Method for draining water of coal mine goafs by crossing adjacent goaf

Abstract

Disclosed in the present invention is a method for draining water of coal mine goafs by crossing an adjacent goaf. An applicable environment of the method comprises a first goaf, a second goaf and a third goaf which are successively arranged on a side of a tunnel, directional drilling mechanisms being provided between the tunnel and the second goaf and between the tunnel and the third goaf, and the directional drilling mechanisms penetrating through a coal seam floor located at the bottom of the goafs so as to communicate with the second goaf and the third goaf. Directional holes comprise a first directional hole and a second directional hole, the first directional hole leading to the second goaf, the second directional hole leading to the third goaf, and a sleeve structure being mounted in the first directional hole. The present invention uses directional drilling, and the directional holes penetrate into and out of the coal seam floor, so as to cross the adjacent goaf, thus increasing the range of explored and drained goafs and the hole length so as to drain in advance water accumulated in the remaining goafs that cannot be drained in a traditional coal mine drilling mode. The present invention can be popularized and used in the field of coal mines to solve the present threat of goaf water to coal mine production.

Description

Method for draining water hazards from old coal mines across adjacent goafs Technical Field

[0001] The invention relates to the technical field of coal mine old goaf water hazard prevention and control, and in particular to a coal mine old goaf water hazard relief method spanning adjacent goaf areas. Background Art

[0002] Mine flooding has long been a significant factor restricting safe coal production in my country. Statistics show that 60% of mine accidents are related to groundwater, and mine flooding accounts for a high proportion of major and serious coal mine accidents in my country. Various forms of water influx into mines not only cause production losses and casualties, leading to various negative environmental impacts, but also threatens the normal mining of large quantities of coal resources.

[0003] Old goaf (i.e., mined-out areas) within and around the mining area are a major flood hazard, and water seepage accidents are primarily caused by water accumulation in old goaf. Exploration and drainage of water is an effective measure to prevent water seepage accidents, and coal mines must do a good job of this work.

[0004] At present, the main means of preventing and controlling old goaf water is to use conventional rotary drilling rigs to conduct advance exploration and discharge of old goaf water to eliminate the threat of old goaf water to coal mine production. However, the current conventional means can only explore and discharge the adjacent goaf on one side of the roadway coal pillar, such as goaf 1-2 shown in Figure 1. Goaf 1-2 is located on the side adjacent to the roadway coal pillar. Advance exploration and discharge are relatively convenient, but if the flood is serious, the water in the remaining goafs cannot be drained in time, thus posing a safety hazard. Moreover, it is currently impossible to conduct exploration and discharge across adjacent goafs, such as goaf 2-3 and goaf 3-4 shown in Figure 1. In addition, the conventional drilling method has a short drilling construction length, and the drilling trajectory is prone to deviate from the design parameters, making it difficult to accurately construct to the designed target layer.

[0005] To this end, in view of the above-mentioned defects, the designers of the present invention have conducted comprehensive underground field construction tests and, targeting the shortcomings of traditional underground old goaf water exploration and release methods, have researched and designed a coal mine old goaf water hazard drainage device and drainage method that spans the adjacent goaf area to overcome the above-mentioned defects.

[0006] Summary of the Invention

[0007] The technical problem to be solved by the present invention is: how to solve the problem that it is currently impossible to cross the adjacent goaf and drain the accumulated water in the remaining goaf.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] The present invention discloses a drainage method for a coal mine old goaf water hazard drainage device that spans adjacent goaf areas, comprising the following steps:

[0010] S1. Calculate the critical value l of hydraulic connection between adjacent goafs by formula;

[0011] S2. Arrange the drilling site according to the required conditions, and then construct the sedimentation tank;

[0012] S3. If the thickness of the coal pillar is less than the critical value l of hydraulic connection between adjacent goafs calculated in step S1, it is determined that the old goaf water in goaf 2 and goaf 3 is hydraulically connected to each other, and only directional drilling 1 is performed; if the thickness of the coal pillar is greater than the critical value l of hydraulic connection between adjacent goafs calculated in step S1, it is determined that the coal pillar completely blocks the old goaf water in goaf 2 and goaf 3, and the two goafs are not hydraulically connected to each other, and directional drilling 2 is required, that is, directional drilling 1 and directional drilling 2 are performed separately;

[0013] S4. After the directional drilling is completed, a water stop casing is placed in the directional drilling hole and cement is used to fix the hole and wait for it to solidify. The hole is sealed and pressure tested until it passes the pressure test.

[0014] S5. After the drilling construction is completed, measure the water output of the borehole. If the water volume decreases, drill down to make a through hole.

[0015] As a further solution of the present invention: the formula for the critical value l of the hydraulic connection between adjacent goaf areas in step S1 is as follows:

[0016] Where: a is the conversion radius of the working face; μ is the Poisson's ratio; E is the shear strength of coal; P is the water pressure. The critical value l of the hydraulic connection between adjacent goafs is calculated, and the calculation result serves as the basis for the drilling construction in step S3.

[0017] As a further solution of the present invention: the trajectories of the directional drilling hole 1 and the directional drilling hole 2 are both U-shaped trajectories.

[0018] As a further solution of the present invention: the construction method of the directional drilling 1 is:

[0019] A1. First, take a large-diameter drill bit and set the drilling angle of the drill bit to -10°;

[0020] A2. When drilling to a depth of 10m-20m, a water-stop casing is installed in the hole. The casing is 8-10m long and flanges, pressure gauges and high-pressure gate valves are installed on the casing.

[0021] A3. The outer wall of the water-stop casing is fixed with polyurethane hole wall and sealed with cement;

[0022] A4. After the drill rod enters the second expected bottom plate position of the goaf, the drill rod is adjusted to an inclined position, and the drilling angle gradually turns from horizontal to the top, and the final inclination angle of the drilling hole is +10°.

[0023] As a further solution of the present invention: the construction method of the directional drilling second is:

[0024] B1. First, take a large-diameter drill bit and set the drilling angle of the drill bit to -10°;

[0025] B2. When drilling to a depth of 10-20m, a water-stop casing is installed in the hole. The casing is 8-10m long and flanges, pressure gauges and high-pressure gate valves are installed on the casing.

[0026] B3. The outer wall of the water-stop casing is fixed with polyurethane hole wall and sealed with cement;

[0027] B4. After the drill rod enters the estimated bottom plate position of the goaf, the drill rod is adjusted to an inclination, and the drilling angle gradually turns from horizontal to the top, with the final inclination angle of the drilling hole being +10;

[0028] B5. When the drilling rig feed pressure suddenly drops or suddenly becomes 0, it is judged that it has entered the goaf area three and drilling is stopped at this time.

[0029] As a further solution of the present invention: the operation method of sealing and pressure testing the water stop casing in step S4 is:

[0030] S41. After the hole is solidified for 48 hours, water is injected into the hole using a mud pump to maintain the pressure at 2.5 MPa for 30 minutes.

[0031] S42, then observe whether there is water leakage near the hole wall and the hole pipe;

[0032] S43. If there is no leakage or the pressure drops by ≤0.5MPa within 30 minutes, it means that the hole is qualified; if leakage occurs or the pressure drops by >0.5MPa, it is necessary to continue grouting and hole fixing until the pressure test is qualified.

[0033] As a further solution of the present invention, the method is applicable to scenarios including goaf 1, goaf 2, and goaf 3 sequentially arranged on one side of a roadway, a directional drilling mechanism is provided between the roadway and goaf 2 and goaf 3, and the directional drilling mechanism penetrates the coal seam floor at the bottom of the goaf and connects to goaf 2 and goaf 3;

[0034] The directional drilling holes include directional drilling hole 1 and directional drilling hole 2. Directional drilling hole 1 is connected to goaf area 2, and directional drilling hole 2 is connected to goaf area 3. Casing structures are installed in both directional drilling hole 1 and directional drilling hole 2.

[0035] As a further solution of the present invention: the directional drilling hole 1 is connected to the directional drilling hole 2, and the directional drilling hole 2 is connected to the end of the directional drilling hole 1, and a casing structure is also provided in the directional drilling hole 2.

[0036] As a further solution of the present invention: the second directional drilling hole is arranged below the first directional drilling hole, and the two are arranged side by side.

[0037] As a further solution of the present invention: the casing structure includes a water-stop casing installed in the directional drilling hole 1 and the directional drilling hole 2, wherein a flange, a pressure gauge and a high-pressure gate valve are installed on the water-stop casing.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] First, the present invention adopts directional drilling. Directional drilling penetrates into and out of the coal seam floor to achieve the goal of drilling across adjacent goafs, thereby increasing the scope of exploration and drainage of old goafs and the length of drilling holes. This allows for the advanced drainage of water in other goafs that cannot be drained by traditional drilling methods in coal mines. The present invention can be promoted and used in the coal mining field to solve the current threat of old goaf water to coal mine production.

[0040] Second, the present invention calculates the critical thickness l of the connected coal pillar through a formula, and the calculation result is used as the design basis for drilling construction. If the thickness of the coal pillar is less than the critical value l of hydraulic connection between adjacent goafs, it is determined that the old goaf water in goaf 2 and goaf 3 is hydraulically connected to each other, and only directional drilling construction is performed; if the thickness of the coal pillar is greater than the critical value l of hydraulic connection between adjacent goafs, it is determined that the old goaf water in goaf 2 and goaf 3 has no hydraulic connectivity with each other, and the coal pillar completely blocks the water accumulation in adjacent goafs, and directional drilling construction is required to increase the second goaf and the third goaf water respectively. The above method can improve the accuracy and safety of drilling across adjacent goafs; and the purposelessness of drilling design can be avoided by calculating through theoretical formulas;

[0041] Third, the present invention installs a water-stop casing in a directional drilled hole, and then solidifies the hole and waits for it to solidify to ensure its stability. Then, a slurry pump is used to inject water into the hole to hold the pressure, and leakage at the hole wall and hole mouth is detected. If leakage occurs or the pressure drops by more than 0.5MPa, grouting is continued until the pressure test is qualified. The above operation can ensure the stable and safe installation of the water-stop casing and prevent leakage from affecting subsequent work.

[0042] 4. In the second section of the drilling project of the present invention, the target stratum for drilling is the sandstone of the coal seam floor. The drilling trajectory is 10-20m away from the coal seam floor. The sandstone is soft in texture. During the drilling process, the drilling trajectory is not easily deviated, the drilling speed is fast, the efficiency is higher than other strata, and drill jamming accidents are less likely to occur than other strata. If the borehole is too close to the coal seam floor, it is easy to penetrate the coal seam by mistake during the drilling construction. If the borehole is too far from the coal seam floor, it is easy to be far away from the coal seam. If it is too close or too far from the coal seam, it is ultimately impossible to accurately enter the target goaf. Therefore, it is appropriate to control the target stratum to be 10 to 20m away from the coal seam floor. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a scene diagram before construction of an embodiment of the present invention;

[0044] FIG2 is a schematic diagram of a directional drilling construction scene according to an embodiment of the present invention;

[0045] FIG3 is an operation flow chart of a coal mine old goaf water hazard drainage device spanning adjacent goafs according to an embodiment of the present invention;

[0046] FIG4 is a schematic diagram of the casing structure according to an embodiment of the present invention;

[0047] Explanation of the accompanying symbols: 1. Tunnel; 2. Goaf 1; 3. Goaf 2; 4. Goaf 3; 5. Coal pillar; 6. Directional drilling hole 1; 7. Directional drilling hole 2; 8. Coal seam floor; 9. Flange; 10. Pressure gauge; 11. High-pressure gate valve; 12. Water-stop casing. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] Example 1

[0050] Referring to Figures 1 and 2, a method for draining water hazards from old coal mine goafs that span adjacent goafs is shown. The method is applicable to scenarios including goaf 1 2, goaf 2 3 and goaf 3 4, which are sequentially arranged on one side of tunnel 1. A directional borehole 1 6 is opened between goaf 2 3 and tunnel 1 for drainage, and a directional borehole 2 7 is opened between goaf 3 4 and tunnel 1 for drainage. Directional borehole 2 7 is arranged below directional borehole 1 6, and the two are arranged side by side. A water-stop casing 12 is installed in directional borehole 1 6.

[0051] It should be noted that a flange 9, a pressure gauge 10 and a high-pressure gate valve 11 are installed on the water-stop sleeve 12. The pressure gauge 10 is used to test the water pressure in the sleeve, and the high-pressure gate valve 11 is used to control the flow rate of the sleeve water.

[0052] The specific operating principle of the coal mine old goaf water hazard drainage device that crosses the adjacent goaf area is as follows:

[0053] Step 1: Calculate the critical value of hydraulic connection between adjacent goafs. The critical value of hydraulic connection between adjacent goafs is derived using the following formula:

[0054] Where: a is the conversion radius of the working face; μ is the Poisson's ratio; E is the shear strength of coal; P is the water pressure. The critical value l of the hydraulic connection between adjacent goafs is calculated, and the calculation result serves as the basis for the drilling construction in step three.

[0055] In this embodiment, a is the conversion radius of the working face (the length of the coal mine working face in this embodiment is 2000m, the tunnel height is 5m, and the a value calculated by the tunnel rock wall area is 60m); μ is 0.3; the shear strength E of the coal is 0.3MPa; the water pressure P is 0.7MPa according to the maximum water pressure P measured on-site in the coal mine in this embodiment, and l is calculated to be 12.75m.

[0056] Step 2: Arrange the drilling site and construct the sedimentation pool:

[0057] The drilling site space must meet the following conditions: 1. There must be more than 12m of space in the longitudinal direction of the drilling rig to facilitate loading and unloading of drill rods; 2. There must be more than 6m of space in the lateral direction of the drilling rig to facilitate drilling operations; the drilling site layout is 12m long, 6m wide, and the height is consistent with the tunnel height.

[0058] Directional drilling requires the drilling site floor to be level. Considering the drilling water demand, the water supply capacity is 12m 3 / h configuration, equipped with 660 / 1140V and 127V two power supplies, total power ≥110kW, and cable specifications and models meet the total power requirements.

[0059] Construction of sedimentation tank: The size of the sedimentation tank is required to be 2m (length) × 2m (width) × 1m (depth), connected to the drainage system, and installed with a drainage pump. The drainage pump capacity should not be less than 1.5 times the expected drainage volume.

[0060] Step 3: Directional drilling first section structure construction:

[0061] If the thickness of the coal pillar (the actual thickness of the coal pillar between goaf 2 3 and goaf 3 4) is less than the critical value l of the hydraulic connection between adjacent goafs calculated in step 1 (the result calculated in step 1 of this embodiment is 12.75m), it is determined that the old goaf water in goaf 2 3 and goaf 3 4 is interconnected, and only the first section of the directional drilling structure construction needs to be carried out; if the thickness of the coal pillar is greater than the critical value l of the hydraulic connection between adjacent goafs (the result calculated in step 1 of this embodiment is 12.75m), it is determined that the old goaf water in goaf 2 and goaf 3 has no hydraulic connectivity with each other, and the water in the two goafs is blocked by the coal pillar, and the first section of the directional drilling structure construction needs to be added, that is, the first sections of the directional drilling hole 1 6 and the directional drilling hole 2 7 are constructed respectively. It should be noted that the construction methods of directional drilling hole 1 6 and directional drilling hole 2 7 are the same.

[0062] The specific construction method of the first section of directional drilling is:

[0063] First, use a large-diameter drill bit (drill bit aperture Φ193mm) to set the drilling rig drill pipe's opening inclination angle to -10°. When drilling to a depth of 10m-20m, place a water-stop casing 12 in the hole. The casing length is 8-10m. Flange 9, pressure gauge 10, and high-pressure gate valve 11 are installed on the casing respectively. The outer wall of the water-stop casing 12 is fixed with polyurethane hole wall and sealed with cement.

[0064] Step 4: Install the water-stop casing and seal it for pressure testing:

[0065] After the water-stop casing 12 is fixed and solidified for 48 hours, a mud pump is used to inject water into the hole to hold the pressure at 2.5MPa for 30 minutes. The hole wall and the orifice pipe are observed to see if there is any leakage. If there is no leakage or the pressure drops by ≤0.5MPa within 30 minutes, the hole is qualified. If leakage occurs or the pressure drops by >0.5MPa, grouting needs to be continued until the pressure test is qualified.

[0066] Step 5: Directional drilling of the second section of the structure

[0067] The specific construction method of the first section of directional drilling is:

[0068] The second section structure first uses a small-diameter drill bit (the drill bit aperture of the second section structure of the drilling is Φ98mm) to continue to set the opening inclination angle of the drill rod of the drill rig to -10°, and after the drill rod drills into the corresponding coal seam floor, the drill rod is adjusted to horizontal, and the drilling angle gradually changes from inclined to horizontal; when drilling to a depth of 10-20m, after the drill rod drills into the expected bottom plate position of goaf three 4, the drill rod is adjusted to inclined, and the drilling angle gradually changes from horizontal to top, and the final drilling hole inclination angle is +10°; when the drilling rig feed pressure suddenly drops or suddenly becomes 0, it is judged that goaf three 4 has entered, and drilling is stopped at this time. If goaf two 3 and goaf three 4 are rich in water, the orifice return water volume increases, and the drilling water discharge volume is recorded.

[0069] It should be noted that, in the second section of structural drilling, the target stratum for drilling is the rock layer below the coal seam floor 8, preferably the floor sandstone, and the drilling trajectory is 10-20m away from the coal seam floor, preferably 10m. The specific reasons are as follows: the sandstone is soft in texture, and during drilling, the drilling trajectory is not easily deviated, the drilling speed is fast, the efficiency is higher than other strata, and drill jamming accidents are less likely to occur than other strata; if the borehole is too close to the coal seam floor 8, it is easy to penetrate the coal seam during the drilling construction process, and if the borehole is too far from the coal seam floor, it is easy to be far away from the coal seam. If the borehole is too close or too far from the coal seam floor, it will ultimately be impossible to accurately enter the target goaf. Therefore, it is appropriate to control the target stratum to be 10 to 20m away from the coal seam floor, preferably 10m.

[0070] The trajectories of directional drilling hole 1 6 and directional drilling hole 2 7 are both set as U-shaped trajectories (as shown in Figure 2). Using the directional drilling U-shaped trajectory, the directional drilling holes penetrate into and out of the coal seam floor to achieve drilling across adjacent goafs, increase the scope of exploration and discharge of old goafs and the length of the holes, and advance the drainage of water in the remaining goafs that cannot be drained by traditional drilling methods in coal mines.

[0071] It should be noted that the drilling design is divided into two sections of hole body structure. The borehole diameter of the first section structure must be larger than the borehole diameter of the second section structure. Otherwise, after the first section structure is lowered into the casing, the drill bit of the second section structure cannot enter the hole due to the smaller borehole diameter. In this embodiment, the borehole diameter of the first section structure is Φ193mm, and the water-stop casing 12 is lowered after drilling to a depth of 10m. The main purpose is to seal the hole mouth formation and install the hole mouth device. The second section structure is a bare hole directional hole section. The borehole diameter of the second section structure is Φ98mm. The second section structure is monitored by the downhole measurement instrument and the drilling trajectory is adjusted so that it is drilled along the designed trajectory. The combined drilling trajectory of the first and second sections is a U-shaped trajectory, and the drilling trajectory is shown in Figure 2.

[0072] Step 6: Through hole:

[0073] After drilling is completed, the water output of the goaf is easily clogged by silt and gravel in the goaf, causing the water output of the drill hole to gradually decrease after the drill is pulled out. If the water output decreases during the drilling process, it is necessary to drill the hole again. After pulling out the drill rod, the water output of the drill hole is first measured, and then the high-pressure gate valve 11 is closed to observe the water pressure. If the water output decreases again during the water discharge process, it is necessary to continue drilling the hole.

[0074] Example 2

[0075] The rest is the same as above, with the difference being that directional drilling hole 1 6 is connected to directional drilling hole 2 7 , and directional drilling hole 2 7 is connected to the end of directional drilling hole 1 6 . Directional drilling hole 2 7 is a branch of directional drilling hole 1 6 , and a water-stop casing 12 structure is also provided in directional drilling hole 2 7 .

[0076] When excavating directional drilling hole 2 7, it is necessary to continue drilling with the drill rod on the basis of directional drilling hole 1 6 until the drill rod drills into the expected bottom plate position of goaf 3 4. The drill rod is adjusted to be inclined, and the drilling angle gradually turns from horizontal to the top. The final drilling hole inclination angle is +10°; when the drilling rig feed pressure suddenly drops or suddenly becomes 0, it is determined that the goaf 3 4 has been entered, and drilling is stopped at this time.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for draining water hazards from an old coal mine space across adjacent goafs, characterized in that: The steps include: S1, calculate the critical value l of hydraulic connection between adjacent goaf areas through the formula; S2. Arrange the drilling site according to the required conditions of the drilling site, and then construct the sedimentation tank; S3, if the thickness of the coal pillar is less than the critical value l of the hydraulic connection between adjacent goafs calculated in step S1, it is determined that the old goaf water in goaf 2 and goaf 3 is hydraulically connected to each other, and only directional drilling 1 is performed; if the thickness of the coal pillar is greater than the critical value l of the hydraulic connection between adjacent goafs calculated in step S1, it is determined that the coal pillar completely blocks the old goaf water in goaf 2 and goaf 3, and the two goafs are not hydraulically connected to each other, and directional drilling 2 needs to be added, that is, directional drilling 1 and directional drilling 2 are constructed separately; S4. After the directional drilling is completed, a water stop casing is placed in the directional drilling hole, and cement is used to fix the hole and wait for solidification, and then the sealing and pressure testing are carried out until the pressure test is qualified; S5. After the drilling construction is completed, measure the water output of the borehole. If the water volume decreases, drill down to the hole.

2. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The formula of the critical value l of hydraulic connection between adjacent goaf areas in step S1 is as follows: Wherein: a is the conversion radius of the working face; μ is the Poisson's ratio; E is the shear strength of coal; P is the water pressure. The critical value l of the hydraulic connection between adjacent goafs is calculated, and the calculation result is used as the basis for the drilling construction in step S3.

3. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The trajectories of the directional drilling hole 1 and the directional drilling hole 2 are both U-shaped trajectories.

4. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The construction method of the directional drilling hole 1 is: A1. First, take a large-diameter drill bit and set the hole opening angle of the drill bit to -10°; A2. When drilling to a depth of 10m-20m, a water stop casing is installed in the hole. The casing length is 8-10m. A flange, a pressure gauge and a high-pressure gate valve are installed on the casing respectively. A3. The outer wall of the water-stop casing is fixed with polyurethane hole wall and sealed with cement; A4. After the drill rod drills into the estimated bottom plate position of the goaf, the drill rod is adjusted to be tilted, and the drilling angle gradually turns from horizontal to the top, and the final hole inclination angle is +10°; A5. When the drilling rig feed pressure suddenly drops or suddenly becomes 0, it is judged that it has entered goaf area 2 and drilling should be stopped at this time.

5. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The construction method of the directional drilling 2 is: B1. First, take a large-diameter drill bit and set the hole opening angle of the drill bit to -10°; B2. When drilling to a depth of 10-20m, a water stop casing is installed in the hole. The length of the casing is 8-10m. A flange, a pressure gauge and a high-pressure gate valve are installed on the casing respectively. B3. The outer wall of the water-stop casing is fixed with polyurethane hole wall and sealed with cement; B4. After the drill rod drills into the estimated bottom plate position of the goaf, the drill rod is adjusted to be inclined, and the drilling angle gradually turns from horizontal to the top, and the final inclination angle of the drilling hole is +10; B5. When the drilling rig feed pressure suddenly drops or suddenly becomes 0, it is judged that it has entered goaf area three and drilling is stopped at this time.

6. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The operation method of stopping the water casing sealing and pressure testing in step S4 is: S41. After the hole is solidified for 48 hours, water is injected into the hole using a mud pump to maintain the pressure at 2.5 MPa for 30 minutes. S42, then observe whether there is water leakage near the hole wall and the hole mouth pipe; S43. If there is no leakage or the pressure drops by ≤0.5MPa within 30 minutes, it means that the hole fixing is qualified; if leakage occurs or the pressure drops by >0.5MPa, it is necessary to continue grouting to fix the hole until the pressure test is qualified.

7. The method for draining water hazards from old coal mines across adjacent goafs according to claim 1 is characterized in that: The method is applicable to scenarios including goaf 1, goaf 2 and goaf 3 which are sequentially arranged on one side of a tunnel, a directional drilling mechanism is arranged between the tunnel and goaf 2 and goaf 3, and the directional drilling mechanism passes through the coal seam floor at the bottom of the goaf and is connected to goaf 2 and goaf 3; The directional drilling holes include directional drilling hole 1 and directional drilling hole 2. Directional drilling hole 1 is connected to goaf area 2, and directional drilling hole 2 is connected to goaf area 3. Casing structures are installed in both directional drilling hole 1 and directional drilling hole 2.

8. The method for draining water hazards from old coal mines across adjacent goafs according to claim 7 is characterized in that: The directional drilling hole 1 is connected to the directional drilling hole 2, and the directional drilling hole 2 is connected to the end of the directional drilling hole 1. A casing structure is also arranged in the directional drilling hole 2.

9. The method for draining water hazards from old coal mines across adjacent goafs according to claim 7, characterized in that: The second directional drilling hole is arranged below the first directional drilling hole, and the two are arranged in parallel.

10. The method for draining water hazards from old coal mines across adjacent goafs according to claim 7, characterized in that: The casing structure comprises a water-stop casing installed in the first directional drilling hole and the second directional drilling hole, wherein a flange, a pressure gauge and a high-pressure gate valve are installed on the water-stop casing.

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