Method and system for eliminating ground fracturing source of extra-thick impact coal seam

Abstract

The invention discloses an extra-thick impact coal seam ground fracturing source elimination method and system, and relates to the technical field of coal mine underground mining safety, and the method comprises the steps: gathering initial mine transparent materials, and recognizing the thickness of a fracturing target layer; identifying the position of the fracturing targeting layer; determining the fracture step pitch of the target layer, and calculating the fracture impact energy of the target layer; calculating the pressure distribution of the target layer, determining a fracturing target point, drilling a hole from the middle part of the working surface, and performing ground fracturing on the position with the maximum pressure of the target layer. The method comprises the following steps: collecting initial transparent mine data of a mine, screening a rock stratum meeting the impact tendency, testing rock stratum mechanical parameters meeting the requirements through experiments, determining the thickness and the position of a target layer, circularly calculating the impact energy of the target layer according to the parameters of the target layer, and determining the fracturing step pitch of the target layer. The position with the maximum pressure in the pressure distribution of the target layer is determined in the fracturing step pitch to serve as a fracturing target point, and the rock burst of the extra-thick impact coal seam is prevented and controlled through precise fracturing of the fracturing target point.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine mining safety, and more particularly to a method and system for eliminating the source of ground fracturing in an extremely thick impact coal seam. Background Art

[0002] Extra-thick coal seams are widely distributed in my country and are the main mining seams for coal production. Extra-thick coal seams with rock burst are difficult to mine. When rock burst occurs, it will cause strong vibrations on the working face, impact the hydraulic supports on the working face, damage the supports, damage other equipment, cause coal mines to stop production, and lead to serious economic losses. It may even lead to secondary disasters such as tunnel destruction, coal and gas outbursts, etc., which seriously threaten the safe production of coal mines and the lives of workers. In addition, the suddenness and high destructiveness of rock burst are even more difficult to predict in the mining of extra-thick coal seams. The thickness of the coal seam increases the difficulty of predicting and preventing rock burst.

[0003] The mining of extra-thick coal seams has greatly limited the traditional means of predicting and controlling rock bursts. Surface fracturing, which has the advantage of advanced prevention and control and is not restricted by the underground environment, has been introduced to control rock bursts in extra-thick coal seams. However, the cost of surface fracturing for preventing and controlling rock bursts remains high, and the entire roof of the impact working face is often fractured. The high cost of fracturing has posed a huge challenge to the economic benefits of coal mines.

[0004] Therefore, how to propose a method and system for eliminating the source of ground fracturing in extra-thick impact coal seams, perform ground fracturing to control the impact ground pressure of extra-thick coal seams, achieve precise fracturing, increase the fracturing step distance, and reduce the fracturing cost is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0005] In view of this, the present invention provides a method and system for eliminating the source of ground fracturing in extra-thick impact coal seams, which performs ground fracturing to control the impact ground pressure of extra-thick coal seams, realizes precise fracturing, increases the fracturing step distance, and reduces the fracturing cost. In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for eliminating the source of surface fracturing in an extremely thick impact coal seam, comprising:

[0007] Step 1: Gather the initial mine transparent materials and identify the thickness of the fracturing target layer;

[0008] Collect the initial exploration data of the mine field, initially establish a transparent mine model, and identify the rock strata with impact tendency above the coal seam according to the rock strata occurrence properties;

[0009] The overlying rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 are screened, and the mechanical parameters of the rock layers that meet the conditions are measured, including the rock stiffness G i , Poisson's ratio μi , elastic modulus E i , compressive strengthσ i and shear strength t i ;

[0010] Thickness of the targeting layer h:

[0011]

[0012] Among them, m is the impact factor, and its value increases from 0 with an interval of 0.01. MATLAB performs loop calculations and stops the calculation when m≥5 or h>15m.

[0013] Step 2: Identify the target layer for fracturing;

[0014] Based on the preliminary data collected, the coal seam thickness h0 and the rock layer thickness parameter h within 50m above the coal seam were measured. i , select the incremental interval of the targeting factor according to the coal seam thickness h0, and judge whether the targeting layer determined in step 1 meets the targeting layer position condition. The targeting layer position condition is that the targeting factor n≥2 or H>200m. If it meets the condition, proceed to step 3. If not, redetermine the targeting layer thickness until the targeting layer meets the requirement;

[0015]

[0016] Among them, H is the layer where the target layer is located; h1…h i is the thickness of the rock layer within 50m above the coal seam, n is the targeting factor, if the coal seam thickness is less than or equal to 10m, its value starts from 0 and increases in intervals of 0.001; if the coal seam thickness is greater than 10m, it starts from 0 and increases in intervals of 0.01. When n≥2 or H>200m, the calculation stops;

[0017] Step 3: Determine the target layer breaking step and calculate the target layer breaking impact energy;

[0018] The initial breaking step and periodic breaking step of the target layer are determined based on the collected mine data. The average initial pressure step of the working face of the same coal seam is taken as the initial breaking step; the average periodic pressure step is taken as the periodic breaking step. The energy of the target layer breaking is as follows:

[0019]

[0020] Among them, U is the energy released by the breaking of the target layer, D1 and D2 are the elastic stiffness of the upper and lower rock layers respectively, D=EI, α, β are the underlying stiffness factors of the targeted layer, which are determined as follows: C1 and C2 are the shear stiffness of the upper and lower rock layers respectively; C = kGS, k is the cross-sectional factor of the target layer, the rectangular surface is taken as the calculation shape, k is 5 / 6, G is the shear modulus of the target layer, v is the rock deformation ratio, which is taken as 0.2, S=Bh, B is the unit width of the target layer, L is the overhang length of the target layer, q is the overburden load on the target layer, E is the elastic modulus of the target layer, D is the bending stiffness of the target layer, and h is the thickness of the target layer. e is a natural number, a, b, c are the pressure distribution factors of the target layer, and the formula is as follows:

[0021]

[0022] Substitute the initial breaking step and periodic breaking step of the target layer into the calculation of the breaking impact energy U1 and U2. If the energy is greater than 10 6 J, then proceed to step 4, otherwise end here and determine that the target layer does not need to be fractured;

[0023] Step 4: Calculate the pressure distribution of the target layer and determine the fracturing target point. The fracturing target point is determined by the pressure distribution. The magnitude of the overburden pressure of the target layer is determined by the following formula:

[0024]

[0025] Among them, x is the coordinate of the target layer advancing along the working surface, Substitute the fracture step of the target layer, derive the pressure distribution data of the target layer, plot the data, and determine the position with the maximum pressure in the target layer as the fracturing target point;

[0026] Step 5: Drill holes from the middle of the working face and perform surface fracturing at the location with the highest pressure in the targeted layer.

[0027] Optionally, step 5 further includes: arranging horizontal wells along the middle of the working surface, and performing fracturing in sequence according to the determined fracturing target points.

[0028] Optionally, a surface fracturing source elimination system for extra-thick impact coal seams includes:

[0029] Collection and identification module: used to collect transparent materials from the initial mine and identify the thickness of the fracturing target layer;

[0030] Target layer position identification module: used to identify the target layer position of fracturing;

[0031] Target layer breaking impact energy calculation module: used to determine the breaking step of the target layer and calculate the breaking impact energy of the target layer;

[0032] Fracturing target determination module: used to calculate the pressure distribution of the target layer and determine the fracturing target.

[0033] Ground fracturing module: used to drill holes from the middle of the working face and perform ground fracturing at the location with the highest pressure in the targeted layer.

[0034] Optionally, the surface fracturing module further includes: arranging horizontal wells along the middle of the working surface, and performing fracturing in sequence according to the determined fracturing target points.

[0035] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method and system for eliminating the source of surface fracturing in an extra-thick impact coal seam, which has the following beneficial effects:

[0036] The present invention proposes a method and system for eliminating the source of ground fracturing in extra-thick impact coal seams. The method collects transparent mining data from the initial stage of the mine, screens rock layers that meet the impact tendency, and experimentally tests the mechanical parameters of the rock layers that meet the requirements to determine the thickness and position of the target layer. The impact energy of the target layer is cyclically calculated based on the target layer parameters, and the fracturing step of the target layer is determined. The maximum pressure position in the pressure distribution of the target layer is determined in the fracturing step as the fracturing target point, and the impact ground pressure of the extra-thick impact coal seams is prevented and controlled through precise fracturing of the fracturing target point. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0038] Figure 1 A schematic flow chart of a method for eliminating the source of surface fracturing in an extra-thick impact coal seam provided by the present invention.

[0039] FIG. 2( a ) is a plan view of the fracturing provided by the present invention.

[0040] FIG2( b ) is a cross-sectional view of the fracturing provided by the present invention.

[0041] Figure 3 Plotting the data provided by the present invention.

[0042] Figure 4 A structural framework diagram of a surface fracturing source elimination system for extra-thick impact coal seams provided by the present invention.

[0043] Among them, 1-extra-thick coal seam, 2-target layer, 3-horizontal fracturing well, 4-fracturing target point, 5-vertical section of fracturing well. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The embodiment of the present invention discloses a method for eliminating the source of ground fracturing in an extremely thick impact coal seam. Figure 1 As shown, including:

[0046] Step 1: Gather the initial mine transparent materials to identify the thickness of the fracturing target layer; collect the initial exploration data of the well field, preliminarily establish the mine transparent model, and identify the rock layer with impact tendency above the coal seam according to the rock layer occurrence properties. Rock layers with impact tendency generally have the characteristics of high strength, high hardness and strong rigidity. The rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 in the overlying rock layers of the coal seam are screened. Measure the mechanical parameters of the rock layers that meet the conditions, including the rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strengthσ i , shear strength t i .

[0047] The thickness h of the fracturing target layer is identified by the following process:

[0048]

[0049] In the formula, the unit of h is m. The above formula is looped by MATLAB. m is the impact factor, and its value increases from 0 with an interval of 0.01. When m≥5 or h>15m, the calculation stops.

[0050] Step 2: Identify the target layer for fracturing; the target layer is determined by the following formula, and the layer condition is that the target factor n ≥ 2 or H> 200m. Based on the preliminary data collected, measure the coal seam thickness h0 and the rock layer thickness parameter h within 50m above the coal seam. i , select the incremental interval of the target factor in the formula according to the coal seam thickness h0. Determine whether the target layer determined in step 1 meets the target layer position condition. If it does, proceed to step 3. If it does not, re-determine the target layer thickness and continue to repeat the steps until the target layer meets the requirements.

[0051]

[0052] Where H is the position of the target layer, in meters; h1…h iis the thickness of the rock layer within 50m above the coal seam, n is the targeting factor, if the coal seam thickness is less than or equal to 10m, its value starts from 0 and increases at an interval of 0.001; if the coal seam thickness is greater than 10m, it starts from 0 and increases at an interval of 0.01. When n≥2 or H>200m, the calculation stops.

[0053] Step 3: Determine the target layer breaking step and calculate the target layer breaking impact energy; the initial breaking step and periodic breaking step of the target layer are based on the collected mine data, and the initial pressure step of the working face of the same coal seam is averaged as the initial breaking step; similarly, the average of the periodic pressure step is taken as the periodic breaking step. The breaking of the target layer above the extra-thick impact coal seam leads to the occurrence of rock burst, which in turn causes the breaking shock wave to be transmitted to the working face. The small energy breaking event is not enough to threaten the safety of the working face. The energy of the target layer breaking is as follows:

[0054]

[0055] Where U is the energy released by the target layer breaking, D1 and D2 are the elastic stiffness of the upper and lower rock layers respectively, D = EI, α, β are the underlying stiffness factors of the targeted layer, which are determined as follows: C1 and C2 are the shear stiffness of the upper and lower rock layers respectively; C = kGS, k is the cross-sectional factor of the target layer, the rectangular surface is taken as the calculation shape, k is 5 / 6, G is the shear modulus of the target layer, v is the rock deformation ratio, which is 0.2, and S = Bh. B is the unit width of the target layer, L is the overhang length of the target layer, q is the overburden load on the target layer, E is the elastic modulus of the target layer, D is the bending stiffness of the target layer, and h is the thickness of the target layer; e is a natural number, a, b, c are the pressure distribution factors of the target layer, and the specific calculation is as follows:

[0056]

[0057] Substitute the initial breaking step and periodic breaking step of the target layer into the calculation of the breaking impact energy U1 and U2. If the energy is greater than 10 6 J, then proceed to step 4, otherwise end here and determine that the target layer does not need to be fractured.

[0058] Step 4: Calculate the pressure distribution of the target layer and determine the fracturing target point. The fracturing target point is determined by the pressure distribution. The magnitude of the overburden pressure of the target layer is determined by the following formula:

[0059]

[0060] Where x is the coordinate of the target layer advancing along the working surface, The fracture step of the target layer is substituted to derive the pressure distribution data of the target layer. According to the data, the position with the maximum pressure in the target layer is determined as the fracturing target point.

[0061] Step 5: Drill holes from the middle of the working face and perform ground fracturing at the location with the highest pressure in the target layer to reduce the pressure in the target layer and eliminate the impact source. The specific implementation method is to arrange horizontal wells along the middle of the working face and perform fracturing in sequence according to the fracturing target points determined in step 4 to prevent the occurrence of rock burst disasters.

[0062] The present invention provides a method for eliminating the source of ground fracturing in extra-thick impact coal seams. The method collects transparent mining data from the initial stage of the mine, screens rock layers that meet the impact tendency, and experimentally tests the mechanical parameters of the rock layers that meet the requirements to determine the thickness and position of the target layer. The impact energy of the target layer is cyclically calculated based on the target layer parameters, and the fracturing step distance of the target layer is determined. The maximum pressure position in the pressure distribution of the target layer is determined as the fracturing target point in the fracturing step distance, and the impact ground pressure of the extra-thick impact coal seams is prevented and controlled by precise fracturing of the fracturing target point. The problem in the related art that the impact ground pressure in extra-thick impact coal seams causes safety hazards and causes huge economic losses to coal mining enterprises is solved. At the same time, the targeted source of impact ground pressure is solved from the source, and the technical problem that the ground fracturing step distance of extra-thick impact coal seams is small and the impact target point cannot be identified is solved.

[0063] In a specific embodiment, a method for eliminating the source of ground fracturing in an extra-thick impact coal seam is provided, and the specific steps are as follows: taking the specific values ​​of a certain underground coal mine as an example, according to the initial exploration data of the coal mine, it is determined that the coal mine belongs to an extra-thick impact coal seam mine. After calculations in the method steps of the present invention, the fracturing target point is finally determined, and the target point position is subjected to ground fracturing, thereby eliminating the impact ground pressure of the mine at the source, ensuring the safe production of the working face, and saving the cost of ground fracturing.

[0064] (1) Gather the initial mine transparent materials to identify the thickness of the target layer for fracturing; collect the initial exploration data of the well field, preliminarily establish the mine transparent model, and identify the rock layer with impact tendency above the coal seam according to the rock layer occurrence properties. Rock layers with impact tendency generally have the characteristics of high strength, high hardness and strong rigidity. The rock layers overlying the coal seam with a thickness greater than 5m and a rock hardness coefficient greater than 3 are screened. The mechanical parameters of the rock layers that meet the conditions are measured, including the rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strengthσ i , shear strength t i .

[0065] According to the initial materials of the mine, there are 6 layers of rock strata with a thickness greater than 5m and a rock hardness coefficient greater than 3 in the overlying rock strata of the coal seam. After testing, their geometric and mechanical parameters are: h1=5.5m, G1=3.5GPa, μ1=0.15, E1=5.2GPa, σ1=3.1MPa, t1=2.3MPa, H1=50m; h2=8.2m, G2=3.7GPa, μ2=0.14, E2=5.0GPa, σ2=3.0MPa, t2=2.1MPa, H2=106m; h3=7.5m, G3=3.9GPa, μ3=0.17, E3=4.6GPa, σ3=3.3MPa, t3=2.4MPa 、H3=150m;h4=15m、G4=4.0GPa、μ4=0.20、E4=6.2GPa、σ4=5.5MPa、t4=3.2MPa、H4=200m;h5=15m、G5=4.0GPa、μ5=0.20、E5=6.2GPa、σ5=5.5MPa、t5=3.2MPa、H5=215m;h6=9.8m、G6=3.4GPa、μ6=0.18、E6=3.7GPa、σ6=4.1MPa、t6=2.6MPa、H6=290m. The initial pressure step of the mine is 80m, the periodic pressure step is 40m, and the overburden load q=3MPa / m

[0066] The thickness h of the fracturing target layer is identified by the following process:

[0067]

[0068] The above formula is looped by MATLAB, where the unit of h is m, m is the impact factor, and its value increases from 0 with an interval of 0.01. When m≥5 or h>15, the calculation stops.

[0069] After the above calculation, it is obtained that m=0.41, h=15.71m>15, so the thickness of the target layer is determined to be two layers of hard top plate with a thickness of 15m.

[0070] (2) Identify the target layer for fracturing; the target layer is determined by the following formula. The layer condition is that the target factor n ≥ 2 or H > 200 m. Based on the collected preliminary data, the coal seam thickness h0 and the rock layer thickness parameter h within 50 m above the coal seam are measured. i , select the incremental interval of the target factor in the formula according to the coal seam thickness h0. Determine whether the target layer determined in step 1 meets the target layer position condition. If it does, proceed to step 3. If it does not, re-determine the target layer thickness and continue to repeat the steps until the target layer meets the requirements.

[0071]

[0072] Where H is the layer where the target layer is located, in meters; h1...h i is the thickness of the rock layer within 50m above the coal seam, n is the targeting factor, if the coal seam thickness is less than or equal to 10m, its value starts from 0 and increases at an interval of 0.001; if the coal seam thickness is greater than 10m, it starts from 0 and increases at an interval of 0.01. When n≥2 or H>200m, the calculation stops.

[0073] The target layer thickness is determined to be 15 m in (1). Substituting it into the above formula and performing a cyclic operation, we obtain n=0.553 and H=201.74 m. Therefore, the target layer determined in (1) meets the requirements.

[0074] (3) Determine the target layer breaking step and calculate the target layer breaking impact energy; the initial breaking step and periodic breaking step of the target layer are based on the collected mine data, and the initial pressure step of the working face of the same coal seam is averaged as the initial breaking step; similarly, the average of the periodic pressure step is taken as the periodic breaking step. The breaking of the target layer above the extra-thick impact coal seam leads to the occurrence of rock burst, which in turn causes the breaking shock wave to be transmitted to the working face. The small energy breaking event is not enough to threaten the safety of the working face. The energy of the target layer breaking is as follows:

[0075]

[0076] Where U is the energy released by the target layer breaking, D1 and D2 are the elastic stiffness of the upper and lower rock layers respectively, D = EI, α, β are the underlying stiffness factors of the targeted layer, which are determined as follows: C1 and C2 are the shear stiffness of the upper and lower rock layers respectively; C = kGS, k is the cross-sectional factor of the target layer, the rectangular surface is taken as the calculation shape, k is 5 / 6, G is the shear modulus of the target layer, v is the rock deformation ratio, which is 0.2, S = Bh. B is the unit width of the target layer, L is the overhang length of the target layer, q is the overburden load on the target layer, E is the elastic modulus of the target layer, D is the bending stiffness of the target layer, and h is the thickness of the target layer. e is a natural number, a, b, c are the pressure distribution factors of the target layer, and the specific calculation is as follows:

[0077]

[0078] Substitute the initial breaking step and periodic breaking step of the target layer into the calculation of the breaking impact energy U1 and U2. If the energy is greater than 10 6 J, then proceed to step 4, otherwise end here and determine that the target layer does not need to be fractured.

[0079] Substituting the data of the target layer and the initial pressure step distance of 80m into the calculation, the energy is: U1 = 3.82 × 10 8 J; Substituting the periodic pressure step distance of 40m into the calculation, the energy released by periodic breaking is: U2 = 1.47 × 10 6 J. According to the calculation results, the energy released by the initial break and the periodic break both meet the fracturing requirements.

[0080] (4) Calculate the pressure distribution of the target layer and determine the fracturing target point. The fracturing target point is determined by the pressure distribution. The magnitude of the overburden pressure of the target layer is determined by the following formula:

[0081]

[0082] Where x is the coordinate of the target layer advancing along the working surface, The fracture step of the target layer is substituted to derive the pressure distribution data of the target layer. According to the data, the position with the maximum pressure in the target layer is determined as the fracturing target point.

[0083] Substituting the initial break data into the above formula, the derived data is:

[0084] (0.2，1272465.571)，(1，1184375.104)，(2，1092684.423)，(3，1017923.41)，(3.2，1004716.793)，(3.4，992038.4771)，(3.6，979867.3282)，(3.8，968183.059)，(4，956966.1925)，(4.2，946198.0315)，(4.4，935860.6265)，(5，907264.0537)，(5.2，898484.1152)，(5.4，890055.3989)，(5.6，881963.8548)，(5.8，874195.9947)，(6，866738.8707)，(6.8，839776.4703)，(7，833696.2239)，(7.2，827859.2044)，(7.8，811712.1419)，(8，806754.5485)，(8.2，801995.2731)，(8.4，797426.3824)，(8.6，793040.2607)，(8.8，788829.5966)，(9，784787.3716)，(9.2，780906.8475)，(9.4，777181.556)，(9.6，773605.2873)，(9.8，770172.0801)，(10，766876.2118)，(10.2，763712.1882)，(11，752272.1756)，(11.2，749692.3601)，(11.4，747215.7457)，(11.6，744838.2042)，(11.8，742555.7725)，(12，740364.646)，(12.2，738261.1723)，(12.4，736241.8452)，(12.6，734303.2985)，(12.8，732442.3011)，(13，730655.7507)，(13.2，728940.6693)，(13.4，727294.1982)，(13.6，725713.5928)，(13.8，724196.2184)，(14，722739.5457)，(14.2，721341.1465)，(14.4，719998.6899)，(14.6，718709.9382)，(14.8，717472.7431)，(15，716285.0423)，(15.2，715144.856)，(15.4，714050.2838)，(15.6，712999.501)，(15.8，711990.7562)，(16，711022.3677)，(16.2，710092.7215)，(16.4，709200.2679)，(16.6，708343.5192)，(16.8，707521.0474)，(17.6，704547.319)，(17.8，703876.7314)，(18，703232.975)，(18.2，702614.9768)，(18.4，702021.7065)，(18.6，701452.1752)，(18.8，700905.4336)，(19，700380.5704)，(19.2，699876.7105)，(19.4，699393.0142)，(19.6，698928.6752)，(19.8，698482.9195)，(20，698055.004)，(20.2，697644.2154)，(20.4，697249.8691)，(20.6，696871.3076)，(20.8，696507.9)，(21，696159.0405)，(21.2，695824.1475)，(21.4，695502.6629)，(22，694613.4066)，(22.2，694340.4068)，(22.4，694078.3421)，(22.6，693826.7757)，(22.8，693585.2882)，(23，693353.477)，(23.2，693130.9559)，(23.4，692917.3538)，(23.6，692712.3147)，(23.8，692515.4969)，(24，692326.5722)，(24.2，692145.2257)，(24.4，691971.1552)，(24.6，691804.0705)，.

[0086] (24.8，691643.6931)，(25，691489.7556)，(25.8，690933.4253)，(26，690808.0386)，

[0087] (26.2，690687.699)，(26.4，690572.2057)，(26.6，690461.3664)，(26.8，690354.9961)，(27，690252.9177)，(27.2，690154.961)，(27.4，690060.9626)，

[0089] (27.6，689970.7659)，(27.8，689884.2206)，(28，689801.1823)，(28.2，689721.5127)，(28.4，689645.079)，(29，689433.9447)，(29.8，689190.573)，

[0091] (30，689135.8502)，(688894.4348)，(31.2，688852.0283)，(31.4，688811.4084)，

[0092] (31.6，688772.5072)，(31.8，688735.2601)，(32，688699.6048)，(32.2，688665.4819)，(32.4，688632.8347)，(32.6，688601.6085)，(32.8，688571.7515)，

[0094] (34，688418.7231)，(34.2，688397.1741)，(34.4，688376.6534)，(35，688320.9274)，

[0095] (36，688245.7378)，(36.2，688233.1209)，(36.4，688221.2589)，(36.6，688210.1319)，(36.8，688199.7216)，(37，688190.0104)，(37.2，688180.9822)，

[0097] (37.4，688172.622)，(37.6，688164.9158)，(37.8，688157.8508)，(38，688151.4152)，

[0098] (38.2，688145.5983)，(38.4，688140.3903)，(38.6，688135.7827)，(38.8，688131.7676)，(39，688128.3385)，(40，688119.8154)，(40.2，688119.8154)，

[0100] (40.4，688120.3814)，(40.6，688121.5144)，(41.6，688135.7827)(42.4，688157.8508)，(42.6，688164.9158)，(42.8，688172.622)，(44，688233.1209)，

[0102] (45，688304.1943)，(46.2，688418.7231)，(47，688515.9479)，(47.8，688632.8347)，

[0103] (48，688665.4819)，(48.2，688699.6048)，(48.4，688735.2601)，(48.6，688772.5072)，(48.8，688811.4084)，(49，688852.0283)，(49.2，688894.4348)，

[0105] (49.4，688938.6985)，(49.6，688984.8932)，(49.8，689033.0959)，(50，689083.3869)，(50.2，689135.8502)，(50.4，689190.573)，(50.6，689247.6467)，

[0107] (50.8，689307.1664)，(51，689369.2312)，(52，689721.5127)，(53，690154.961)，

[0108] (53.2，690252.9177)，(53.4，690354.9961)，(53.6，690461.3664)，(53.8，690572.2057)，(54，690687.699)，(55，691342.0015)，(55.2，691489.7556)，

[0110] (55.4，691643.6931)，(55.6，691804.0705)，(55.8，691971.1552)，(56，692145.2257)，(56.2，692326.5722)，(56.4，692515.4969)，(56.6，692712.3147)，

[0112] (56.8，692917.3538)，(57，693130.9559)，(57.2，693353.477)，(57.4，693585.2882)，

[0113] (57.6，693826.7757)，(57.8，694078.3421)，(58，694340.4068)，(58.2，694613.4066)，(58.4，694897.7965)，(58.6，695194.0507)，(58.8，695502.6629)，

[0115] (60，697644.2154)，(60.2，698055.004)，(60.4，698482.9195)，(60.6，698928.6752)，

[0116] (60.8，699393.0142)，(61，699876.7105)，(61.2，700380.5704)，(61.4，700905.4336)，(61.6，701452.1752)，(61.8，702021.7065)，(62，702614.9768)，

[0118] (62.2，703232.975)，(62.4，703876.7314)，(62.6，704547.319)，(62.8，705245.8555)，

[0119] (63，705973.5054)，(63.2，706731.4815)，(63.4，707521.0474)，(63.6，708343.5192)，(63.8，709200.2679)，(64，710092.7215)，(64.2，711022.3677)，

[0121] (64.4，711990.7562)，(64.6，712999.501)，(64.8，714050.2838)，(65，715144.856)，

[0122] (65.2，716285.0423)，(65.4，717472.7431)，(65.6，718709.9382)，(65.8，719998.6899)，(66，721341.1465)，(66.2，722739.5457)，(66.4，724196.2184)，

[0124] (66.6，725713.5928)，(66.8，727294.1982)，(67，728940.6693)，(67.2，730655.7507)，(67.4，732442.3011)，(67.6，734303.2985)，(67.8，736241.8452)，

[0126] (68，738261.1723)，(68.2，740364.646)，(68.4，742555.7725)，(68.6，744838.2042)，

[0127] (68.8，747215.7457)，(69，749692.3601)，(69.2，752272.1756)，(69.4，754959.4926)，(69.6，757758.7906)，(69.8，760674.7356)，(70，763712.1882)，

[0129] (70.2，766876.2118)，(70.4，770172.0801)，(70.6，773605.2873)，(70.8，777181.556)，(71，780906.8475)，(71.2，784787.3716)，(71.4，788829.5966)，

[0131] (71.6，793040.2607)，(71.8，797426.3824)，(72，801995.2731)，(72.2，806754.5485)，(72.4，811712.1419)，(72.6，816876.3171)，(72.8，822255.6824)，

[0133] (73, 827859.2044), (73.2, 833696.2239), (73.4, 839776.4703), (73.6, 846110.0789), (73.8, 852707.6072), (74, 859580.0526), ​​(74.2, 866738.8707), (74.4, 874195.9 947), (74.6, 881963.8548), (74.8, 890055.3989), (75, 898484.1152), (75.2, 907264.0537), (75.4, 916409.8489), (75.6, 925936.7465), (75.8, 935860.6265), (76, 946 198.0315), (76.2, 956966.1925), (76.4, 968183.059), (76.6, 979867.3282), (76.8, 992038.4771), (77, 1004716.793), (77.2, 1017923.41), (77.4, 1031680.343), (77. 6, 1046010.521), (77.8, 1060937.833), (79, 1164509.964), (79.2, 1184375.104), (79.4, 1205068.017), (79.6, 1226623.196), (79.8, 1249076.572), (80, 1272465.571);

[0135] By data and Figure 3 It can be seen that the pressure of the target layer is distributed at both ends, so the initial fracturing position is 80m away from the opening of the cut for pre-fracture, and subsequently a fracturing target point is arranged every 40m for pre-fracture.

[0136] (5) As shown in Figure 2(a) and Figure 2(b), L p is the subsequent fracturing step distance of the initial fracturing, m. It includes an extra-thick coal seam 1, a target layer 2, a horizontal fracturing well 3, a fracturing target point 4 and a vertical section 5 of the fracturing well. A hole is drilled from the middle of the working face, and the surface fracturing is performed at the position with the maximum pressure of the target layer to reduce the pressure of the target layer and eliminate the impact source. The specific implementation method is to arrange horizontal wells along the middle of the working face, and perform fracturing in sequence according to the fracturing target points determined in step 4 to prevent the occurrence of rock burst disasters.

[0137] In a specific embodiment, a system for eliminating the source of ground fracturing in an extra-thick impact coal seam is provided. Figure 4 As shown, including:

[0138] Collection and identification module: used to collect transparent materials from the initial mine and identify the thickness of the fracturing target layer;

[0139] Target layer position identification module: used to identify the target layer position of fracturing;

[0140] Target layer breaking impact energy calculation module: used to determine the breaking step of the target layer and calculate the breaking impact energy of the target layer;

[0141] Fracturing target determination module: used to calculate the pressure distribution of the target layer and determine the fracturing target.

[0142] Ground fracturing module: used to drill holes from the middle of the working face and perform ground fracturing at the location with the highest pressure in the targeted layer.

[0143] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0144] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for eliminating the source of surface fracturing in extra-thick impact coal seams, characterized in that: include: Step 1: Gather the initial mine transparent materials and identify the thickness of the fracturing target layer; Collect the initial exploration data of the mine field, initially establish a transparent mine model, and identify the rock strata with impact tendency above the coal seam according to the rock strata occurrence properties; The overlying rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 are screened, and the mechanical parameters of the rock layers that meet the conditions are measured, including the rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strengthσ i and shear strength t i ; Thickness of the targeting layer h: Among them, m is the impact factor, and its value increases from 0 with an interval of 0.

01. MATLAB performs loop calculations and stops the calculation when m≥5 or h>15m. Step 2: Identify the target layer for fracturing; Based on the preliminary data collected, the coal seam thickness h0 and the rock layer thickness parameter h within 50m above the coal seam were measured. i , select the incremental interval of the targeting factor according to the coal seam thickness h0, and judge whether the targeting layer determined in step 1 meets the targeting layer position condition. The targeting layer position condition is that the targeting factor n≥2 or H>200m. If it meets the condition, proceed to step 3. If not, redetermine the targeting layer thickness until the targeting layer meets the requirement; Among them, H is the layer where the target layer is located; h1…h i is the thickness of the rock layer within 50m above the coal seam, n is the targeting factor, if the coal seam thickness is less than or equal to 10m, its value starts from 0 and increases in intervals of 0.001; if the coal seam thickness is greater than 10m, it starts from 0 and increases in intervals of 0.

01. When n≥2 or H>200m, the calculation stops; Step 3: Determine the target layer breaking step and calculate the target layer breaking impact energy; The initial breaking step and periodic breaking step of the target layer are determined based on the collected mine data. The average initial pressure step of the working face of the same coal seam is taken as the initial breaking step; the average periodic pressure step is taken as the periodic breaking step. The energy of the target layer breaking is as follows: Among them, U is the energy released by the breaking of the target layer, D1 and D2 are the elastic stiffness of the upper and lower rock layers respectively, D = EI, α, β are the underlying stiffness factors of the targeted layer, which are determined as follows: C1 and C2 are the shear stiffness of the upper and lower rock layers respectively; C = kGS, k is the cross-sectional factor of the target layer, the rectangular surface is taken as the calculation shape, k is 5 / 6, G is the shear modulus of the target layer, v is the rock deformation ratio, which is taken as 0.2, S=Bh, B is the unit width of the target layer, L is the overhang length of the target layer, q is the overburden load on the target layer, E is the elastic modulus of the target layer, D is the bending stiffness of the target layer, and h is the thickness of the target layer. e is a natural number, a, b, c are the pressure distribution factors of the target layer, and the formula is as follows: Substitute the initial breaking step and periodic breaking step of the target layer into the calculation of the breaking impact energy U1 and U2. If the energy is greater than 10 6 J, then proceed to step 4, otherwise end here and determine that the target layer does not need to be fractured; Step 4: Calculate the pressure distribution of the target layer and determine the fracturing target point. The fracturing target point is determined by the pressure distribution. The magnitude of the overburden pressure of the target layer is determined by the following formula: Among them, x is the coordinate of the target layer advancing along the working surface, Substitute the fracture step of the target layer, derive the pressure distribution data of the target layer, plot the data, and determine the position with the maximum pressure in the target layer as the fracturing target point; Step 5: Drill holes from the middle of the working face and perform surface fracturing at the location with the highest pressure in the targeted layer.

2. A method for eliminating the source of surface fracturing in an extra-thick impact coal seam according to claim 1, characterized in that: The step 5 also includes: arranging horizontal wells along the middle of the working surface, and performing fracturing in sequence according to the determined fracturing target points.

3. A system for eliminating the source of surface fracturing in extra-thick impact coal seams, characterized in that: include: Collection and identification module: used to collect transparent materials from the initial mine and identify the thickness of the fracturing target layer; Target layer position identification module: used to identify the target layer position of fracturing; Target layer breaking impact energy calculation module: used to determine the breaking step of the target layer and calculate the breaking impact energy of the target layer; Fracturing target determination module: used to calculate the pressure distribution of the target layer and determine the fracturing target. Ground fracturing module: used to drill holes from the middle of the working face and perform ground fracturing at the location with the highest pressure in the targeted layer.

4. The system for eliminating the source of surface fracturing in extra-thick impact coal seams according to claim 3 is characterized in that: The surface fracturing module also includes: arranging horizontal wells along the middle of the working surface, and performing fracturing in sequence according to the determined fracturing target points.

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