A three-dimensional grouting method based on spatial void distribution in the caving area

Abstract

The present invention discloses a three-dimensional grouting method based on the spatial void distribution of a caving area. The caving area is divided into zone I, zone II and zone III according to the residual spatial distribution law of the caving area, the caving amount of the roof rock layer and the density of the gangue. 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 are determined. The layout layer, the end hole position and the angle of the grouting long boreholes corresponding to the zones I, II and III are determined. The grouting pipeline is laid from the ground grouting station to the high-position grouting chamber, and the grouting slurry is filled into the caving area. The method makes full use of the spatial void distribution characteristics and laws of the caving area, links the grouting filling with the spatial void distribution characteristics and laws of the caving area, divides the grouting area into different grouting areas according to the caving amount of the roof rock layer and the density of the gangue to carry out multi-layer three-dimensional grouting, can make full use of the grouting space, effectively increase the mining-injection ratio, has broad application prospects, and has important practical significance for the field of grouting filling in the caving area of ​​coal mines.

Description

Technical Field

[0001] The invention relates to the field of coal mine filling mining, and in particular to a three-dimensional grouting method based on spatial gap distribution in a caving area. Background Art

[0002] The caving zones formed after high-intensity 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, produced during coal chemical processing, creates land and pollutes the surrounding air and water. Backfill mining can effectively address these issues. Drawing on paste backfill technology, fluidized backfilling technology has been widely used in caving zones in recent years.

[0003] The fluidized filling technology for caving areas 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 caving areas underground. Regarding the filling of the caving area, the prior art discloses a method for segmented cementation grouting filling of the caving area in a coal mine (application number: 202210441681.X), a method for determining the timing of gangue grouting in the space after coal mining (application number: 202210876397.5), etc. It can be found that the existing technology selects the grouting layer in the caving area and subsequent space of the mining working face, directly injects grouting into the caving area through the two lanes of the coal seam, carries out adjacent grouting in the two lanes of another working face through isolation coal pillars, or directly drills holes in the working face to inject grouting into the caving area, and carries out high-position grouting (Zhu Lei, et al. "Research Progress and Prospects of Gangue Slurry Filling Technology in Caving Areas." Coal Science and Technology. doi: 10.13199 / j.cnki.cst.2022-1725.). Studies have found that the residual space in the caving zone has a "void-void-pore" distribution pattern (collectively referred to as the residual space distribution pattern in the caving zone in this application), which can be divided into specific areas according to the amount of caving of the roof rock layer and the density of gangue (Li Liang, et al. "Underground treatment of coal gangue and fluidized filling technology in caving zone" Journal of Xi'an University of Science and Technology 42.05(2022):865-873.doi:10.13800 / j.cnki.xakjdxxb.2022.0504.).

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

[0005] In view of this, how to provide a grouting method 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 three-dimensional grouting method based on the spatial gap distribution of the caving area to solve the problems existing in the above-mentioned prior art and enable multi-layer and three-dimensional grouting in the caving area.

[0007] To achieve the above object, the present invention provides the following solution: The present invention provides a three-dimensional grouting method based on the spatial gap distribution in the caving area, comprising the following steps:

[0008] Step 1: Divide the caving area into three different grouting areas: Area I, Area II, and Area III according to the residual spatial distribution law of the caving area, the caving amount of the roof rock layer (including the pseudo roof, direct roof, basic roof and all rock layers above), and the density of the waste rock. Determine the regional range of Area I, Area II, and Area III, including height, length, and width;

[0009] 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.

[0010] 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 holes are located above the zone III; a plurality of long grouting holes are opened along the soft rock interlayer, which are inclined downward and the end holes are close to the basic top plate, so that the end holes are located above 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 holes are close to the direct top plate, so that the end holes are located above 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;

[0011] 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;

[0012] Step 5: When the working face is mined to the boundary of Zone I, and the distribution of the voids in the caving area shows the regional characteristics of Zones I, II, and III, the valve of the long grouting borehole located above Zone III is opened, and the filling slurry flows along the gap between the soft rock interlayer and the basic top to the caving space below the basic top; when the voids and caving space in Zone III are completely filled, the valve of the long grouting borehole located above Zone III is closed, and the valve of the long grouting borehole located above Zone II is opened, and the filling slurry flows along the gap between the basic top and the immediate top to the caving space below the immediate top; when the voids and caving space in Zone II are completely filled, the valve of the long grouting borehole located above Zone II is closed, and the valve of the long grouting borehole located above Zone I is opened, and the filling slurry flows along the gap between the immediate top and the coal seam roof to the caving area behind the working face frame.

[0013] Furthermore, 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 caving area, and the diffusion performance of the fluidized slurry. The detailed steps are as follows:

[0014] (1) The subsidence curve of the overburden in the stope is formed based on the theory of masonry beams in the stope roof, the subsidence law of the overburden in the caving area, the distribution state of the rock blocks in the caving area, and the stress characteristics. (The principle can be found in Li Liang et al. "Study on the Four-Level Zoning Model of the Fluidized Gangue Filling Caving Area", Journal of Mining and Safety Engineering 40.01(2023):11-16.doi:10.13545 / j.cnki.jmse.2022.0024.)

[0015] (2) The force relationship between the caving block and the working face advancement time is derived based on the subsidence curve of the overburden strata in the stope. The relationship between the stability coefficient of the caving zone and the working face advancement time is determined after deduction and calculation. (The principle can be referred to Li Liang et al. "Study on the four-level zoning model of the caving zone in the fluidized filling of waste rock", Journal of Mining and Safety Engineering 40.01(2023):11-16.doi:10.13545 / j.cnki.jmse.2022.0024.)

[0016] (3) Establish a “strike-trend” zoning model of the caving zone based on the relationship between the stability coefficient of the caving zone and the advancement time of the working face;

[0017] (4) Determine the filling area of ​​the caving area based on the "strike-dip" zoning model of the caving area, thereby determining the regional scope of the aforementioned zones I, II, and III. The length of this zone is the length of the working face, and the width is determined based on the relationship between the stability coefficient and the advancement time of the working face. 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 and floor (zone I), the direct roof and floor (zone II), and the basic roof and floor (zone III). The diffusion performance of the fluidized slurry is mainly characterized by the diffusion radius of the slurry. The function of this parameter is to verify the regional scope of the aforementioned zones I, II, and III finally determined in the above steps.

[0018] Furthermore, the high-position grouting chamber is located 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 rock gate starting position is determined based on the high-position grouting chamber. The rock gate starting position and the grouting chamber are aligned and perpendicular to the working face ventilation lane. The length of the rock gate is calculated through geometric trigonometric conversion based on the coal seam inclination 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 located 10m beyond the stop-mining line.

[0019] Furthermore, the angle between two horizontally adjacent long grouting boreholes 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". The angle between two horizontally adjacent long grouting boreholes is between 20-70 degrees.

[0020] Furthermore, the seamless floral pipe is one-tenth the length of the long grouting borehole and is made of DN180 seamless steel floral pipe. The seamless floral pipe is welded to the long grouting borehole with an inner sleeve. The seamless floral pipe serves to create a "shower-like" grouting effect at the grouting port of the long grouting borehole, increasing the grouting range. Setting its length to one-tenth the length of the long grouting borehole is intended to ensure a sufficient grouting range and guarantee grouting efficiency.

[0021] Furthermore, in the fifth step, intermittent grouting is adopted for the filling slurry, and the water-solid ratio of the filling slurry used in multiple grouting increases from low to high. The filling slurry contains a viscosity enhancer. The above scheme can avoid sudden blockage of the long grouting borehole caused by large-dose grouting or high water-solid ratio grouting. The viscosity enhancer is mainly used to make the slurry solidify quickly after grouting to support the top plate and achieve the effect of reducing ground subsidence. Flushing the long grouting borehole with clean water before intermittent grouting can prevent the channel from being blocked.

[0022] The beneficial effects of the present invention are:

[0023] (1) The spatial void distribution characteristics and laws of the caving area are fully utilized, and the grouting filling is linked to the spatial void distribution characteristics and laws of the caving area. The grouting areas are divided into different areas according to the caving amount of the roof rock layer and the density of the gangue to carry out multi-layer three-dimensional grouting, which can make full use of the grouting space and effectively increase the production-injection ratio.

[0024] (2) By grouting in different grouting areas in sequence, the caving law of the overlying rock strata is changed, the bearing capacity of the injection material on the overlying rock strata is accelerated, thereby reducing the sinking of the overlying rock strata, positively affecting the multi-layer three-dimensional grouting, and effectively increasing the grouting volume in the caving area.

[0025] (3) By arranging downward grouting holes, pipe blockage during grouting of the span-type roof can be avoided. The use of long drilling holes for grouting avoids the problem of increased grouting costs caused by the construction of high-level tunnels and slows down the surface subsidence.

[0026] (4) This method is easy to operate, safe, and economical, and has broad application prospects. It has important practical significance in the field of grouting filling in coal mine caving areas. 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. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative 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 4 A top view of the present invention;

[0032] Among them, 1 is the stop-mining line, 2 is the high-position grouting chamber, 3 is the working face, 4 is the stone gate, 5 is the long grouting borehole, 501 is the 1-1 long grouting borehole, 502 is the 1-2 long grouting borehole, 503 is the 1-3 long grouting borehole, 504 is the 2-1 long grouting borehole, 505 is the 2-2 long grouting borehole, 506 is the 2-3 long grouting borehole, 507 is the 3-1 long grouting borehole, 508 is the 3-2 long grouting borehole, 509 is the 3-3 long grouting borehole, 6 is the ground grouting station, 7 is the grouting pipeline, and 8 is the seamless flower pipe. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] With reference to the accompanying drawings, the present invention provides a three-dimensional grouting method based on the spatial gap distribution in the caving area, comprising the following steps:

[0036] Step 1: Divide the caving area into three different grouting areas: Area I, Area II and Area III according to the residual spatial distribution law of the caving area, the amount of caving of the roof rock layer and the density of the 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 stope roof, the subsidence law of the overburden in the caving area and the diffusion performance of the fluidized slurry. The detailed steps are as follows: According to the theory of masonry beams on the stope roof, the subsidence law of the overburden in the caving area, the diffusion performance of the fluidized slurry The distribution and stress characteristics of the rock blocks in the caving zone form a subsidence curve for the overburden in the stope. Based on this subsidence curve, the stress relationship of the caving blocks as the working face advances is derived. The relationship between the stability coefficient of the caving zone and the time of working face advance is then calculated. A "strike-dip" zoning model for the caving zone is established based on the relationship between the stability coefficient and the time of working face advance. Based on this "strike-dip" zoning model, the refillable areas in the caving zone are determined, thereby defining the regional boundaries of Zones I, II, and III. The length of each zone is the length of working face 3, and the width is determined based on the relationship between the stability coefficient and the time of working face advance. The width is calculated by multiplying the advance time by the advance speed. The height is the distance from the coal seam floor to the pseudo-roof (Zone I), the direct roof (Zone II), and the basic roof (Zone III), respectively.

[0037] 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; the high-position grouting chamber 2 is set 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 from the hard rock floor to 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 working face 3 air lane. The length of the stone gate 4 is obtained through 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.

[0038] 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;

[0039] Step 4: Lay out the 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 the filling slurry;

[0040] Step 5: When the working face 3 is mined to the boundary of zone I, and the spatial void distribution in the caving zone shows the regional characteristics of zones I, II, and III, the valve of the long grouting borehole 5 located above zone III is opened, and the filling slurry flows along the gap between the soft rock interlayer and the basic top to the caving space below the basic top; when the voids and caving space in zone III are completely filled, the valve of the long grouting borehole 5 located above zone III is closed, and the valve of the long grouting borehole 5 located above zone II is opened, and the filling slurry flows along the gap between the basic top and the immediate top to the caving space below the immediate top; when the voids and caving space in zone II are completely filled, the valve of the long grouting borehole 5 located above zone II is closed, and the valve of the long grouting borehole 5 located above zone I is opened, and the filling slurry flows along the gap between the immediate top and the coal seam roof to the caving zone behind the working face 3.

[0041] In this embodiment, 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.

[0042] In this embodiment, 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.

[0043] The present invention provides a three-dimensional grouting method based on the spatial void distribution of the caving area, which makes full use of the spatial void distribution characteristics and laws of the caving area, links the grouting filling with the spatial void distribution characteristics and laws of the caving area, divides the area into different grouting areas according to the caving amount of the roof rock layer and the density of the gangue to carry out multi-layer three-dimensional grouting, which can make full use of the grouting space and effectively increase the mining-injection ratio; changes the caving law of the overlying rock layer by grouting in different grouting areas, accelerates the bearing of the injection material on the overlying rock layer, thereby weakening the sinking of the overlying rock layer, positively affects the multi-layer three-dimensional grouting, and effectively increases the grouting amount of the caving area; avoids pipe blockage during the grouting and filling of the caving-span type roof by arranging downward grouting holes, avoids the problem of increased grouting cost caused by the construction of high-level tunnels by using long drilling grouting; the method is simple to operate, safe, and economical, has broad application prospects, and has important practical significance for the field of grouting filling in the caving area of ​​coal mines.

[0044] 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.

[0045] 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 three-dimensional grouting method based on the spatial gap distribution of the caving area, characterized in that: The following steps are involved: Step 1: Divide the caving area into three different grouting areas: Area I, Area II and Area III according to the residual spatial distribution law of the caving area, the amount of caving of the roof rock layer and the density of the gangue, and determine the regional range of Area I, Area II and Area III, which includes height, length and width; the regional range of Area I, Area II and Area III is determined according to the theory of the masonry beam of the mining area roof, the subsidence law of the overburden in the caving area and the diffusion performance of the fluidized slurry. The detailed steps are as follows: Based on the theory of the masonry beam of the mining area roof, the subsidence law of the overburden in the caving area, the distribution state and stress characteristics of the rock blocks in the caving area, form the subsidence curve of the overburden in the mining area; Based on the subsidence curve of the overburden in the mining area, deduce the stress relationship of the caving rock blocks with the advancement time of the working face (3) The relationship between the stability coefficient of the caving area and the advancement time of the working face (3) is determined after deduction and calculation; a "strike-trend" zoning model of the caving area is established according to the relationship between the stability coefficient of the caving area and the advancement time of the working face (3); the filling area of ​​the caving area is determined according to the "strike-trend" zoning model of the caving area, thereby determining the regional range of Zone I, Zone II, and Zone III; wherein, the regional length of Zone I, Zone II, and Zone III is the length of the working face (3), and the regional width is determined according to the relationship between the stability coefficient and the advancement time of the working face (3), and the advancement time multiplied by the advancement speed is the regional width; the regional heights of Zone I, Zone II, and Zone III are the distances from the coal seam floor to the pseudo roof floor, the direct roof floor, and the basic roof floor, respectively; 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 holes are located above the zone III; a plurality of grouting long boreholes (5) are opened along the soft rock interlayer and the end holes are close to the basic top plate so that the end holes are located above 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 holes are located above 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; Step 5: When the working face (3) is mined to the boundary of the zone I, the distribution of the voids in the caving zone shows the regional characteristics of the zones I, II, and III. The valve of the long grouting borehole (5) located above the zone III is opened, and the filling slurry flows along the gap between the soft rock interlayer and the basic roof to the caving space below the basic roof; when the voids and caving space in zone III are completely filled, the valve of the long grouting borehole (5) located above the zone III is closed, and the valve of the long grouting borehole (5) located above the zone II 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 voids and caving space in zone II are completely filled, the valve of the long grouting borehole (5) located above the zone II is closed, and the valve of the long grouting borehole (5) located above the zone I is opened, and the filling slurry flows along the gap between the immediate roof and the coal seam roof to the caving zone behind the working face (3).

2. A three-dimensional grouting method based on the spatial gap distribution of the caving area according to claim 1, 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.

3. The three-dimensional grouting method based on the spatial gap distribution in the caving area according to claim 1 is characterized in that: 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".

4. The three-dimensional grouting method based on the spatial gap distribution in the caving area 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°.

5. The three-dimensional grouting method based on the spatial gap distribution in the caving area 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.

6. The three-dimensional grouting method based on the spatial gap distribution in the caving area 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.

7. A three-dimensional grouting method based on the spatial gap distribution of the caving area according to claim 6, characterized in that: Before intermittent grouting, flush the long borehole (5) with clean water.

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