A method and system for eliminating the source of surface fracturing in extra-thick impact coal seams

Abstract

The present invention discloses a method and system for eliminating the source of ground fracturing in extra-thick impact coal seams, which relates to the field of coal mine mining safety technology, including: collecting initial transparent mine materials, identifying the thickness of the target layer for fracturing; identifying the position of the target layer for fracturing; determining the fracture step of the target layer, calculating the impact energy of the fracture of the target layer; calculating the pressure distribution of the target layer, determining the fracturing target point, drilling a hole from the middle of the working face, and performing ground fracturing on the position where the pressure of the target layer is the largest. The present invention collects initial transparent mine data of the mine, screens rock layers that meet the impact tendency, and determines the thickness and position of the target layer through experimental testing of the mechanical parameters of the rock layer that meet the requirements. The impact energy of the target layer is cyclically calculated based on the parameters of the target layer, and the fracture step of the target layer is determined. The position with the maximum pressure in the pressure distribution of the target layer in the fracture step is determined as the fracturing target point, and the rock burst pressure of the extra-thick impact coal seam is prevented and controlled by 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 surface fracturing in extremely thick impact coal seams. Background Art

[0002] Extra-thick coal seams are widespread in my country and are currently the primary mining target. Mining these extra-thick seams, which are susceptible to rock bursts, is difficult. Rock bursts can cause severe vibrations at the working face, impacting hydraulic supports, damaging them and other equipment, leading to mine shutdowns and significant economic losses. These can even lead to secondary hazards such as tunnel destruction and coal and gas outbursts, posing a serious threat to mine safety and the lives of workers. Furthermore, the sudden and destructive nature of rock bursts is particularly difficult to predict in extra-thick coal seams, as the thickness of the coal seam complicates both prediction and prevention.

[0003] The mining of extremely thick coal seams significantly limits traditional methods for predicting and controlling rock bursts. Surface fracturing, which offers the advantages of proactive prevention and control and is not restricted by underground environments, has been introduced to control rock bursts in these seams. However, the cost of surface fracturing remains high, often requiring the entire roof of the working face to be fractured. This high cost poses a significant challenge to the economic profitability 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 extremely thick coal seams, which can be used to control the rock burst in extremely thick coal seams by ground fracturing, achieve precise fracturing, increase the fracturing step distance, and reduce the fracturing cost. 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 extremely thick impact coal seams, comprising:

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

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

[0009] Screen the overlying rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 in the coal seam, and measure the mechanical parameters of the rock layers that meet the conditions, including rock stiffness G i , Poisson's ratio μi , elastic modulus E i , compressive strength σ i and shear strength t i ;

[0010] Thickness of the targeting layer h:

[0011]

[0012] Where 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 > 15 m.

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

[0014] Based on the collected preliminary data, 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 of the initial pressure step of the working face of the same coal seam is taken as the initial breaking step; the average of the 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 target layer breaking, D1 and D2 are the elastic stiffness of the upper and lower 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 of 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, and 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] Where 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 location 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 target layer.

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

[0028] Optional: A surface fracturing source elimination system for extra-thick impact coal seams, including:

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

[0030] Target layer identification module: used to identify the target layer for 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 target 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 provides a method and system for eliminating the source of surface fracturing in extra-thick impact coal seams, 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. By collecting transparent mining data at the initial stage of the mine, screening rock layers that meet the impact tendency, and experimentally testing the mechanical parameters of the rock layers that meet the requirements, the thickness and position of the target layer are determined, the impact energy of the target layer is cyclically calculated based on the target layer parameters, the fracturing step distance of the target layer is determined, and the maximum pressure position in the pressure distribution of the target layer is determined in the fracturing step distance as the fracturing target point. The impact ground pressure of the extra-thick impact coal seams is prevented and controlled by 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any 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] FIG2( 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 this invention.

[0042] Figure 4 This is 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 clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts 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 surface fracturing in extra-thick impact coal seams, such as Figure 1 Shown, including:

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

[0047] The thickness h of the fracture 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, where the layer condition is that the target factor n ≥ 2 or H > 200m. Based on the collected preliminary data, 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 based on the coal seam thickness h0. Determine whether the target layer determined in step 1 meets the target layer position conditions. If it does, proceed to step 3. If not, re-determine the target layer thickness and repeat the steps until the target layer meets the requirements.

[0051]

[0052] Where H is the target layer position, unit is m; 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 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.

[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. 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 used 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 set to 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, and 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, Substitute the fracture step of the target layer to derive the pressure distribution data of the target layer. Based on 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 of the target layer is determined. The position with the maximum pressure in the pressure distribution of the target layer is determined as the fracturing target in the fracturing step. The impact ground pressure of extra-thick impact coal seams is prevented and controlled by precise fracturing of the fracturing target. This method solves 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. At the same time, the method solves the target source of impact ground pressure from the source, and solves the technical problem that the ground fracturing step of extra-thick impact coal seams is small and the impact target point cannot be identified.

[0063] In a specific embodiment, a method for eliminating the source of ground fracturing in an extremely thick rock burst coal seam is described. The method includes the following steps: Using specific values from a specific underground coal mine as an example, the mine is determined to be an extremely thick rock burst coal seam based on initial mine exploration data. Through calculations using the method steps, a fracturing target is ultimately determined, and ground fracturing is performed at the target location. This eliminates the source of rock burst in the mine, ensuring safe production at 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 with thickness greater than 5m and 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 rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strength σ 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 layer of the coal seam. After testing, their geometric and mechanical parameters are as follows: 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 distance of this mine is 80m, the periodic pressure step distance is 40m, and the overburden load q=3MPa / m

[0066] The thickness h of the fracture 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 target layer thickness 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, where 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 based on the coal seam thickness h0. Determine whether the target layer determined in step 1 meets the target layer position conditions. If it does, proceed to step 3. If not, re-determine the target layer thickness and repeat the steps until the target layer meets the requirements.

[0071]

[0072] Where H is the target layer position, unit is m; 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.

[0073] After determining the thickness of the target layer as 15 m in (1), substituting it into the above formula and performing a cyclic operation, we can 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 the periodic breaking step of the target layer are based on the collected mine data. 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 set to 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, and 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 fracture and the periodic fracture 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, Substitute the fracture step of the target layer to derive the pressure distribution data of the target layer. Based on the data, the position with the maximum pressure in the target layer is determined as the fracturing target point.

[0083] Substituting the initial fracture 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)，(24.8，691643.6931)，(25，691489.7556)，(25.8，690933.4253)，(26，690808.0386)，(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)，(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)，(30，689135.8502)，(688894.4348)，(31.2，688852.0283)，(31.4，688811.4084)，(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)，(34，688418.7231)，(34.2，688397.1741)，(34.4，688376.6534)，(35，688320.9274)，(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)，(37.4，688172.622)，(37.6，688164.9158)，(37.8，688157.8508)，(38，688151.4152)，(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)，(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)，(45，688304.1943)，(46.2，688418.7231)，(47，688515.9479)，(47.8，688632.8347)，(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)，(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)，(50.8，689307.1664)，(51，689369.2312)，(52，689721.5127)，(53，690154.961)，(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)，(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)，(56.8，692917.3538)，(57，693130.9559)，(57.2，693353.477)，(57.4，693585.2882)，(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)，(60，697644.2154)，(60.2，698055.004)，(60.4，698482.9195)，(60.6，698928.6752)，(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)，(62.2，703232.975)，(62.4，703876.7314)，(62.6，704547.319)，(62.8，705245.8555)，(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)，(64.4，711990.7562)，(64.6，712999.501)，(64.8，714050.2838)，(65，715144.856)，(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)，(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)，(68，738261.1723)，(68.2，740364.646)，(68.4，742555.7725)，(68.6，744838.2042)，(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)，(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)，(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)，(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, 874195.9947), (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, 946198.0315), (76.2, 956966.1925), (76.4, 968183.05 9), (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);.

[0085] By data and Figure 3 It can be seen that the pressure of the target layer is distributed at both ends. Therefore, the initial fracturing position is 80m away from the opening hole for pre-fracture, and subsequently a fracturing target point is arranged every 40m for pre-fracture.

[0086] (5) As shown in Figure 2(a) and Figure 2(b), L p is the subsequent fracturing step length after the initial fracturing, in meters. This 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. Drilling begins in the middle of the working face, and surface fracturing is performed at the location with the highest pressure in the target layer to reduce the pressure in the target layer and eliminate the source of the shock. A specific implementation involves arranging horizontal wells along the middle of the working face and sequentially fracturing the target points determined in step 4 to prevent rock burst disasters.

[0087] In a specific embodiment, a system for eliminating the source of surface fracturing in an extra-thick impact coal seam is provided. Figure 4 Shown, including:

[0088] Collection and identification module: used to collect initial mine transparent materials and identify the thickness of the fracturing target layer;

[0089] Target layer identification module: used to identify the target layer for fracturing;

[0090] 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;

[0091] Fracturing target determination module: used to calculate the pressure distribution of the target layer and determine the fracturing target.

[0092] 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 target layer.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0094] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform 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 initial mine transparent materials and identify the thickness of the fracturing target layer; Collect initial exploration data of the well field, initially establish a transparent mine model, and identify the rock layers above the coal seam with impact tendency based on the rock layer occurrence properties; Screen the overlying rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 in the coal seam, and measure the mechanical parameters of the rock layers that meet the conditions, including rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strength σ i and shear strength t i ; Thickness of the targeting layer h: Where 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 > 15 m. Step 2: Identify the target layer for fracturing; Based on the collected preliminary data, 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 of the initial pressure step of the working face of the same coal seam is taken as the initial breaking step; the average of the 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 target layer breaking, D1 and D2 are the elastic stiffness of the upper and lower 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 of 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, and 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: Where 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 location 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 target layer.

2. The 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 further includes: arranging horizontal wells along the middle of the working face, 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 initial mine transparent materials and identify the thickness of the fracturing target layer; Collect initial exploration data of the well field, initially establish a transparent mine model, and identify the rock layers above the coal seam with impact tendency based on the rock layer occurrence properties; Screen the overlying rock layers with a thickness greater than 5m and a rock hardness coefficient greater than 3 in the coal seam, and measure the mechanical parameters of the rock layers that meet the conditions, including rock stiffness G i , Poisson's ratio μ i , elastic modulus E i , compressive strength σ i and shear strength t i ; Thickness of the targeting layer h: Where 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 > 15 m. Target layer identification module: used to identify the target layer for fracturing; based on the collected preliminary data, 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 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. 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; the initial breaking step and periodic breaking step of the target layer are determined based on the collected mine data. The average of the initial pressure step of the working face of the same coal seam is taken as the initial breaking step; the average of the 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 target layer breaking, D1 and D2 are the elastic stiffness of the upper and lower 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 of 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, and 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; Fracturing target determination module: used to calculate the pressure distribution of the target layer and determine the fracturing target. The fracturing target is determined by the pressure distribution. The magnitude of the overburden pressure of the target layer is determined by the following formula: Where 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 location with the maximum pressure in the target layer as the fracturing target point; 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 target 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 further comprises: arranging horizontal wells along the middle of the working surface, and performing fracturing in sequence according to the determined fracturing target points.

Images