A multi-layered filling method for coal mine goaf based on directional long drilling groups

Abstract

The present invention discloses a multi-layered gradation filling method for a coal mine goaf based on a directional long drill hole group. According to the distribution law of the residual space in the goaf, the method divides the goaf into different grouting areas according to the amount of roof rock collapse and the density of gangue. A high-position grouting chamber is arranged on the hard rock floor, and a directional long drill hole is drilled in the floor of the high-position grouting chamber. The directional long drill holes in different layout layers form a directional long drill hole group. By changing the layer position of the directional long drill hole end hole position and the grouting sequence, a multi-layered gradation filling space of the directional long drill hole group is formed, thereby generating a supporting force for the basic roof and the overlying rock strata, further reducing the collapse of the basic roof, indirectly changing the collapse degree and caving law of the overlying rock strata, and effectively increasing the grouting volume of the goaf. At the same time, the downhole avoids pipe blockage during the grouting filling of the roof of the mining-spanning type. The use of directional long drill hole grouting avoids the problem of increased grouting costs caused by the construction of high-position tunnels, and slows down surface subsidence.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine filling, and in particular relates to a multi-layered and graded filling method for a coal mine goaf based on a directional long drill hole group. Background Art

[0002] Goafs and overburden areas formed after intensive coal mining are prone to secondary subsidence, spontaneous combustion of coal seams, accumulation of hazardous gases, and water inrush. Furthermore, the accumulation of coal-based solid wastes such as fly ash and desulfurization gypsum generated during coal chemical processing also creates land and pollutes the surrounding air and water. To address these two issues, backfill mining can effectively address these issues. Drawing on paste backfill technology, backfill mining has been widely used in recent years.

[0003] Goaf filling technology is a new filling technology that crushes coal-based solid waste such as gangue and then simply cements them according to a certain proportion or directly adds water to make slurry and pumps it into the goaf where it has collapsed underground. Regarding filling goaf, there is a publicly available method for segmented cementation grouting filling of coal mine goaf (application number: 202210441681.X), a method for determining the timing of gangue grouting in the space after coal mining (application number: CN202210876397.5), etc. It can be found that the current existing technologies select the grouting layer in the goaf and subsequent space of the mining working face, directly grouting into the goaf through the two lanes of the coal seam, carrying out adjacent grouting in the two lanes of another working face through isolated coal pillars, or directly drilling holes in the working face to grout the goaf and carry out high-position grouting (Zhu Lei, et al. "Research Progress and Prospects of Coal Gangue Slurry Filling Technology in Goaf Areas." Coal Science and Technology. doi: 10.13199 / j.cnki.cst.2022-1725.). Studies have found that the residual space in the goaf has a "void-void-pore" distribution pattern, and can be divided into specific areas according to the amount of roof rock strata falling and the density of gangue (Li Liang, et al. "Underground treatment of coal gangue and fluidized filling technology in goaf." Journal of Xi'an University of Science and Technology).

[0004] It can be found that the filling methods involved in existing research only calculate the filling space through the distribution law of the voids in the goaf, and do not consider the rational use of the residual space distribution law in the goaf to carry out multi-layer three-dimensional grouting; at the same time, for the roof of the mining-as-you-go type, adjacent grouting and direct drilling of holes on the working face to grout the goaf will have the risk of pipe blockage, and the cost of high-position grouting filling is too high.

[0005] In view of this, how to provide a multi-layered tiered filling method for coal mine goaf that can partially or completely solve the above technical problems is a technical problem that people in this field urgently need to solve. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-layered and graded filling method for coal mine goaf based on a group of directional long drill holes to solve the above problems.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A multi-layered filling method for coal mine goaf based on a directional long drill hole group comprises the following steps:

[0009] Step 1: Divide the goaf into three different grouting areas: Area I, Area II, and Area III according to the residual space distribution pattern of the goaf, the amount of roof rock stratum caving, and the density of waste rock. Determine the regional range of Area I, Area II, and Area III, which includes height, length, and width. The three different grouting areas of Area I, Area II, and Area III respectively form hierarchical spaces at different levels.

[0010] Step 2: Determine the distance between the high-position grouting chamber and the stop-mining line, the height from the coal seam, and the starting position and length of the stone gate. The high-position grouting chamber is located in the hard rock floor.

[0011] The third step: determine the layout layer, end hole position and the angle between two adjacent long grouting holes in the horizontal direction of the long grouting holes corresponding to the zones I, II and III; wherein the layout layer and end hole position of the long grouting holes are as follows: a plurality of long grouting holes are horizontally opened along the hard rock bottom plate from the high-position grouting chamber, so that the end hole is located at the upper center of the zone III; a plurality of long grouting holes are opened along the soft rock interlayer, which are inclined downward and the end hole is close to the basic top plate, so that the end hole is located at the upper center of the zone II; a plurality of long grouting holes are opened along the soft rock interlayer and the basic top, which are inclined downward and the end hole is close to the direct top plate, so that the end hole is located at the upper center of the zone I; the high-position grouting chamber is connected to each of the long grouting holes, and a seamless flower pipe is installed at the end hole of each long grouting hole;

[0012] Step 4: Laying a grouting pipeline from the ground grouting station to the high-position grouting chamber, wherein the grouting pipeline is a pipeline for pumping filling slurry; a nine-way grouting pipeline is laid in the high-position grouting chamber, wherein the feed port of the nine-way grouting pipeline is connected to the grouting pipeline; and the plurality of discharge ports of the nine-way grouting pipeline are each connected to a long grouting borehole;

[0013] Step 5: Determine the grouting order of Zone I, Zone II, and Zone III according to the grouting pressure of the echelon space; when the working face is mined to the boundary of Zone I and the regional characteristics of Zone I, Zone II, and Zone III appear, open the valve of the long grouting borehole above Zone III, and let the filling slurry flow along the gap between the soft rock interlayer and the basic roof to the caving space below the basic roof; when the gap and caving space in Zone III are completely filled and the grouting pressure increases significantly, close the valve of the long grouting borehole above Zone III, open the valve of the long grouting borehole above Zone II, and let the filling slurry flow along the gap between the basic roof and the immediate roof to the caving space below the immediate roof; when the gap and caving space in Zone II are completely filled and the grouting pressure increases significantly, close the valve of the long grouting borehole above Zone II, open the valve of the long grouting borehole above Zone I, and let the filling slurry flow along the gap between the immediate roof and the coal seam roof to the goaf behind the working face frame.

[0014] The area ranges of Zone I, Zone II, and Zone III are determined based on the stope roof masonry beam theory, the subsidence law of the overlying rock strata in the goaf, and the diffusion performance of the fluidized slurry. The detailed steps are as follows:

[0015] The overburden subsidence curve of the stope is formed based on the stope roof masonry beam theory, the subsidence law of the overburden in the goaf, the distribution state of the rock blocks in the goaf and the stress characteristics.

[0016] The force relationship between the falling rock blocks and the working face advancement time is deduced based on the overburden rock subsidence curve of the stope, and the relationship between the stability coefficient of the goaf and the working face advancement time is determined after deduction and calculation;

[0017] According to the relationship between the stability coefficient of the goaf and the advancing time of the working face, a "strike-dip" zoning model of the goaf is established;

[0018] The goaf area that can be filled is determined based on the "strike-dip" zoning model of the goaf, thereby determining the regional scope of the areas I, II and III.

[0019] The high-position grouting chamber is arranged outside the influence range of the advance support pressure of the stop-mining line. The height of the high-position grouting chamber from the coal seam is the vertical distance between the hard rock floor and the center of the working face; the stone gate starting position is determined according to the high-position grouting chamber, the stone gate starting position and the grouting chamber are in a straight line and are arranged perpendicular to the working face air lane, and the length of the stone gate is obtained by geometric triangulation conversion based on the inclination of the coal seam and the height of the high-position grouting chamber from the coal seam.

[0020] The angle between two adjacent long grouting boreholes in the horizontal direction is determined according to the top and bottom lithology of the overlying rock layer of the coal seam and the height of the "three zones".

[0021] The angle between two adjacent long grouting boreholes in the horizontal direction is between 20° and 70°.

[0022] The length of the seamless flower pipe is one tenth of the length of the long grouting drill hole, and the material is DN180 seamless steel flower pipe. The seamless flower pipe and the long grouting drill hole are welded with an inner sleeve.

[0023] In the fifth step, the filling slurry is grouted intermittently, and the water-solid ratio of the filling slurry used in multiple grouting is from low to high, and the filling slurry contains a viscosity enhancer.

[0024] Rinse the long grouting holes with clean water before intermittent grouting.

[0025] Compared with the existing technology, the present invention has the following advantages and technical effects: the present invention divides the goaf into different grouting areas according to the distribution law of the residual space in the goaf, by the amount of roof rock stratum collapse and the density of the gangue, and arranges a high-position grouting chamber on the hard rock floor outside the influence range of the advance support pressure of the stop-mining line, drills a directional long borehole in the floor of the high-position grouting chamber, and arranges a nine-way grouting pipeline inside, which is connected to the grouting casing in the directional long borehole.

[0026] Directional long boreholes in different layout layers form a directional long borehole group. By changing the layer of the final hole position of the directional long borehole and the order of grouting, a multi-layered filling space of the directional long borehole group is formed, which will generate support force for the basic roof and overlying rock strata, further weaken the collapse of the basic roof, indirectly change the collapse degree and the falling law of the overlying rock strata, and effectively increase the grouting volume of the goaf; at the same time, the downward hole avoids pipe blockage (intermittent grouting) during the grouting of the span-type roof during mining. The use of directional long borehole grouting avoids the problem of increased grouting costs caused by the construction of high-level tunnels and slows down surface subsidence. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work.

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0029] Figure 2 It is a cross-sectional schematic diagram of the present invention;

[0030] Figure 3 It is a schematic diagram of the filling effect of the present invention;

[0031] Figure 4A top view of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of a nine-way grouting pipeline in one embodiment of the present invention;

[0033] Figure 6 This is a flowchart of an embodiment of the present invention.

[0034] Among them, 1. Stop mining line; 2. High-position grouting chamber; 3. Working face; 4. Stone gate; 5. Long grouting borehole; 501, 1-1 long grouting borehole; 502, 1-2 long grouting borehole; 503, 1-3 long grouting borehole; 504, 2-1 long grouting borehole; 505, 2-2 long grouting borehole; 506, 2-3 long grouting borehole; 507, 3-1 long grouting borehole; 508, 3-2 long grouting borehole; 509, 3-3 long grouting borehole; 6. Ground grouting station; 7. Grouting pipeline; 8. Seamless flower pipe; 9. Nine-way grouting pipeline; 901, feed inlet; 902, main pipeline gate valve; 903, discharge port; 904, valve. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] A multi-layered filling method for coal mine goaf based on a directional long drill hole group comprises the following steps:

[0038] Step 1: Divide the goaf into three different grouting areas: Area I, Area II and Area III according to the residual spatial distribution law of the goaf, the amount of roof rock strata falling and the density of gangue, and determine the regional range of Area I, Area II and Area III. The regional range includes height, length and width. The regional range of Area I, Area II and Area III is determined according to the theory of masonry beams on the goaf roof, the law of subsidence of the overburden in the goaf and the diffusion performance of fluidized slurry. The detailed steps are as follows: According to the theory of masonry beams on the goaf roof, the law of subsidence of the overburden in the goaf and the diffusion performance of fluidized slurry, the grouting area is divided into three different grouting areas: Area I, Area II and Area III. The ... II and Area III. The distribution state and stress characteristics of the rock blocks in the goaf form the subsidence curve of the overlying strata in the mining area; based on the subsidence curve of the overlying strata in the mining area, the stress relationship of the falling rock blocks with the advancement time of the working face 3 is derived, and the relationship between the stability coefficient of the goaf and the advancement time of the working face 3 is determined after deduction and calculation; according to the relationship between the stability coefficient of the goaf and the advancement time of the working face 3, a "strike-dip" zoning model of the goaf is established; based on the "strike-dip" zoning model of the goaf, the filling area of ​​the goaf is determined, thereby determining the regional range of Zone I, Zone II, and Zone III. Among them, the three different grouting areas of Zone I, Zone II, and Zone III form hierarchical spaces of different layers respectively; the length of this area is the length of the working face 3, and the width is determined according to the relationship between the stability coefficient and the advancement time of the working face 3. The advancement time multiplied by the advancement speed is the width, and the height is the distance from the coal seam floor to the pseudo roof floor (Zone I), the direct roof floor (Zone II), and the basic roof (Zone II) floor respectively;

[0039] Step 2: Determine the distance between the high-position grouting chamber 2 and the stop-mining line 1, the height from the coal seam, and the starting position and length of the stone gate 4. The high-position grouting chamber 2 is arranged in the hard rock floor.

[0040] Step 3: Determine the layout layer, terminal hole position and the angle between two adjacent grouting long boreholes 5 in the horizontal direction of the grouting long boreholes 5 corresponding to Zone I, Zone II and Zone III; wherein, the layout layer and terminal hole position of the grouting long boreholes 5 are as follows: three grouting long boreholes 5 are opened horizontally along the hard rock bottom plate from the high-position grouting chamber 2 so that the terminal holes are located above Zone III, namely 1-1 grouting long borehole 501, 1-2 grouting long borehole 502, and 1-3 grouting long borehole 503; multiple grouting long boreholes 5 are opened along the soft rock interlayer, which are inclined downward and the terminal holes are close to the basic top plate, so that the terminal holes are located above Zone III. Above the II zone, there are 2-1 long grouting borehole 504, 2-2 long grouting borehole 505, and 2-3 long grouting borehole 506 respectively; along the soft rock interlayer and the basic top, a plurality of grouting long boreholes 5 are opened, which are inclined downward and the end hole is close to the direct top plate, so that the end hole is located above the I zone, namely 3-1 long grouting borehole 507, 3-2 long grouting borehole 508, and 3-3 long grouting borehole 509, and the angle between two adjacent long grouting boreholes 5 in the horizontal direction is 20°; the high-position grouting chamber 2 is connected to each long grouting borehole 5, and a seamless flower pipe 8 is installed at the end hole of each long grouting borehole 5;

[0041] Step 4: Lay out a grouting pipeline 7 from the ground grouting station 6 to the high-position grouting chamber 2. The grouting pipeline 7 is a pipeline for pumping filling slurry. A nine-way grouting pipeline is laid out in the high-position grouting chamber 2. The feed port of the nine-way grouting pipeline is connected to the grouting pipeline 7. Several discharge ports of the nine-way grouting pipeline are each connected to a long grouting borehole 5.

[0042] Step 5: Determine the grouting order of Zone I, Zone II, and Zone III according to the grouting pressure of the echelon space; when the working face 3 is mined to the boundary of Zone I, and the regional characteristics of Zone I, Zone II, and Zone III appear, open the valve of the long grouting borehole 5 above Zone III, and let the filling slurry flow along the gap between the soft rock interlayer and the basic roof to the caving space below the basic roof; when the gap and caving space in Zone III are completely filled and the grouting pressure increases significantly, close the valve of the long grouting borehole 5 above Zone III, open the valve of the long grouting borehole 5 above Zone II, and let the filling slurry flow along the gap between the basic roof and the immediate roof to the caving space below the immediate roof; when the gap and caving space in Zone II are completely filled and the grouting pressure increases significantly, close the valve of the long grouting borehole 5 above Zone II, open the valve of the long grouting borehole 5 above Zone I, and let the filling slurry flow along the gap between the immediate roof and the coal seam roof to the goaf behind the working face 3.

[0043] Among them, when the grouting pressure increases significantly, it can be determined that the corresponding space is completely filled.

[0044] The scope of Zones I, II, and III is determined based on the stope roof masonry beam theory, the subsidence law of the overlying rock strata in the goaf, and the diffusion performance of the fluidized slurry. The detailed steps are as follows:

[0045] 1. The overburden subsidence curve of the stope is formed based on the stope roof masonry beam theory, the subsidence law of the overburden in the goaf, the distribution state of the rock blocks in the goaf and the stress characteristics;

[0046] In one embodiment of the present invention, its principle can refer to Li Liang, et al. "Research on the four-level zoning model of gangue fluidization filling goaf" Journal of Mining and Safety Engineering 40.01(2023):11-16.doi:10.13545 / j.cnki.jmse.2022.0024.

[0047] 2. The force relationship between the falling rock blocks and the advancement time of the working face 3 is derived based on the subsidence curve of the overlying rock strata in the stope. The relationship between the stability coefficient of the goaf and the advancement time of the working face 3 is determined after deduction and calculation;

[0048] In one embodiment of the present invention, its principle can refer to Li Liang, et al. "Research on the four-level zoning model of gangue fluidization filling goaf" Journal of Mining and Safety Engineering 40.01(2023):11-16.doi:10.13545 / j.cnki.jmse.2022.0024.

[0049] 3. Establish a “strike-trend” zoning model of the goaf according to the relationship between the goaf stability coefficient and the advancement time of the working face 3;

[0050] 4. Determine the filling area of ​​the goaf based on the "strike-dip" zoning model of the goaf, thereby determining the regional scope of Zone I, Zone II, and Zone III.

[0051] In one embodiment of the present invention, the length of the area is the length of the working face, the width is determined according to the relationship between the stability coefficient and the working face advancement time, the advancement time multiplied by the advancement speed is the width, and the height is the distance from the coal seam floor to the pseudo roof floor (zone I), the direct roof floor (zone II), and the basic roof (zone II) floor.

[0052] Furthermore, the high-position grouting chamber 2 is arranged outside the influence range of the advance support pressure of the stop-mining line 1, and the height of the high-position grouting chamber 2 from the coal seam is the vertical distance between the hard rock floor and the center of the working face; the stone gate starting position is determined according to the high-position grouting chamber, and the stone gate starting position and the grouting chamber are in a straight line and arranged perpendicular to the working face air lane. The length of the stone gate is obtained by geometric trigonometric conversion based on the inclination of the coal seam and the height of the high-position grouting chamber from the coal seam; for example, if the influence range of the advance support pressure is 0-10m, the high-position grouting chamber needs to be arranged 10m away from the stop-mining line.

[0053] The high-position grouting chamber 2 is set outside the influence range of the advance support pressure of the stop-mining line 1. The height of the high-position grouting chamber 2 from the coal seam is the vertical distance between the hard rock floor and the center of the working face 3; the starting position of the stone gate 4 is determined according to the high-position grouting chamber 2, and the starting position of the stone gate 4 and the grouting chamber are in a straight line and are set perpendicular to the air lane of the working face 3. The length of the stone gate 4 is obtained by geometric triangulation conversion based on the inclination of the coal seam and the height of the high-position grouting chamber 2 from the coal seam.

[0054] The angle between two adjacent long grouting boreholes 5 in the horizontal direction is determined according to the lithology of the overlying rock layer top and floor of the coal seam and the height of the "three zones".

[0055] In one embodiment of the present invention, the “three zones” are the coal wall support influence zone, the separation zone and the recompaction zone.

[0056] The angle between two adjacent long grouting boreholes 5 in the horizontal direction is between 20° and 70°.

[0057] The length of the seamless flower tube 8 is one tenth of the length of the grouting long drill hole 5, and the material is DN180 seamless steel flower tube. The seamless flower tube 8 and the grouting long drill hole 5 are welded with an inner sleeve.

[0058] In the fifth step, the filling slurry is injected intermittently. The water-solid ratio of the filling slurry used in multiple injections increases from low to high, and the filling slurry contains a viscosity enhancer.

[0059] Before intermittent grouting, flush the long borehole 5 with clean water.

[0060] In an embodiment of the present invention, the high-position grouting chamber 2 has a nine-way discharge port, which is connected to each grouting long borehole 5, and a flange is provided at the connection point. The inner diameter of the discharge port and each grouting long borehole 5 is consistent, both of which are 180 mm. A valve is installed at about 10 cm away from each grouting long borehole 5 to individually control the filling slurry flow and start and stop of each grouting long borehole 5; the feed port of the high-position grouting chamber 2 is connected to the grouting pipeline 7, and a flange is provided at the connection point. A main pipeline gate valve is provided at about 20 cm away from the feed port of the grouting pipeline 7 to control the flow and start and stop of the filling slurry as a whole; the length of the seamless flower pipe 8 is one tenth of the length of the grouting long borehole 5, and the material is DN180 seamless steel flower pipe. The seamless flower pipe 8 and the grouting long borehole 5 are welded with an inner sleeve.

[0061] In this embodiment, in the fifth step, the filling slurry is intermittently grouting, and the water-solid ratio of the filling slurry used in multiple grouting is from low to high, and the filling slurry contains a viscosity enhancer.

[0062] The present invention provides a multi-layered filling method for coal mine goaf based on a directional long drill hole group. Figure 6 As shown, according to the distribution law of the residual space in the goaf, the area is divided into different grouting areas according to the amount of roof rock stratum falling and the density of gangue, and a high-position grouting chamber 2 is arranged on the hard rock floor outside the influence range of the advance support pressure of the stop-mining line. A directional long borehole is drilled in the bottom plate of the high-position grouting chamber 2, and a nine-way grouting pipeline 9 is arranged inside. The nine-way grouting pipeline 9 is connected to the grouting pipeline 7 in the directional long borehole. Directional long boreholes in different layout layers form a directional long borehole group. By changing the layer of the final hole position of the directional long borehole and the order of grouting, a multi-layered filling space of the directional long borehole group is formed, which will generate support force for the basic roof and the overlying rock strata, further weaken the collapse of the basic roof, indirectly change the collapse degree and the falling law of the overlying rock strata, and effectively increase the grouting volume of the goaf; at the same time, the downhole avoids pipe blockage (intermittent grouting) during the grouting and filling of the span-type roof during mining. The use of directional long borehole grouting avoids the problem of increased grouting costs caused by the construction of high-level tunnels and slows down surface subsidence. This method is simple, safe, and economical to operate, has broad application prospects, and has important practical significance for the field of grouting and filling of coal mine goafs.

[0063] In one embodiment of the present invention, Figure 5 As shown, one end of the nine-way grouting pipeline 9 is a feed port 901, and the other end is nine discharge ports 903. The feed port 901 is connected to the grouting pipeline 7, and the discharge port 903 is connected to the grouting sleeve in the long grouting borehole 5.

[0064] The feed port 901 is welded with a flange, one end of which is connected to the grouting pipeline 7. A main pipeline gate valve 902 is welded 20 cm from the flange to control the overall flow of the grouting material. One end is connected to the nine-way grouting pipeline 9, and the nine-way grouting pipeline 9 has nine discharge ports 903 welded to the upper, middle, and lower parts of the center and the upper, middle, and lower parts of the left and right sides. The angle between the left and right discharge ports 903 and the center discharge port 903 is between 20-70 degrees, adjusted according to the actual situation on site. Each discharge port 903 is connected to the long grouting borehole 5 with a flange and screws, and the pipe diameter of both is consistent with 180 mm. A valve 904 is installed 10 cm from each discharge port 903 to control the flow of each discharge port 903.

[0065] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A multi-layered filling method for coal mine goaf based on a directional long drilling group, characterized in that: The following steps are involved: Step 1: Divide the goaf into three different grouting areas: Area I, Area II, and Area III according to the residual space distribution pattern of the goaf, the amount of roof rock stratum caving, and the density of waste rock. Determine the regional range of Area I, Area II, and Area III, which includes height, length, and width. The three different grouting areas of Area I, Area II, and Area III respectively form hierarchical spaces at different levels. Step 2: Determine the distance between the high-position grouting chamber (2) and the stop-mining line (1), the height from the coal seam, and the starting position and length of the stone gate (4), wherein the high-position grouting chamber (2) is arranged in a hard rock floor; The third step: determining the layout layer, the end hole position and the angle between two adjacent grouting long boreholes (5) in the horizontal direction of the grouting long boreholes (5) corresponding to the zones I, II and III; wherein the layout layer and the end hole position of the grouting long boreholes (5) are as follows: a plurality of grouting long boreholes (5) are horizontally opened along the hard rock bottom plate from the high-position grouting chamber (2) so that the end hole is located at the upper center of the zone III; a plurality of grouting long boreholes (5) are opened along the soft rock interlayer and the end hole is close to the basic top plate so that the end hole is located at the upper center of the zone II; a plurality of grouting long boreholes (5) are opened along the soft rock interlayer and the basic top so that the end hole is located at the upper center of the zone I; the high-position grouting chamber (2) is connected to each of the grouting long boreholes (5), and a seamless flower pipe (8) is installed at the end hole of each of the grouting long boreholes (5); Step 4: Laying a grouting pipeline (7) from the ground grouting station (6) to the high-position grouting chamber (2), wherein the grouting pipeline (7) is a pipeline for pumping filling slurry; a nine-way grouting pipeline is laid in the high-position grouting chamber (2), wherein the feed port of the nine-way grouting pipeline is connected to the grouting pipeline (7); and each of the several discharge ports of the nine-way grouting pipeline is connected to a long grouting borehole (5); Step 5: Determine the grouting order of Zone I, Zone II, and Zone III according to the grouting pressure of the stepped space; when the working face (3) is mined to the boundary of Zone I, and the regional characteristics of Zone I, Zone II, and Zone III appear, open the valve of the grouting long borehole (5) above Zone III, and allow the filling slurry to flow along the gap between the soft rock interlayer and the basic top to the caving space below the basic top; when the gap and caving space of Zone III are completely filled, and the grouting pressure rises significantly, close the valve above Zone III. The valve of the long grouting borehole (5) is opened, and the valve of the long grouting borehole (5) located above the II zone is opened, and the filling slurry flows along the gap between the basic roof and the immediate roof to the caving space below the immediate roof; when the gap and the caving space of the II zone are completely filled and the grouting pressure rises significantly, the valve of the long grouting borehole (5) located above the II zone is closed, and the valve of the long grouting borehole (5) located above the I zone is opened, and the filling slurry flows along the gap between the immediate roof and the coal seam roof to the goaf behind the working face (3).

2. The method for multi-layer filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized by: The area ranges of Zone I, Zone II, and Zone III are determined based on the stope roof masonry beam theory, the subsidence law of the overlying rock strata in the goaf, and the diffusion performance of the fluidized slurry. The detailed steps are as follows: (1) Based on the stope roof masonry beam theory, the subsidence law of the overlying strata in the goaf, the distribution state of the rock blocks in the goaf and the stress characteristics, a subsidence curve of the overlying strata in the stope is formed; (2) The force relationship between the falling rock blocks and the advancing time of the working face (3) is derived based on the subsidence curve of the overlying rock strata in the mining area, and the relationship between the stability coefficient of the goaf and the advancing time of the working face (3) is determined after deduction and calculation; (3) Establish a goaf area "strike-tendency" zoning model based on the relationship between the goaf area stability coefficient and the working face (3) advancement time; (4) Determine the filling area of ​​the goaf based on the "strike-dip" zoning model of the goaf, thereby determining the regional scope of the aforementioned Zone I, Zone II, and Zone III.

3. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized in that: The high-position grouting chamber (2) is arranged outside the influence range of the advance support pressure of the stop-mining line (1); the height of the high-position grouting chamber (2) from the coal seam is the vertical distance between the hard rock floor and the center of the working face (3); the starting position of the stone gate (4) is determined according to the high-position grouting chamber (2); the starting position of the stone gate (4) and the grouting chamber form a straight line and are arranged perpendicular to the air lane of the working face (3); the length of the stone gate (4) is obtained by geometric trigonometric conversion according to the coal seam inclination and the height of the high-position grouting chamber (2) from the coal seam.

4. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized by: The angle between two adjacent long grouting boreholes (5) in the horizontal direction is determined according to the top and bottom lithology of the overlying rock layer of the coal seam and the height of the "three zones".

5. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized in that: The angle between two adjacent long grouting boreholes (5) in the horizontal direction is between 20° and 70°.

6. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized in that: The length of the seamless flower tube (8) is one tenth of the length of the long grouting borehole (5), and the material is a DN180 seamless steel flower tube. The seamless flower tube (8) and the long grouting borehole (5) are welded by an inner sleeve.

7. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 1 is characterized in that: In the fifth step, the filling slurry is grouted intermittently, and the water-solid ratio of the filling slurry used in multiple grouting is from low to high, and the filling slurry contains a viscosity enhancer.

8. The method for multi-layered filling of coal mine goaf based on directional long drilling groups according to claim 7 is characterized in that: Before intermittent grouting, flush the long borehole (5) with clean water.

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