Arrangement method for continuous mining of protected layer working face goaf roadway

Abstract

The invention discloses a continuous mining protected face working face goaf roadway arrangement method. The method comprises the steps that a goaf lateral coal body limit stress balance area range x1 is calculated; calculating the horizontal distance xf between the boundary of the stress reduction area and the edge of the protective layer coal pillar; comparing the x1 with the xf, and judging whether the width of the limit equilibrium region is all within the range of the stress reduction region; calculating the distance L2 from the stress peak point of the protective layer coal pillar to the edge position of the coal pillar; calculating the periodic caving step pitch of the overlying surrounding rock of the protective layer; calculating the distance from the stress peak point of the protective layer goaf compaction area to the edge of the goaf; determining the distance x'from the lowest stress point of the coal-rock mass below the protective layer to the stress peak position of the coal pillar area; and determining the position of the stress peak point in the coal seam according to the L2 distance, and determining the arrangement position of the free roadway according to x ', namely arranging the free roadway at the lowest stress position of the coal-rock mass under the protective layer. The reasonable arrangement position of the free roadway can be determined, and the impact danger of the free roadway is reduced.

Description

Technical Field

[0001] The invention relates to an empty tunnel arrangement method for continuously mining a protected layer working surface, belonging to the technical field of safe mining in coal mines. Background Art

[0002] Rock burst is a typical mining dynamic phenomenon, which is extremely harmful. This dynamic phenomenon instantly releases a large amount of elastic deformation energy accumulated in the coal and rock mass in a sharp and violent form, causing coal and rock mass destruction and generating strong vibrations. The power throws the broken coal and rock into the mining space of the shaft and tunnel, making a strong noise, causing equipment damage, shaft and tunnel damage, and casualties.

[0003] The traditional non-continuous single working face protective layer mining method requires a wide coal pillar to be left between the working faces of the protected layer to ensure that the working face of the protected layer is within the effective protection range of the protective layer. However, this arrangement contradicts the fact that narrow coal pillars should be arranged in the rock burst coal seam. That is, when narrow coal pillars are left in the working face of the protected layer to form continuous mining, the risk of rock burst disaster is low.

[0004] For multi-coal seam mining, the upper protective layer is mined first, so that the coal seams below that are within the effective pressure relief range are protected, which can effectively reduce the impact hazard of the coal seams below that are mined later. At present, a lot of research has been done on the pressure relief effect after the upper protective layer is mined, but there is relatively little research on the continuous mining of the protected layer's open tunnels, which cannot meet the needs of safe mining in coal mines. Summary of the invention

[0005] The purpose of the invention is to provide a method for arranging empty tunnels facing the working face of a protected layer for continuous mining. The method can determine the reasonable position of the empty tunnel arrangement, reduce the impact risk of the empty tunnel, and ensure the safe mining of the coal mine.

[0006] In order to achieve the above object, the present invention provides a method for arranging empty tunnels in a working face of a continuously mined protected layer, comprising the following steps:

[0007] S1. Calculate the range of the lateral ultimate stress balance zone of the coal body in the goaf area. The calculation formula is:

[0008]

[0009] Where H represents the thickness of the coal seam, in m; x 1 It indicates the width of the limit equilibrium zone, in m; m is the mining height of the coal seam; is the internal friction angle of the coal seam, reflecting the magnitude of the internal friction between the particles inside the coal rock mass; k is the stress concentration coefficient of the coal body; γ is the average density of the rock layer C 0 is the cohesion of coal, P xis the lateral restraint force of the goaf of the protected layer on the coal pillar; A represents the proportional coefficient;

[0010] S2. Calculate the horizontal distance x between the boundary line of the stress reduction zone and the edge of the protective layer coal pillar f , the calculation formula is:

[0011]

[0012] Among them, x f Indicates the horizontal distance from the boundary line of the stress reduction zone to the edge of the coal pillar, in meters; h f It indicates the depth of the tunnel from the coal seam floor, in meters; α indicates the coal seam inclination; δ indicates the stress transfer angle of the floor; L 0 Indicates the length of the coal seam working face, in m;

[0013] S3. Compare x 1 and x f The size of the limit equilibrium zone is used to determine whether the width of the limit equilibrium zone is entirely within the stress reduction zone: x 1 ≤x f When x 1 >x f When , it means that the tunnels are not all arranged in the stress reduction zone, and it is necessary to avoid arranging the tunnels outside the stress reduction zone;

[0014] S4. Calculate the distance between the peak stress point of the protective layer coal pillar and the edge of the coal pillar. The calculation formula is:

[0015]

[0016] Where m′ represents the mining height of the protective layer; L 2 Indicates the distance between the peak stress point of the protective layer coal pillar and the edge of the coal pillar; L 1 is the width of the protective coal pillar area, in m;

[0017] S5. Calculate the periodic collapse step distance of the surrounding rock overlying the protective layer. The calculation formula is:

[0018]

[0019] Among them, L w is the periodic collapse step distance of the surrounding rock above the protective layer, in m; σ is the tensile strength of the roof rock layer, in Pa; H′ is the height of the roof rock layer, in m; q is the pressure of the overlying rock layer on the roof, in Pa;

[0020] S6. Calculate the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf. The calculation formula is:

[0021] L3 =2.5L w ;

[0022] Among them, L 3 It indicates the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf, in m;

[0023] S7. Determine the distance between the lowest stress point of the coal rock mass below the protective layer and the peak stress position of the coal pillar area. The calculation formula is:

[0024]

[0025] Where x′ represents the distance between the lowest stress point of the coal-rock mass below the protective layer and the peak stress position of the coal pillar area, in m;

[0026] S8, first according to S4 obtained L 2 That is, the distance between the peak stress point of the coal pillar in the protective layer and the edge of the coal pillar. Since the position of the coal pillar is determined, the position of the stress peak point in the coal seam is obtained; then according to the x′ obtained by S7, the distance x′ between the lowest stress point of the coal rock mass below the protective layer and the peak stress point of the coal pillar area is the layout position of the air tunnel. This position is the position with the lowest stress in the air tunnel layout, that is, the optimal layout position.

[0027] Furthermore, in S1, P x The calculation formulas for and A are:

[0028] P x =KHC;

[0029] Among them, K represents the ratio of the elastic modulus of the coal seam to the elastic modulus of the rock layer; H represents the thickness of the coal seam, in meters; C represents the lateral constraint coefficient, which reflects the degree of constraint between the coal seam and the surrounding rock;

[0030] A = (μ / (1-μ);

[0031] Here, μ represents Poisson's ratio.

[0032] The present invention obtains the reasonable layout position of the protected layer's empty tunnel by calculating the pressure relief range and angle after mining the upper protective layer, and then verifies the rationality of the tunnel layout position by calculating the vertical stress through the empty tunnel position, providing theoretical guidance for whether the layout position of the protected layer's empty tunnel needs to be adjusted for subsequent continuous mining of the mine. The present invention ensures the safe mining of coal mines, has important practical significance and significant social benefits for the continuous safe production of protective layer mining mines, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a work flow chart of the method of the present invention;

[0034] Figure 2 It is a schematic diagram of continuous mining of the protective layer of the present invention;

[0035] Figure 3 It is a schematic diagram of stress distribution around the air-access tunnel of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] like Figure 1 As shown, a method for arranging empty tunnels for continuous mining of a protected layer working surface includes the following steps:

[0038] S1. Calculate the range of the lateral ultimate stress balance zone of the coal body in the goaf area. The calculation formula is:

[0039]

[0040] Where H represents the thickness of the coal seam, in m; x 1 It indicates the width of the limit equilibrium zone, in m; m is the mining height of the coal seam; is the internal friction angle of the coal seam, reflecting the magnitude of the internal friction between the particles inside the coal rock mass; k is the stress concentration coefficient of the coal body; γ is the average density of the rock layer C 0 is the cohesion of coal, P x is the lateral restraint force of the goaf of the protected layer on the coal pillar; A represents the proportional coefficient;

[0041] S2. Calculate the horizontal distance x between the boundary line of the stress reduction zone and the edge of the protective layer coal pillar f , the calculation formula is:

[0042]

[0043] Among them, x f Indicates the horizontal distance from the boundary line of the stress reduction zone to the edge of the coal pillar, in meters; h f It indicates the depth of the tunnel from the coal seam floor, in meters; α indicates the coal seam inclination; δ indicates the stress transfer angle of the floor; L 0 Indicates the length of the coal seam working face, in m;

[0044] S3. Compare x 1 and x f The size of the limit equilibrium zone is used to determine whether the width of the limit equilibrium zone is entirely within the stress reduction zone: x 1 ≤x f When x 1 >x f When , it means that the tunnels are not all arranged in the stress reduction zone, and it is necessary to avoid arranging the tunnels outside the stress reduction zone;

[0045] S4, such as Figure 2 and Figure 3 As shown in the figure, the distance between the peak stress point of the protective layer coal pillar and the edge of the coal pillar is calculated, and the calculation formula is:

[0046]

[0047] Where m′ represents the mining height of the protective layer; L 2 Indicates the distance between the peak stress point of the protective layer coal pillar and the edge of the coal pillar; L 1 is the width of the protective coal pillar area, in m;

[0048] S5. Calculate the periodic collapse step distance of the surrounding rock overlying the protective layer. The calculation formula is:

[0049]

[0050] Among them, L w is the periodic collapse step distance of the surrounding rock above the protective layer, in m; σ is the tensile strength of the roof rock layer, in Pa; H′ is the height of the roof rock layer, in m; q is the pressure of the overlying rock layer on the roof, in Pa;

[0051] S6. Calculate the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf. The calculation formula is:

[0052] L 3 =2.5L w ;

[0053] Among them, L 3 It indicates the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf, in m;

[0054] S7. Determine the distance between the lowest stress point of the coal rock mass below the protective layer and the peak stress position of the coal pillar area. The calculation formula is:

[0055]

[0056] Where x′ represents the distance between the lowest stress point of the coal-rock mass below the protective layer and the peak stress position of the coal pillar area, in m;

[0057] S8, first according to S4 obtained L 2 That is, the distance between the peak stress point of the coal pillar in the protective layer and the edge of the coal pillar. Since the position of the coal pillar is determined, the position of the stress peak point in the coal seam is obtained; then according to the x′ obtained by S7, the distance x′ between the lowest stress point of the coal rock mass below the protective layer and the peak stress point of the coal pillar area is the layout position of the air tunnel. This position is the position with the lowest stress in the air tunnel layout, that is, the optimal layout position.

[0058] Furthermore, P x The calculation formulas for and A are:

[0059] P x =KHC;

[0060] Among them, K represents the ratio of the elastic modulus of the coal seam to the elastic modulus of the rock layer; H represents the thickness of the coal seam, in meters; C represents the lateral constraint coefficient, which reflects the degree of constraint between the coal seam and the surrounding rock;

[0061] A = μ / (1-μ);

[0062] Here, μ represents Poisson's ratio.

[0063] A mine with a protective layer has experienced rock burst in its open tunnel. The location of the mine's open tunnel in the protected layer has a potential rock burst hazard. The location of the open tunnel is determined by the following calculation method:

[0064] (1) The coal seam mining height is 10 m, the Poisson's ratio is 0.5, the internal friction angle is 20°, the stress concentration factor is 2, and the average density of the rock layer is 2.5 t / m 3 , the burial depth is 1200m, the cohesion is 2MPa, and the lateral restraint is 0; the width of the limit equilibrium zone can be calculated:

[0065] (2) The depth of the goaf from the coal seam floor is 10 m, the coal seam inclination is 15°, the vertical stress transfer angle of the coal seam floor is 20°, and the minimum distance from the stress reduction zone to the edge of the coal pillar is:

[0066] (3) Since x is calculated 1 Less than x f0 , the mine's limit equilibrium zone is not entirely within the stress reduction zone, and it is necessary to find the lowest stress point to arrange the roadway to avoid arranging the roadway outside the stress reduction zone;

[0067] (4) The mining height of the protective layer working face is 4 m, the Poisson's ratio is 0.5, the internal friction angle is 20°, and the width of the rock pillar area is 5 m. The position of the stress peak point under the protective layer coal rock pillar is determined as follows:

[0068] (5) The tensile strength of the roof rock is 8.1 MPa, the height of the roof rock is 20 m, and the pressure of the overlying rock on the roof is 10 MPa. Then the periodic collapse step is

[0069] (6) The periodic collapse step is 6m. Calculate the distance between the stress peak point of the protective layer goaf and the edge of the goaf: L 3 =2.5L w =15m;

[0070] (7) Calculation formula for the position of the lowest stress point of the coal rock mass below the protective layer:

[0071] (8) The location of the open tunnel for continuous mining of the protected layer in the mine is 8.25 m away from the edge of the coal pillar. The calculated stress is the lowest, the possibility of rock burst events is the lowest, and the optimized layout of the tunnel is reasonable.

Claims

1. A method for arranging empty tunnels for continuous mining of protected layer working surface, characterized in that: The steps include: S1. Calculate the range of the lateral ultimate stress balance zone of the coal body in the goaf area. The calculation formula is: Among them, H represents the thickness of the coal seam, in m; x1 represents the width of the limit equilibrium zone, in m; m is the mining height of the coal seam; is the internal friction angle of the coal seam, reflecting the magnitude of the internal friction between the particles inside the coal rock mass; k is the stress concentration coefficient of the coal body; γ is the average density of the rock layer; C0 is the cohesion of the coal body, P x is the lateral restraint force of the goaf of the protected layer on the coal pillar; A represents the proportional coefficient; S2. Calculate the horizontal distance x between the boundary line of the stress reduction zone and the edge of the protective layer coal pillar f , the calculation formula is: Among them, x f Indicates the horizontal distance from the boundary line of the stress reduction zone to the edge of the coal pillar, in meters; h f It indicates the depth of the roadway from the coal seam floor, in m; α indicates the coal seam inclination; δ indicates the stress transfer angle of the floor; L0 indicates the length of the coal seam working face, in m; S3, compare x1 and x f The size of the limit equilibrium zone is used to determine whether the width of the limit equilibrium zone is entirely within the stress reduction zone: when x1≤x f When x1>x f When , it means that the tunnels are not all arranged in the stress reduction zone, and it is necessary to avoid arranging the tunnels outside the stress reduction zone; S4. Calculate the distance between the peak stress point of the protective layer coal pillar and the edge of the coal pillar. The calculation formula is: Wherein, m′ represents the mining height of the protective layer; L2 represents the distance between the stress peak point of the protective layer coal pillar and the edge of the coal pillar; L1 represents the width of the protective layer coal pillar area, in m; S5. Calculate the periodic collapse step distance of the surrounding rock overlying the protective layer. The calculation formula is: Among them, L w is the periodic collapse step distance of the surrounding rock above the protective layer, in m; σ is the tensile strength of the roof rock layer, in Pa; H′ is the height of the roof rock layer, in m; q is the pressure of the overlying rock layer on the roof, in Pa; S6. Calculate the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf. The calculation formula is: <h2 style=";text-align:left;direction:ltr">L3=2.5L<h2 style=";text-align:left;direction:ltr"> w <h2 style=";text-align:left;direction:ltr"> ; Among them, L3 represents the distance between the stress peak point of the compaction zone of the protective layer goaf and the edge of the goaf, in m; S7. Determine the distance between the lowest stress point of the coal rock mass below the protective layer and the peak stress position of the coal pillar area. The calculation formula is: Where x′ represents the distance between the lowest stress point of the coal-rock mass below the protective layer and the peak stress position of the coal pillar area, in m; S8. First, based on L2 obtained in S4, that is, the distance between the peak stress point of the coal pillar in the protective layer and the edge of the coal pillar, since the position of the coal pillar is determined, the position of the stress peak point in the coal seam is obtained; then based on x′ obtained in S7, that is, the distance x′ between the lowest stress point of the coal rock mass below the protective layer and the peak stress point of the coal pillar area is the layout position of the air tunnel. This position is the position with the lowest stress in the air tunnel layout, that is, the optimal layout position.

2. The method for arranging empty tunnels for continuous mining of protected layer working surface according to claim 11 is characterized in that: The S1P x The calculation formulas for and A are: P x =KHC; Among them, K represents the ratio of the elastic modulus of the coal seam to the elastic modulus of the rock layer; H represents the thickness of the coal seam, in meters; C represents the lateral constraint coefficient, which reflects the degree of constraint between the coal seam and the surrounding rock; A = μ / (1-μ); Here, μ represents Poisson's ratio.

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