High-efficiency drainage method for accumulated water in short-distance multi-coal-seam repeated mining goaf

Abstract

The invention relates to the technical field of mine water disaster prevention and control, and provides a close-range multi-coal-seam repeated mining goaf accumulated water efficient drainage method which comprises the following steps that ground geophysical exploration is conducted on a prevention and control area, and mining information of goaf coal seams is collected; delineating an abnormal ponding area and a low-lying terrain area in the prevention and treatment area; water level monitoring holes and ground pumping and draining holes are formed in the water accumulation abnormal area and the terrain low-lying area; an underground directional drilling hole is designed and constructed, and it is ensured that the track of the underground directional drilling hole can cover the water accumulation abnormal area and the terrain low-lying area; performing hole penetrating work on the underground directional drill holes until the water yield of each underground directional drill hole is reduced to be below a target value; performing drainage effect inspection on the prevention and control area; ground geophysical exploration is carried out on the prevention and control area, the collected stoping information of the overlying coal seam of the goaf is combined, the water accumulation abnormal area and the terrain low-lying area can be accurately delineated, the water level monitoring holes and the ground pumping and draining holes are formed in the delineated key area, real-time monitoring of the underground water level of the areas is achieved, and the water level monitoring accuracy is improved. Meanwhile, the capability of synchronously draining up and down the well is also realized; by designing and constructing underground directional drilling holes, it is ensured that the track covers the water accumulation abnormal area and the terrain low-lying area, and water accumulation of the coal seam overlying goaf in the target area can be prevented and controlled more directly and effectively.

Description

Technical Field

[0001] The invention relates to the technical field of mine water hazard prevention and control, and in particular to a method for efficiently draining water accumulated in goaf areas of repeated mining of multiple coal seams at close range. Background Art

[0002] Water hazards are one of the main disasters that affect the safety of underground coal mines. The main types of water hazards include surface water, goaf water, fissure water, karst water, pore water, etc., among which goaf water is the most common. In the process of multi-coal seam mining, with the continuous mining work in the mine, the mining thickness and area gradually increase, the distribution range of goaf areas gradually increases, and the amount of water accumulation and the range of water accumulation in the goaf areas also gradually increase with the increase of the area of ​​the goaf areas; and when there is a water channel between the water accumulation in the goaf area and the mining operation surface of normal production, the water accumulation in the goaf area will flow into the mining space along the water-conducting fissures under the action of water pressure, seriously threatening the safety of mining operations in the mine. Therefore, before mining the lower coal layer, the range of water accumulation in the goaf area of ​​the upper coal layer must be detected, the amount of water accumulation must be preliminarily estimated, and effective measures must be taken to release it.

[0003] At present, the main prevention and control measures for water accumulation in mine goafs include detection, conventional drilling and drainage, and plugging of water-conducting fissures. Among them, drainage of water in goafs and effective reduction of water volume and height can greatly reduce the safety threat of water accumulation in goafs.

[0004] At present, there are two main methods for draining water in goaf: (1) drilling holes in the goaf on the ground, drilling to the screen pipe under the goaf, and then lowering water pumps to pump water; (2) drilling ordinary holes at a certain interval from the lower coal tunnel to the upper goaf to drain water. However, both methods have disadvantages such as long construction period, high cost, high intensity and low drainage efficiency. Summary of the invention

[0005] The invention provides a method for efficiently draining water accumulated in goaf areas during repeated mining of multiple coal seams at close range, so as to solve the defect of low efficiency of draining water accumulated in goaf areas in the prior art.

[0006] The present invention provides a method for efficiently draining water from goaf areas of multiple coal seams repeatedly mined in close proximity, comprising the following steps: Conduct ground geophysical surveys in the prevention and control areas and collect mining data on the goaf of the overlying coal seams; Delineate areas with abnormal water accumulation and low-lying areas within the prevention and control area; Arrange water level monitoring holes and ground drainage holes in the abnormal water accumulation area and the low-lying area; Design and construct downhole directional drilling to ensure that the trajectory of the downhole directional drilling can cover the abnormal water accumulation area and the low-lying area; Performing drilling work on the downhole directional boreholes until the water output of each downhole directional borehole drops below a target value; Conduct drainage effectiveness test on the prevention and control area.

[0007] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the design and construction of underground directional drilling holes ensure that the trajectory of the underground directional drilling holes can cover the abnormal water accumulation area and the low-lying area, and then include: Whether to open a branch hole is determined based on the water output of the main hole of the downhole directional drilling. When the water output is less than a first preset value, multiple branch holes are opened on the drilling trajectory of the main hole, and the multiple branch holes are arranged around the end of the main hole.

[0008] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the criteria for conducting through-hole work on the underground directional drilling holes are: the water output of the underground directional drilling holes and the branch holes is less than a second preset value, the second preset value is greater than the target value, and the second preset value is less than the first preset value.

[0009] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the underground directional boreholes are drilled until the water output of each of the underground directional boreholes drops below a target value, including: If the water output after the first hole penetration is greater than the second preset value, continue to drain; If the water output after multiple drillings is still less than the second preset value, it is determined that the reduction in water output is not caused by hole blockage. The water is drained continuously until the water output is less than the target value. It is judged that the accumulated water in the drilling control area has been drained to the expected effect, and no subsequent drilling work is required.

[0010] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the abnormal water accumulation area and low-lying area are delineated in the prevention and control area, including: delineating the abnormal water accumulation area based on the results of ground geophysical exploration; Based on the elevation data of the coal seam floor in the goaf, a contour map of the coal seam floor in the goaf is drawn to demarcate low-lying areas prone to water accumulation.

[0011] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the water level monitoring holes and the ground drainage holes are arranged at intervals, and dynamic monitoring equipment for the water level of water in the goaf is provided in the water level monitoring holes for real-time dynamic monitoring of the water elevation in the goaf; a water pump is provided in the ground drainage hole for draining water.

[0012] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the drainage effect of the control area is tested, including: The water level elevation of the goaf area is observed in real time through the water level monitoring hole; Conduct ground geophysical exploration again in the prevention and control area to check whether there are local low-resistance abnormal areas.

[0013] According to the method for efficiently draining water from goaf areas in close-range multi-coal seam repeated mining provided by the present invention, when the exploration results show that there are still local low-resistance anomalies, additional underground directional drilling is performed in the area with the low-resistance anomaly.

[0014] According to the method for efficiently draining water in goaf areas of repeated mining of multiple coal seams at close range provided by the present invention, when the exploration results show no abnormalities, the water drainage work in the current area is completed.

[0015] According to the method for efficiently draining water from goafs in close-range multi-coal seam repeated mining provided by the present invention, the spacing between the water level monitoring holes and the ground drainage holes is 300m, and the length of the underground directional drilling hole is no more than 500m.

[0016] The present invention provides a method for efficiently draining water in goaf areas with repeated mining of multiple coal seams at close range. By conducting ground geophysical exploration of the prevention and control area and combining the collected mining information of the coal seams overlying the goaf, the method can accurately delineate abnormal waterlogging areas and low-lying areas. This method improves the accuracy of identifying potential waterlogging areas and provides reliable data support for subsequent prevention and control. By arranging water level monitoring holes and ground drainage holes in the delineated key areas, not only real-time monitoring of the groundwater level in these areas is achieved, but also preliminary ground drainage capabilities are provided. By designing and constructing underground directional drilling holes to ensure that their trajectories cover abnormal waterlogging areas and low-lying areas, it is possible to more directly and effectively carry out joint drainage in and out of the well for the target area, greatly improving drainage efficiency and prevention and control effects.

[0017] In addition, the branch hole design increases the number and distribution density of drainage points, thereby improving drainage efficiency. Through the through-hole drilling of underground directional holes until the water output of each hole drops below the target value, the effectiveness and sustainability of the drilling are guaranteed. This process is crucial to solving the problem of poor drainage caused by blockage, and ensures the effective and stable operation of the entire system.

[0018] Finally, the drainage effect of abnormal waterlogging areas and low-lying areas was tested, and strategies were adjusted or further measures were taken according to actual conditions to ensure the quality and effectiveness of the entire prevention and control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a flow chart of a method for efficiently draining water from goaf areas of repeated mining of multiple coal seams at close range provided by the present invention.

[0021] Figure 2 It is a schematic diagram for delineating geophysical anomaly areas and low-lying areas provided by an embodiment of the present invention.

[0022] Figure 3 It is a schematic diagram of trajectory design for downhole directional drilling provided by an embodiment of the present invention.

[0023] Figure 4 It is a schematic diagram of the trajectories of the main hole and the branch holes provided in an embodiment of the present invention.

[0024] Figure 5 It is a flow chart of underground directional drilling and drainage of water in goaf areas provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0026] The main disadvantages of the current airspace water drainage technology are: Regarding the method of drilling holes on the ground in goaf areas, there is a problem of limited construction sites for straight holes, especially in mountainous areas, where it is impossible to drill holes to geophysical anomaly areas or target areas. If directional drilling is performed on the ground, it will be difficult to lower the pump in the later stage. Moreover, relying solely on ground drilling for water drainage not only has a long construction period, great difficulty and high cost, but also when the drilling construction reaches the roof fracture zone above the goaf, the borehole is prone to collapse and the porosity is low, and it is also difficult to lower the casing and screen pipe after the later drilling is completed. In addition, the displacement of the water pump will also be affected by the borehole diameter. In the case of large displacement, the volume of the pump required increases, and the corresponding borehole diameter must be increased accordingly, and the construction cost is too high. The corresponding water pump displacement of small-diameter ground drilling is low, the drainage efficiency is not high, and the silt is easy to accumulate near the screen pipe and block the screen pipe, which will inevitably reduce the effective water output and extend the drainage period.

[0027] Regarding the method of draining water by ordinary drilling in underground construction, there are problems such as small borehole diameter, limited water output, long drainage cycle, and affected by rock hardness, which makes the drilling trajectory uncontrollable and the error of the final hole landing point large. Specifically, when the working face of the goaf is wide, the ordinary drilling is limited by the drilling capacity. On the one hand, the corresponding area in the middle of the working face cannot be constructed, especially when the difference in height between the two drifts of the working face is large and the inclination of the coal seam is large, the low drift is difficult to construct to the corresponding area in the middle of the working face, and the high drift forms a depression-angle drill hole, which is difficult to drain water. On the other hand, since the length of the ordinary drilling hole is short (less than 200m) and it is a single-point drainage, the drainage area is small, and multiple drilling sites need to be constructed, the equipment is frequently moved, the labor intensity is high, and the drainage cycle is long, the drainage efficiency is low, which affects the continuity of coal mining.

[0028] Therefore, it is very important to provide an efficient, high-quality and accurate method for draining water from goaf areas. The present invention provides an efficient method for draining water from goaf areas with repeated mining of multiple coal seams at close range.

[0029] Combine the following Figure 1-Figure 5 The invention describes a method for efficiently draining water from goaf areas during repeated mining of multiple coal seams at close distances.

[0030] The embodiment of the present invention provides a method for efficiently draining water from goaf areas during repeated mining of multiple coal seams at close range, comprising the following steps: Step 100: Conduct ground geophysical survey of the prevention and control area and collect mining data of the goaf of the overlying coal seam.

[0031] Specifically, geophysical exploration is carried out on the ground in the prevention and control area (i.e., the area where drainage is planned), such as using transient electromagnetic method, resistivity imaging and other methods, to detect the geoelectric characteristics of the underground goaf space to obtain abnormal water accumulation areas, and collect data on the overlying coal seam mining, which includes the location, scope, mining method, etc. of the goaf area, and obtain the elevation H0 of the coal seam floor in the goaf area. The goaf area of ​​the overlying coal seam refers to the coal seam area above the currently mined coal seam that has been previously mined and has formed goafs, collapses, and fissures (i.e., goaf areas).

[0032] Step 200: Identify abnormal waterlogging areas and low-lying areas within the prevention and control area.

[0033] Specifically, this step includes: based on the results of ground geophysical exploration, delineating abnormal waterlogging areas, that is, delineating abnormal areas where waterlogging may exist; drawing contour maps of the coal seam floors in goaf areas based on the elevation data of the coal seam floors in goaf areas, and dividing out low-lying areas prone to waterlogging; through the drawn contour maps of the coal seam floors in goaf areas, the undulating trend of the underground goaf space floor can be intuitively displayed, and by analyzing the contour maps, low-lying areas prone to waterlogging, such as low terrain and syncline axes (a geological structure with a downward depression in the terrain), can be divided out. These areas are more prone to waterlogging due to topography or geological structure; combining the abnormal area results obtained by geophysical exploration and the low-lying areas determined based on the contour maps, the comprehensive abnormal waterlogging areas are further clarified, and the waterlogging risk points that require special attention are more accurately located. This step comprehensively considers the results of geophysical exploration and geological data analysis, and improves the accuracy of determining abnormal waterlogging areas.

[0034] Step 300: Arrange water level monitoring holes and ground drainage holes in abnormal water accumulation areas and low-lying areas.

[0035] First, based on the abnormal water accumulation areas delineated by ground geophysical exploration (i.e. areas where large amounts of water may accumulate), and the low-lying areas divided according to the contour lines of the floor of the coal seam goaf (these areas are more prone to water accumulation due to the terrain), and then combined with the surface terrain characteristics, the specific locations of the water level monitoring holes and ground drainage holes in the ground goaf are determined.

[0036] Specifically, water level monitoring holes and ground pumping holes are arranged at intervals, and the hole spacing between the water level monitoring holes and the ground pumping holes can be set to 300m. For example, in the current area, a water level monitoring hole is set first, and then a ground pumping hole is set 300m away from it, and so on. This layout helps to cover a larger range of target areas while ensuring the effectiveness of monitoring and pumping.

[0037] A dynamic monitoring device for the water level in the goaf is installed in the water level monitoring hole, which is used for real-time dynamic monitoring of the water elevation H in the goaf, so as to timely obtain the changes of the water in the goaf; a water pump is installed in the ground drainage hole for water drainage. This step directly targets the identified waterlogged area and can efficiently drain the water.

[0038] Furthermore: the amount of water accumulated in the goaf can be calculated and analyzed based on the coal seam floor elevation H0 in the goaf and the water accumulation elevation H in the goaf.

[0039] Specifically, dynamic recharge volume Q is calculated based on the water accumulation in the goaf. 动 and static water volume Q 静 Calculate and obtain the comprehensive water accumulation in the goaf, which provides a scientific basis for the subsequent construction of the drilling site drainage system and the estimation of the drainage cycle. The dynamic recharge volume Q 动and static water volume Q 静 The calculation is as follows: Dynamic supply: Q 动 = ; Where K is the permeability coefficient, in meters per day (m / d); M is the thickness of the aquifer, in meters (m); S is the water level drawdown, in meters (m); r0 is the reference radius of the tunnel system (large well), and the calculation formula is r0= , in meters (m); F is the mining area, in square meters (m 2 ); R0 is the impact radius of groundwater in the mine drainage, in meters (m); R0=r0+R, R= .

[0040] Static water volume: Q 静 =MHK1 / cosα; H = H 积 -H0; Where M is the water accumulation area of ​​the goaf, in square meters (m 2 ); H is the water accumulation height in the goaf, in meters (m); α is the average inclination of the coal seam; K1 is the water filling coefficient of the goaf; Preferably, the water filling coefficient K1 is 0.25-0.5.

[0041] Step 400: Design and construct downhole directional drilling, and give priority to ensuring that the trajectory of the downhole directional drilling can cover the abnormal water accumulation area and the low-lying area.

[0042] Specifically, in areas of geophysical anomalies and low-lying areas, a batch of initial directional boreholes are first designed and constructed. The purpose of these boreholes is to obtain more detailed geological information, verify the geophysical results, and provide a basis for the design and layout of subsequent boreholes. After completing the construction and data analysis of the initial boreholes, three different types of directional boreholes, long, medium and short, can be designed and arranged according to the geological information revealed by these boreholes, the coverage of the working face and the specific conditions of water accumulation in the goaf. Among them, the long hole is used to go deep into the goaf to detect and drain water at the far end, the medium hole is used to detect and drain water in the middle or closer areas of the goaf, and the short hole is used to drain water in the area near the near end of the drilling site. These boreholes can cover different depths and ranges of the goaf to ensure that the accumulated water is effectively drained, thereby reducing the impact of water accumulation in the goaf on coal mine safety production.

[0043] In this embodiment, the waterlogged area consisting of abnormal waterlogging areas and low-lying areas is also divided into multiple working surfaces.

[0044] It should be noted that, on the one hand, when directional drilling is carried out in the goaf, the risks of drill sticking and drill burial are easily caused by the fracture zone in the bottom plate of the goaf. Therefore, the length of a single borehole needs to be controlled. When the construction length of the underground directional drilling is about 500m or less, the drilling efficiency is the highest and the construction period is also short. Therefore, the coverage area of ​​the underground directional drilling is controlled to a range of 500m in diameter, that is, a drilling site is arranged every 500m until the waterlogged area is covered. The long hole length is set to 400-500m, the medium hole length is 250-400m, and the hole length within 250m is a short hole.

[0045] On the other hand, it is necessary to rationally design the drilling trajectory, control the trajectory to steadily increase the inclination and drill into the goaf or drill at a small inclination angle, and increase the inclination angle when drilling to 40-80m away from the final hole to drill into the goaf to reduce the risk of drill sticking or drill burial when encountering bottom plate fractures.

[0046] Among them, steadily increasing inclination drilling means that in the initial stage, the drilling trajectory will gradually increase the inclination at a predetermined angle. This method can help the borehole enter the target layer more smoothly and improve the safety and efficiency of the drilling process; small elevation drilling means that a smaller elevation angle is selected for drilling according to actual conditions. This method helps to reduce the length of the borehole passing through the bottom plate fracture zone, thereby reducing the risk of drill stuck due to fractures; when the borehole approaches the final position (40-80 meters from the final hole), the inclination of the borehole is appropriately increased as needed to quickly enter the goaf. This adjustment can minimize the distance crossed through the bottom plate fracture zone and reduce the frequency of drill stuck or buried.

[0047] Step 500: drilling the downhole directional boreholes until the water output of each downhole directional borehole drops below the target value.

[0048] Wherein, drilling refers to clearing the blockages such as rock debris in the borehole by physical methods (such as using high-pressure water flow, mechanical dredging, etc.) to restore its normal drainage capacity; the judgment standard for drilling is: the water output of the downhole directional drilling is less than the second preset value, and the second preset value is greater than the target value. In some embodiments, the second preset value is 20m 3 / h, target value is 10m 3 / h.

[0049] Step 600: Check the drainage effect of the prevention and control area.

[0050] Specifically, on the one hand, the water level elevation of the goaf area is observed in real time through the water level monitoring holes; On the other hand, the ground geophysical survey is conducted again in the prevention and control area to check whether there are local low-resistance anomaly areas; when the survey results show that there are still local low-resistance anomalies, it means that the resistivity of some areas is significantly lower than the resistivity of the surrounding strata, indicating that there are still some waterlogged areas, and then the remaining low-resistance anomaly areas are supplemented with underground directional drilling. In other words, the process of steps 400 to 500 is performed again for the low-resistance anomaly area until the survey results show that there are no anomalies, and the water drainage work in the current area is completed.

[0051] In some specific embodiments, downhole directional drilling adopts a primary casing and a two-stage aperture design. When drilling begins, a large-size drill bit is first used to construct the first-level aperture. Then, a casing is placed in the first-level aperture and fixed with single-liquid cement slurry. The main function of the casing is to prevent the hole wall from collapsing and to provide structural support for the drilling in the subsequent process. A 193mm drill bit is used for the first-level aperture. After the first-level casing is installed, a 120mm drill bit is replaced to drill the open hole to the designed hole depth. After the drilling construction is completed, the drill is withdrawn and the water output of the borehole is observed every 5-10 minutes until the water output gradually stabilizes. The purpose of this process is to evaluate the stable water output of the borehole. Specifically, the amount of water flowing out of the borehole within a certain period of time is observed and recorded, and the water level changes in the goaf area observed by the ground water level observation hole and the borehole water pressure are combined to determine the static storage and dynamic replenishment of the goaf water, which is crucial for guiding subsequent drainage work.

[0052] In this embodiment, step 400 includes step 401: determining whether to open a branch hole according to the water output of the main hole of the downhole directional drilling, when the water output is less than a first preset value, opening a plurality of branch holes on the drilling trajectory of the main hole, and the plurality of branch holes are arranged around the end of the main hole, and the first preset value is greater than the second preset value, for example, the first preset value is 50m 3 / h, the second preset value is 20m 3 / h.

[0053] That is to say, these branch holes extend from the main hole. Compared with constructing the entire branch hole separately, this method can reduce the workload of drilling and improve construction efficiency. By opening branch holes, the drainage area of ​​the drilling hole can be significantly increased and the drainage efficiency can be improved.

[0054] For example, Figure 4 As shown in the figure, the short hole is the main hole. After the main hole is completed and the drill is withdrawn, when the water output is less than 50m 3 / h, a branch hole is opened on the drilling trajectory. With the end point of the main hole as the center, multiple branch holes are constructed in a plum blossom shape around 30m away from the end of the main hole. The water output from the hole is observed. The water output increases to 100m 3 / h or more, stop construction. Otherwise, continue construction and construct up to 4 branch holes. If there is still little water volume, it means that there is less water accumulation in this area, and construction of other drilling holes can be carried out.

[0055] Furthermore, step 500 includes: if the water output after the first drilling is greater than a second preset value, continue to drain the water; if the water output after multiple drillings is still less than the second preset value, the possibility of reduced water output due to hole blockage can be ruled out, and drainage continues until the water output is less than the target value, and it is determined that the accumulated water in the drilling control area has been drained to the expected effect, and no subsequent drilling work is required.

[0056] For example, as the drainage work proceeds, the water in the waterlogged area will gradually be discharged, so the water output of a single borehole will also decrease accordingly. This is a normal phenomenon. In addition to the natural reduction in water volume, there may also be poor drainage due to blockage inside the borehole (such as mud, rock chips, etc.). Therefore, this factor is eliminated by drilling through the borehole. When the water output of a single borehole drops to a second preset value, it is believed that blockage may have occurred, and the borehole is drilled in time. If the water output after drilling through the borehole is greater than the second preset value, it indicates that there is blockage inside the borehole. After drilling through the borehole, the normal water output state is restored and it can continue to be used for drainage. Sometimes one drilling may not be enough to completely solve the problem, and multiple drilling operations need to be repeated until the water output no longer increases significantly. If after multiple drilling attempts, the water output still remains below the second preset value, this means that the problem is not caused by blockage, but because the accumulated water in the area has been basically drained or the remaining water is very limited. In this case, the changes in water output should continue to be monitored. When the water output is further reduced to the target value or below, and stabilizes at this state, it is considered that the accumulated water in the borehole control area has been effectively drained to the expected effect, and there is no need to perform additional drilling or other operations on this borehole.

[0057] In this embodiment, it also includes: after the water drainage work in the goaf of the current working face is completed, the water drainage work in the next working face is carried out, and the above work process is repeated until the water in the goaf in the prevention and control area is completely drained.

[0058] With this setup, a phased drainage method is used, first focusing on a specific area, such as the first 500 meters to drain the water. After the drainage work in the current area is completed, the drill will be relocated to the next area that needs drainage. This process involves the disassembly, transportation and reinstallation of the equipment to ensure that it can continue to operate smoothly in the new location. With the relocation of the drill, the prevention and control work will be transferred to the next area, and the previous process such as drilling, perforation, drainage, etc. will be repeated, and then the subsequent waterlogged areas will be drained until the entire waterlogged area is effectively drained. Through this phased approach, the waterlogging problem in the entire prevention and control area is gradually dealt with, and the safety hazards caused by the waterlogging in the goaf are finally eliminated, effectively solving the threat of waterlogging in the overlying goaf area faced by the mine, and ensuring the safe production of the coal mine.

[0059] The present invention provides a method for efficiently draining water from goafs with repeated mining of multiple coal seams at close range. By conducting ground geophysical surveys on the prevention and control areas and combining the collected mining information of the overlying coal seams in the goafs, the method can accurately delineate abnormal waterlogging areas and low-lying areas. This method improves the accuracy of identifying potential waterlogging areas and provides reliable data support for subsequent prevention and control. By arranging water level monitoring holes and ground drainage holes in the delineated key areas, not only real-time monitoring of the groundwater level in these areas is achieved, but also coordinated drainage capabilities above and below the wells are achieved. By designing and Directional drilling in the construction well ensures that its trajectory covers areas with abnormal water accumulation and low-lying areas, which can more directly and effectively carry out prevention and control in the target areas; by adopting branch hole design, the number and distribution density of water drainage points in the goaf are increased, the drainage area is increased, and the construction efficiency and water drainage volume are greatly improved; by drilling through the underground directional drilling holes until the water output of each borehole drops below the target value, the stability and continuity of the water output from the boreholes are guaranteed. This process is crucial to solving the problem of poor drainage caused by blockage and ensures the stable and efficient operation of the entire drainage system.

[0060] Finally, the drainage effect of the entire prevention and control area is tested, and the strategy is adjusted or further measures are taken according to the actual situation to ensure the quality and effect of the entire drainage process. This method effectively overcomes the shortcomings of few ground drilling control points, high construction cost, small drainage area of ​​single-point underground drilling, poor landing point accuracy, low drainage efficiency, and inability to drain remote areas.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. 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 embodiments of the present invention.

Claims

1. A method for efficiently draining water from goaf areas of multiple coal seams repeatedly mined in close proximity, characterized in that: The steps include: Conduct ground geophysical surveys in the prevention and control areas and collect mining data on the goaf of the overlying coal seams; Delineate areas with abnormal water accumulation and low-lying areas within the prevention and control area; Arrange water level monitoring holes and ground drainage holes in the abnormal water accumulation area and the low-lying area; Design and construct downhole directional drilling to ensure that the trajectory of the downhole directional drilling can cover the abnormal water accumulation area and the low-lying area; Performing drilling work on the downhole directional boreholes until the water output of each downhole directional borehole drops below a target value; Conduct drainage effectiveness test on the prevention and control area.

2. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 1 is characterized in that: The design and construction of downhole directional drilling ensures that the trajectory of the downhole directional drilling can cover the abnormal water accumulation area and the low-lying area, and then includes: Whether to open a branch hole is determined based on the water output of the main hole of the downhole directional drilling. When the water output is less than a first preset value, multiple branch holes are opened on the drilling trajectory of the main hole, and the multiple branch holes are arranged around the end of the main hole.

3. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 2 is characterized in that: The judgment criterion for performing through-hole work on the downhole directional drilling hole is: the water output of the downhole directional drilling hole and the branch hole is less than a second preset value, the second preset value is greater than the target value, and the second preset value is less than the first preset value.

4. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 3 is characterized in that: The downhole directional drilling is performed until the water output of each downhole directional drilling hole drops below a target value, including: If the water output after the first hole penetration is greater than the second preset value, continue to drain; If the water output after multiple drillings is still less than the second preset value, it is determined that the reduction in water output is not caused by hole blockage. The water is drained continuously until the water output is less than the target value. It is judged that the accumulated water in the drilling control area has been drained to the expected effect, and no subsequent drilling work is required.

5. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 1 is characterized in that: Delineating abnormal water accumulation areas and low-lying areas within the prevention and control area includes: delineating abnormal water accumulation areas based on the results of ground geophysical exploration; Based on the elevation data of the coal seam floor in the goaf, a contour map of the coal seam floor in the goaf is drawn to demarcate low-lying areas prone to water accumulation.

6. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 1 is characterized in that: The water level monitoring holes and the ground drainage holes are arranged at intervals. Dynamic monitoring equipment for the water level in the goaf is provided in the water level monitoring holes for real-time dynamic monitoring of the water level in the goaf. A water pump is provided in the ground drainage holes for drainage of the water.

7. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 4 is characterized in that: Conduct drainage effect inspection on the control area, including: The water level elevation of the goaf area is observed in real time through the water level monitoring hole; Conduct ground geophysical exploration again in the prevention and control area to check whether there are local low-resistance abnormal areas.

8. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 7 is characterized in that: When the exploration results show that there are still local low-resistance anomalies, additional underground directional drilling should be carried out in the areas with low-resistance anomalies.

9. The method for efficiently draining water from goafs in close-range multi-coal seam repeated mining according to claim 7 is characterized in that: When the survey results show no abnormalities, the water drainage work in the current area is completed.

10. The method for efficiently draining water from goaf areas in close-range multi-coal seam repeated mining according to claim 6 is characterized in that: The distance between the water level monitoring hole and the ground drainage hole is 300m, and the length of the underground directional drilling hole does not exceed 500m.

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