurs, which can effectively improve the effect of grouting and filling in controlling surface deformation.

[0004] Technical solution: To achieve the above technical purpose, the present invention provides a method for accurate grouting of gangue filling slurry in layers and stages, the steps of which include:

[0005] Step 1, division of different overburden void structure blocks: conduct field surveys and investigations, select multiple typical coal seam mining areas where the overburden strata are damaged and deformed, in order to accurately explore the development and characteristics of the collapse zone, fracture zone, and separation zone after coal seam mining. By monitoring the distribution characteristics of voids formed by the destruction and deformation of the overburden strata after the above-mentioned multiple typical coal seams are mined, the division of the separation zone, fracture zone, and collapse zone blocks formed after the destruction and deformation of the overburden strata after mining in the typical mining area is obtained;

[0006] Step 2, determining the slurry flow index of the layered blocks: according to step 1, the blocks of the delamination area, fracture zone, and collapse zone formed after the overlying rock strata are destroyed and deformed after multiple typical coal seams are mined are divided, and according to the void structure characteristics of different blocks, coarse-grained gangue slurry or fine-grained gangue slurry is selected to fill the delamination area, fracture zone, and collapse zone blocks, so as to determine the preferred index that satisfies the slurry transportation performance of the delamination area, fracture zone, and collapse zone blocks, so as to judge whether to select coarse-grained gangue slurry or fine-grained gangue slurry when implementing layered grouting for different blocks;

[0007] Step 3: Staged grouting method based on the evolution of overburden voids: The discrete element numerical simulation method is used to solve the spatiotemporal evolution characteristics of the void ratio of the overburden strata in the post-mining space as the working face advances, and a staged grouting method is performed according to the development of overburden voids in different periods;

[0008] Step 4, precise control of the amount of gangue grouting filling: According to the judgment result of step 2, the discrete particle group method is used for numerical simulation of different blocks to obtain the flow and diffusion laws of coarse-grained gangue slurry and fine-grained gangue slurry in their respective filling blocks, and the flow and diffusion characteristics of coarse-grained gangue slurry and fine-grained gangue slurry in different blocks are obtained. Combined with the characteristics of the overburden pores, the grouting layer and grouting timing are determined, and the grouting filling amount of each block and each stage of the staged grouting method is precisely controlled to facilitate engineering management and control.

[0009] Furthermore, the particle size ranges of the coarse and fine particle size gangue slurries described in step 2 are 0-5 mm and 0-2 mm, respectively, and the specific parameters are: the concentration of the coarse particle size gangue slurry is 60%-70%, and the mass ratio of 2-5 mm, 0.15-2 mm, and 0-0.15 mm gangue reaches (0-0.3):2:1; the concentration of the fine particle size gangue slurry is 55%-65%, and the mass ratio of 0.15-2 mm and 0-0.15 mm gangue reaches (0-2):1.

[0010] Furthermore, the preferred indicators for the conveying performance of the filling slurry described in step 2 are: the expansion degree is the preferred indicator for the blocks in the delamination area, and the gangue processing capacity is the preferred indicator for the fracture zone and the collapse zone. Therefore, fine-grained gangue slurry is used to fill the delamination area, and coarse-grained gangue slurry is used to fill the fracture zone and the collapse zone.

[0011] Further, the discrete element numerical simulation method described in step 3 comprises the following steps:

[0012] a1. Calibration of measured data: Based on the measured data of the target area, the length of the working face, advancement distance, mining depth, mining height and overburden lithology of the measured mine are preliminarily determined. A data inversion surface subsidence calculation model is established based on the discrete element method DEM. The overburden creep parameters of the surface subsidence calculation model are adjusted based on the total subsidence of the measured surface deformation monitoring base point until the displacement curve of the measured base point coincides with the discrete element simulation curve, thereby determining the overburden lithology and creep parameters;

[0013] a2. Establishing the Mohr-Coulomb model of overburden: Using the discrete element numerical simulation software 3DEC, the Mohr-Coulomb model of overburden is established according to the determined overburden lithology and creep parameters, and the size of the Mohr-Coulomb model of overburden, the length of the simulated working face and the advancement distance are determined. The boundary surface velocity in the XX and YY directions is set to zero, the top surface of the Mohr-Coulomb model of overburden is set to be a free surface, and the top of the Mohr-Coulomb model of overburden is set to be a loose layer without applying load. Protective coal pillars are left at both ends of the Mohr-Coulomb model of overburden to reduce the boundary influence;

[0014] a3. Binarization solution: Using the numerical model of the overburden Mohr-Coulomb model, draw the distribution map of overburden cracks at different advancement distances, and perform binarization processing to calculate the curve of overburden porosity changing with advancement distance, and determine the spatiotemporal evolution characteristics of the porosity of the overburden strata.

[0015] Further, the staged grouting method described in step 3 obtains the state and characteristics of the separation area, fracture zone, and collapse zone formed after the coal seam mining in the mining area according to the discrete element numerical simulation information, so as to perform the following steps:

[0016] Stage 1: After the working face advances to the collapse zone, the fracture zone is obviously developed. Grouting holes are arranged on the ground to fill the fracture zone and collapse zone with coarse-grained gangue slurry. The grouting holes are arranged above the fracture zone.

[0017] Stage 2: When mining and collapse cause the overlying strata to continue to move and deform to the delamination area, fine-grained gangue slurry is started to be filled in the delamination area while filling the fracture zone, and the grouting drilling holes are arranged in the upper part of the delamination area;

[0018] Stage 3: When the fracture zone continues to develop and is connected to the delamination area, the grouting holes can be arranged only in the upper part of the delamination area, and coarse-grained gangue slurry can be used to fill the delamination area, fracture zone and collapse zone at the same time.

[0019] Further, the discrete particle population method described in step 4 comprises:

[0020] s1. Obtain the morphology of gangue particles in the slurry: Use Matlab software to analyze the image of the gangue particles photographed, obtain a digital image of the material boundary contour with only black and white colors, obtain the curve function of the gangue shape by fitting, and stack and connect multiple groups of closed curves into closed surfaces in CAD to obtain the particle morphology of the gangue;

[0021] s2. Calibration of the model parameters of gangue slurry: Conduct laboratory tests and simulation tests to test the natural repose angle of gangue and the slump expansion of slurry, compare the test results of the two, and the simulation parameters corresponding to the simulation results that are consistent with the laboratory test results are used as calibration parameters;

[0022] s3. Establishing the filling space model: Using PFC numerical simulation software, design the size of the filling space model according to the actual conditions of the stope, and use the rock block template to fill the filling space model on the basis of ensuring the porosity, and generate the Rblock unit of the broken rock mass; the porosity of the rock plate in the model is obtained according to the on-site sampling test;

[0023] s4. Calculation of the flow and diffusion characteristics of gangue slurry: Generate slurry particles of designed particle size in the grouting borehole, assign them the slurry parameters obtained in s2, attach a certain initial grouting velocity outside the borehole, set the grouting time and grouting pressure, and obtain the diffusion radius and diffusion depth of the gangue slurry.

[0024] Beneficial Effects

[0025] This method determines the void distribution characteristics of the typical mining area's delamination area, collapse zone, and fracture zone based on the post-mining overburden void structure obtained from actual measurements in the mining area, and proposes a layered grouting method that determines different filling slurry particle size ranges based on the void characteristics of different filling areas, then tests the slurry's transportation performance and the proportion of gangue particle size, determines the slurry concentration and particle size grading used for filling based on the performance optimization index, and then obtains the variation curve of the void ratio of the overburden strata in the goaf with the advancement distance through discrete element numerical simulation calculation, based on the spatiotemporal evolution characteristics of the void ratio; This method proposes a layered grouting method based on the post-mining overburden void structure obtained from actual measurements in the mining area, determines the optimization index of the filling slurry in different blocks, and then proposes a staged grouting method based on the spatiotemporal evolution characteristics of the mining overburden void ratio, and determines the grouting layer, grouting timing, and grouting amount based on the flow and diffusion characteristics of gangue slurry in different blocks to achieve the effect of precise grouting. This method can improve the effect of gangue grouting filling in controlling surface deformation and effectively improve the filling efficiency of grouting materials. It can effectively reduce the time and cost of slurry preparation, reduce the amount of surface subsidence, achieve the dual effects of gangue disposal and surface deformation control, and provide a reference for improving the effect of gangue grouting filling in controlling surface deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a flow chart of a method for accurate grouting of gangue filling slurry in layers and stages for the present invention;

[0027] Figure 2 The present invention is a schematic diagram of a method for accurate grouting of gangue filling slurry in layers and stages; (a) is stage one, (b) is stage two, and (c) is stage three.

[0028] In the figure: 1, 2, 3—grouting holes; A—detached layer area; B—fracture zone; C—collapse zone. DETAILED DESCRIPTION

[0029] In conjunction with the accompanying drawings, a method for efficiently preparing millimeter-level gangue filling slurry for mining and grouting in layers and stages according to the present invention is described in detail and an implementation case analysis is provided.

[0030] like Figure 1 As shown, a method for accurate grouting of gangue filling slurry in layers and stages for mining of the present invention comprises the following steps:

[0031] Step 1: Different overburden void structure block division. Conduct field surveys and select 10 different typical areas where the overburden strata are damaged and deformed after coal seam mining in the mining area. Use borehole monitoring to monitor the distribution characteristics of overburden voids and obtain the block division of the delamination area A, fracture zone B, and collapse zone C in the typical mining area.

[0032] Step 2, determine the slurry flow index of the layered blocks. According to the block division obtained in step 1, a layered grouting method is proposed, and gangue slurry with coarse and fine particle sizes is selected. According to the void structure characteristics of different blocks, the preferred indicators that meet the slurry transportation performance of filling materials in different blocks are determined. Among them, the coarse and fine particle size gangue slurries are both prepared by mixing water and gangue particles. According to the block division results and the void structure characteristics of the overburden block, a layered grouting method is proposed, and gangue slurry with coarse and fine particle sizes is selected. Based on the expansion degree of the delamination area A as the preferred indicator, the fracture zone B and the collapse zone C take the gangue processing capacity as the preferred indicator, it is determined to select 0-5mm coarse particle size gangue slurry to fill the fracture zone B and the collapse zone C, and select 0-2mm fine particle size gangue slurry to fill the delamination area A.

[0033] The gangue particle size range of the coarse-grained gangue slurry is 0-5mm, and the gangue particle size range of the fine-grained gangue slurry is 0-2mm. Different slurries are mixed with multiple gangue particles of different particle sizes within the range. The concentration of the coarse-grained gangue slurry is 60%-70%, and the mass ratio of 2-5mm, 0.15-2mm, and 0-0.15mm gangue reaches (0-0.3):2:1; the concentration of the fine-grained gangue slurry is 55%-65%, and the mass ratio of 0.15-2mm and 0-0.15mm gangue reaches (0-2):1.

[0034] Step 3: A phased grouting method based on the evolution of overburden voids. Using the discrete element numerical simulation method, a numerical model is established and assigned parameters to solve the spatiotemporal evolution characteristics of the void ratio of the overburden strata after mining as the working face advances. A phased grouting method is proposed, and grouting is performed according to the development of overburden voids in different periods.

[0035] Step 4: Precise control of the amount of gangue grouting. The discrete particle group method is used to numerically simulate the flow and diffusion law of gangue slurry, and the flow and diffusion characteristics of coarse and fine particle slurry in the corresponding blocks are obtained. Combined with the characteristics of the overburden pores, the grouting layer and grouting time are determined, and the grouting filling amount of each block and each stage is precisely controlled.

[0036] The specific implementation cases of the staged grouting method are as follows:

[0037] 1. Background of the Project

[0038] The coal seam mined in a mine in Ordos is 4-2 coal, with a thickness of 3.0m and a burial depth of 170.75m. The aquifer group within the mining area contains aquifers and confined water. Affected by the environment in the area, the protection of the surface aquifer is particularly important in the coal mining process. Therefore, the mine is designed to use the gangue grouting filling method to control surface subsidence and achieve the purpose of protecting the surface aquifer.

[0039] (II) Application of gangue grouting filling method

[0040] The mine uses a ground filling station to prepare gangue slurry, which is transported to the grouting borehole through a grouting pipeline and then filled in the target area. The concentration of the 0-2mm gangue slurry is 60%, and the concentration of the 0-5mm gangue slurry is 65%.

[0041] The ground filling station is built in the industrial square. The filling is equipped with two-stage crushing devices (the first-stage crushing adopts a double-toothed roller crusher with a discharge particle size of ≤100mm, the second-stage crushing adopts a two-stage bottomless screen high-fine crusher with a discharge particle size of ≤5mm, and the second-stage crushing is passed through the two-stage bottomless screen high-fine crusher again to obtain a particle size of ≤2mm), batching devices, slurry stirring devices, slurry pumping devices and other necessary facilities, as well as cement silos, fly ash silos, gangue aggregate sheds and other raw material storage areas; the grouting pipeline is arranged in a way of laying along the road with a wall thickness of 14.0mm and Φ219.0mm seamless steel pipes, with a maximum laying distance of about 3116m, and the slurry is transported to the grouting borehole by industrial pumps, with a maximum theoretical working pressure of 20MPa; the grouting borehole is arranged using the staged grouting method described in the invention, and the staged grouting method is as follows: Figure 2 As shown, the specific details are as follows:

[0042] (a) Stage 1: After the working face advances a certain distance, the collapse zone C has been formed and the fracture zone B is obviously developed. The fracture zone B and the collapse zone C are filled with coarse-grained gangue slurry, and the grouting borehole 1 is arranged on the upper part of the fracture zone;

[0043] (b) Stage 2: When the overburden continues to move and deform until the separation zone A appears, the separation zone A is filled with fine-grained gangue slurry while the fracture zone is being filled, and the grouting borehole 2 is arranged at the upper part of the separation zone;

[0044] (c) Stage 3: When the fracture zone B continues to develop and is connected to the delamination area A, three grouting holes can be arranged on the upper part of the delamination area A, and the delamination area A, fracture zone B, and collapse zone C can be filled with coarse-grained gangue slurry at the same time.

[0045] According to the design of the layered and phased precise grouting method and the necessary related research, the mine adopted a local filling method, with a grouting drilling spacing of 150m, a filling range of 100m, and an equivalent mining height of 1500mm. The surface subsidence reduction effect achieved was higher than 50%, effectively realizing the protection of the surface aquifer.

[0046] The discrete particle group method was used to numerically simulate the flow and diffusion law of gangue slurry, and the flow and diffusion characteristics of gangue slurry with particle sizes of 0-5mm and 0-2mm in the corresponding blocks were obtained. Combined with the characteristics of the overburden pores, the grouting layer and grouting timing were determined, and the grouting filling amount of each block and each stage was accurately controlled.

[0047] Specifically, the discrete particle population method comprises the following steps:

[0048] s1. Obtaining the morphology of gangue particles. The image of the gangue particles photographed was analyzed using Matlab software to obtain a digital image of the material boundary contour in only black and white colors. The curve function of the gangue shape was obtained by fitting, and multiple groups of closed curves were stacked and connected into closed surfaces in CAD to obtain the particle morphology of the gangue.

[0049] s2. Calibration of the model parameters of gangue slurry. Laboratory tests and simulation tests were carried out to test the natural repose angle of gangue and the slump expansion of slurry. The simulation test scheme and results of the natural repose angle of gangue are shown in Table 1, and the test scheme and results of the slump expansion of slurry are shown in Table 2. The laboratory test obtained that the natural repose angle of gangue was 8.1, and the slump expansion of slurry was 253mm. The test results of the two were compared respectively, and the simulation parameters corresponding to the simulation results consistent with the laboratory test results were the calibration parameters, and the friction coefficient was 0.75, the rolling friction coefficient was 0.1, the maximum attraction was 2.2e-3, and the attraction range was 7.5e-4.

[0050] Table 1 Simulation test scheme and results of natural repose angle of gangue

[0051]

[0052] Table 2 Slurry slump expansion simulation test plan and results

[0053]

[0054]

[0055] s3. Establishment of filling space model. Using PFC numerical simulation software, the model size is designed to be 300m×150m×150m (length×width×height) according to the actual conditions of the stope, and the stone with a void ratio of 19% is constructed based on the rock block template to generate the Rblock unit of the broken rock mass.

[0056] s4, Gangue slurry flow diffusion characteristics solution. Generate slurry particles with a particle size of 0-5mm in the grouting borehole, and assign the slurry parameters obtained in s2. Add a certain initial grouting velocity outside the borehole, set the grouting time to 3h, and the grouting pressure to 15.0MPa, and obtain the gangue slurry diffusion radius of 90.3m and the diffusion depth of 86.2m.

Claims

1. A method for accurate grouting of gangue filling slurry in layers and stages, characterized in that: The steps include: Step 1, division of different overburden void structure blocks: conduct field surveys and investigations, select multiple typical coal seam mining areas where the overburden strata are damaged and deformed, in order to accurately explore the development and characteristics of the collapse zone, fracture zone, and separation zone after coal seam mining. By monitoring the distribution characteristics of voids formed by the destruction and deformation of the overburden strata after the above-mentioned multiple typical coal seams are mined, the division of the separation zone, fracture zone, and collapse zone blocks formed after the destruction and deformation of the overburden strata after mining in the typical mining area is obtained; Step 2, determining the slurry flow index of the layered blocks: according to step 1, the blocks of the delamination area, fracture zone, and collapse zone formed after the overlying rock strata are destroyed and deformed after multiple typical coal seams are mined are divided, and according to the void structure characteristics of different blocks, coarse-grained gangue slurry or fine-grained gangue slurry is selected to fill the delamination area, fracture zone, and collapse zone blocks, so as to determine the preferred index that satisfies the slurry transportation performance of the delamination area, fracture zone, and collapse zone blocks, so as to judge whether to select coarse-grained gangue slurry or fine-grained gangue slurry when implementing layered grouting for different blocks; Step 3: Staged grouting method based on the evolution of overburden voids: The discrete element numerical simulation method is used to solve the spatiotemporal evolution characteristics of the void ratio of the overburden strata in the post-mining space as the working face advances, and a staged grouting method is performed according to the development of overburden voids in different periods; Step 4, precise control of the amount of gangue grouting filling: According to the judgment result of step 2, the discrete particle group method is used for numerical simulation of different blocks to obtain the flow and diffusion laws of coarse-grained gangue slurry and fine-grained gangue slurry in their respective filling blocks, and the flow and diffusion characteristics of coarse-grained gangue slurry and fine-grained gangue slurry in different blocks are obtained. Combined with the characteristics of the overburden pores, the grouting layer and grouting timing are determined, and the grouting filling amount of each block and each stage of the staged grouting method is precisely controlled to facilitate engineering management and control.

2. A method for accurate grouting of gangue filling slurry in layers and stages according to claim 1, characterized in that: The particle size ranges of the coarse and fine particle size gangue slurries described in step 2 are 0~5mm and 0~2mm, respectively, and the specific parameters are: the concentration of the coarse particle size gangue slurry is 60%~70%, and the mass ratio of 2~5mm, 0.15~2mm, and 0~0.15mm gangue reaches (0~0.3):2:1; the concentration of the fine particle size gangue slurry is 55%~65%, and the mass ratio of 0.15~2mm and 0~0.15mm gangue reaches (0~2):

1.

3. The method for accurate grouting of gangue filling slurry in layers and stages according to claim 1, characterized in that: The preferred indicators for the filling slurry transportation performance described in step 2 are: the expansion degree is the preferred indicator for the blocks in the delamination area, and the gangue processing capacity is the preferred indicator for the fracture zone and the collapse zone. Therefore, fine-grained gangue slurry is used to fill the delamination area, and coarse-grained gangue slurry is used to fill the fracture zone and the collapse zone.

4. The method for accurate grouting of gangue filling slurry in layers and stages according to claim 1, characterized in that: The discrete element numerical simulation method described in step 3 comprises the following steps: a1. Calibration of measured data: Based on the measured data of the target area, the length of the working face, advancement distance, mining depth, mining height and overburden lithology of the measured mine are preliminarily determined. A data inversion surface subsidence calculation model is established based on the discrete element method DEM. The overburden creep parameters of the surface subsidence calculation model are adjusted based on the total subsidence of the measured surface deformation monitoring base point until the displacement curve of the measured base point coincides with the discrete element simulation curve, thereby determining the overburden lithology and creep parameters; a2. Establishing the Mohr-Coulomb model of overburden: Using the discrete element numerical simulation software 3DEC, the Mohr-Coulomb model of overburden is established according to the determined overburden lithology and creep parameters, and the size of the Mohr-Coulomb model of overburden, the length of the simulated working face and the advancement distance are determined. The boundary surface velocity in the XX and YY directions is set to zero, the top surface of the Mohr-Coulomb model of overburden is set to be a free surface, and the top of the Mohr-Coulomb model of overburden is set to be a loose layer without applying load. Protective coal pillars are left at both ends of the Mohr-Coulomb model of overburden to reduce the boundary influence; a3. Binarization solution: Using the numerical model of the overburden Mohr-Coulomb model, draw the distribution map of overburden cracks at different advancement distances, and perform binarization processing to calculate the curve of overburden porosity changing with advancement distance, and determine the spatiotemporal evolution characteristics of the porosity of the overburden strata.

5. A method for accurate grouting of gangue filling slurry in layers and stages according to claim 4, characterized in that: The staged grouting method described in step 3 obtains the state and characteristics of the separation area, fracture zone, and collapse zone formed after coal seam mining in the mining area based on the discrete element numerical simulation information, and then performs the following three stage steps: Stage 1: After the working face advances to the collapse zone, the fracture zone is obviously developed. Grouting holes are arranged on the ground to fill the fracture zone and collapse zone with coarse-grained gangue slurry. The grouting holes are arranged above the fracture zone. Stage 2: When mining and collapse cause the overlying strata to continue to move and deform to the delamination area, fine-grained gangue slurry is started to be filled in the delamination area while filling the fracture zone, and the grouting drilling holes are arranged in the upper part of the delamination area; Stage 3: When the fracture zone continues to develop and is connected to the delamination area, the grouting holes can be arranged only in the upper part of the delamination area, and coarse-grained gangue slurry can be used to fill the delamination area, fracture zone and collapse zone at the same time.

6. The method for accurate grouting of gangue filling slurry in layers and stages according to claim 1, characterized in that: The discrete particle population method described in step 4 comprises: s1. Obtain the morphology of gangue particles in the slurry: Use Matlab software to analyze the image of the gangue particles photographed, obtain a digital image of the material boundary contour with only black and white colors, obtain the curve function of the gangue shape by fitting, and stack and connect multiple groups of closed curves into closed surfaces in CAD to obtain the particle morphology of the gangue; s2. Calibration of the model parameters of gangue slurry: Conduct laboratory tests and simulation tests to test the natural repose angle of gangue and the slump expansion of slurry, compare the test results of the two, and the simulation parameters corresponding to the simulation results that are consistent with the laboratory test results are used as calibration parameters; s3. Establishing the filling space model: Using PFC numerical simulation software, design the size of the filling space model according to the actual conditions of the stope, and use the rock block template to fill the filling space model on the basis of ensuring the porosity, and generate the Rblock unit of the broken rock mass; the porosity of the rock plate in the model is obtained according to the on-site sampling test; s4. Calculation of the flow and diffusion characteristics of gangue slurry: Generate slurry particles of designed particle size in the grouting borehole, assign them the slurry parameters obtained in s2, attach the initial grouting velocity outside the borehole, set the grouting time and grouting pressure, and obtain the diffusion radius and diffusion depth of the gangue slurry.

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