A method for discharging roof water in a multi-seam high-gas working face

Abstract

The present invention discloses a method for discharging roof water in a multi-seam high-gas working face, including: Step 1: calculating the height H of the water-conducting fractured zone during coal seam mining, m; Step 2: determining the final hole target points of the water discharge holes and setting the density of the final hole target points of the water discharge holes within the working face in zones; Step 3: after determining the drilling displacement S, setting the water discharge drilling holes according to the determined final hole target points of the water discharge holes, so as to achieve roof water discharge; S ≤ 500 m. In the present invention, the main hole of the directional hole group is located on the roof of the high-gas coal seam, reducing the number of times of passing through the coal seam, reducing the gas risk, and at the same time avoiding the problems of coal seam collapse and hole shrinkage in the open hole section. 导 , m; Step 2: determining the final hole target points of the water discharge holes and setting the density of the final hole target points of the water discharge holes within the working face in zones; Step 3: after determining the drilling displacement S, setting the water discharge drilling holes according to the determined final hole target points of the water discharge holes, so as to achieve roof water discharge; S ≤ 500 m. In the present invention, the main hole of the directional hole group is located on the roof of the high-gas coal seam, reducing the number of times of passing through the coal seam, reducing the gas risk, and at the same time avoiding the problems of coal seam collapse and hole shrinkage in the open hole section.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine roof water prevention and water-preserved coal mining, and relates to a method for discharging roof water in a multi-seam high-gas working face. Background Technique

[0002] Gas and water disasters are the main natural disasters in coal mines. Gas and water exist as fluids in the voids of coal-bearing strata, both having a certain pressure and fluidity, and are prone to bursting into the mine under the action of mining disturbances, causing disasters. The main gas prevention technology is extraction and drainage, and advanced treatment is carried out through gas holes + bottom extraction roadways or surface directional gas extraction holes. The main roof water prevention technology is to drill multiple groups of roof water discharge holes along the machine roadway and air roadway of the working face for drainage. For multi-seam high-gas coal mines, the main problems existing in the construction of roof water discharge holes are as follows: 1) It is not conducive to gas management. All water discharge holes need to be drilled through coal seams, and frequent exposure of coal seam gas may cause gas overrun or even explosion. Gas will also gush out during the water discharge process, posing a serious threat to underground safety production; 2) Considering gas extraction during the water discharge process, the water discharge cycle is long, affecting the replacement of working faces; 3) The water discharge drill occupies the roadway construction area, and there is a parallel space between water discharge and roadway excavation construction and monorail crane operation. The water discharge project and the excavation of the working face roadway restrict and affect each other, resulting in a long roadway construction cycle, which is not conducive to the rapid formation of the working face ventilation system and poses a safety hazard. Summary of the Invention

[0003] The purpose of the invention is to provide a method for discharging roof water in a multi-seam high-gas working face, and solve the problems existing in the prior art: 1) The construction of water prevention and control projects is not conducive to gas management; 2) Considering gas safety, the water discharge cycle is long, affecting the replacement of working faces; 3) There is a parallel space between water discharge and excavation work, which affects each other and is not conducive to the rapid formation of the working face ventilation system.

[0004] The technical solution adopted by the invention is as follows:

[0005] A method for discharging roof water in a multi-seam high-gas working face, comprising:

[0006] Step 1: Calculate the height H of the water-conducting fissure zone formed by coal seam mining 导 , m;

[0007] H 导 = aM;

[0008] In the formula: a - the ratio of fissure to mining height, determined according to the actual measurement data of the mine; M - the coal seam mining height, m;

[0009] Step 2: Determine the end-hole target points of the water discharge holes, and set the density zoning of the end-hole target points of the water discharge holes within the working face range;

[0010] In the length range of 2 to 3 times the inclined width B along the working face strike, grid division is carried out, and the row spacing and column spacing of the grid are both Where: b - coefficient, taking 4 to 6; J - drawdown of the roof aquifer, m; k - permeability coefficient of the roof aquifer;

[0011] Outside the range of 2 to 3 times the inclined width along the working face strike and within the working face, non-dense area grid division is carried out, and the row spacing and column spacing of the grid are both Where: c - coefficient, taking 6 to 10;

[0012] Step 3: After determining the borehole displacement S, set the water drainage boreholes according to the determined final hole target points of the water drainage and release holes, so as to realize the drainage of the roof water;

[0013] S ≤ 500m.

[0014] Optionally, the determination method of the dense area within the length range of 2 to 3 times the inclined width B along the working face strike includes:

[0015] Within the length L of 2 to 3 times the inclined width B along the working face strike 走 =(2 - 3)B, the final hole target points of the water release holes are arranged densely, and the expansion distance L outward along the working face dip and the cutting hole 外 =H 导 / tanα, where: α - fracture angle, °; that is, the size of the above range is length × width = (L 走 +L 外 )×(B + 2L 外 ).

[0016] Optionally, the target points are arranged in a plum blossom pile pattern at the nodes of the grid.

[0017] Optionally, the method for determining the borehole displacement includes: the height of the final hole target point from the coal seam roof is H 终 =H 导 +(4 - 6)M, the coal seam elevation corresponding to the target point +H 终 =the target elevation, the target elevation minus the opening elevation is the elevation difference H 差 , the elevation difference H 差 is controlled within 150 - 200m; determine the borehole displacement S according to the range of the elevation difference H 差 , the elevation difference H 差 +H 终 =S.

[0018] Optionally, step 4 is also set: design the water drainage and release boreholes;

[0019] Arrange the water drainage and release boreholes according to the range that can be covered by the final hole target points and the borehole displacement determined in step 2 and step 3;

[0020] The water drainage and release boreholes are arranged in a hole group pattern. One hole group includes multiple main holes. The main holes are arranged along the first aquifer on the coal seam roof. Multiple branch holes are drilled on one main hole, and the branch holes end at the H final height of the coal seam roof (i.e., the end hole target point).

[0021] Optionally, if the working face is relatively long (generally greater than 400m), multiple hole groups are set, and the hole groups are arranged in an overlapping manner.

[0022] Optionally, it further includes Step Five: constructing the main holes of the water drainage and release hole group;

[0023] According to the design in Step Four, first construct the main holes of the water drainage and release hole group to the end holes; perform backstepping side drilling to construct the branch holes on the main holes to the end hole target points; repeat this step until all the boreholes for the water drainage and release project are completed.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1) It is beneficial to the management of borehole gas

[0026] The conventional straight hole open hole sections underground all need to penetrate high gas coal seams, and gas will also gush out during the water release process, posing a serious threat to underground safety production. However, with the main holes of the directional hole group located on the high gas coal seam roof, the number of times of penetrating the coal seam is reduced, the gas risk is lowered, and at the same time, the problems of coal seam collapse and hole shrinkage in the open hole sections penetrating the coal seam are avoided.

[0027] 2) Avoid frequent movement of the drilling rig and improve the water drainage and release efficiency

[0028] The technology of long-distance water drainage from the roof using a directional drilling rig in coal mines realizes "water drainage in one open hole area", there is no phenomenon of frequent rig movement, reducing the time waste caused by rig movement and the occurrence of electromechanical accidents. It completely separates exploration and excavation, reduces accidents caused by cross-operation, and eliminates the damage to the coal seam on the roadway floor when the rig moves. The time for moving the drilling rig is reduced, the effective drilling time is increased, and the drilling task can be completed faster for roof water drainage and release.

[0029] 3) Avoid mutual influence between tunneling and water exploration and release projects, and is beneficial to improving the water drainage and release efficiency

[0030] The underground directional drill uses a special drill site for construction, does not occupy the roadway construction area, avoids conflicts with roadway tunneling construction and monorail crane operation. Water exploration and tunneling can be carried out in parallel, shortening the time for water drainage and release boreholes. At the same time, it can realize advanced water exploration and release to cover roadway tunneling and reduce the water exploration work during tunneling.

[0031] 4) It is beneficial to the management of water inrush and improve the water drainage and release efficiency

[0032] Drainage of the roof aquifer is carried out using one main hole and multiple branch holes, achieving centralized drainage, avoiding scouring the coal floor, facilitating water inrush management. Especially when the water inrush is large, the water discharge can be increased to shorten the drainage time. At the same time, it also creates a good environment for underground tunneling operations.

[0033] 5) Facilitates the safety management of underground operation personnel

[0034] The directional drill requires a set of drilling rigs and a drilling team, reducing the number of underground operation personnel, which is conducive to personnel safety management. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are used to provide a further understanding of the present disclosure and form a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0036] Figure 1 Is the design plan view of the final hole target point of the drainage hole;

[0037] Figure 2 Is the design drawing of the plane track of the drainage hole group;

[0038] Figure 3 Is the sectional design drawing of the main drainage hole and branch holes;

[0039] Each label in the figure represents:

[0040] 1 - cutting roadway, 2 - air roadway, 3 - final hole target point, 4 - target division grid line, 5 - hole opening point, 6 - main hole, 7 - branch hole, 8 - first aquifer, 9 - final hole elevation line, 10 - height line of water - conducting fissure zone, 11 - coal seam. SPECIFIC EMBODIMENTS

[0041] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0042] Target elevation: The elevation of the target point where the drilling penetrates.

[0043] Hole opening elevation: The elevation of the hole mouth of the drilling.

[0044] Coal seam elevation: The elevation of the coal seam floor.

[0045] The final hole target point refers to the final hole point.

[0046] The method for draining the roof water of a multi - coal - seam high - gas working face of the present invention includes:

[0047] Step 1: Calculate the height H of the water - conducting fissure zone formed during coal seam mining 导 , m;

[0048] H 导 = aM;

[0049] Where: a—the mining - splitting ratio, determined according to the actual measured data of the mine; M—the mining height of the coal seam, m;

[0050] Step 2: Determine the final - hole target points of the water - drainage and - release holes, and set the density zoning of the final - hole target points of the water - drainage holes within the working face range;

[0051] In the intensive area, within the length range of 2 - 3 times the inclined width B of the working face, grid division is carried out, and the row spacing and column spacing of the grid are both L 密 =bJ√k, where: b—a coefficient, taking 4 - 6; J—the drawdown of the roof aquifer, m; k—the permeability coefficient of the roof aquifer;

[0052] In the non - intensive area, outside the range of 2 - 3 times the inclined width of the working face and within the working face, grid division is carried out, and the row spacing and column spacing of the grid are both L 正 =cJ√k, where: c—a coefficient, taking 6 - 10;

[0053] Step 3: After determining the borehole displacement S, set the water - drainage and - release boreholes according to the determined final - hole target points of the water - drainage and - release holes, so as to realize the drainage of the roof water;

[0054] S≤500m.

[0055] In the embodiment of the present disclosure, the determination method of the intensive area within the length range of 2 - 3 times the inclined width B of the working face includes:

[0056] Within the length L of 2 - 3 times the inclined width B of the working face 走 =(2 - 3)B, the final - hole target points of the water - drainage holes are arranged densely, and the out - ward expansion distance L of the air roadway and the cutting - eye of the working face 外 =H 导 / tanα, where: α—the fracture angle, °; that is, the size of the above - mentioned range is length×width=(L 走 +L 外 )×(B + 2L 外 ).

[0057] In the embodiment of the present disclosure, the target points are arranged in a plum - blossom pile pattern at the nodes of the grid.

[0058] In the embodiment of the present disclosure, the method for determining the borehole displacement includes: the height of the final - hole target point from the coal - seam roof is H 终 =H 导 +(4 - 6)M, the coal - seam elevation corresponding to the target point+H 终 =the target elevation, the elevation difference H is obtained by subtracting the opening elevation from the target elevation 差 , and the elevation difference H 差 is controlled within 150 - 200m; according to the elevation - difference H 差 range, determine the borehole displacement S, the elevation difference H 差 +H终 = S.

[0059] In an embodiment of the present disclosure, Step Four is further provided: designing water drainage boreholes;

[0060] Arrange water drainage boreholes according to the final hole target point determined in Step Two and the range that can be covered by the borehole displacement;

[0061] The water drainage boreholes are arranged in a hole group pattern. One hole group includes multiple main holes. The main holes are arranged along the first aquifer in the coal seam roof. Multiple branch holes are opened on one main hole, and the branch holes end at the H final height of the coal seam roof (i.e., at the final hole target point).

[0062] In an embodiment of the present disclosure, if the working face is relatively long (greater than 400 m), multiple hole groups are set, and the hole groups are arranged in an overlapping manner.

[0063] In an embodiment of the present disclosure, Step Five is further included: constructing the main holes of the water drainage hole group;

[0064] According to the design in Step Four, first construct the main holes of the water drainage hole group to the final hole; perform backstepping side drilling to construct the branch holes on the main hole to the final hole target point; repeat this step until all the boreholes for the water drainage project are completed.

[0065] Example One:

[0066] The 87 mining area of Zouzhuang Coal Mine is for multi-seam mining, mainly mining Coal 72 and Coal 82. First, Coal 72 is mined. There are multiple coal seams such as Coal 51, Coal 52, and Coal 62 occurring within the disturbed range of the roof of Coal 72. The coal seam gas content is high and the pressure is high, making it a coal and gas outburst mine. At the same time, the thickness of the roof sandstone is large, and the water-richness is weak to medium. The drainage of roof water faces the problem of gas prevention. The present invention is used to achieve the drainage of roof water in a multi-seam high-gas working face.

[0067] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] Step One: Calculate the height of the water-conducting fissure zone during coal seam mining.

[0069] H 导 = aM;

[0070] In the formula: H 导 —the height of the water-conducting fissure zone, m; a—the fracture-mining ratio, determined according to the actual measured data of the mine; M—the coal seam mining height, m.

[0071] In this example, a = 14, M = 5 m, H 导 = 70 m, that is, 70 m above the roof of the mined coal seam is the water-conducting fissure zone height line 10.

[0072] Step Two: Determine the final hole target point of the water drainage borehole.

[0073] As Figure 1 , the end-hole target density of the water discharge holes within the working face range is set in zones.

[0074] 1) Within the length L 走 = (2 - 3)B of 2 - 3 times the inclined width B along the working face strike, the end-hole targets 3 of the water discharge holes are arranged in a dense pattern. The outwards expansion distance L 外 = H 导 / tanα, where: α - fracture angle, °; that is, the dimensions of the above range are length × width = (L 走 + L 外 ) × (B + 2L 外 );

[0075] Grid lines 4 are drawn within the delineated range, and both the row spacing and column spacing are where: b - coefficient, taking 4 - 6; J - drawdown of the roof aquifer, m; k - permeability coefficient of the roof aquifer.

[0076] The end-hole targets 3 are arranged in a plum blossom pile pattern at the nodes of the grid.

[0077] In this example, B = 200m, the distance L along the working face strike 走 = 2.5B = 500m; α = 72°, the outwards expansion distance L of the air return roadway and the cutting 外 = H 导 / tanα = 23m. Therefore, the range of the dense area is 523m × 246m.

[0078] In this example, K = 0.003m / d, J = 200m, b = 5.5, and based on this, the row spacing and column spacing of the grid in the dense area are calculated

[0079]

[0080] 2) Outside the range of 2 - 3 times the inclined width along the working face strike, the end-hole targets of the water discharge holes are arranged normally. The drainage range is within the working face and does not expand outwards.

[0081] Grid lines are drawn within the delineated range, and both the row spacing and column spacing are where: c - coefficient, taking 6 - 10. The targets are arranged in a plum blossom pile pattern at the nodes of the grid.

[0082] In this example, c = 7.1, calculate

[0083] The layout of the end-hole targets 3 of the boreholes in this example is as Figure 1 . From 23m outside the cutting and the air return roadway to 500m inside the working face is the dense area, and the end-hole targets are arranged in a plum blossom pile pattern at a spacing of 60m × 60m. In other areas of the working face, the end-hole targets are arranged in a plum blossom pile pattern at a spacing of 80m × 80m.

[0084] Step 3: Determine the drilling displacement according to the elevation difference between the open hole and the final hole.

[0085] The height of the final hole target point from the coal seam roof is H 终 = H 导 +(4 - 6)M. Calculate the target point elevation based on the coal seam elevation corresponding to the target point. The elevation difference H is the target point elevation minus the open hole elevation, and it is controlled within 150 - 200m. 差 Control it within 150 - 200m.

[0086] Determine the drilling displacement S according to the elevation difference range, and at the same time S ≤ 500m.

[0087] In this example, H 终 = H 导 + 6M = 100m, H 差 = 200m, S = 500m.

[0088] Step 4: Design the water drainage and release boreholes.

[0089] Such as Figure 2 , arrange the water release boreholes according to the target points determined in Step 2 and Step 3 and the coverage range that the boreholes can cover.

[0090] The water drainage and release boreholes are arranged in a hole group pattern. The cross-section of the hole group is as Figure 3 , one hole group includes multiple main holes arranged along the first aquifer 8 of the coal seam roof. Multiple branch holes 7 are opened on one main hole 6, and the branch holes 7 end at the coal seam roof H 终 height.

[0091] If the working face is relatively long, set multiple hole groups and arrange them in an overlapping manner.

[0092] The plan view of the borehole arrangement in this example is as Figure 2 , a total of 5 drill sites are arranged, 5 hole groups are designed, each hole group is designed with 3 - 6 main holes 6, and each main hole is designed with 3 - 5 branch holes 7.

[0093] Step 5: Construct the main holes of the water drainage and release hole group.

[0094] According to the design in Step 4, first construct the main hole 6 of the water drainage and release hole group to the final hole.

[0095] Such as Figure 3 shown, in this example, the main hole is drilled along the sandstone of the 62 coal roof to the final hole position.

[0096] Step 6: Construct the water drainage and release branch holes.

[0097] At the retreating side drilling after the completion of the constructed main hole, construct the branch hole 7 on this main hole to the final hole target point. The branch hole 7 intersects obliquely with the thin coal seam 11 and each aquifer in the roof at a large angle.

[0098] As Figure 3 shown, in this example, the branch hole is drilled by retreating side drilling in the main hole, and the final hole is at 100 m above the coal seam roof.

[0099] Step Seven: Complete the construction of all hole groups.

[0100] Repeat Step Five and Step Six to complete all the main holes 6 and branch holes 7 in the hole groups. Then construct other hole groups until all the boreholes for the water drainage project are completed.

[0101] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0102] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0103] Furthermore, any combination can be made among the various different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for draining roof water in a multi-seam high-gas working face, characterized in that, Including: Step 1: Calculate the height H of the water-conducting fissure zone in coal seam mining 导 , m; H 导 = aM; Where: a—the mining crack ratio, determined according to the actual measured data of the mine; M—the mining height of the coal seam, m; Step 2: Determine the final hole target points of the water drainage holes, and set the density zoning of the final hole target points of the water drainage holes within the working face range; The dense area is divided into grids within the length range of 2 to 3 times the inclined width B in the working face strike direction, and the row spacing and column spacing of the grids are both In the formula: b - coefficient, taking 4 to 6; J - drawdown of the roof aquifer, m; k - permeability coefficient of the roof aquifer; the determination method of the dense area within the length range of 2 to 3 times the inclined width B in the working face strike direction includes: within the length L 走 =(2 - 3)B, the end hole target points of the water discharge holes are arranged densely, and the expansion distance L outward from the working face dip and the cutting eye 外 =H 导 / tanα, in the formula: α - fracture angle, °; that is, the size of the above range is length × width = (L 走 +L 外 )×(B + 2L 外 ); Outside the range of 2 to 3 times the inclined width along the working face strike and within the working face, non-dense areas are divided into grids, and the row spacing and column spacing of the grids are both In the formula: c—coefficient, taking 6 to 10; Step 3: After determining the borehole displacement S, set the water drainage boreholes according to the determined final hole target points of the water drainage holes, so as to realize the drainage of the roof water; S≤500m; The method for determining the drilling displacement includes: the height of the final hole target point from the coal seam roof is H 终 =H 导 +(4~6)M, the coal seam elevation corresponding to the target point +H 终 = Target elevation, target elevation minus opening elevation is elevation difference H 差 , elevation difference H 差 Controlled within 150~200m; according to the elevation difference H 差 The range determines the drilling displacement S and the elevation difference H 差 / tanβ=S, β—pseudo-inclination of coal seam in the direction of maximum elevation difference, °; Step 4: Design water drainage boreholes; arrange water drainage boreholes according to the final hole target points determined in Step 2 and Step 3 and the range covered by the borehole displacement; the water drainage boreholes are arranged in a hole group pattern, where a hole group includes multiple main holes. The main holes are arranged along the first aquifer in the coal seam roof. Multiple branch holes are drilled on one main hole, and the branch holes end at the coal seam roof at a height of H 终 height; Step 5: Construct the main hole of the water drainage hole group; according to the design in Step 4, first construct the main hole of the water drainage hole group to the final hole; drill the branch holes on the main hole in a retreating side drilling manner to the final hole target points; repeat this step until all the boreholes of the water drainage project are completed.

2. The method for discharging roof water in a multi-seam high-gas working face according to claim 1, characterized in that, Arrange the target points in a plum blossom pile pattern at the nodes of the grid.

3. The method for discharging roof water in a multi - coal - seam high - gas working face according to claim 1 or 2, characterized in that, For a working face with a length greater than 400m, multiple hole groups are set, and the hole groups are arranged in an overlapping manner.

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