Coal mine continuous mining water inflow dynamic prediction method based on attenuation coefficient

Abstract

The invention discloses a coal mine continuous mining water inflow dynamic prediction method based on an attenuation coefficient, and belongs to the field of coal mining water disaster prevention and control. The method comprises the following steps: collecting water inflow monitoring data after stoping of a first mining working face is completed; determining a goaf water inflow attenuation coefficient based on the water inflow monitoring data; hydrogeological parameters of a plurality of to-be-predicted working faces are obtained, and based on the hydrogeological parameters, the predicted normal goaf water inflow of each to-be-predicted working face is calculated through a catchment gallery method; and on the basis of the goaf water inflow attenuation coefficient and the coal mine continuous mining plan, weighted summation is carried out on the goaf predicted normal water inflow of the multiple to-be-predicted working faces, and an overall normal water inflow prediction result of the goaf formed by coal mine continuous mining is obtained.

Description

Technical Field

[0001] This invention belongs to the field of coal mining water hazard prevention technology, and particularly relates to a dynamic prediction method for water inflow in coal mines based on attenuation coefficient. Background Technology

[0002] When estimating the normal water inflow of coal mines during continuous mining operations, the water inflow of previously developed working faces significantly decreases and stabilizes as the number of goaf faces increases. However, the overall normal water inflow forecast still uses the entire goaf area as the calculation region, failing to consider the attenuation of water inflow in goaf areas of already mined working faces. This results in a significantly higher predicted overall normal water inflow than the actual figure. Accurately predicting the roof water inflow in goaf areas is crucial for the effective layout of coal mine drainage systems and the prevention of roof water hazards. Therefore, this invention provides a dynamic prediction method for coal mine water inflow during continuous mining operations based on an attenuation coefficient. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a dynamic prediction method for water inflow in coal mines based on attenuation coefficients, thereby resolving the issues present in the existing technologies.

[0004] To achieve the above objectives, this invention provides a method for dynamic prediction of water inflow in coal mines based on attenuation coefficients, comprising:

[0005] Collect monitoring data on water inflow after the first mining face has been mined out;

[0006] Based on the water inflow monitoring data, the water inflow attenuation coefficient of the goaf area is determined;

[0007] Obtain the hydrogeological parameters of multiple working faces to be predicted, and calculate the expected normal water inflow of the goaf area of ​​each working face to be predicted using the water collection corridor method based on the hydrogeological parameters.

[0008] Based on the attenuation coefficient of the goaf water inflow and the coal mine succession mining plan, the expected normal water inflow of the goaf of multiple working faces to be predicted is weighted and summed to obtain the overall normal water inflow prediction result of the goaf formed by the coal mine succession mining.

[0009] Optionally, the process of determining the attenuation coefficient of the goaf water inflow based on the water inflow monitoring data includes:

[0010] The water inflow monitoring data is periodically divided based on the date of completion of the first mining face.

[0011] The slope of the fitted line is obtained by linearly fitting the water inflow data for each cycle.

[0012] The attenuation coefficient of water inflow in the goaf is calculated based on the slope of the fitted line.

[0013] Optionally, when the absolute value of the slope of the fitted line is less than or equal to 0.05, the attenuation coefficient of the corresponding period and subsequent periods is assigned a value of 1.

[0014] Optionally, the hydrogeological parameters include: permeability coefficient, aquifer thickness, water column height, goaf length, and goaf width.

[0015] Optionally, the expression for calculating the permeability coefficient is:

[0016] ;

[0017] In the formula, K is the permeability coefficient, R0 is the radius of influence, r0 is the aperture, Q is the expected normal water inflow in the goaf, H is the water column height, h is the height of the residual water column, and M is the aquifer thickness.

[0018] Optionally, the expression used to calculate the expected normal inflow of water into the goaf using the water collection gallery method is as follows:

[0019] ;

[0020] In the formula, Q is the expected normal water inflow in the goaf, K is the permeability coefficient, H is the water column height, h is the residual water column height, M is the aquifer thickness, B is the length of the water collection corridor, and R is the radius of influence.

[0021] Optionally, the expression for calculating the overall normal inflow prediction result is as follows:

[0022] Q=Q 1* α 1* α 2…* α m…* α n +Q 2* α 1* α 2…… α n-1 +……+Q n-1* α1 +Q n ;

[0023] In the formula, Q represents the overall predicted normal water inflow, Q1 represents the estimated normal water inflow of the goaf after the first working face is mined out, Q2 represents the estimated normal water inflow of the goaf after the first working face is mined out, and Q... n The normal water inflow in the goaf of the working face is α1; α1 is the attenuation coefficient of the goaf water inflow in the first cycle. m Let α be the attenuation coefficient of water inflow in the goaf during the m-th cycle. n This is the attenuation coefficient of water inflow in the goaf during the nth cycle.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The method for predicting normal mine water inflow provided by this invention fully considers the attenuation and stabilization process of water inflow in the goaf area during the early stages of mining. It considers the attenuation coefficient and proposes a calculation method for the attenuation coefficient. An analytical method is used to predict the normal water inflow of the roof in the working face goaf area. Instead of using the entire goaf area as the calculation area, the method uses the goaf area of ​​each working face as the calculation area, multiplying the attenuation by the corresponding attenuation coefficient based on the number of years the goaf area will be mined. The normal water inflow of the working face goaf area currently being mined is not considered for the attenuation coefficient. The same method is used to calculate the normal water inflow of other working face goaf areas. Finally, the normal water inflow of all working face goaf areas is summed to obtain the predicted result of the normal water inflow of the entire goaf area. Based on this method, the normal mine water inflow can be predicted more accurately, providing data reference for the design and construction of drainage systems and the prevention of roof water hazards, thereby ensuring safe mine production. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a flowchart illustrating the implementation of the method according to an embodiment of the present invention;

[0028] Figure 2 This is an example of the layout of a coal mine working face in an embodiment of the present invention (where working face 2101 is the first working face of the mine).

[0029] Figure 3 This is data on the change in water inflow since the first mining operation at the 2101 working face in this embodiment of the invention;

[0030] Figure 4 This is a sample of the water inflow and related fitted curve after the completion of the first mining operation at the 2101 working face in this embodiment of the invention.

[0031] Figure 5 This is a schematic diagram of the water collection corridor when the 2217 working face is completed in 2028, according to an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of the water collection corridor when the 2215 working face is completed in 2030, according to an embodiment of the present invention.

[0033] Figure 7 This is a schematic diagram of the water collection corridor when the 2213 working face is completed in 2033, according to an embodiment of the present invention. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0036] Example 1

[0037] like Figure 1 As shown, this embodiment provides a method for dynamic prediction of coal mine water inflow based on attenuation coefficient, including the following steps:

[0038] S1. Based on the mining method, collect data on the change in water inflow since the first mining face of the mining area or mine has been mined. In step S1, the mine is divided into different mining areas or panels according to the thickness of the coal seam being mined, and data on the change in water inflow since the first mining face of the mining area or panel has been collected. If the mine has not been divided into mining areas or panels, data on the change in water inflow since the first mining face of the mine can also be collected.

[0039] This step specifically involves: based on the layout of a coal mine's working face, such as... Figure 2 As shown, the data on the change in water inflow at the first mining face 2101 are as follows: Figure 3 As shown, since the start of mining on December 21, 2017, the initial inflow was 82 m³. 3 / h, as of February 9, 2019, the first mining face of 2101 had completed its longwall mining, with a water inflow of 308 m³. 3 / h, with a maximum water inflow of 355.4 m³ during the extraction period. 3 / h. After the mining operation ended, by February 9, 2020, one year after the end of the mining operation, the water inflow decreased to 205 m³. 3 / h; By February 9, 2021, two years after the end of extraction, the water inflow had decreased to 150 m³. 3 / h; By February 9, 2022, three years after the end of extraction, the water inflow had decreased to 146 m³. 3 / h; Data recording ended on December 31, 2022, with a flow rate of 144 m³. 3 / h, the final inflow rate stabilized at 150 m³ / h. 3 / h or so.

[0040] S2. Determine the relevant hydrogeological parameters for the estimated water inflow in the mined-out area;

[0041] The specific steps are as follows: collect relevant borehole data around the calculation area, organize the distribution of coal seam thickness, calculate the development and distribution of water-conducting fracture zones in the mining area using the fracture-to-mining ratio, determine the aquifer thickness (M) within the development height of the water-conducting fracture zone in the goaf (within the fracture height), collect and organize the aquifer water level elevation H1, the aquifer floor elevation H2, the goaf length a, and the goaf width b. Wherein, the water column height H = H1 - H2. The permeability coefficient (K) can be determined based on the corresponding aquifer permeability coefficient value obtained from the mine hydrogeological borehole pumping test, or based on the water inflow data from the first mining face, determining the normal water inflow value of the working face, and then calculating the corresponding permeability coefficient value using analytical methods.

[0042] Since the permeability coefficient value of the aquifer within the expected guide height of the first mining face 2101 is not available from relevant hydrological well pumping tests, but the maximum water inflow during the mining process of the first mining face 2101 is known to be 355.1 m³,... 3 / h, then the value is 337.3 m 3 / h, and other relevant parameters, as shown in Table 1, can be used in conjunction with calculation software or Excel spreadsheets, and the steady flow rate calculation formula for a complete well transitioning from pressure to unpressured in the "large well method" to back-calculate the value of the permeability coefficient (K). The formula for calculating the permeability coefficient (K) is as follows:

[0043] ,in , , .

[0044] The permeability coefficient of the first mining face 2101 was calculated to be 0.0314 m / d.

[0045] Table 1

[0046]

[0047] Continue to collect and organize relevant hydrogeological parameters of working faces 2217, 2215 and 2213 in panel 22 to predict the water inflow in the goaf, as shown in Tables 2, 3 and 4.

[0048] Table 2

[0049]

[0050] Table 3

[0051]

[0052] Table 4

[0053]

[0054] S3. Calculate and determine the attenuation coefficient of water inflow in the goaf. The specific method is to collect water inflow data from the first mining face, take the completion date of the first mining face as the starting point, and use the year (quarter or month) as the cycle to perform linear fitting on the water inflow data for each cycle, and obtain the slope k of the fitting line. Then the attenuation coefficient of water inflow in the goaf is α=1+k. When |k|≤0.05, it is considered that the water inflow in the goaf has basically attenuated to a stable stage, and k=0 is taken. After that, the attenuation coefficient is taken as α=1.

[0055] Based on the water inflow data after the completion of the first mining operation at the 2101 working face, the data was divided into annual periods. A linear fit was performed on the water inflow for each year, and the attenuation coefficient of the water inflow in the goaf of the 2101 working face was calculated based on the slope k of the fitted line. Figure 4 As shown, on February 9, 2019, the first mining face of 2101 completed its longwall mining, with a water inflow of 308 m³. 3 / h, where in the first year after mining is completed, the slope of the fitted line is k1=-0.26642; in the second year after mining is completed, the slope of the fitted line is k2=-0.1673; in the third year after mining is completed, the slope of the fitted line is k3=-0.00934; and in the fourth year after mining is completed, the slope of the fitted line is k4=-0.0174. Therefore, the water inflow attenuation coefficient in the goaf in the first year is α1=1+k1=0.73358, and the water inflow attenuation coefficient in the second year is α2=1+k2=0.8327. Since |k3|≤0.05 and |k4|≤0.05, the water inflow in the goaf has basically attenuated to a stable stage. Taking k=0, therefore α1=α2……=α n =1.

[0056] S4. Based on the hydrogeological parameters, attenuation coefficients, and coal mine follow-up mining plans determined in steps S2 and S3, the normal water inflow of the continuously expanding goaf area in the mine is predicted using the water collection corridor method. The mining plan for the three working faces (2217, 2215, and 2213) in the 22nd panel of a certain coal mine from 2026 to 2033 is as follows: Figure 2 As shown in Tables 5, 6, and 7, the relevant hydrogeological parameters of the three working faces are calculated based on the normal water inflow of the goaf formed by continuous mining of the coal mine, as follows:

[0057] Q=Q 1* α 1* α 2…* α m…* α n +Q 2* α 1* α 2…… α n-1 +……+Q n-1* α1 +Q n

[0058] In the formula, Q1 represents the expected normal water inflow in the goaf area after the first working face is mined out, and so on, Q... n α1 represents the normal water inflow in the goaf of the working face; α1 is the attenuation coefficient of the goaf water inflow in the first cycle, and so on, up to α... m =1, then α m ...α n All calculations are taken as 1.

[0059] ① In accordance with the mining plan, the first working face of the 2217 working face in the 22 panel area will be completed and mined out in 2028, with a normal water inflow Q. 2017 =363.19m 3 At this time, the estimated normal water inflow Q in the goaf of panel 22 is shown in Table 5 and... Figure 5 As shown:

[0060] Table 5

[0061]

[0062] Therefore, when the 2217 working face finishes mining in 2028, the normal water inflow in the goaf of the 22 panel will be Q = Q 2217 =363.19m 3 / h.

[0063] ②The second working face in the 22nd panel area, 2215, was completed and mining was finished in 2030. The normal water inflow of the 2215 working face is Q. 2015 =214.35m 3 / h, at this time, the estimated normal water inflow Q of the goaf in panel 22 should be the sum of the normal water inflows of the goaf in working face 2217 and working face 2215. Since working face 2217 has been mined for 2 years, the normal water inflow of working face 2217 should be multiplied by the attenuation coefficients of the first year after mining completion (2029) and the second year after mining completion (2030), i.e., α1=0.73358 and α2=0.8327. The estimated normal water inflow Q of the goaf in panel 22 is shown in Table 6 and Figure 6 As shown:

[0064] Table 6

[0065]

[0066] Therefore, when the 2215 working face finishes mining in 2030, the normal water inflow in the goaf of the 22 panel will be Q = Q 2217 *α1*α2+Q 2215 =423.04m 3 / h.

[0067] ③The third working face in panel 22, 2213, was completed in 2033. The normal water inflow of working face 2213 is Q. 2013 =206.41m 3 / h, at this point, the estimated normal water inflow Q for the goaf of panel 22 should be the sum of the normal water inflows of the goafs of working faces 2217, 2215, and 2213. Since working face 2217 has been mined for 5 years, the normal water inflow of the goaf of working face 2217 should be multiplied by the attenuation coefficient from the first year (2029) to the fifth year (2033) after mining completion, i.e., α1=0.733. 58. α2=0.8327, α3=1, α4=1, α5=1, and at this time, the 2215 working face has been mined for 3 years. The normal water inflow of the goaf of the 2215 working face should be multiplied by the attenuation coefficient from the first year (2031) to the third year (2033) after mining is completed, i.e., α1=0.73358, α2=0.8327, α3=1. The estimated normal water inflow Q of the goaf of the 22 panel is shown in Table 7 and Figure 7 As shown:

[0068] Table 7

[0069]

[0070] Therefore, when the 2213 working face finishes mining in 2033, the normal water inflow in the goaf of the 22 panel will be Q = Q 2217 *α1*α2*α3*α4*α5+Q 2215 *α1*α2*α3+Q 2213 =546.03m 3 / h.

[0071] In step S4, the calculation formula for the water inflow of the stable flow mine in the confined-to-unconfined water complete well using the water collection gallery method is as follows:

[0072] ,in .

[0073] In the formula: Q is the water inflow in the goaf, taken as 95% of the maximum water inflow during the working face mining process (to eliminate the randomness of the maximum water inflow), m 3 / d; K is the aquifer permeability coefficient, m / d; H is the water column height, m; S is the drawdown, m, which is the distance from the static water level to the drainage elevation (bottom of the aquifer), S=H; h is the residual water column height, since the water level often drops to the bottom of the working face, h=0, m; M is the aquifer thickness, m; r0 is the reference borehole diameter of the "large well", m, "large well" is rectangular; R0 is the reference radius of the "large well", m; R is the radius of influence, m; a is the length of the goaf, m; b is the width of the goaf, m; η is the generalization coefficient, the values ​​of which are shown in Table 8.

[0074] Table 8

[0075]

[0076] S5. The normal water inflow in the goaf formed by continuous mining in coal mines is calculated using the following formula:

[0077] Q=Q 1* α 1* α 2…* α m…* α n +Q 2* α 1* α 2…… α n-1 +……+Q n-1* α1 +Q n

[0078] In the formula, Q1 represents the expected normal water inflow in the goaf area after the first working face is mined out, and so on, Q... n α1 represents the normal water inflow in the goaf of the working face; α1 is the attenuation coefficient of the goaf water inflow in the first cycle, and so on, up to α... m =1, then α m ...α n All calculations are 1.

[0079] In summary, this invention, by fully considering the attenuation and stabilization process of water inflow in the goaf during the early stages, proposes an attenuation coefficient and lists methods for calculating the attenuation coefficient. An analytical method is used to predict the normal water inflow in the roof of the working face goaf. Furthermore, instead of using the entire goaf area as the calculation region, the estimated mine water inflow is calculated for each working face goaf, multiplying the attenuation by the corresponding attenuation coefficient based on the number of years the goaf has been mined. The normal water inflow in the working face goaf currently being mined is not considered for the attenuation coefficient. The same analytical method is used to calculate the normal water inflow in other working face goafs. Finally, the normal water inflow in all working face goafs is summed to obtain the estimated normal water inflow for the entire goaf area. Based on this method, the normal mine water inflow can be predicted more accurately, providing data reference for the design and construction of drainage systems and the prevention of roof water hazards, thereby ensuring safe mine production.

[0080] This invention uses an analytical method to predict the normal water inflow in the goaf of a mine, and considers the attenuation coefficient of the water inflow at the goaf face, so as to achieve a more accurate prediction of the overall normal water inflow of the mine. It solves the problems of lack of attenuation and incomplete consideration of the prediction process in the prediction of mine water inflow, and provides data support for the design of mine drainage system, thereby ensuring safe production in coal mines.

[0081] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for dynamic prediction of water inflow in coal mines based on attenuation coefficient, characterized in that, Includes the following steps: Collect monitoring data on water inflow after the first mining face has been mined out; Based on the water inflow monitoring data, the water inflow attenuation coefficient of the goaf area is determined; Obtain the hydrogeological parameters of multiple working faces to be predicted, and calculate the expected normal water inflow of the goaf area of ​​each working face to be predicted using the water collection corridor method based on the hydrogeological parameters. Based on the attenuation coefficient of the goaf water inflow and the coal mine succession mining plan, the expected normal water inflow of the goaf of multiple working faces to be predicted is weighted and summed to obtain the overall normal water inflow prediction result of the goaf formed by the coal mine succession mining.

2. The method for dynamic prediction of coal mine water inflow based on attenuation coefficient according to claim 1, characterized in that, The process of determining the attenuation coefficient of water inflow in the goaf based on the water inflow monitoring data includes: The water inflow monitoring data is periodically divided based on the date of completion of the first mining face. The slope of the fitted line is obtained by linearly fitting the water inflow data for each cycle. The attenuation coefficient of water inflow in the goaf is calculated based on the slope of the fitted line.

3. The method for dynamic prediction of water inflow in coal mines based on attenuation coefficient according to claim 2, characterized in that, When the absolute value of the slope of the fitted line is less than or equal to 0.05, the attenuation coefficient of the corresponding period and subsequent periods is assigned a value of 1.

4. The method for dynamic prediction of coal mine water inflow based on attenuation coefficient according to claim 1, characterized in that, The hydrogeological parameters include: permeability coefficient, aquifer thickness, water column height, goaf length, and goaf width.

5. The method for dynamic prediction of coal mine water inflow based on attenuation coefficient according to claim 4, characterized in that, The expression for calculating the permeability coefficient is as follows: ； In the formula, K is the permeability coefficient, R0 is the radius of influence, r0 is the aperture, Q is the expected normal water inflow in the goaf, H is the water column height, h is the height of the residual water column, and M is the aquifer thickness.

6. The method for dynamic prediction of water inflow in coal mines based on attenuation coefficient according to claim 4, characterized in that, The expression used to calculate the expected normal inflow of water into the goaf using the water collection gallery method is as follows: ； In the formula, Q is the expected normal water inflow in the goaf, K is the permeability coefficient, H is the water column height, h is the residual water column height, M is the aquifer thickness, B is the length of the water collection corridor, and R is the radius of influence.

7. The method for dynamic prediction of coal mine water inflow based on attenuation coefficient according to claim 1, characterized in that, The expression for calculating the overall normal inflow prediction result is as follows: Q=Q 1* a 1* a 2…* a m…* a n +Q 2* a 1* a 2…… a n-1 +……+Q n-1* α1 +Q n ; In the formula, Q represents the overall predicted normal water inflow, Q1 represents the estimated normal water inflow of the goaf after the first working face is mined out, Q2 represents the estimated normal water inflow of the goaf after the first working face is mined out, and Q... n The normal water inflow in the goaf of the working face is α1; α1 is the attenuation coefficient of the goaf water inflow in the first cycle. m Let α be the attenuation coefficient of water inflow in the goaf during the m-th cycle. n This is the attenuation coefficient of water inflow in the goaf during the nth cycle.

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