Arrangement method for working face of protected layer of close-range coal seam of rock burst mine

Abstract

The invention discloses a protected layer working face arrangement method for a close coal seam of a rock burst mine. The method comprises the steps that the position relation between a protection layer and the protected layer, the inclination length of a goaf, the length of a first mining working face and the vertical pressure relief depth are determined; judging whether the vertical pressure relief depth of the protective layer meets conditions or not; determining a strike pressure relief angle, an inclined pressure relief angle and a residual coal pillar stress transfer angle of the protective layer; calculating an effective value range of the edge horizontal staggering distance between the working face main roadway and the upper protective layer goaf; determining a target layer A, a condition layer B and a factor layer C; calculating to obtain a weight matrix of the factor layer C; obtaining a stress peak value matrix, a weighted average value matrix of stress peak values and horizontal staggered distances L1, L2, L3 and L4, and determining the positions of an open-off cut and a withdrawing channel; and finally determining the working face position of the protected layer on the mining engineering plane graph. The method belongs to the technical field of coal mining design and disaster prevention and control, the schemes can be quantitatively compared, and the key parameter determination basis is clear.

Description

Technical Field

[0001] The invention belongs to the technical fields of coal mining design and coal mine power disaster prevention and control, and relates to a method for arranging a working face of a protected layer in a close proximity coal seam in a rock burst mine. Background Art

[0002] Protective layer mining is an effective regional rock burst prevention technology, especially suitable for rock burst disaster prevention under the condition of close-range coal seam group occurrence. However, in actual application, the layout of the protected layer working face is unreasonable, too dependent on engineering experience, the schemes cannot be quantitatively compared, and the basis for determining key parameters is vague. It is not only difficult to achieve the effect of pressure relief and anti-impact, but also has the possibility of inducing rock burst. The reasonable layout of the protected layer working face not only needs to comprehensively consider factors such as coal seam spacing, residual section coal pillars, the pressure relief range of the protective layer, and the time and space relationship of mining, but also requires a set of systematic methods based on the low stress principle for guidance. However, such methods have not yet been proposed in the industry. Summary of the invention

[0003] The purpose of the present invention is to provide a protected layer working face layout method suitable for close-range coal seams in rock burst mines, so as to solve the problems that the existing layout methods are unreasonable, the schemes cannot be quantitatively compared, and the basis for determining key parameters is vague.

[0004] The technical solution adopted by the present invention is a method for arranging a working face of a protected layer in a close-range coal seam in a rock burst mine, which is implemented according to the following steps: Step 1, determining the positional relationship between the protective layer and the protected layer; Step 2, determine the inclined length C1 of the goaf of the protective layer and the length C2 of the first mining working face of the protected layer; Step 3: Determine the vertical pressure relief depth of the protective layer H ; Step 4: Determine the vertical pressure relief depth of the protective layer H Whether the conditions are met ； Step 5: Determine the relief angle of the protective layer α ; Step 6: Determine the relief angle of the protective layer β ; Step 7: Determine the stress transfer angle of the remaining coal pillar in the protective layer c ; Step 8, determine the effective pressure relief interval of the main tunnel of the working face, and calculate the effective range of the horizontal offset between the main tunnel of the working face and the edge of the goaf of the upper protective layer; Step 9: Establish a hierarchical analysis model to determine the target layer A, condition layer B and factor layer C; Step 10: According to the weight judgment, the weight matrix W of the factor layer C is calculated; Step 11, respectively calculating the stress peak values ​​to obtain a stress peak matrix; Step 12: Perform matrix operations to obtain a weighted average matrix of the stress peak value; Step 13: Determine the horizontal offset between the two main tunnels of the working face and the edge of the goaf of the upper protective layer L 1. L 2; Step 14: Determine the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer. L 3. L 4. Determine the location of the incision and the retracement channel; Step 15: Combine L 1. L 2. L 3. L 4. Based on the calculation results, the position of the protected layer working surface is finally determined on the mining project plan.

[0005] The beneficial effects of the present invention include the following aspects: 1) Based on the low stress principle, the present invention comprehensively considers multiple factors such as the coal seam spacing, the remaining coal pillars, the pressure relief range of the protective layer, the time and space relationship of mining, etc., and proposes a systematic design method for the working face layout of the protected layer, which solves the problem that the existing method is too dependent on engineering experience and cannot be quantitatively compared between schemes.

[0006] 2) The conclusions of the present invention on the vertical unloading depth of the protective layer, the strike unloading angle, the dip unloading angle, and the stress transfer angle of the residual coal pillar are all based on field measurements, and a specific measurement method is proposed. The layout method of the protected layer working face based on hierarchical analysis and evaluation is determined, which provides guidance for the reasonable selection and layout of the protective layer working face in mines with similar conditions. Compared with traditional empirical methods, it is more scientific and objective. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is the overall flow chart of the method of the present invention; Figure 2 It is a schematic diagram of an optical fiber monitoring scheme for the vertical pressure relief depth of the protective layer in the method of the present invention; Figure 3 It is a schematic diagram of an optical fiber monitoring scheme for the relief angle of the protective layer in the method of the present invention; Figure 4 It is a schematic diagram of an optical fiber monitoring scheme for the inclination relief angle of the protective layer in the method of the present invention; Figure 5 It is a schematic diagram of a stress monitoring scheme for the stress transfer angle of the remaining coal pillar in the method of the present invention; Figure 6 It is a schematic diagram for determining the horizontal offset between two main tunnels of the protected layer working face and the edge of the protective layer goaf in the method of the present invention; Figure 7 It is a schematic diagram for determining the horizontal offset between the opening of the cut, the withdrawal channel and the edge of the goaf of the upper protective layer in the method of the present invention; Figure 8 is a scatter diagram of changes in the stress release rate along the working surface in Example 1 of the present invention; Figure 9 is a stress monitoring curve in the coal body below the remaining coal pillar in Example 1 of the present invention; Figure 10 It is a hierarchical analysis model for the layout of the working surface of the protected layer in Example 1 of the present invention. DETAILED DESCRIPTION

[0008] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0009] Reference Figure 1 The protected layer working face arrangement method applicable to the close-range coal seam in rock burst mine of the present invention is implemented according to the following steps: Step 1, determine the positional relationship between the protective layer and the protected layer. If the protective layer is the upper coal seam and the protected layer is the lower coal seam, the method of the present invention is applicable and proceeds to step 2; otherwise, the method of the present invention is not applicable and exits.

[0010] Step 2: According to the mine excavation project plan, determine the inclined length C1 of the protective layer goaf and the length C2 of the first mining working face of the protected layer. If C1>C2, the method of the present invention is applicable and proceeds to step 3; otherwise, the protective layer arrangement conditions are not met, the method of the present invention is not applicable and exits.

[0011] Step 3: Determine the vertical pressure relief depth of the protective layer H , the specific process is: 3.1) If there is a working face in the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the vertical pressure relief depth of the protective layer. H ; 3.2) If Figure 2 As shown in the figure, three groups of holes are drilled on the side of the protected layer floor of the return air chute of the mining face, and the distance between the drilling hole construction position and the current working face position is recorded. l 1, where boreholes 1 and 2 are arranged parallel to the working face, and the angles between them and the coal seam floor are d 1. d Boreholes 2 and 3 are arranged along the working face, with an angle of d 3. The angle between the strike section and the coal seam floor is ; Preferably, l 1≧100m, 15º≦ d1<30°, 30°≦ d 2<45°, 45°≦ d 3≦60º, 15º≦ <30º. The advantage of this is that it can improve the accuracy of vertical pressure relief depth detection, facilitate the actual measurement of the strike and dip pressure relief angle, and facilitate drilling construction.

[0012] 3.3) After the three sets of bottom plate drilling construction are completed, the metal-based cable-shaped strain optical cable and the fiber grating sensor are implanted in the PVC casing, the casing is lowered into the borehole, and the sensor is connected to the downhole communication optical cable to transmit the monitoring information to the ground data monitoring system; 3.4) Grouting and sealing of the drilled holes; 3.5) Continuously monitor the stress and strain data of the optical fiber in the borehole from the current mining position of the working face to the 100m drilling construction position of the working face mining; 3.6) Count the stress-strain data of the fiber Bragg gratings at the bottom of the three groups of boreholes on a daily basis, and calculate the stress change rate every day R , the calculation formula is as follows (2): (2) In the formula, s 0 is the initial stress of the optical fiber, s i is the stress value of the optical fiber at the bottom of the borehole; 3.7) During the optical fiber monitoring period, if there are more than two groups of optical fibers in the three groups of boreholes, the stress change rate R ≧10%, indicating the vertical pressure relief depth of the protective layer H ≧ d On the contrary, the vertical pressure relief depth of the protective layer H < d , indicating that the protective layer has not been depressurized.

[0013] 3.8) If the protective layer does not meet the optical fiber measurement conditions, the empirical value can be used. d ≦30m, it is considered that the vertical pressure relief depth of the protective layer H ≧ d ,like d >30m, then H < d .

[0014] Step 4: Determine the vertical pressure relief depth of the protective layer H Is it satisfied? H ≧ d, d The distance between the protective layer and the protected layer d ; If satisfied, the method of the present invention is applicable and proceeds to step 5; if not satisfied, indicating that the protective layer has failed, the conventional method of the prior art can be used to arrange the working surface.

[0015] Step 5: Determine the relief angle of the protective layer α , the specific process is: 5.1) If there is a working face in the same panel area within the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the strike relief angle of the protective layer. α ; 5.2) If the optical fiber measurement method is used, the optical fiber layout and data monitoring method are the same as steps 3.2) to 3.6); 5.3) If Figure 3 As shown, when drilling hole No. 3 R When the value is ≧10%, the current work advancement position is recorded and the distance between the drilling construction position and the current working surface position is calculated. l 2; 5.4) Calculate the relief angle of the protective layer α , the calculation formula is as follows (3): (3) In the formula, d is the coal seam spacing, b is the thickness of the protected layer, l 3 is the oblique length of the strike projection of borehole No. 3; 5.5) If the protective layer of the same panel area does not have the conditions for on-site measurement, the empirical value is selected, and the preferred value is α = 63.5º.

[0016] Step 6: Determine the relief angle of the protective layer β , the specific process is: 6.1) If there is a working face in the same panel area within the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the strike relief angle of the protective layer. α ; 6.2) If the optical fiber measurement method is used, the optical fiber layout and data monitoring method are the same as steps 3.2) to 3.5); 6.3) If Figure 4 As shown in the figure, the maximum stress change rate of the optical fiber at the bottom of No. 1, No. 2, and No. 3 boreholes during the mining period of the working face is recorded respectively, and is recorded as R max1 , R max2 and R max3 , the distance along the inclination of the working face is recorded as D 1. D 2 and D 3; 6.4) Based on the three sets of drilling optical fiber maximum stress change rate data and the inclination distance data along the working surface, draw a scatter plot of the change of stress release along the inclination of the working surface; 6.5) Perform nonlinear fitting on the scatter plot through a logarithmic curve to obtain the maximum stress change rate R Distance from working surface D The fitting formula of 6.6) R =10% is substituted into the fitting formula to obtain the distance between the area where the stress release rate is reduced to 10% and the boundary of the working surface. D ; 6.7) Calculation of the relief angle of the protective layer β , the calculation formula is as follows (4): (4) In the formula, d is the coal seam spacing, b is the thickness of the protected layer, D is the strike projection length of borehole No. 3; 6.8) If the protective layer of the same panel area does not have the conditions for on-site measurement, select the empirical value, preferably β = 53.7º.

[0017] Step 7: Determine the stress transfer angle of the remaining coal pillar in the protective layer c , the specific process is: 7.1) If there is an excavated tunnel below the remaining coal pillar in the same panel area, and the tunnel has the conditions for conducting coal body stress monitoring, the stress measurement method is used to determine the stress transfer angle of the remaining coal pillar in the protective layer. c ; 7.2) If Figure 5 As shown, directly below and before and after the remaining coal pillar in the protective layer S Coal body stress gauges are arranged within the range to monitor the stress of coal seams. The specific arrangement method is as follows: take one side of the remaining coal pillar as the coordinate origin, arrange coal body stress gauges on the same side of the tunnel at a spacing of ≤10m, and the sensitive components of the coal body stress gauges penetrate into the stress concentration area of ​​the coal wall. The buried depth of the stress gauges is ≥10m. Preferably, S ≧1.8d, d is the distance between the upper and lower coal seams. The advantage of this arrangement is that it can cover all possible ranges of stress propagation angles of the remaining coal pillars without wasting coal body stress gauges and drilling engineering.

[0018] 7.3) After the coal body stress gauge is installed, the coal body stress in the roadway is continuously monitored. After the continuous monitoring time exceeds 30 days, the maximum stress readings of each group of monitoring points are read respectively. s max ; 7.4) The distance between each group of monitoring points and the coordinate origin s is the horizontal axis, the maximum stress reading s maxAs the vertical axis, the stress monitoring curve in the coal body below the remaining coal pillar is drawn; 7.5) The measured value of coal body stress in the protective layer working face without overlying goaf, mining disturbance and geological structure abnormality area is taken as the normal stress value. s c , s c and s max The curve has two intersection points, and the horizontal coordinate values ​​of the intersection points are called S 1. S 2; 7.6) Calculation of stress transfer angle of the remaining coal pillar c , the calculation formula is as follows (5): (5) In the formula, d is the coal seam spacing, B The width of the coal pillar left for the protective layer; 7.7) If there is no on-site measurement condition under the remaining coal pillar in the same panel area, the empirical value is selected, and the preferred value is c = 45º.

[0019] Step 8: According to the parameters determined in steps 3 to 6, combined with the width D2 of the first mining face of the protected layer and the width B of the section coal pillar, determine the effective pressure relief interval of the main roadway of the working face, and calculate the effective range of the horizontal offset between the main roadway of the working face and the edge of the goaf of the upper protective layer. The specific process is: 8.1) If Figure 6 As shown in the figure, the main tunnel 1 of the protected layer working face should be arranged within the stress reduction zone 1, the main tunnel 2 should be arranged within the stress reduction zone 2, and the horizontal offset between the main tunnel 1 and the edge of the goaf of the upper protective layer is L 1 value range, calculated according to formula (6): (6) 8.2) If Figure 6 As shown, the horizontal offset between the main tunnel 2 and the edge of the upper protective layer goaf L 2 value range, calculated according to formula (7): (7) Step 9. Considering the influence of tunnel excavation, working face mining and residual coal pillars, a hierarchical analysis model is established to determine the target layer A, condition layer B and factor layer C; among which, the target layer A is used to determine the optimal horizontal offset of the working face of the protected layer; the condition layer B is the stress condition, that is, the stress condition that is favorable for the excavation, maintenance and working face mining of the main tunnel is selected according to the low stress principle; the factor layer C is the stress of the main tunnel, working face and residual coal pillars at different mining periods.

[0020] Step 10: According to the relative importance of each factor in the conditional layer B, the weight matrix W of the factor layer C is calculated. The specific process is: 10.1) According to the relative importance of each factor in the condition layer B, the weight judgment is performed to obtain the judgment matrix J of the condition layer B relative to the target layer A. The judgment matrix J is a k The square array of the order, k is the number of factors in the conditional layer B; The value of each element in the matrix is ​​as follows: if two factors are equally important, the value is 1; if the former is slightly more important than the latter, the value is 2; if the former is significantly more important than the latter, the value is 3; if the order is reversed, the value is the reciprocal. 10.2) Use equations (8) and (9) to calculate the product of each row value in the judgment matrix J ,as well as The nth root value of , the expression is as follows: (8) (9) 10.3) Formula (10) is used to calculate the judgment matrix J of the conditional layer B relative to the target layer A, which is expressed as: (10) 10.4) Repeat steps 10.1) to 10.3) to obtain the weight matrix W of factor layer C relative to conditional layer B. W is a j A row-by-column matrix, j is the number of factors in factor layer C.

[0021] Step 11: Calculate the stress peak values ​​of the main tunnels and working faces at different mining periods to obtain the stress peak matrix ,in, is a i OK j Column matrix, i is the horizontal offset within the valid value range L The number of values ​​​​of j is the number of factors in factor layer C. The specific process is: 11.1) Within the range of values, the horizontal offset of the main lane 1 L 1. Quantify the values ​​and determine 5-6 groups of different horizontal offset values ​​to form the number of rows of the matrix; 11.2) The numerical simulation method is used to simulate the stress peak values ​​in different areas under different conditions before the excavation of the main tunnel 1, before the excavation of the main tunnel 2, during the mining of the main tunnel 1, during the mining of the main tunnel 2, before the excavation under the legacy coal pillar, and during the mining under the legacy coal pillar. The number of columns in the matrix is ​​filled in with relevant values ​​in the corresponding areas of the matrix to obtain the stress peak matrix , the stress peak matrix is a i OK j Column matrix, i is the horizontal offset within the valid value range L The number of values ​​​​of j is the number of factors in factor layer C.

[0022] Step 12: Perform matrix operations to obtain the weighted average matrix of the stress peak value. , as shown in formula (11): (11) in, is a i A row-by-column matrix, i is the horizontal offset within the valid value range L The number of values.

[0023] Step 13: According to the low stress principle, select The horizontal offset value with the lowest stress in the matrix determines the horizontal offset between the two main tunnels of the working face and the edge of the goaf of the upper protective layer L 1. L 2; Step 14: Determine the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer. L 3. L 4. Determine the location of the incision and the retracement channel; the specific process is: 14.1) If Figure 7 As shown in the figure, the opening of the protected layer working face should be arranged within the stress reduction zone of the protective layer. At the same time, in order to maximize the exploitation of coal resources, the horizontal offset between the opening position and the edge of the goaf of the upper protective layer should be L 3 According to formula (12), we can get: (12) 14.2) If Figure 7 As shown in the figure, the retreat channel of the protected layer working face should be arranged within the stress reduction zone of the protective layer. At the same time, in order to maximize the exploitation of coal resources, the horizontal offset between the retreat channel position and the edge of the goaf of the upper protective layer should be L 4= L 3.

[0024] Step 15: Combine L 1. L 2. L 3. L 4. Based on the calculation results, the position of the protected layer working surface is finally determined on the mining project plan.

[0025] Example 1 The implementation mine of this embodiment 1 is the 2-1 coal seam and the 2-2 middle coal seam of a coal mine. According to the method for arranging the working face of the protected layer of the close-distance coal seam based on the hierarchical analysis evaluation of the present invention, the implementation steps are as follows: Step 1. Select the implementation mine as 2-1 coal seam and 2-2 middle coal seam of a coal mine, among which 2-1 coal seam is the upper coal seam and 2-2 middle coal seam is the lower coal seam. 2-1 coal seam is mined first and has the conditions of a protective layer. Therefore, this method is applicable and proceed to step 2.

[0026] Step 2. According to the mine excavation project plan, there are 2 working faces mined in the 2-1 coal seam, and the width of each working face is 320m, that is, C1=640m; the length of the first mining working face of the protected layer is C2=320m, C1>C2, so this method is applicable, and proceed to step 3.

[0027] Step 3: Determine the vertical pressure relief depth of the protective layer H , the specific process is: 3.1) There is a working face in the 2-1 coal seam, and the distance between the working face and the end of mining is no less than 300m. Therefore, optical fiber measurement is used to determine the vertical pressure relief depth of the protective layer. H ; 3.2) Use Figure 2 The optical fiber drilling arrangement method shown in the figure constructs three groups of holes on the lateral protected layer bottom plate of the return air trough of the mining working face. The drilling angles of No. 1, No. 2, and No. 3 are respectively d 1 = 22°, d 2 = 35°, d 3 = 50°, d 3 ’ =20º.

[0028] 3.3) After the three groups of bottom plate drilling construction are completed, the metal-based cable-shaped strain optical cable and the fiber grating sensor are implanted in the PVC casing, the casing is lowered into the borehole, and the sensor is connected to the downhole communication optical cable to transmit the monitoring information to the ground data monitoring system.

[0029] 3.4) Seal the drilled holes with grouting.

[0030] 3.5) From the current mining position of the working face to the 100m drilling construction position of the working face mining, the stress and strain data of the optical fiber in the borehole are continuously monitored.

[0031] 3.6) The stress-strain data of the fiber Bragg gratings at the bottom of the three groups of boreholes are counted daily, and the stress change rate of the bottom fiber is calculated daily according to formula (2): R .

[0032] 3.7) According to monitoring data, the strain rate of the bottom optical fiber of boreholes 1, 2, and 3 reached 10% on July 6, July 15, and July 30, 2022, respectively, indicating that the 2-2 coal area has been depressurized and the vertical depressurization depth of the protective layer H ≧ d .

[0033] Step 4: From step 3.7), it can be seen that the vertical pressure relief depth of the protective layer meets H ≧ d , this method is applicable, go to step 5.

[0034] Step 5: Determine the relief angle of the protective layer α , the main process is: Using the optical fiber monitoring method described in steps 3.2) to 3.6), when borehole No. 3 R When ≧10%, record the current work advancement position and obtain the distance between the drilling construction position and the current working surface position l 2=71.4m.

[0035] According to formula (3), the unloading angle of the protective layer and the spacing between coal seams are calculated. d =26m, protective layer thickness b= 4m, the strike projection of borehole No. 3 is obliquely long l 3=95.7m, calculated a = 58.3º.

[0036] Step 6: Determine the relief angle of the protective layer β , the main process is: 6.1) Using the optical fiber monitoring method described in step 3.2) to step 3.5), the maximum stress change rate and working face inclination distance of the optical fiber at the bottom of boreholes 1, 2, and 3 during the mining period of the working face are recorded respectively. R max1 = 35.6%, R max2 = 26.2%, R max3 = 17.8%, D 1 = 102.7m, D 2 = 58.6m, D 3 = 32.4m.

[0037] 6.2) Based on the three sets of drilling optical fiber maximum stress change rate data and the distance data along the working surface, a scatter plot of the change of stress release rate along the working surface is drawn, such as Figure 8 shown.

[0038] 6.3) Perform nonlinear fitting of the scatter plot using a logarithmic curve to obtain the maximum stress change rate R Distance from working surface D The fitting formula is: y = 15.418ln( x ) - 36.065; R² = 0.9977.

[0039] 6.4) R =10% is substituted into the fitting formula to obtain the distance between the area where the stress release rate is reduced to 10% and the boundary of the working surface. D= 19.84m.

[0040] 6.5) Calculate the protective layer inclination relief angle according to formula (4): β= 56.5º.

[0041] Step 7: Determine the stress transfer angle of the remaining coal pillar in the protective layer c , the main process is: 7.1) There is an excavated tunnel below the remaining coal pillar in this panel area, and the tunnel has the conditions for conducting coal body stress monitoring. The stress measurement method is used to determine the stress transfer angle of the remaining coal pillar in the protective layer. c ; 7.2) The width of the remaining coal pillar is 35m. Coal body stress gauges are arranged directly below the remaining coal pillar in the protective layer and within 50m before and after to monitor the stress of the coal seam. The spacing between the stress gauges is 10m, the burial depth is 15m, and the total monitoring length is 135m.

[0042] 7.3) After the stress gauge is installed, the stress of the coal body in the roadway is continuously monitored. After the continuous monitoring time exceeds 30 days, the maximum stress readings of each group of monitoring points are read respectively. s max ; 7.4) The distance between each group of monitoring points and the coordinate origin s is the horizontal axis, the maximum stress reading s max As the vertical axis, the stress monitoring curve in the coal body below the remaining coal pillar is drawn, such as Figure 9 As shown; 7.5) The measured value of coal body stress in the protective layer working face without overlying goaf, mining disturbance and geological structure abnormality area is taken as the normal stress value. s c =12MPa, sc and s max The curve has two intersection points, and the horizontal coordinate values ​​of the intersection points are S 1=28m, S 2=102m; 7.6) Calculate the stress transfer angle of the remaining coal pillar according to formula (5): c =53.3°.

[0043] Step 8: Figure 6 As shown, the main tunnel 1 of the protected layer working face is arranged within the stress reduction zone 1, with a horizontal offset of L The value range of 1 is 17.2m≦ L 1≦283.4m; horizontal offset L 2The value range is 337.2m≦ L 1≦657.8m.

[0044] Step 9: Establish a hierarchical analysis model that takes into account the influence of tunnel excavation, working face mining and residual coal pillars, and determine the target layer A, condition layer B and factor layer C, such as Figure 10 shown.

[0045] Step 10: Calculate the weight matrix W of the factor layer C based on the weight judgment. The specific process is: 10.1) According to the relative importance of each factor, the weight judgment is made to obtain the judgment matrix J of the condition layer B relative to the target layer A, as shown in Table 1.

[0046] Table 1. Judgment matrix of conditional layer B relative to target layer A

[0047] 10.2) Use equation (8) and equation (9) to calculate the product of each row value in the judgment matrix ,as well as The nth root value of ; 10.3) Using formula (10), we can calculate the judgment matrix J of conditional layer B relative to target layer A, and get .

[0048] 10.4) Repeat steps 10.1) to 10.3) to obtain the weight matrix W of factor layer C relative to condition layer B, and calculate .

[0049] Step 11: Within the range of values, adjust the horizontal offset of main lane 1. L1 is quantified to determine 5 different sets of horizontal offset values, which are 20m, 40m, 60m, 80m, and 100m, respectively, to form the number of matrix rows; the numerical simulation method is used to simulate the stress peak values ​​in different areas under different conditions such as before the excavation of the main tunnel 1, before the excavation of the main tunnel 2, during the mining of the main tunnel 1, during the mining of the main tunnel 2, before the excavation under the residual coal pillar, and during the mining under the residual coal pillar, to form the number of matrix columns, and fill in the relevant values ​​in the corresponding areas of the matrix to obtain the stress peak matrix , as shown in Table 2.

[0050] Table 2. Values ​​of each row and column of the stress peak matrix

[0051] Step 12: Perform matrix operations according to formula (11) to obtain the weighted average matrix of the stress peak value: , .

[0052] Step 13: According to the low stress principle, The third value in the matrix is ​​the lowest, so when L 1 = 60m when the stress is the lowest. L 2=60m+320m=380m, thus determining the locations of the two main tunnels.

[0053] Step 14: Calculate the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer according to formula (12): L 3= L 4= 16.06m.

[0054] Step 15: Combine L 1. L 2. L 3. L 4. Based on the calculation results, the position of the protected layer working surface is finally determined on the mining project plan.

[0055] The method for arranging the working face of the protected layer of the close-range coal seam based on hierarchical analysis evaluation of the present invention in Example 1 can significantly reduce the dynamic phenomena such as abnormal mine pressure and impact ground pressure caused by unreasonable arrangement of the working face of the protected layer, and maximize the conservation of coal resources and avoid waste of resources while ensuring safety. It has strong guiding significance for the arrangement of mining working faces in the protected layers of coal mines.

[0056] Example 2 The mine selected for implementation in this embodiment 2 is the 3-1 upper coal seam and 3-1 coal seam of a coal mine. According to the method for arranging the working face of the protected layer of the close-range coal seam based on the hierarchical analysis evaluation of the present invention, the implementation steps are as follows: Step 1: In the selected implementation mine, the 3-1 upper coal seam is the overlying coal seam, and the 3-1 coal seam is the underlying coal seam. The 3-1 upper coal seam is mined first and has the conditions of a protective layer. Therefore, this method is applicable and proceed to step 2.

[0057] Step 2. According to the mine excavation project plan, there are 3 working faces mined in the 3-1 upper coal seam, and the width of the working face is 200m, that is, C1=600m; the length of the first mining working face of the protected layer is C2=300m, C1>C2, so this method is applicable, and go to step 3.

[0058] Step 3: Determine the vertical pressure relief depth of the protective layer H , the specific process is: 3.1) There is a working face in the 2-1 coal seam, and the distance between the working face and the end of mining is no less than 300m. Therefore, optical fiber measurement is used to determine the vertical pressure relief depth of the protective layer. H ; 3.2) Use Figure 2 The fiber optic drilling arrangement method shown in the figure constructs three groups of holes on the lateral side of the protected layer bottom plate of the return air trough of the mining face. The drilling angles of No. 1, No. 2, and No. 3 are respectively d 1 = 22°, d 2 = 35°, d 3 = 50°, d 3 ’ =20º.

[0059] 3.3) After the three groups of bottom plate drilling construction are completed, the metal-based cable-shaped strain optical cable and fiber grating sensor are implanted in a PVC casing, the casing is lowered into the borehole, and the sensor is connected to the downhole communication optical cable to transmit the monitoring information to the ground data monitoring system.

[0060] 3.4) Seal the drilled holes with grouting.

[0061] 3.5) From the current mining position of the working face to the 100m drilling construction position of the working face mining, the stress and strain data of the optical fiber in the borehole are continuously monitored.

[0062] 3.6) Statistic the stress-strain data of the three groups of fiber Bragg gratings at the bottom of the borehole on a daily basis, and calculate the stress change rate of the fiber at the bottom daily according to formula (2): R .

[0063] 3.7) According to monitoring data, the strain rate of the bottom optical fiber of boreholes 1, 2, and 3 reached 10% on January 9, January 13, and January 17, 2023, respectively, indicating that the 2-2 coal area has been depressurized and the vertical depressurization depth of the protective layer H ≧ d .

[0064] Step 4: From step 3.7), it can be seen that the vertical pressure relief depth of the protective layer meets H ≧ d , this method is applicable, go to step 5.

[0065] Step 5: Determine the relief angle of the protective layer α , the specific process is: 5.1) Using the optical fiber monitoring method described in steps 3.2) to 3.6), when borehole No. 3 R When ≧10%, record the current work advancement position and obtain the distance between the drilling construction position and the current working surface position l 2=85m.

[0066] 5.2) Calculate the relief angle of the protective layer and the spacing between coal seams according to formula (3). d =15m, protective layer thickness b= 5m, the strike projection of borehole No. 3 is obliquely long l 3=101.3m, calculated a = 61.7º.

[0067] Step 6: Determine the relief angle of the protective layer β , the main process is: The optical fiber monitoring method described in step 3.2) to step 3.5) is used to record the maximum stress change rate and the working face inclination distance of the optical fiber at the bottom of boreholes 1, 2, and 3 during the mining period of the working face. R max1 = 34.7%, R max2 = 30.2%, R max3 = 21.1%, D 1 = 113.4m, D 2 = 63.5m, D 3 = 33.7m.

[0068] According to the data of maximum stress change rate of three groups of drilling optical fibers and the data of distance along the working surface, a scatter plot of the change of stress release rate along the working surface was drawn, and the maximum stress change rate was obtained by nonlinear fitting of the scatter plot. R Distance from working surface D The fitting formula is: y = 17.41825ln( x ) - 35.565; R² = 0.9644.

[0069] WillR =10% is substituted into the fitting formula to obtain the distance between the area where the stress release rate is reduced to 10% and the boundary of the working surface. D= 22.67m.

[0070] According to formula (4), the protective layer inclination relief angle is calculated as β= 60.9º.

[0071] Step 7: Determine the stress transfer angle of the remaining coal pillar in the protective layer c , There is no excavated tunnel under the remaining coal pillar in this panel area, so it is not possible to carry out coal body stress monitoring. The empirical value can be used. c = 45º.

[0072] Step 8: Calculate the horizontal offset of the main tunnel 1 of the protected layer working surface according to formula (6): L 1Value range: 8.37m≦ L 1≦191.63m; Calculate the horizontal offset according to formula (7) L 2The value range is 308.37m≦ L 1≦491.63m.

[0073] Step 9: Establish a hierarchical analysis model that takes into account the influence of tunnel excavation, working face mining and residual coal pillars, and determine the target layer A, condition layer B and factor layer C, such as Figure 10 shown.

[0074] Step 10: According to the relative importance of each factor in the conditional layer B, the weight matrix W of the factor layer C is calculated. The specific process is: 10.1) According to the relative importance of each factor, the weight judgment is made to obtain the judgment matrix J of the condition layer B relative to the target layer A, as shown in Table 3.

[0075] Table 3. Judgment matrix of conditional layer B relative to target layer A

[0076] 10.2) Use equation (8) and equation (9) to calculate the product of each row value in the judgment matrix ,as well as The nth root value of ; 10.3) Using formula (10), we can calculate the judgment matrix J of conditional layer B relative to target layer A, and get .

[0077] 10.4) Repeat steps 10.1) to 10.3) to obtain the weight matrix W of factor layer C relative to condition layer B, and calculate .

[0078] Step 11: Within the range of values, adjust the horizontal offset of main lane 1. L 1 is quantitatively selected to determine 5 groups of different horizontal offset values, which are 10m, 30m, 50m, 70m, and 90m, respectively, to form the number of matrix rows; the numerical simulation method is used to simulate the stress peak values ​​in different areas under different conditions such as before the excavation of the main tunnel 1, before the excavation of the main tunnel 2, during the mining of the main tunnel 1, during the mining of the main tunnel 2, before the excavation under the residual coal pillar, and during the mining under the residual coal pillar, to form the number of matrix columns, and fill in the relevant values ​​in the corresponding areas of the matrix to obtain the stress peak matrix , as shown in Table 4.

[0079] Table 4. Values ​​of each row and column of the stress peak matrix

[0080] Step 12: Perform matrix operations according to formula (11) to obtain the weighted average matrix of the stress peak value: , .

[0081] Step 13: According to the low stress principle, The first value in the matrix is ​​the lowest, so when L The stress is lowest when 1=10m. L 2=10m+300m=310m, thus determining the locations of the two main tunnels.

[0082] Step 14: Calculate the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer according to formula (12): L 3= L 4= 8.08m.

[0083] Step 15: Combine L 1. L 2. L 3. L 4. Based on the calculation results, the position of the protected layer working surface is finally determined on the mining project plan.

[0084] Example 3 In this embodiment 3, the selected implementation mine is the 3rd and 4th coal seams of a coal mine. According to the method for arranging the working face of the protected layer of the close-distance coal seam based on the hierarchical analysis evaluation of the present invention, the implementation steps are as follows: Step 1: In the selected implementation mine, coal seam 3 is the overlying coal seam, coal seam 4 is the underlying coal seam, and coal seam 3 is mined first and has the conditions of a protective layer. Therefore, this method is applicable and proceed to step 2.

[0085] Step 2: According to the mine excavation project plan, there are 2 working faces mined in 3 coal seams, and the width of the working faces is 200m, that is, C1=400m; the length of the first mining working face of the protected layer is C2=200m, C1>C2, so this method is applicable, and go to step 3.

[0086] Step 3: Is there any working face in the coal seam 3 of this mine? Therefore, it is impossible to arrange fiber grating measurement. The vertical pressure relief depth of the protective layer is determined by an empirical formula. H , coal seam spacing d = 25m≦30m, so it is considered that the vertical pressure relief depth of the protective layer H ≧ d .

[0087] Step 4: From step 3, it can be seen that the vertical pressure relief depth of the protective layer meets H ≧ d , this method is applicable, go to step 5.

[0088] Step 5: Since there is no actual measurement condition for optical fiber, use the empirical value and take a = 63.5º.

[0089] Step 6: Since there is no actual measurement condition for optical fiber, use the empirical value and take β = 53.7º.

[0090] Step 7: There is no tunnel under the remaining coal pillar in this panel area, so it is not possible to carry out coal body stress monitoring. The empirical value can be used to obtain c = 45º.

[0091] Step 8: Calculate the horizontal offset of the main tunnel 1 of the protected layer working surface according to formula (6): L 1Value range: 18.38m≦ L 1≦181.62m; Calculate the horizontal offset according to formula (7) L 2The value range is 218.38m≦ L 1≦381.62m.

[0092] Step 9: Establish a hierarchical analysis model that takes into account the influence of tunnel excavation, working face mining and residual coal pillars, and determine the target layer A, condition layer B and factor layer C, such as Figure 10 shown.

[0093] Step 10: According to the relative importance of each factor in the conditional layer B, the weight matrix W of the factor layer C is calculated. The specific process is: 10.1) According to the relative importance of each factor, weight judgment is performed to obtain the judgment matrix J of the condition layer B relative to the target layer A, as shown in Table 5.

[0094] Table 5. Judgment matrix of conditional layer B relative to target layer A

[0095] 10.2) Use equation (8) and equation (9) to calculate the product of each row value in the judgment matrix ,as well as The nth root value of ; 10.3) Using formula (10), we can calculate the judgment matrix J of conditional layer B relative to target layer A, and get .

[0096] 10.4) Repeat steps 10.1) to 10.3) to obtain the weight matrix of factor layer C relative to condition layer B , calculated .

[0097] Step 11: Within the range of values, adjust the horizontal offset of main lane 1. L 1 is quantified to determine 5 different horizontal offset values, which are 25m, 35m, 45m, 55m, and 65m, respectively, to form the number of matrix rows; the numerical simulation method is used to simulate the stress peak values ​​in different areas under different conditions such as before the excavation of the main tunnel 1, before the excavation of the main tunnel 2, during the mining of the main tunnel 1, during the mining of the main tunnel 2, before the excavation under the residual coal pillar, and during the mining under the residual coal pillar, to form the number of matrix columns, and fill in the relevant values ​​in the corresponding areas of the matrix to obtain the stress peak matrix , as shown in Table 6.

[0098] Table 6. Values ​​of each row and column of the stress peak matrix

[0099] Step 12: Perform matrix operations according to formula (11) to obtain the weighted average matrix of the stress peak value: , .

[0100] Step 13: According to the low stress principle, The fourth value in the matrix is ​​the lowest, so when L 1 = 55m when the stress is the lowest. L 2=55m+200m=255m, thus determining the locations of the two main tunnels.

[0101] Step 14: Calculate the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer according to formula (12): L 3= L 4= 12.5m.

[0102] Step 15: CombineL 1、 L 2、 L 3、 L 4. Calculate the results and finally determine the position of the protected coal seam working face on the mining engineering plan.

[0103] Example 4 In this Example 4, the selected implementation mine is a certain coal mine's No. 3-1 coal seam and No. 4 coal seam. According to the method for arranging the working face of the protected coal seam in close-distance coal seams based on analytic hierarchy process evaluation of the present invention, the main steps are as follows: Step 1: In the selected implementation mine, the No. 3-1 coal seam is the overlying coal seam, and the No. 4 coal seam is the underlying coal seam. The No. 3-1 coal seam is mined first and meets the conditions of the protective coal seam. Therefore, this method is applicable, and proceed to Step 2.

[0104] Step 2: According to the mining engineering plan of the mine, a total of 3 working faces are mined in the No. 3-1 coal seam, and the width of each working face is 300 m, that is, C1 = 900 m; the length of the first mining working face of the protected coal seam C2 = 300 m, and C1 > C2. Therefore, this method is applicable, and proceed to Step 3.

[0105] Step 3: There is no working face in the No. 3 coal seam of this mine that is being mined. Therefore, it is impossible to arrange fiber Bragg grating measurement. The vertical pressure relief depth of the protective coal seam is determined by using the empirical formula H , coal seam spacing d = 50 m > 30 m. Therefore, it is considered that the vertical pressure relief depth of the protective coal seam H < d .

[0106] Step 4: It can be judged from Step 3 that the vertical pressure relief depth of the protective coal seam does not meet H ≧ d , and the method of the present invention is not applicable.

[0107] Step 5: Use the conventional method to normally carry out the design of the position of the protected coal seam working face without considering the pressure relief effect of the protective coal seam.

[0108] Example 5 In this example, the selected implementation mine is a certain coal mine's No. 4 coal seam and No. 6 coal seam. According to the method for arranging the working face of the protected coal seam in close-distance coal seams based on analytic hierarchy process evaluation of the present invention, the main steps are as follows: Step 1: The selected implementation mine is a certain coal mine's No. 4 coal seam and No. 6 coal seam. Among them, the No. 4 coal seam is the overlying coal seam, and the No. 6 coal seam is the underlying coal seam. The No. 4 coal seam is mined first and meets the conditions of the protective coal seam. Therefore, this method is applicable, and proceed to Step 2.

[0109] Step 2: According to the mining engineering plan of the mine, a total of 1 working face is mined in the No. 4 coal seam, and the width of the working face is 200 m, that is, C1 = 200 m; the length of the first mining working face of the protected coal seam C2 = 300 m, and C1 < C2. Therefore, the method of the present invention is not applicable.

[0110] Step 3: Use conventional methods to design the position of the working surface of the protected layer normally without considering the pressure relief effect of the protective layer.

[0111] Example 6 The mine selected for implementation in this embodiment 6 is the 3-1 coal seam and the 2-2 middle coal seam of a coal mine. According to the method for arranging the working face of the protected layer of the close-distance coal seam based on the hierarchical analysis evaluation of the present invention, the main steps are: Step 1: In the selected implementation mine, the 2-2 coal seam is the overlying coal seam, the 3-1 coal seam is the underlying coal seam, the 3-1 coal seam is mined first, and the 2-2 coal seam has not yet been mined and does not meet the conditions of a protective layer, so the method of the present invention is not applicable.

[0112] Step 2: Use conventional methods to design the position of the working surface of the protected layer normally without considering the pressure relief effect of the protective layer.

Claims

1. A method for arranging the working face of the protected layer of a close-range coal seam in a rock burst mine, characterized in that: Follow these steps to implement: Step 1, determining the positional relationship between the protective layer and the protected layer; Step 2, determine the inclined length C1 of the goaf of the protective layer and the length C2 of the first mining working face of the protected layer; Step 3: Determine the vertical pressure relief depth of the protective layer H ; Step 4: Determine the vertical pressure relief depth of the protective layer H Whether the conditions are met ； Step 5: Determine the relief angle of the protective layer α ; Step 6: Determine the relief angle of the protective layer β ; Step 7: Determine the stress transfer angle of the remaining coal pillar in the protective layer γ ; Step 8, determine the effective pressure relief interval of the main tunnel of the working face, and calculate the effective range of the horizontal offset between the main tunnel of the working face and the edge of the goaf of the upper protective layer; Step 9: Establish a hierarchical analysis model to determine the target layer A, condition layer B and factor layer C; Step 10: According to the weight judgment, the weight matrix W of the factor layer C is calculated; Step 11, respectively calculating the stress peak values ​​to obtain a stress peak matrix; Step 12: Perform matrix operations to obtain a weighted average matrix of the stress peak value; Step 13: Determine the horizontal offset between the two main tunnels of the working face and the edge of the goaf of the upper protective layer L 1. L 2; Step 14: Determine the horizontal offset between the opening cut, the withdrawal channel and the edge of the goaf of the upper protective layer. L 3. L 4. Determine the location of the incision and the retracement channel; Step 15: Combine L 1. L 2. L 3. L 4. Based on the calculation results, the position of the protected layer working surface is finally determined on the mining project plan.

2. The method for arranging the working face of the protected layer of the close-range coal seam in the rock burst mine according to claim 1 is characterized in that: In step 3, the specific process is: 3.1) If there is a working face in the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the vertical pressure relief depth of the protective layer. H ; 3.2) Construct three groups of holes on the lateral side of the protected layer of the return air chute of the mining face, and record the distance between the drilling hole construction position and the current working face position. l 1, where boreholes 1 and 2 are arranged parallel to the working face, and the angles between them and the coal seam floor are δ 1. δ Boreholes 2 and 3 are arranged along the working face, with an angle of δ 3. The angle between the strike section and the coal seam floor is ; 3.3) After the three sets of bottom plate drilling construction are completed, the metal-based cable-shaped strain optical cable and the fiber grating sensor are implanted in the PVC casing, the casing is lowered into the borehole, and the sensor is connected to the downhole communication optical cable to transmit the monitoring information to the ground data monitoring system; 3.4) Grouting and sealing of the drilled holes; 3.5) Continuously monitor the stress and strain data of the optical fiber in the borehole from the current mining position of the working face to the 100m drilling construction position of the working face mining; 3.6) Count the stress-strain data of the fiber Bragg gratings at the bottom of the three groups of boreholes on a daily basis, and calculate the stress change rate every day R , the calculation formula is as follows (2): （2） In the formula, σ 0 is the initial stress of the optical fiber, σ i is the stress value of the optical fiber at the bottom of the borehole; 3.7) During the optical fiber monitoring period, if there are more than two groups of optical fibers in the three groups of boreholes, the stress change rate R ≧10%, indicating the vertical pressure relief depth of the protective layer H ≧ d On the contrary, the vertical pressure relief depth of the protective layer H < d , indicating that the protective layer is not depressurized; 3.8) If the protective layer does not meet the optical fiber measurement conditions, the empirical value is used. d ≦30m, it is considered that the vertical pressure relief depth of the protective layer H ≧ d ,like d > 30m, then H < d .

3. The method for arranging the protected layer working face of the close-range coal seam in the rock burst mine according to claim 1 is characterized in that: In step 5, the specific process is: 5.1) If there is a working face in the same panel area within the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the strike relief angle of the protective layer. α ; 5.2) If the optical fiber measurement method is used, the optical fiber layout and data monitoring method are the same as steps 3.2) to 3.6); 5.3) When drilling hole 3 R When the value is ≧10%, the current work advancement position is recorded and the distance between the drilling construction position and the current working surface position is calculated. l 2; 5.4) Calculate the relief angle of the protective layer α , the calculation formula is as follows (3): （3） In the formula, d is the coal seam spacing, b is the thickness of the protected layer, l 3 is the oblique length of the strike projection of borehole No. 3; 5.5) If the protective layer of the same panel area does not have the conditions for on-site measurement, the empirical value shall be used. α = 63.5º.

4. The method for arranging the working face of the protected layer in the close-range coal seam of the rock burst mine according to claim 1 is characterized in that: In step 6, the specific process is: 6.1) If there is a working face in the same panel area within the protective layer, and the distance between the working face and the end of the mining is not less than 300m, use optical fiber measurement to determine the strike relief angle of the protective layer. α ; 6.2) If the optical fiber measurement method is used, the optical fiber layout and data monitoring method are the same as steps 3.2) to 3.5); 6.3) Record the maximum stress change rate of the optical fiber at the bottom of No. 1, No. 2, and No. 3 boreholes during the mining period of the working face, and record it as R max1 , R max2 and R max3 , the distance along the inclination of the working face is recorded as D 1. D 2 and D 3; 6.4) Based on the three sets of drilling optical fiber maximum stress change rate data and the inclination distance data along the working surface, draw a scatter plot of the change of stress release along the inclination of the working surface; 6.5) Perform nonlinear fitting on the scatter plot through a logarithmic curve to obtain the maximum stress change rate R Distance from working surface D The fitting formula of 6.6) R =10% is substituted into the fitting formula to obtain the distance between the area where the stress release rate is reduced to 10% and the boundary of the working surface. D ; 6.7) Calculation of the relief angle of the protective layer β , the calculation formula is as follows (4): （4） In the formula, d is the coal seam spacing, b is the thickness of the protected layer, D is the strike projection length of borehole No. 3; 6.8) If the protective layer of the same panel area does not have the conditions for on-site measurement, choose the empirical value β = 53.7º.

5. The method for arranging the working face of the protected layer of the close-range coal seam in the rock burst mine according to claim 1 is characterized in that: In step 7, the specific process is: 7.1) If there is an excavated tunnel below the remaining coal pillar in the same panel area, and the tunnel has the conditions for conducting coal body stress monitoring, the stress measurement method is used to determine the stress transfer angle of the remaining coal pillar in the protective layer. γ ; 7.2) Directly below and before and after the remaining coal pillars in the protective layer S Coal body stress gauges are arranged within the range to monitor the stress of coal seams. The specific arrangement method is as follows: take one side of the remaining coal pillar as the coordinate origin, arrange coal body stress gauges on the same side of the tunnel at a spacing of ≤10m, and the sensitive components of the coal body stress gauges penetrate into the stress concentration area of ​​the coal wall. The buried depth of the stress gauges is ≥10m. 7.3) After the coal body stress gauge is installed, the coal body stress in the roadway is continuously monitored. After the continuous monitoring time exceeds 30 days, the maximum stress readings of each group of monitoring points are read respectively. σ max ; 7.4) The distance between each group of monitoring points and the coordinate origin s is the horizontal axis, the maximum stress reading σ max As the vertical axis, the stress monitoring curve in the coal body below the remaining coal pillar is drawn; 7.5) The measured value of coal body stress in the protective layer working face without overlying goaf, mining disturbance and geological structure abnormality area is taken as the normal stress value. σ c , σ c and σ max The curve has two intersection points, and the horizontal coordinate values ​​of the intersection points are called S 1. S 2; 7.6) Calculation of stress transfer angle of the remaining coal pillar γ , the calculation formula is as follows (5): （5） In the formula, d is the coal seam spacing, B The width of the coal pillar left for the protective layer; 7.7) If there is no on-site measurement condition under the remaining coal pillar in the same panel area, select the empirical value γ = 45º.

6. The method for arranging the working face of the protected layer in the close proximity coal seam of the rock burst mine according to claim 1 is characterized in that: In step 8, the specific process is: 8.1) The main tunnel 1 of the protected layer working face should be arranged within the stress reduction zone 1, and the main tunnel 2 should be arranged within the stress reduction zone 2. The horizontal offset between the main tunnel 1 and the edge of the goaf of the upper protective layer is L 1 value range, calculated according to formula (6): （6） 8.2) Horizontal offset between main tunnel 2 and the edge of the goaf of the upper protective layer L 2 The value range is calculated according to the following formula: .

7. The method for arranging the protected layer working face of the close-range coal seam in the rock burst mine according to claim 1 is characterized in that: In step 10, the specific process is: 10.1) According to the relative importance of each factor in the condition layer B, the weight judgment is performed to obtain the judgment matrix J of the condition layer B relative to the target layer A. The judgment matrix J is a k The square array of the order, k is the number of factors in the conditional layer B; The value criteria for each element in the matrix are: when two factors are compared, if they are of equal importance, the value is 1; two If the former is slightly more important than the latter, the value is 2; if the former is significantly more important than the latter, the value is 3; if the order is reversed, the value is the reciprocal; 10.2) Use equations (8) and (9) to calculate the product of each row value in the judgment matrix J ,as well as The nth root value of , the expression is as follows: （8） （9） 10.3) Formula (10) is used to calculate the judgment matrix J of the conditional layer B relative to the target layer A, which is expressed as: （10） 10.4) Repeat steps 10.1) to 10.3) to obtain the weight matrix W of factor layer C relative to conditional layer B. W is a j A row-by-column matrix, j is the number of factors in factor layer C.

8. The method for arranging the protected layer working face of the close-range coal seam in a rock burst mine according to claim 1, characterized in that: In step 11, the specific process is: 11.1) Within the range of values, the horizontal offset of the main lane 1 L 1. Quantify the values ​​and determine 5-6 groups of different horizontal offset values ​​to form the number of rows of the matrix; 11.2) The numerical simulation method is used to simulate the stress peak values ​​in different areas under different conditions before the excavation of the main tunnel 1, before the excavation of the main tunnel 2, during the mining of the main tunnel 1, during the mining of the main tunnel 2, before the excavation under the legacy coal pillar, and during the mining under the legacy coal pillar. The number of columns in the matrix is ​​filled in with relevant values ​​in the corresponding areas of the matrix to obtain the stress peak matrix , the stress peak matrix is a i OK j Column matrix, i is the horizontal offset within the valid value range L The number of values ​​​​of j is the number of factors in factor layer C.

9. The method for arranging the working face of the protected layer in the close proximity coal seam of the rock burst mine according to claim 1, characterized in that: In step 12, the specific process is: Weighted mean matrix As shown in formula (11): （11） in, is a i A row-by-column matrix, i is the horizontal offset within the valid value range L The number of values.

10. The method for arranging the working face of the protected layer in the close proximity coal seam of the rock burst mine according to claim 1, characterized in that: In step 14, the specific process is: 14.1) The opening of the protected layer working face should be arranged within the stress reduction zone of the protective layer. At the same time, in order to maximize the exploitation of coal resources, the horizontal offset between the opening position and the edge of the goaf of the upper protective layer should be L 3 According to formula (12), we can get: （12） 14.2) The withdrawal channel of the protected layer working face should be arranged within the stress reduction zone of the protective layer. At the same time, in order to maximize the exploitation of coal resources, the horizontal offset between the withdrawal channel position and the edge of the goaf of the upper protective layer should be L 4= L 3.

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