Optimal selection method of coal mine filling material
Through on-site experiments and numerical simulations, the optimal coal mine filling material ratio was determined, which solved the problem of poor filling effect in complex geological environments, and achieved safer and more economical coal mining.
Patent Information
- Application Number
- CN202411841496.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-06-27
AI Technical Summary
When selecting coal mine filling materials, the prior art fails to accurately consider the impact of rock formation excavation damage on the filling material under complex geological or complex stress environments, resulting in poor filling effect.
Through on-site rock mechanics uniaxial experiments and numerical simulations, a FLAC3D numerical model was established to simulate the compaction process of the goaf fall belt and the deterioration process of the top slab rock layer, pre-select the filling material ratio of different schemes, and determine the best solution through engineering technology and economic comparison.
It improves the coal mine filling effect under complex geological or complex stress environments, ensures the safety of coal mine mining, and provides a theoretical basis for coal mine disaster prevention and control.
Smart Images
Figure CN120217629A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of coal mine filling mining, and particularly relates to a method for optimizing the selection of coal mine filling materials. Background Art
[0002] During the underground coal resource mining process, the compaction characteristics of the filling material after filling in the goaf affect the roof subsidence and the conduction of fractures in the overlying strata, and have an important impact on the layout of gob-side entry, the control of rib spalling in front of the working face, the gas drainage in the working face, the prediction of surface subsidence, etc. Therefore, the compaction characteristics of the goaf filling material are of great significance to the complex response of the underground rock strata caused by mining.
[0003] Currently, the selection of filling materials is usually carried out by conducting tests on the materials in the early stage, changing the material ratio to obtain parameters such as different uniaxial compressive strengths or shear strengths of the filling materials, and then optimizing the material ratio according to engineering experience. This method is more practical under working conditions with relatively simple geological conditions and stress environments. However, for complex geological or complex stress environments, such as steeply inclined coal seams, composite roofs, and "three-soft" coal seams, etc., the influence of rock excavation damage on the requirements of the filling body material must be accurately considered. After the coal seam is excavated, due to the influence of excavation disturbance, the surrounding rock deteriorates the original defects under the action of external loads, and usually only the initial damage is considered in engineering, ignoring the additional damage caused by mining and other factors. Therefore, the current optimization method may produce poor filling effects due to the inaccurate estimation of the damage to the roof or rib. Summary of the Invention
[0004] Aiming at the above deficiencies in the prior art, a method for optimizing the selection of coal mine filling materials provided by the present invention solves the problem of poor filling effects that may occur after optimizing the material ratio in the prior art.
[0005] In order to achieve the above invention purpose, the technical solution adopted by the present invention is: a method for optimizing the selection of coal mine filling materials, including the following steps:
[0006] S1: Select on-site rocks for uniaxial rock mechanics experiments to obtain the uniaxial peak strain ε p , the uniaxial peak strength σ p , the average value E0 of the rock elastic modulus, and the strain threshold ε0.
[0007] S2: Determine the position, length, and width of the filling area in the working face, and calculate the caving zone range of the unfilled area.
[0008] S3: Establish FLAC according to the engineering geological conditions 3DThe numerical model uses a program based on the compaction theory of goaf to simulate the mechanical characteristics of the goaf zone compaction process according to the range of the caving zone. At the same time, the program that considers the additional damage of excavation is run on the top rock layer to simulate the degradation process of the overlying rock layer. In particular, if there is no collapse area, only the program that considers the additional damage of excavation needs to be run.
[0009] S4: Pre-select several filling materials with different proportions, assign the verified mechanical parameters and constitutive model of the filling material to the filling area model respectively, and continue to run the program until the model is balanced.
[0010] S5: Make engineering technical and economic comparisons of different filling material schemes to determine the best one.
[0011] Furthermore, in the above-mentioned method for selecting coal mine filling materials, S2 is specifically as follows: determining the length and width of the filling zone of the working face, and calculating the range of the caving zone, using the following formula:
[0012]
[0013] Where: h is mining height, m; c1, c2 are parameters related to roof lithology, see Table 1.
[0014] Table 1 Selection of roof lithology parameters
[0015]
[0016] Furthermore, in the above-mentioned method for selecting coal mine filling materials, the goaf compaction theory in S3 adopts the Salamon goaf compaction theory, and the elastic modulus E2 of the gangue is obtained as follows:
[0017]
[0018] Where: σ is the vertical stress in the goaf; E1 is the initial elastic modulus of the gangue; ε is the current vertical strain; b is the comprehensive expansion coefficient of the filling body. Based on formula (2), a program is compiled to make the elastic modulus change with the compaction of the roof, so as to realize the accurate simulation of the compaction of the gangue.
[0019] Furthermore, in the above-mentioned method for selecting optimal filling materials for coal mines, the implementation process of the program for considering additional damage caused by excavation in S3 adopts the following steps:
[0020] S31: Obtain the scale parameter x0 and shape parameter m of the Weibull distribution, where the calculation formula is as follows:
[0021]
[0022] By combining equations (3) to (5), we can directly select the parameters obtained from rock mechanics experiments to obtain x0 and m.
[0023] S32: Use the Weibull distribution function to describe the spatial distribution of the elastic modulus of the rock in the roof. Substitute the parameters obtained in step S31 to obtain the relationship between the elastic modulus of the roof and its strain:
[0024]
[0025] S33: Apply the above relationship to the Mohr-Coulomb model in FLAC 3D and compile a program based on equation (6) to make the elastic modulus change with rock damage. When ε < ε0, the rock material is in the elastic deformation stage. When the axial strain ε is greater than the strain threshold ε0.
[0026] Furthermore, the mechanical parameters and constitutive model of the filling material in S4 are determined by the following method:
[0027] Establish a numerical model of a 50mm×100mm cylindrical standard specimen, and calibrate the gob gangue with the Double-Yield, Mohr-Coulomb, and Strain-Softening models respectively with the uniaxial test data. Select a suitable constitutive model according to the calibration results and determine the material constitutive model parameters.
[0028] The beneficial effects of the present invention are as follows: By analyzing the physical processes such as the additional damage of coal and rock mass during mining, the collapse and compaction of the gob, and the support and bearing of the filling material, the optimal filling material ratio is determined, solving the problem that in complex geological or complex stress environments, such as steeply inclined coal seams, composite roofs, and "three-soft" coal seams, poor filling effects may occur due to inaccurate estimation of roof or rib failure. The present invention is more accurate and economical than traditional methods, ensuring safer coal mining and providing a theoretical basis for coal mine disaster prevention and control. Description of the Drawings
[0029] Figure 1 is the flow chart of the present invention
[0030] Figure 2 is the stress-strain curve obtained by Scheme 1 in the embodiment of the present invention and the calibrated curve
[0031] Figure 3 is the stress-strain curve obtained by Scheme 2 in the embodiment of the present invention and the calibrated curve
[0032] Figure 4 is the stress-strain curve obtained by Scheme 3 in the embodiment of the present invention and the calibrated curve
[0033] Figure 5 is the stress-strain curve obtained by Scheme 4 in the embodiment of the present invention and the calibrated curve
[0034] Figure 6 For the vertical stress in the filling body of each solution in the embodiments of the present invention Specific embodiments
[0035] The following describes the specific embodiments of the present invention according to the embodiments, so as to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.
[0036] As Figure 1 shown, it is a flowchart of a preferred method for a coal mine filling material of the present invention, mainly including the following steps:
[0037] S1: Select on-site rocks for uniaxial rock mechanics experiments, and respectively obtain the uniaxial peak strain ε p , the uniaxial peak strength σ p of the rock, the average value E0 of the elastic modulus of the rock, and the strain threshold ε0, as shown in Table 1.
[0038] Table 1 Parameters obtained from uniaxial rock mechanics experiments
[0039]
[0040] S2: Determine the position of the filling area of the working face and the length 122 m and width 25 m of the filling belt, and calculate the caving zone range of the unfilled area. The following formula is used for calculation:
[0041]
[0042] In the formula: the mining height h is 3.6 m; c1 and c2 are taken as 6.2 and 32 according to Table 1.
[0043] S3: Establish a FLAC 3D numerical model according to the engineering geological conditions. The model is 300 m long and 200 m wide. According to the caving zone range, the mechanical properties simulation of the caving zone compaction process in the goaf is realized by using a program based on the goaf compaction theory. Using the Salamon goaf compaction theory, the elastic modulus E2 of the gangue is obtained as:
[0044]
[0045] Where σ is the vertical stress in the goaf; E1 is the initial elastic modulus of the gangue, which is 250 MPa obtained from rock mechanics experiments; ε is the current vertical strain; b is the comprehensive expansion coefficient of the filling body, which is 1.3 obtained from the experiment. Based on formula (2), a program is compiled to make the elastic modulus change with the compaction of the roof, so as to achieve accurate simulation of the compaction of the gangue.
[0046] The program considering additional damage from excavation is run on the top rock layer to simulate the degradation process of the overlying rock mass. The following steps are used to implement the program considering additional damage from excavation:
[0047] S31: Obtain the scale parameter x0 and shape parameter m of the Weibull distribution, and the calculation formula is as follows:
[0048]
[0049] By combining equations (3) to (5), we can directly select the parameters obtained from rock mechanics experiments to obtain x0 and m, as shown in Table 2.
[0050] Table 2 Weibull distribution scale parameter x0 and shape parameter m values
[0051]
[0052]
[0053] S32: Use the Weibull distribution function to describe the spatial distribution of the rock elastic modulus in the roof. Substitute the parameters obtained in step S31 to obtain the relationship between the elastic modulus of the roof and its strain:
[0054]
[0055] S33: Apply the above relationship to FLAC 3D In the Mohr-Coulomb model in, a program is compiled based on formula (6) to make the elastic modulus change with rock damage. When ε<ε0, the rock material is in the elastic deformation stage, and when the axial strain ε is greater than the strain threshold ε0.
[0056] S4: Pre-select four filling materials with different proportions, assign the mechanical parameters and constitutive model of the verified filling materials to the filling area model respectively, and continue to run the program until the model is balanced. The mechanical parameters of the filling material, the selection and verification of the constitutive model are determined by the following method:
[0057] A numerical model of a 50mm×100mm cylindrical standard specimen was established. The gob gangue was calibrated with the uniaxial test data using the Double-Yield, Mohr-Coulomb, and Strain-Softening models respectively. According to the calibration results, a suitable constitutive model was selected and the parameters of the material constitutive model were determined. It was found that the Strain-Softening model had a better fitting effect. The stress-strain curves obtained from the experiment and the calibrated curves are as Figures 2 to 5 shown, and the calibration parameters are shown in Table 3.
[0058] Table 3 Simulated mechanical parameters of the filling material
[0059]
[0060] S5: Conduct engineering technology and economic comparisons on different filling material schemes to determine the best scheme:
[0061] As Figure 6 , the difference in the vertical stress in the filling bodies of Scheme 1 and Scheme 2 is not significant, and the difference in the vertical stress in the filling bodies of Scheme 3 and Scheme 4 is not significant. According to the parameters of the filling body obtained in Step S4, most of the filling bodies in Scheme 3 and 4 have entered the yield stage, and their bearing capacity is weak and not suitable for maintaining the stability of the working face. Considering the needs of the filling body itself and the stability of the working face, it is considered that the material filling scheme with a water-solid ratio of 3:1 in Scheme 2 meets the strength requirements of the filling body and has higher economic benefits.
[0062] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.
Claims
1. A method for selecting coal mine filling materials, characterized in that: The following steps are involved: S1: Select the on-site rocks for uniaxial rock mechanics experiments and obtain the rock uniaxial peak strain ε p , rock uniaxial peak strength σ p , mean rock elastic modulus E0, strain threshold ε0. S2: Determine the position of the filling area of the working face, the length and width of the filling belt, and calculate the range of the caving belt in the unfilled area. S3: Establish FLAC based on engineering geological conditions 3D The numerical model uses a program based on the compaction theory of goaf to simulate the mechanical characteristics of the goaf zone compaction process according to the range of the caving zone. At the same time, the program that considers the additional damage of excavation is run on the top rock layer to simulate the degradation process of the overlying rock layer. In particular, if there is no collapse area, only the program that considers the additional damage of excavation needs to be run. S4: Pre-select several filling materials with different proportions, assign the verified mechanical parameters and constitutive model of the filling material to the filling area model respectively, and continue to run the program until the model is balanced. S5: Make engineering technical and economic comparisons of different filling material schemes to determine the best one.
2. A method for selecting coal mine filling materials according to claim 1, characterized in that: S2 is specifically: determine the length and width of the filling zone of the working face, and calculate the range of the caving zone, using the following formula:
3. A method for selecting coal mine filling materials according to claim 1, characterized in that: The compaction theory of goaf in S3 adopts Salamon's goaf compaction theory, and the elastic modulus E2 of gangue is obtained as follows: The program is compiled to change the elastic modulus as the roof compacts, achieving accurate simulation of gangue compaction.
4. A method for selecting coal mine filling materials according to claim 1, characterized in that: The implementation process of the program considering additional damage due to excavation in S3 adopts the following steps: S31: Obtain the scale parameter x0 and shape parameter m of the Weibull distribution, where the calculation formula is as follows: S32: Use the Weibull distribution function to describe the spatial distribution of the rock elastic modulus in the roof. Substitute the parameters obtained in step S31 to obtain the relationship between the elastic modulus of the roof and its strain: S33: Apply the above relationship to FLAC 3D In the Mohr-Coulomb model in, a program is compiled based on formula (6) to make the elastic modulus change with rock damage. When ε<ε0, the rock material is in the elastic deformation stage, and when the axial strain ε is greater than the strain threshold ε0.
5. A method for selecting coal mine filling materials according to claim 1, characterized in that: The mechanical parameters and constitutive model selection of the filling material in S4 are determined by the following method: A numerical model of a 50mm×100mm cylindrical standard specimen was established, and the goaf gangue was calibrated with the Double-Yield, Mohr-Coulomb and Strain-Softening models and the uniaxial test data. According to the calibration results, a suitable constitutive model was selected and the material constitutive model parameters were determined.