A method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working faces

Abstract

The present invention relates to a method for optimizing spatiotemporal parameters of water-preserving mining of an underground longwall working face, comprising: investigating and acquiring hydrogeological characteristics of a mine and occurrence characteristics of a coal seam; constructing a three-dimensional geological model according to the geological conditions of the mine and the physical and mechanical parameters of coal and rock; designing a simulation scheme for spatiotemporal parameters of mining; determining the maximum horizontal deformation value of an aquiclude of each simulation scheme; determining the sensitivity ranking of factors affecting the maximum horizontal deformation of the aquiclude, and establishing a functional relationship between the spatiotemporal parameters of mining and the maximum horizontal deformation of the aquiclude; constructing a parameter group to be analyzed, calculating the maximum horizontal deformation value of an aquiclude of the parameter group to be analyzed and the critical horizontal deformation value of instability of the aquiclude of a target underground longwall working face; and judging whether the parameter group to be analyzed is the optimal parameter by comparing the maximum horizontal deformation value of an aquiclude of the parameter group to be analyzed with a data range that can realize water-preserving mining of a target underground longwall working face.

Description

Technical Field

[0001] The invention relates to a method for optimizing spatiotemporal parameters of water-preserving mining in an underground longwall working face, belongs to the technical field of water-preserving mining, and is a water-preserving mining technology based on mining source control. Background Art

[0002] Underground longwall coal mining faces are generally characterized by large-scale mining and high disturbance intensity, which can easily cause the movement, deformation, collapse and breakage of the stratum aquifer, resulting in a large loss of water resources in the overlying (underlying) aquifer and serious damage to the ecological environment.

[0003] In order to reduce the damage of underground coal mining to the surface ecology, patent CN114233392A proposes to adjust the length, width and height of the working face to control the surface subsidence and damage level. In addition, existing studies have shown that the degree of deformation and damage of the aquiclude is closely related to the spatiotemporal parameters of longwall working face mining, and the stability of the aquiclude is the key target area of ​​water conservation mining technology. However, how to establish the relationship between the spatiotemporal parameters of working face mining and the water-insulating stability of the aquiclude, and then achieve the control of the water-insulating stability of the aquiclude by optimizing the spatiotemporal parameters of working face mining, as well as the protection of water resources and ecological environment of the aquifer, is still an unresolved technical problem.

[0004] Therefore, to address this problem, it is necessary to develop a method for optimizing the spatiotemporal parameters of underground longwall working face water-preserving mining from the perspective of underground aquifer water resource protection to meet the needs of actual use. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method for optimizing spatiotemporal parameters of water-preserving mining in an underground longwall working face.

[0006] A method for optimizing spatiotemporal parameters of water-saving mining in an underground longwall working face, characterized in that: the functional relationship between the mining spatiotemporal parameters and the maximum horizontal deformation value of the impermeable layer is obtained according to the following steps SA1 to SA5, and then the optimal mining spatiotemporal parameters are obtained according to steps SP1 to SP5, so as to achieve water-saving mining in a target underground longwall working face:

[0007] Step SA1, obtaining the mine geological and hydrogeological characteristics and coal seam occurrence characteristics of the target underground longwall working face, and then proceeding to step SA2;

[0008] Step SA2, constructing a three-dimensional geological model of the target underground longwall working face according to the mine geological conditions and the physical and mechanical parameters of coal and rock, and verifying the three-dimensional geological model, and then proceeding to step SA3;

[0009] Step SA3, based on the preset initial values ​​corresponding to the mining time and space parameters, combined with the preset gradient rules corresponding to the mining time and space parameters, obtain the progressive values ​​corresponding to the mining time and space parameters, and through the combination of the progressive values ​​of the mining time and space parameters, form a simulation scheme of the selected mining time and space parameters corresponding to the target underground longwall working face, and then enter step SA4;

[0010] Step SA4, for each selected mining space-time parameter simulation scheme corresponding to the target underground longwall working face, determine the maximum horizontal deformation value of the aquiclude corresponding to each selected mining space-time parameter simulation scheme according to the three-dimensional geological model of the target underground longwall working face, and then enter step SA5;

[0011] Step SA5, determining the sensitivity ranking of each mining time-space parameter on the maximum horizontal deformation of the aquiclude, forming a time-space parameter sensitivity ranking, and establishing a functional relationship between the parameter group formed by each mining time-space parameter and the maximum horizontal deformation of the aquiclude;

[0012] Execute steps SP1 to SP4 based on the spatiotemporal parameter sensitivity ranking;

[0013] Step SP1, based on the mutual constraints between the mining time and space parameters and the mine development design range, the random values ​​of the mining time and space parameters are defined in the order of the sensitivity of the time and space parameters, and the parameter group to be analyzed that does not participate in step SP2 to step SP4 is constructed, and then step SP2 is entered;

[0014] Step SP2, using the functional relationship between the parameter group constructed by each mining time and space parameter and the maximum horizontal deformation of the aquiclude, calculate the maximum horizontal deformation value of the aquiclude corresponding to the parameter group to be analyzed , then proceed to step SP3;

[0015] Step SP3: According to the physical and mechanical parameters of coal and rock, the critical horizontal deformation value of the instability of the water-proof layer of the target underground longwall working face is calculated. Perform calculations and then proceed to step SP4;

[0016] Step SP4: based on the critical horizontal deformation value of the instability of the aquiclude of the target underground longwall working face , construct the data range that can achieve water conservation mining of the target underground longwall working face, and determine the corresponding parameter group to be analyzed Whether it is within the data range, if so, the parameters constituting the parameter group to be analyzed are the optimal mining time and space parameters of the target underground longwall working face, and the optimization is completed; otherwise, execute step SP1.

[0017] Furthermore, the hydrogeological characteristics of the mine in step SA1 include: thickness of the aquifer or aquiclude, burial depth, aquifer recharge, runoff, and discharge conditions; and the occurrence characteristics of the coal seam include: thickness and burial depth of the coal seam.

[0018] Furthermore, the mine geological conditions and coal rock physical and mechanical parameters in step SA2 include: burial depth, rock layer thickness, density, bulk modulus, shear modulus, internal friction angle, cohesion, and tensile strength.

[0019] Furthermore, when the step SA2 is calibrated, a simulation scheme is constructed based on the actual mining plan and a preset fluctuation range, and numerical calculations are used based on the three-dimensional geological model to obtain numerical output values ​​corresponding to the simulation scheme, and the output values ​​are compared with the field measurement values, and the simulation parameters of the three-dimensional geological model are adjusted according to the errors.

[0020] Furthermore, the step SA5 uses the sensitivity determination method of the grey correlation analysis method to determine the sensitivity ranking of each mining time and space parameter on the maximum horizontal deformation of the aquiclude; and uses regression analysis to establish the functional relationship between the parameter group constructed by each mining time and space parameter and the maximum horizontal deformation of the aquiclude.

[0021] Furthermore, in step SP3, the critical horizontal deformation value of the instability of the water-proof layer of the target underground longwall working face is calculated based on the acquired physical and mechanical parameters of the coal and rock, using the following formula:

[0022] {\varepsilon}_{c}=\frac {1-\mu} {{E}_{a}}\left [ {{tan}^{2}\left ( {{45}^{\circ}-\frac {\varphi} {2}} \right )\gamma {H}_{0}+2ctan\left ( {{45}^{\circ}-\frac {\varphi} {2}} \right )} \right ]-\frac {\mu} {{E}_{a}}\gamma {H}_{0} ;

[0023] Where: It is the horizontal deformation of the aquiclude due to instability; is the Poisson's ratio of the aquiclude; is the compression modulus of the water-insulating layer; is the internal friction angle of the aquiclude; is the natural bulk density of the aquiclude; The depth of the aquiclude; c It is the cohesion of the waterproof layer.

[0024] The method for determining the functional relationship between the spatiotemporal parameters of working face mining and the maximum horizontal deformation of the aquiclude and the method for calculating the critical horizontal deformation of the aquiclude for water-insulating stability and instability proposed in the present invention are universal. Therefore, the present invention is also suitable for optimizing the spatiotemporal parameters of water-preserving mining of the roof aquifer and the floor aquifer of the coal seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic diagram of the process flow of implementing a method for optimizing spatiotemporal parameters of water-preserving mining in an underground longwall working face.

[0026] Figure 2 It is a comprehensive histogram of the strata in the embodiment of the present invention.

[0027] Figure 3 The figure is a schematic diagram of constructing a three-dimensional geological model according to an embodiment of the present invention.

[0028] Figure 4 It is the horizontal deformation curve of the waterproof layer in the embodiment of the present invention.

[0029] Figure 5 It is a comparison curve of the simulated value and the fitted predicted value of the horizontal deformation of the aquiclude in the embodiment of the present invention.

[0030] Figure 6 This is the groundwater level variation curve after the spatiotemporal parameters of water-preserving mining on the working face are optimized in the embodiment of the present invention. DETAILED DESCRIPTION

[0031] refer to Figure 1 , a method for optimizing spatiotemporal parameters of water-saving mining in an underground longwall working face, obtaining a functional relationship between the mining spatiotemporal parameters and the maximum horizontal deformation value of the impermeable layer according to the following steps SA1 to SA5, and then obtaining the optimal spatiotemporal parameters of mining according to steps SP1 to SP5, for achieving water-saving mining in a target underground longwall working face:

[0032] Step SA1, through on-site investigation, obtain the hydrogeological characteristics of the underground longwall working face of the target mine and the characteristics of the coal seam occurrence. Among them, the drainage conditions are used to determine whether the aquifer needs to be protected; the thickness and burial depth of the aquifer, aquiclude or coal seam, etc. Figure 2 As shown in Figure 2, the gravel aquifer is mainly recharged by atmospheric rainfall and snowmelt from the mountains, with a recharge rate of 2.01×10 -4 m / d, that is, under no discharge conditions, the water level of the gravel aquifer will increase by 2.01×10 -4 m;

[0033] Step SA2, based on the mine geological conditions and coal rock physical and mechanical parameters, wherein the coal rock physical and mechanical parameters are specifically referred to in Table 1, and in Table 1, 21-1 coal is a number for coal seams in geological exploration, 21 represents No. 21 coal, and 1 represents the upper layer of No. 21 coal, construct a three-dimensional geological model of the target underground longwall working face, such as Figure 3 As shown, the three-dimensional geological model is checked, that is, based on the actual mining plan, a simulation plan is constructed with a fluctuation interval of 5%, and based on the three-dimensional geological model, numerical calculation is used to obtain the numerical output value corresponding to the simulation plan, where the output value can be the surface subsidence monitored on site or the advance support pressure, and the output value is compared with the on-site measurement value, and the simulation parameters of the three-dimensional geological model are adjusted according to the error;

[0034] Table 1

[0035] Lithology Thickness (m) <![CDATA[Density (kg / m 3 ).]]> Bulk modulus (GPa) Shear modulus (GPa) Internal friction angle (°) Cohesion (MPa) Tensile strength (MPa) Silt layer 20 2045 0.40 0.26 15 0.6 0.3 Gravel layer 10 2240 0.48 0.34 25 1.7 1.3 Mudstone 5 2300 0.80 0.53 35 2.0 1.60 sandstone 50 2450 1.05 0.66 37 3.2 2.6 Mudstone 10 2250 0.83 0.56 32 2.6 2.3 sandstone 10 2600 0.96 0.58 33 3.4 2.8 Mudstone 10 2300 0.90 0.54 35 1.8 1.5 21-1 Coal 5 1400 0.50 0.28 26 0.8 0.4 Mudstone 25 2350 0.88 0.65 35 2.5 2.1

[0036] Step SA3, select the mining height L 1 , working surface length L 2 , continuous advancement length L 3 , sampling speed L 4 As mining time and space parameters, the initial values ​​of mining height, working face length, continuous advancement length and mining speed are designed according to the engineering analogy method. L 10 =3.0m, L 20 =100m, L 30 =500m, L 40 =6.0m / d, that is, the initial mining speed is 6.0m per day, and it is increased by the gradient rule of 0.5m, 50m, 500m, and 1.5m / d respectively. By combining the mining height, working face length, continuous advancement length, and the incremental value of the mining speed, 25 groups of candidate mining time and space parameter simulation schemes corresponding to the target underground longwall working faces are obtained. See Table 2 for details;

[0037] Table 2

[0038] Serial number Mining height (m) Working surface length (m) Continuous propulsion length (m) Mining speed (m / d) 1 3.0 100 500 6.0 2 3.0 150 1500 10.5 3 3.0 200 2500 7.5 4 3.0 250 1000 12.0 5 3.0 300 2000 9.0 6 3.5 100 2500 10.5 7 3.5 150 1000 7.5 8 3.5 200 2000 12.0 9 3.5 250 500 9.0 10 3.5 300 1500 6.0 11 4.0 100 2000 7.5 12 4.0 150 500 12.0 13 4.0 200 1500 9.0 14 4.0 250 2500 6.0 15 4.0 300 1000 10.5 16 4.5 100 1500 12.0 17 4.5 150 2500 9.0 18 4.5 200 1000 6.0 19 4.5 250 2000 10.5 20 4.5 300 500 7.5 21 5.0 100 1000 9.0 22 5.0 150 2000 6.0 23 5.0 200 500 10.5 24 5.0 250 1500 7.5 25 5.0 300 2500 12.0

[0039] Step SA4, for the 25 groups of selected mining time-space parameter simulation schemes corresponding to the target underground longwall working face, according to the three-dimensional geological model of the target underground longwall working face, determine the maximum horizontal deformation value of the aquiclude corresponding to each selected mining time-space parameter simulation scheme. The maximum horizontal deformation value of the aquiclude is specifically shown in Table 3, and the horizontal deformation curve of the aquiclude is shown in Figure 4 As shown;

[0040] Table 3

[0041] plan Horizontal deformation (mm / m) plan Horizontal deformation (mm / m) plan Horizontal deformation (mm / m) plan Horizontal deformation (mm / m) plan Horizontal deformation (mm / m) 1 6.61 6 10.84 11 11.50 16 14.34 21 12.98 2 8.76 7 9.44 12 10.92 17 15.86 22 14.92 3 9.45 8 11.95 13 13.01 18 14.16 23 14.70 4 9.72 9 10.44 14 14.87 19 15.93 24 16.50 5 10.57 10 12.02 15 13.57 20 13.33 25 19.80

[0042] Step SA5, based on the sensitivity determination method of the grey correlation analysis method, the sensitivity of the impact of mining height, working face length, continuous advancement length, and mining speed on the maximum horizontal deformation of the aquiclude is determined as follows: mining height > working face length > mining speed > continuous advancement length. At the same time, through regression analysis, the functional relationship between the four factors of mining height, working face length, continuous advancement length, and mining speed and the maximum horizontal deformation of the aquiclude is established, and the fitting prediction value and simulation value are as follows: Figure 5 As shown:

[0043] ;

[0044] Step SP1, based on the mutual constraints between various mining time and space parameters and the design scope of mine development, that is, based on not leaving behind coal resources and efficient development of coal resources, and after the mining area is divided, the advancement distance can be determined, and the mining height, face length, and mining speed can be adjusted according to the actual production process. Therefore, the initial design parameters of the mine are first analyzed, and the mining height of 4.0m, the working face length of 200m, the continuous advancement length of 1500m, and the mining speed of 7.0m / d are defined in turn, and constructed as parameter group 1 to be analyzed;

[0045] Step SP2: Substitute the parameter group 1 to be analyzed determined in step SP1 into the functional relationship established in step SA5. After calculation, the maximum horizontal deformation value of the aquiclude corresponding to the parameter group 1 to be analyzed can be obtained. =12.94mm / m;

[0046] Step SP3, calculate the critical horizontal deformation value of the water-proof stability of the target underground longwall working face based on the physical and mechanical parameters of the coal rock ,in The calculation formula is:

[0047] {\varepsilon}_{c}=\frac {1-\mu} {{E}_{a}}\left [ {{tan}^{2}\left ( {{45}^{\circ}-\frac {\varphi} {2}} \right )\gamma {H}_{0}+2ctan\left ( {{45}^{\circ}-\frac {\varphi} {2}} \right )} \right ]-\frac {\varphi} {{E}_{a}}\gamma {H}_{0} ;

[0048] Where: It is the horizontal deformation of the aquiclude due to instability; is the Poisson's ratio of the aquiclude; is the compression modulus of the water-insulating layer; is the internal friction angle of the aquiclude; is the natural bulk density of the aquiclude; Buried as a water barrier; c is the cohesion of the water-blocking layer. After calculation, we can get: =18.12mm / m;

[0049] Step SP4: based on the critical horizontal deformation value of the instability of the aquiclude of the target underground longwall working face , the data range for achieving water conservation mining of the target underground longwall working face is 0.9 ≤ ≤ ， And compare the corresponding parameters of the parameter group 1 to be analyzed In relation to the preset range, the results show that: =12.94mm / m<0.9 =16.31mm / m, indicating that the mining time and space parameters in the parameter group 1 to be analyzed failed to give full play to the water-proof performance of the aquiclude, and the design parameters were relatively safe and not the optimal parameters;

[0050] Return to step SP1 to define random values ​​of each mining time and space parameter: mining height 5.0m, working face length 200m, continuous advancement length 1500m, mining speed 7.0m / d, and construct them as parameter group 2 to be analyzed. Execute steps SP2 to SP4 again to obtain the corresponding values ​​of parameter group 2 to be analyzed. =15.98mm / m<0.9 =16.31mm / m, indicating that the mining time and space parameters in parameter group 2 to be analyzed failed to give full play to the water-proof performance of the aquiclude, and are not optimal parameters;

[0051] Return to step SP1 again to define the random values ​​of each mining time and space parameter: mining height 5.0m, working face length 300m, continuous advancement length 1500m, mining speed 7.0m / d, and construct them as parameter group 3 to be analyzed. Execute steps SP2 to SP4 again to obtain the corresponding values ​​of parameter group 3 to be analyzed. =17.20mm / m, and 0.9 =16.31mm / m< =17.20mm / m<0.95 =17.21 mm / m, indicating that the mining time-space parameters constituting the parameter group 3 to be analyzed are the optimal mining time-space parameters of the target underground longwall working face, and the mining time-space parameters of the target underground longwall working face are optimized;

[0052] When the target underground longwall working face was mined with the optimized mining time and space parameters (i.e., mining height 5.0m, working face length 300m, continuous advancement length 1500m, and mining speed 7.0m / d), no large-scale water-conducting fractures were generated inside the aquiclude, and the aquiclude had good water-proof properties. When the overburden movement stabilized, the water level of the aquifer gradually recovered under the action of water source recharge. For details, see the model verification included in Figure 6 , the working face achieved water-conserving mining.

[0053] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for optimizing spatiotemporal parameters of water-saving mining in an underground longwall working face, characterized in that: The functional relationship between the mining time-space parameters and the maximum horizontal deformation value of the aquiclude is obtained according to the following steps SA1 to SA5, and then the optimal mining time-space parameters are obtained according to steps SP1 to SP5 to achieve water-preserving mining at the target underground longwall working face: Step SA1, obtaining the mine geological and hydrogeological characteristics and coal seam occurrence characteristics of the target underground longwall working face, and then proceeding to step SA2; Step SA2, constructing a three-dimensional geological model of the target underground longwall working face according to the mine geological conditions and the physical and mechanical parameters of coal and rock, and verifying the three-dimensional geological model, and then entering step SA3; Step SA3, based on the preset initial values ​​corresponding to the mining time and space parameters, combined with the preset gradient rules corresponding to the mining time and space parameters, obtain the progressive values ​​corresponding to the mining time and space parameters, and through the combination of the progressive values ​​of the mining time and space parameters, form a simulation scheme of the selected mining time and space parameters corresponding to the target underground longwall working face, and then enter step SA4; Step SA4, for each selected mining space-time parameter simulation scheme corresponding to the target underground longwall working face, determine the maximum horizontal deformation value of the aquiclude corresponding to each selected mining space-time parameter simulation scheme according to the three-dimensional geological model of the target underground longwall working face, and then enter step SA5; Step SA5, determining the sensitivity ranking of each mining time-space parameter on the maximum horizontal deformation of the aquiclude, forming a time-space parameter sensitivity ranking, and establishing a functional relationship between the parameter group formed by each mining time-space parameter and the maximum horizontal deformation of the aquiclude; Execute steps SP1 to SP4 based on the spatiotemporal parameter sensitivity ranking; Step SP1, based on the mutual constraints between the mining time and space parameters and the mine development design range, the random values ​​of the mining time and space parameters are defined in the order of the sensitivity of the time and space parameters, and the parameter group to be analyzed that does not participate in step SP2 to step SP4 is constructed, and then step SP2 is entered; Step SP2, using the functional relationship between the parameter group constructed by each mining time and space parameter and the maximum horizontal deformation of the aquiclude, calculate the maximum horizontal deformation value of the aquiclude corresponding to the parameter group to be analyzed , then proceed to step SP3; Step SP3: According to the physical and mechanical parameters of coal and rock, the critical horizontal deformation value of the instability of the water-proof layer of the target underground longwall working face is calculated. Perform calculations and then proceed to step SP4; Step SP4: based on the critical horizontal deformation value of the instability of the aquiclude of the target underground longwall working face , construct the data range that can achieve water-saving mining of the target underground longwall working face, and determine the corresponding parameter group to be analyzed Whether it is within the data range, if so, the parameters constituting the parameter group to be analyzed are the optimal mining time and space parameters of the target underground longwall working face, and the optimization is completed; otherwise, execute step SP1.

2. The method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working face according to claim 1, characterized in that: The hydrogeological characteristics of the mine in step SA1 include: thickness of aquifer or impermeable layer, burial depth, aquifer recharge, runoff, and discharge conditions; the occurrence characteristics of coal seams include: thickness and burial depth of coal seams.

3. The method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working face according to claim 1, characterized in that: The mine geological conditions and coal rock physical and mechanical parameters in step SA2 include: burial depth, rock layer thickness, density, bulk modulus, shear modulus, internal friction angle, cohesion, and tensile strength.

4. The method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working face according to claim 1, characterized in that: When the step SA2 is verified, a simulation scheme is constructed based on the actual mining scheme and the preset fluctuation range, and numerical calculation is used based on the three-dimensional geological model to obtain the numerical output value corresponding to the simulation scheme, and the output value is compared with the field measurement value, and the simulation parameters of the three-dimensional geological model are adjusted according to the error.

5. The method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working face according to claim 1, characterized in that: The step SA5 uses the sensitivity determination method of the grey correlation analysis method to determine the sensitivity ranking of each mining time and space parameter on the maximum horizontal deformation of the aquiclude; and uses regression analysis to establish the functional relationship between the parameter group constructed by each mining time and space parameter and the maximum horizontal deformation of the aquiclude.

6. The method for optimizing spatiotemporal parameters of water-saving mining in underground longwall working face according to claim 1, characterized in that: In step SP3, the critical horizontal deformation value of the instability of the water-proof layer of the target underground longwall working face is calculated based on the obtained physical and mechanical parameters of the coal and rock, using the following formula: ； Where: It is the horizontal deformation of the aquiclude due to instability; is the Poisson's ratio of the aquiclude; is the compression modulus of the water-insulating layer; is the internal friction angle of the aquiclude; is the natural bulk density of the aquiclude; The depth of the aquiclude; c It is the cohesion of the waterproof layer.

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