Mining space gangue grouting filling diffusion simulation method based on 3D printing

Abstract

The invention discloses a mining space gangue grouting filling diffusion simulation method based on 3D printing, and belongs to the technical field of grouting filling. Combining mining space void structure characteristics and fracture development laws, determining property requirements of similar model materials according to 3D printing technical characteristics of the mining space, preparing gangue filling slurry in proportion based on laboratory results after the materials are selected, and performing a grouting test after the model is printed and air-dried and formed, and then the model completing grouting is subjected to slice analysis, and according to the dyeing condition of grouting in slices, the coal mining space gangue grouting diffusion route, the diffusion form and the relation between the grout injection amount and the diffusion distance are analyzed. The method is clear in logic and easy to operate, the flowing condition of the gangue slurry in the mining space can be predicated, gangue grouting filling design can be guided, and a theoretical basis is provided for reducing mining damage of filling engineering.

Description

Technical Field

[0001] The invention relates to a mining space gangue grouting filling diffusion simulation method based on 3D printing, belonging to the technical field of grouting filling. Background Art

[0002] Coal resource mining 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, mining spaces such as collapse zones and fissure zones will be formed behind the working face. After continuous development, they will cause surface deformation and damage to buildings. Gangue disposal and surface deformation control have become increasingly 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 injecting gangue into the well by making slurry. Since the flow of gangue slurry is limited by the void structure in the mining space, and the void distribution of the collapse zone and fissure zone formed by coal seam mining is irregular, the flow of gangue slurry in the void becomes difficult to predict, which restricts the improvement of gangue grouting filling effect. In view of the urgent need to improve the efficiency of gangue grouting filling, it is of great significance to develop a research method for the diffusion law of gangue slurry based on the void distribution characteristics of mining space.

[0003] The prior art with publication number CN110108838A discloses a simulation test method for the diffusion of grouting slurry in directional drilling, which belongs to the technical field of grouting control of mine water hazards. The test system adopted by it includes a grouting test bench, a branch hole crack simulation system, a control system, a grouting system and a real-time monitoring system. By magnetically adsorbing the branch hole crack mold on the test bench body, the test bench body can be transformed at multiple angles by rotating the rotating shaft, thereby realizing the simulation of different types of branch hole cracks. This method can only observe the diffusion of slurry in the area of ​​this type by the extension of the injected slurry from the outside of the pattern. Therefore, it can only obtain the grouting diffusion of a single sample, and it is impossible to simulate the grouting diffusion and penetration of an entire auxiliary area. It has great limitations. At the same time, it is impossible to obtain accurate information on the diffusion of slurry inside the pattern. It can only be inferred or a small amount of information can be obtained by endoscopy, which is not intuitive and reliable enough. Summary of the invention

[0004] In view of the shortcomings of the existing technology, a 3D printing-based simulation method for the diffusion of gangue grouting filling in a mining space is provided, which can quickly restore the model of the mining space through 3D printing technology, and then grouting and slicing the restored model of the mining space to quickly and intuitively obtain the diffusion of the grouting slurry in the restored model of the mining space.

[0005] Technical solution: To achieve the above technical objectives, the present invention discloses a method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing. According to the void structure characteristics and crack development laws of the mining space measured near the working face, 3D printing technology is used to quickly and accurately construct a model that is physically similar to the mining space measured near the working face using printed materials and measured data. After the model is formed, a grouting test is carried out on the model using gangue slurry. The model that has completed the grouting test is first subjected to mining simulation, and then the model is sliced ​​to visualize the slurry diffusion. According to the physical simulation results, the gangue grouting diffusion route, diffusion form and the relationship between the slurry injection amount and diffusion distance of the mining space are analyzed to obtain the slurry diffusion law of the gangue slurry in the mining space. Finally, the dimensional parameters of the similar model can be reversed to the actual situation to guide the engineering site of the grouting filling material.

[0006] The specific steps are as follows:

[0007] S1. Investigate the geological conditions of the filling working face, determine the length L, width D, height H, void diameter φ, void volume V of the post-mining space in the 3D printing similarity model based on the measured void structure characteristics and fissure development of the collapse zone and fissure zone after the collapse mining of the adjacent working face, and combine the size parameters of the 3D printing similarity model to be prepared. g ;

[0008] S2. Since it is necessary to analyze the distribution characteristics of the internal voids of the 3D printed similar model, based on the technical characteristics of 3D printing, pumpability / rheology, extrudability, buildability, and interlayer bonding strength are used as the property requirements of the printing material. Combined with the strong demand for the accuracy of the void distribution characteristics of the model similar to the physical characteristics of the mining space, the order of interlayer bonding strength, buildability, pumpability, and extrudability is used as the optimization standard to determine the printing material and ratio of the physical similar model of the post-mining space;

[0009] S3. Carry out the performance ratio test of gangue filling slurry, and combine the pore structure of mining space to test the slump S and water seepage rate W of gangue slurry. t , viscosity μ, and uniaxial compressive strength R, adjust and determine the concentration and proportion of gangue slurry;

[0010] S4. Based on the void structure of the mining space in the 3D printed similarity model, a physical similarity model of the mining space is established using 3D printing technology. The physical similarity model of the mining space can accurately restore the pore channel information on site;

[0011] S5. After the 3D printed similar model is printed and air-dried, a gangue grouting filling diffusion simulation test is carried out on the 3D printed similar model, and the gangue grouting diffusion route, diffusion form and the relationship between the slurry injection amount and diffusion distance in the mining space are analyzed based on the results of the gangue grouting filling diffusion simulation test.

[0012] Furthermore, the size parameters of the 3D printed similar model in step S1 include: geometric similarity ratio α1, gravity similarity ratio α γ , time similarity ratio α t , similarity ratio of uniaxial compressive strength α R , elastic modulus similarity ratio α E , cohesion similarity ratio α c 、Similarity ratio of internal friction angle α f , similarity ratio of gravitational acceleration α g , and its calculation formula is shown in formula (1):

[0013]

[0014] In the formula, l m , γ m ,t m , R m 、f m , g m They are the geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration of 3D printed similar models; l p , γ p ,t p , R p 、f p , g p It is the actual geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration on site.

[0015] Furthermore, the printing material used in the S2 step is a mixture of cement, fine sand, silica fume, expansion agent, double-fast cement, water reducing agent, and water in a mass ratio of 60:100:8:7:4:1:30; under this ratio, the 3D printed similar model can reflect the void structure characteristics and fracture development of the collapse zone and fracture zone after mining, while meeting the rapid prototyping capability, flow properties and mechanical properties of 3D printing, and is easy to cut without deformation and damage due to cutting.

[0016] Furthermore, the process of 3D printing technology in step S4 is mainly divided into three stages: data model preparation stage, model printing material preparation stage, and model structure printing stage.

[0017] Furthermore, the gangue grouting filling diffusion simulation test in step S5 comprises the following steps:

[0018] a1. After the 3D printed model is air-dried and formed, a grouting pipe connected to the reserved pore channel is installed on the top of the 3D printed model;

[0019] a2. Determine the grouting volume required for the test based on the measured data of the void space in the 3D printed model, adjust the grouting speed and grouting pressure according to the actual grouting process, and add a certain amount of red ink to the slurry to facilitate recording the diffusion route, diffusion form, and diffusion distance of the slurry;

[0020] a3. Use pipeline pressure gauge to monitor grouting pressure in real time, and use pipeline flow meter to monitor the injection volume of gangue slurry. When the injection volume is reached, stop the grouting pump in time and record the injection volume of slurry;

[0021] a4. After the grouting is completed and the slurry solidifies, the grouting model is dismantled and sliced ​​to observe the flow and diffusion of the slurry inside the model at different positions.

[0022] Beneficial effect: This method proposes a simulation method for the diffusion of gangue grouting filling in mining space based on the distribution characteristics of the voids in the mining space measured at the working face, combined with 3D printing technology and similar model size parameters. The ratio of printing material and gangue slurry is determined based on the property requirements of the model material and the performance requirements of the gangue filling slurry. Then, the physical similarity model of the mining space is quickly and accurately established through 3D printing technology, and the complex conditions of the void distribution in the mining space on site are reproduced to the 3D printing model in the laboratory. The diffusion of the grouting slurry in the goaf of the 3D printing model is quickly and intuitively obtained by grouting the 3D printing model and then slicing. The actual distribution of the voids in the mining space can be reversed in combination with the size parameters of the similar model to guide the engineering site of the grouting filling material. The 3D printing model material of the present invention has good reducibility and can restore various complex scenes with little difference from the site. At the same time, the 3D printing model is convenient for slicing research and will not deform after slicing to affect the research effect. This method provides a theoretical basis for reducing mining damage in filling projects. It provides a reference for improving the slurry diffusion control effect in mining space by gangue grouting filling. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing of the present invention;

[0024] Figure 2The following is a result diagram of the observed diffusion of grouting of gangue in the mining space after slicing the 3D printed model of an embodiment of the present invention; Figure (a) is a complete 3D printed model in the embodiment; A in Figure (a) is a grouting hole; Numbers 1, 2, 3, and 4 are cutting lines for slicing the 3D printed model; Figure (b) is a cross-sectional image of the 3D printed model of Figure (a) sliced ​​along tangent 1; Figure (c) is a cross-sectional image of the 3D printed model of Figure (a) sliced ​​along tangent 2; Figure (d) is a cross-sectional image of the 3D printed model of Figure (a) sliced ​​along tangent 3; Figure (e) is a cross-sectional image of the 3D printed model of Figure (a) sliced ​​along tangent 4. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0026] like Figure 1 As shown, the present invention discloses a method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing. By investigating the geological conditions of the mining face and the void structure characteristics and crack development of the mining space of the adjacent working face, the physical similarity model is designed in combination with 3D printing technology and similar model size parameters, and the preferred ratio of printing material and gangue slurry is determined according to the property requirements of the model material and the performance requirements of the gangue filling slurry. Then, the physical similarity model of the mining space is established by 3D printing technology, and the three-dimensional rock void structure is constructed. After the model is air-dried and formed, the gangue grouting filling diffusion simulation test is carried out to obtain the slurry diffusion law of the gangue slurry in the mining space. The method can predict the flow of gangue slurry in the mining space, guide the design of gangue grouting filling, and provide a theoretical basis for reducing mining damage in filling projects.

[0027] The specific steps are as follows:

[0028] s1. Investigate the geological conditions of the filling working face, and based on the measured void structure characteristics and fissure development of the collapse zone and fissure zone after the collapse mining of the adjacent working face, combined with the size parameters of the similar model, determine the length L of the post-mining space model to be 300mm, the width D to be 300mm, the height H to be 300mm, the minimum void diameter φ to be 18mm, and the void volume V g 400mL;

[0029] s2. According to the technical characteristics of 3D printing, pumpability (rheology), extrudability, buildability, and interlayer bonding strength are used as the property requirements of the model material. The printing materials and proportions of the post-mining space physical similarity model are determined as follows: cement: fine sand: silica fume: expansion agent: double fast: water reducer: water = 60:100:8:7:4:1:30 (mass ratio);

[0030] s3. Carry out the performance ratio test of gangue filling slurry, and combine the pore structure of mining space to test the slump S and water seepage rate W of gangue slurry. t According to the requirements of properties such as viscosity μ, uniaxial compressive strength R, the optimal concentration of gangue slurry is adjusted and determined to be 65% and the particle size ratio is 0-2mm;

[0031] s4. According to the void structure of the mining space and based on the process of 3D printing technology, compile the printing program of the physical model, set the printing speed of the 3D printer to 10mm / s, pour the prepared similar model material into the storage bin, import and run the program, and establish the physical similarity model of the mining space;

[0032] s5. After the model is air-dried, a gangue grouting filling diffusion simulation test is carried out, and the gangue grouting diffusion route, diffusion form and the relationship between the slurry injection volume and diffusion distance in the mining space are analyzed based on the physical simulation results.

[0033] Specifically, the method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing is characterized in that the size parameters of the similarity model in step s1 include: geometric similarity ratio α1, gravity similarity ratio α γ , time similarity ratio α t , similarity ratio of uniaxial compressive strength α R , elastic modulus similarity ratio α E , cohesion similarity ratio α c 、Similarity ratio of internal friction angle α f , similarity ratio of gravitational acceleration α g , the calculation formula and result are shown in formula (1):

[0034]

[0035] In the formula, l m , γ m ,t m , R m 、f m , g m They are the geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration of 3D printed similar models; l p , γ p ,t p , R p 、f p , g p It is the actual geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration on site.

[0036] Specifically, the method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing is characterized in that the pumpability in the step s2 refers to the performance that the material can be smoothly pumped from the barrel to the printing extruder, the extrudability printing material can be smoothly extruded from the printing extruder and the extrusion of uniform printing strips can be achieved, the constructability refers to the performance that the size of the overall component does not change with the increase of hardening time during printing, and the interlayer bonding strength refers to the bonding ability between the concrete printing strips of adjacent layers;

[0037] Specifically, the method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing is characterized in that the process of 3D printing technology in step s4 is mainly divided into three stages: data model preparation stage, concrete material preparation stage, and model structure printing stage;

[0038] Specifically, the method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing is characterized in that the gangue grouting filling diffusion simulation test in step s5 comprises the following steps:

[0039] a1. After the 3D printed model is air-dried and formed indoors, install the grouting pipe on the top of the model to reserve a pore channel;

[0040] a2. Determine the grouting volume required for the test according to the void volume in the 3D printed model, adjust the grouting speed and grouting pressure according to the actual grouting process, and add a certain amount of red ink to the slurry to facilitate recording the diffusion route, diffusion form, and diffusion distance of the slurry;

[0041] a3. Use a pipeline pressure gauge with a range of 0-1MPa to monitor the grouting pressure in real time, and use a pipeline flow meter with a measuring range of 0-20L / min to monitor the injection volume of gangue slurry. When the injection volume is reached, stop the grouting pump in time and record the injection volume of slurry under different working conditions (Table 1);

[0042] a4. After the grouting is completed and the slurry solidifies, the grouting model is dismantled and sliced ​​to observe the flow and diffusion of the slurry inside the model at different positions (as shown in Table 1, Figure 2 shown).

[0043] Table 5-12 Slurry injection conditions in various working conditions

[0044]

Claims

1. A method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing, characterized in that: According to the void structure characteristics and crack development laws of the mining space measured near the working face, 3D printing technology is used to quickly and accurately construct a model that is physically similar to the mining space measured near the working face using printed materials and measured data. After the model is formed, a grouting test is carried out on the model using gangue slurry. First, the model that has completed the grouting test is divided into mining simulations, and then the model is sliced ​​to visualize the slurry diffusion. According to the physical simulation results, the gangue grouting diffusion route and diffusion form of the mining space as well as the relationship between the slurry injection volume and diffusion distance are analyzed to obtain the slurry diffusion law of gangue slurry in the mining space. Finally, the dimensional parameters of the similar model can be reversed to the actual situation to guide the engineering site of grouting filling materials. The specific steps are as follows: S1. Investigate the geological conditions of the filling working face, determine the length L, width D, height H, void diameter φ, void volume V of the post-mining space in the 3D printing similarity model based on the measured void structure characteristics and fissure development of the collapse zone and fissure zone after the collapse mining of the adjacent working face, and combine the size parameters of the 3D printing similarity model to be prepared. g ; S2. Since it is necessary to analyze the distribution characteristics of the internal voids of the 3D printed similar model, based on the technical characteristics of 3D printing, pumpability / rheology, extrudability, buildability, and interlayer bonding strength are used as the property requirements of the printing material. Combined with the strong demand for the accuracy of the void distribution characteristics of the model similar to the physical characteristics of the mining space, the order of interlayer bonding strength, buildability, pumpability, and extrudability is used as the optimization standard to determine the printing material and ratio of the physical similar model of the post-mining space; S3. Carry out the performance ratio test of gangue filling slurry, and combine the pore structure of mining space to test the slump S and water seepage rate W of gangue slurry. t , viscosity μ, and uniaxial compressive strength R, adjust and determine the concentration and proportion of gangue slurry; S4. Based on the void structure of the mining space in the 3D printed similarity model, a physical similarity model of the mining space is established using 3D printing technology. The physical similarity model of the mining space can accurately restore the pore channel information on site; S5. After the 3D printed similar model is printed and air-dried, a gangue grouting filling diffusion simulation test is carried out on the 3D printed similar model, and the gangue grouting diffusion route, diffusion form and the relationship between the slurry injection amount and diffusion distance in the mining space are analyzed based on the results of the gangue grouting filling diffusion simulation test.

2. According to the 3D printing-based mining space gangue grouting filling diffusion simulation method according to claim 1, it is characterized in that: The size parameters of the 3D printed similar model in step S1 include: geometric similarity ratio α1, gravity similarity ratio α γ , time similarity ratio α t , similarity ratio of uniaxial compressive strength α R , elastic modulus similarity ratio α E , cohesion similarity ratio α c 、Similarity ratio of internal friction angle α f , similarity ratio of gravitational acceleration α g , and its calculation formula is shown in formula (1): In the formula, l m , γ m ,t m , R m 、f m , g m They are the geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration of 3D printed similar models; l p , γ p ,t p , R p 、f p , g p It is the actual geometric dimensions, bulk density, time, internal friction angle, and gravitational acceleration on site.

3. The method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing according to claim 1 is characterized in that: The printing material used in the S2 step is a mixture of cement, fine sand, silica fume, expansion agent, double-fast cement, water reducing agent, and water in a mass ratio of 60:100:8:7:4:1:30; under this ratio, the 3D printed similar model can reflect the void structure characteristics and fracture development of the collapse zone and fracture zone after mining, while meeting the rapid prototyping capability, flow performance and mechanical properties of 3D printing, and is easy to cut without deformation and damage due to cutting.

4. The method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing according to claim 1, characterized in that: The 3D printing process in step S4 is mainly divided into three stages: data model preparation stage, model printing material preparation stage, and model structure printing stage.

5. The method for simulating the diffusion of gangue grouting filling in mining space based on 3D printing according to claim 1, characterized in that: The gangue grouting filling diffusion simulation test in step S5 comprises the following steps: a1. After the 3D printed model is air-dried and formed, a grouting pipe connected to the reserved pore channel is installed on the top of the 3D printed model; a2. Determine the grouting volume required for the test based on the measured data of the void space in the 3D printed model, adjust the grouting speed and grouting pressure according to the actual grouting process, and add a certain amount of red ink to the slurry to facilitate recording the diffusion route, diffusion form, and diffusion distance of the slurry; a3. Use pipeline pressure gauge to monitor grouting pressure in real time, and use pipeline flow meter to monitor the injection volume of gangue slurry. When the injection volume is reached, stop the grouting pump in time and record the injection volume of slurry; a4. After the grouting is completed and the slurry solidifies, the grouting model is dismantled and sliced ​​to observe the flow and diffusion of the slurry inside the model at different positions.

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