Ground large-diameter drilling efficient danger relieving method for sealing accumulated water in goaf

Abstract

The invention provides a ground large-diameter drilling efficient danger relieving method for sealing accumulated water in a goaf, and relates to the technical field of coal mining. The ground large-diameter drilling efficient danger relieving method for sealing goaf water accumulation comprises the steps that the overlying strata damage height D is determined, and the goaf static water accumulation amount Q accumulation and the aquifer dynamic replenishment amount Q dynamic replenishment are determined on the basis of the overlying strata damage height D; determining a drilling point location for large-diameter pumping drainage, and determining the drilling depth based on the drilling point location; determining parameters of the water pumps and the preparation number of the water pumps; a large-diameter drill hole is formed in the drilling point position; and monitoring the accumulated water change in the goaf. The goaf water burst strength and mining geological conditions are analyzed, ground large-diameter drilling point positions are accurately arranged and constructed, accumulated water changes in the goaf are intelligently monitored, long-time stable operation is achieved, goaf water disaster threats of the closed goaf under the condition of abundant supply sources are effectively relieved, and efficient danger relieving is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to an efficient method for resolving danger by drilling large diameter holes on the ground to seal water accumulation in a goaf area. Background Art

[0002] In the process of coal mining, after the excavation of coal resources is completed, a large area of ​​goaf is formed in the completed mining area. The rock layer of the coal seam roof collapses and breaks due to the mining, resulting in the destruction of the aquifer (water barrier) layer in a large range of strata above the coal seam roof, resulting in water-conducting cracks, water release from the aquifer, and the formation of goaf water accumulation in the goaf area. With the passage of time, the scope and amount of water accumulation in the goaf area gradually increase, especially in the closed goaf area with abundant supply sources. The large amount of goaf water and high pressure formed pose a serious threat to coal mine safety production. Since the old goaf water in the closed space generally has the characteristics of large water volume, high water head and good concealment, if no effective measures are taken to resolve the danger, once it is touched, it will suddenly burst into the mine and cause sudden old goaf water seepage accidents. At present, the following two methods are usually used to deal with water accumulation in closed goaf areas under complex conditions: One is to leave a method to protect the coal pillar. For closed old goaf water with abundant supply sources, large water volume, high water head, strong concealment, great difficulty in control and high control cost, coal mines often directly designate them as old goaf water prohibited mining areas in accordance with the "three zones" management method for old goaf water. According to the mine pressure theory, the width of the old goaf water waterproof coal pillar is calculated, and waterproof coal (rock) pillar is left. This method leaves waterproof coal pillars from a standardized and scientific perspective to effectively resist the pressure of old goaf water and avoid the threat of water disasters. It is simple and easy to implement, and eliminates the old goaf water control process and cost. However, this method is too simple and crude, occupies recoverable coal resources, reduces the recovery rate of coal resources, causes waste of resources, and has a negative impact on the mining efficiency and production benefits of coal mining enterprises. It is not in line with the rational development and utilization of coal resources.

[0003] The other is the underground drainage drilling method, which is the most traditional and conventional method for coal mine old goaf water treatment. This method of underground treatment of old goaf water is often subject to the characteristics of old goaf water and the equipment capacity of the underground drainage system of the coal mine to achieve a better treatment effect. When the goaf water belongs to static reserve water and the head pressure is not high, the underground construction drainage drilling is used to eliminate the threat of old goaf water damage. It has certain safety and effectiveness. However, in the face of closed goaf areas with large water accumulation and abundant dynamic replenishment, conventional drainage drilling is used to eliminate the threat of old goaf water damage. At the same time, the treatment effect is often unsatisfactory and often faces multiple bottlenecks. First, the drainage system capacity of the mine may not be able to effectively meet the drainage needs of large amounts of old goaf water. Secondly, closed goafs often require the construction of special drainage tunnels to ensure the drainage effect. Faced with this situation, conventional underground drainage technology methods require the addition of corresponding tunnel projects, the addition of corresponding drainage equipment and even systematic drainage modifications, which greatly increases the engineering investment and time cost of old goaf water hazard control, and is difficult to control in terms of economic benefits and implementation difficulty.

[0004] Among the existing technologies for managing old goaf water, especially when facing water accumulation in closed goaf under conditions of abundant supply sources, there is no efficient and stable technology that is safe and reliable while taking into account economic benefits, and does not add extra burden to the underground system or waste coal resources. Summary of the invention

[0005] The present invention provides an efficient method for resolving water accumulation in a closed goaf with a large-diameter ground borehole, which is used to solve the problems in the prior art of requiring additional burden on the underground system and wasting coal resources.

[0006] The present invention provides an efficient method for resolving danger of large-diameter ground drilling holes in a closed goaf area, comprising: Determine the overburden failure height D, and determine the static water accumulation volume Q of the goaf based on the overburden failure height D 积 and the dynamic recharge of the aquifer Q 动补 ; Determining a drilling point for large-diameter extraction, and determining a drilling depth based on the drilling point; Determine the parameters of the water pump and the number of water pumps to be equipped; Setting a large-diameter borehole at the drilling point; Monitor the changes in water accumulation in the goaf.

[0007] According to the invention, a method for efficiently resolving water accumulation in a closed goaf with a large-diameter ground borehole is provided, wherein the step of determining the overburden damage height D comprises: According to the measured results of the overburden damage height of the goaf under the same coal seam, the same geological mining conditions and the same mining parameters in the mine, divided by the mining height, the crack mining ratio C is obtained to obtain the measured data of the goaf; Based on the crack-mining ratio C obtained by analyzing the measured data, the overburden failure height D is determined by analogy according to the actual mining thickness M of the goaf to be drained.

[0008] According to the invention, a method for efficiently solving the problem of ground large-diameter drilling in a closed goaf area with water accumulation is provided, wherein the static water accumulation volume Q of the goaf is determined based on the overburden damage height D. 积 and the dynamic recharge of the aquifer Q 动补 The steps include: The static water volume Q of the goaf is determined based on the water outflow volume, water level, water filling coefficient, mining height and coal seam inclination of the goaf. 积 ; The dynamic recharge Q of the aquifer is determined by analytical methods and hydrogeological analogy 动补 .

[0009] According to the invention, a method for efficiently resolving water accumulation in a closed goaf by drilling large diameter holes on the ground, the step of determining the drilling points for large diameter drainage comprises: According to the bottom plate elevation of the working face tunnel and the goaf space in the goaf, the water accumulation parameters are determined, and based on the water accumulation parameters, the relatively low water collection point is determined as the drilling point; wherein the water accumulation parameters include the distribution range of water accumulation in the goaf, the water accumulation depth and the dynamic recharge amount.

[0010] According to the present invention, a method for efficiently resolving the danger of large-diameter ground drilling in a closed goaf area, the method of determining the drilling depth based on the drilling point position includes: Determining the ground elevation of the drilling point; The drilling depth is obtained according to the difference between the ground elevation and the elevation of the bottom plate of the goaf.

[0011] According to the present invention, a method for efficiently resolving the danger of large-diameter ground drilling for sealing water accumulation in a goaf is provided, and the step of setting a large-diameter drilling hole at the drilling point comprises: A primary casing is arranged in the loose sand layer or the topsoil layer at the drilling point, and the lower end of the primary casing is arranged below the top interface of the bedrock; Fixing the primary casing by cement slurry; A secondary casing is arranged in the large-diameter borehole, and the lower end of the secondary casing is arranged below the bottom plate of the goaf.

[0012] According to the invention, a high-efficiency method for resolving danger of large-diameter ground drilling for sealing water accumulation in goaf areas is provided, wherein the lower end of the primary casing is arranged 5-10 m below the top interface of the bedrock.

[0013] According to the present invention, a method for efficiently resolving water accumulation in a closed goaf with large-diameter ground drilling is provided, wherein the lower end of the secondary casing is arranged 5-10m below the bottom plate of the goaf, and the inner diameter of the secondary casing is at least 150mm larger than the outer diameter of the water pump.

[0014] According to the present invention, an efficient method for resolving water accumulation in a closed goaf by drilling large diameter holes on the ground is provided, wherein the secondary casing from 5 m above the top boundary of the water-conducting fracture zone to the hole mouth is a solid pipe, and the secondary casing from 5 m above the top boundary of the water-conducting fracture zone to the hole bottom is a screen pipe.

[0015] According to the invention, a method for efficiently resolving danger of large-diameter ground drilling in a closed goaf area, the step of monitoring the change of water accumulation in the goaf includes: Determine the flow rate and time curve, the water level and time curve, and the flow rate and water level curve according to the acquired water level in the borehole and the flow rate of the drainage pipe; The water accumulation change in the goaf is obtained based on the flow rate and time curve, the water level and time curve, and the flow rate and water level curve.

[0016] The method for efficiently solving the problem of water accumulation in a closed goaf by drilling large diameter holes on the ground provided by the present invention has the following advantages: 1. The method for efficiently eliminating water accumulation in closed goafs with large-diameter ground drilling of the present invention analyzes the water gushing intensity of the goafs and the mining geological conditions, accurately arranges and constructs the large-diameter ground drilling points, and intelligently monitors the changes of water accumulation in the goafs. It operates stably for a long time, effectively eliminating the threat of water damage in closed goafs with old water under the condition of abundant supply sources, and achieves efficient elimination of the danger.

[0017] 2. The method of the present invention for efficiently solving the problem of water accumulation in closed goaf with large-diameter ground drilling is independent of the mine production system, avoids increasing the burden on the mine drainage system and the investment in complex underground treatment projects, does not affect the normal operation of the mine system, and is significantly superior to traditional underground methods for draining old goaf water.

[0018] 3. The high-efficiency method for resolving water accumulation in closed goaf areas with large-diameter ground drilling of the present invention can customize and optimize the large-diameter ground drainage plan according to the goal of old goaf water treatment, taking into account both effect and cost control.

[0019] 4. The high-efficiency method for resolving water accumulation in closed goaf areas by drilling large diameter holes on the ground of the present invention reduces the amount of water accumulation and the water head height in the closed goaf areas after implementation, ensures safe production of mine water prevention and control, and improves the utilization rate of coal resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 It is a schematic diagram of the spatial position of overburden damage and water-containing (isolated) rock layers provided by the present invention.

[0022] Figure 2 It is a schematic diagram of installing a submersible pump in a borehole provided by the present invention.

[0023] Figure 3 It is a schematic structural diagram of the large-diameter drilling provided by the present invention.

[0024] Figure 4 The invention is a method for efficiently solving the problem of water accumulation in a closed goaf with a large-diameter ground borehole. 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] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] Combine the following Figure 1-Figure 3 The specific implementation method of the method for efficiently resolving water accumulation in a closed goaf area by drilling large diameter holes on the ground according to the present invention is described.

[0031] like Figure 1 As shown in the figure, the efficient methods to solve the problem of water accumulation in the closed goaf with large-diameter ground drilling include: Step S100, determine the overburden damage height D, and determine the static water accumulation volume Q of the goaf based on the overburden damage height D 积 and the dynamic recharge of the aquifer Q 动补 ; Step S200, determining a drilling point for large-diameter extraction, and determining a drilling depth based on the drilling point; Step S300, determining the parameters of the water pump and the number of water pumps to be equipped; Step S400, setting a large diameter drill hole at a drilling point; Step S500, monitoring the change of water accumulation in the goaf.

[0032] The method for efficiently resolving water accumulation in closed goafs with large-diameter ground drillings of the present invention analyzes the water gushing intensity of the goafs and the mining geological conditions, accurately arranges and constructs large-diameter ground drilling points, and intelligently monitors the changes of water accumulation in the goafs, thereby stably operating for a long time, effectively eliminating the threat of water hazard from old goaf water in closed goafs under the condition of abundant supply sources, thereby achieving efficient resolution of the crisis.

[0033] The high-efficiency method for resolving water accumulation in closed goaf areas by drilling large diameter holes on the ground of the present invention is independent of the mine production system, avoids increasing the burden on the mine drainage system and the investment in complex underground treatment projects, does not affect the normal operation of the mine system, and is significantly superior to traditional underground treatment methods for draining old goaf water.

[0034] The high-efficiency method for resolving water accumulation in closed goaf areas with large-diameter ground drilling of the present invention can customize and optimize the large-diameter ground drainage plan according to the goal of old goaf water treatment, taking into account both effect and cost control.

[0035] The high-efficiency method for resolving water accumulation in closed goaf areas with large-diameter ground drilling of the present invention reduces the amount of water accumulation and water head height in the closed goaf areas after implementation, ensures safe production of mine water prevention and control, and improves the utilization rate of coal resources.

[0036] In one embodiment of the present invention, the step of determining the overburden failure height D comprises: Step S110, according to the measured result of the overburden damage height of the goaf under the same coal seam, the same geological mining conditions and the same mining parameters in the mine, divided by the mining height, the crack mining ratio C is obtained to obtain the measured data of the goaf; Step S120, based on the crack-mining ratio C obtained by analyzing the measured data, the overburden damage height D is determined according to the actual mining thickness M of the goaf to be drained by analogy.

[0037] like Figure 1 As shown in the figure, assuming that the regional cracking ratio is C and the coal seam mining thickness is M under the mining conditions, the overburden damage height of the coal seam mining is D=M*C.

[0038] In one embodiment of the present invention, the static water volume Q of the goaf is determined based on the overburden damage height D. 积 and the dynamic recharge of the aquifer Q 动补 The steps include: Step S130, determine the static water volume Q of the goaf based on the water outflow volume, water level, water filling coefficient, mining height and coal seam inclination of the goaf 积 ; like Figure 1 As shown, the fracture zone has aquifers H1 and H2, and the static water accumulation in the goaf area Q is determined 积 and the dynamic recharge of the aquifer Q 动补It is necessary to analyze the recharge intensity of the aquifers (aquifer H1 and aquifer H2) within the mining influence range. The main analysis parameters are: aquifer thickness M, permeability coefficient K, aquifer water level H and water inflow Q of the mining face during production. 正 ; Step S140, determining the dynamic recharge of the aquifer Q by analytical method and hydrogeological analogy method 动补 .

[0039] In one embodiment of the present invention, the step of determining the drilling point for large diameter extraction comprises: Step S210, determine the water accumulation parameters according to the bottom plate elevations of the working face tunnels and goaf spaces in the goaf, and determine the relatively low water collection points as the drilling points based on the water accumulation parameters; wherein the water accumulation parameters include the distribution range, water accumulation depth and dynamic recharge volume of water accumulation in the goaf.

[0040] The setting of large-diameter drainage drilling points is crucial and directly affects the efficiency of water drainage. When determining the drilling points, the topography and the impact on the surrounding environment should also be considered. Under the same conditions, choosing flat and well-drained points as the layout locations of large-diameter drilling holes can better ensure drainage efficiency and reduce the impact on the surrounding environment.

[0041] In one embodiment of the present invention, determining the drilling depth based on the drilling point position includes: Step S220, measuring the ground elevation of the drilling point; Step S230, obtaining the drilling depth according to the difference between the ground elevation and the goaf floor elevation.

[0042] It should be noted here that after determining the large-diameter drilling point, the ground elevation H of the drilling point is measured using the RTK instrument. 地面 , analyze the corresponding goaf floor elevation H 底板 , calculate the drilling depth L=H 地面 -H 底板 , the drilling depth is calculated to calculate the water pump head.

[0043] like Figure 2 As shown in the figure, the selection and configuration of the drainage pump is also crucial, which is directly related to the drainage efficiency and treatment effect of the water in the goaf. After determining the drilling point and the pump head, the hourly drainage volume of the pump is determined according to the old goaf water treatment target. According to the hourly drainage volume and drainage head of the pump, the corresponding pump parameters and the number of equipment are designed. When selecting the pump type, the actual efficiency and head loss of the pump should be considered. The head of the selected pump should be greater than the sum of the expected head loss value and the required head. A deep well vertical centrifugal pump with stable performance, high efficiency and low maintenance cost should be selected.

[0044] In one embodiment of the present invention, the step of setting a large diameter borehole at a drilling point includes: Step S410, setting a primary casing in the loose sand layer or topsoil layer at the drilling point, with the lower end of the primary casing being set below the top interface of the bedrock; After determining the parameters of the water pump and the number of water pumps, it is necessary to design the parameters of the large-diameter borehole. The large-diameter borehole parameters include the aperture and the borehole structure. According to the selected water pump model and the predicted height of the overburden damage at the working face, the ground large-diameter borehole parameters are determined in combination with the overburden characteristics. Two-stage holes are generally used on the surface covered with loose sand or topsoil. The first-level casing is set to prevent the borehole from collapsing in the loose sand or topsoil layer. The lower end of the first-level casing is set 5-10m below the top interface of the bedrock.

[0045] Step S420, fixing the primary casing with cement slurry; Step S430, a secondary casing is installed in the large diameter borehole, and the lower end of the secondary casing is installed below the bottom plate of the goaf.

[0046] like Figure 3 As shown in the figure, cement slurry is used to fix the primary casing to improve the stability of the primary casing. The diameter of the primary casing should be larger than the diameter of the secondary casing by two levels. The lower end of the secondary casing is set 5-10m below the bottom plate of the goaf. The inner diameter of the secondary casing is at least 150mm larger than the outer diameter of the water pump to facilitate the lifting and lowering of the water pump. The primary casing is a solid pipe, and the secondary casing is a combination of a solid pipe and a screen pipe. The secondary casing from 5m above the top boundary of the water-conducting fracture zone to the hole mouth is a solid pipe, and the secondary casing from 5m above the top boundary of the water-conducting fracture zone to the bottom of the hole is a screen pipe.

[0047] Directional drilling rigs are preferred for the construction of large-diameter boreholes. Considering the economic cost, non-directional drilling rigs can be used for step-by-step guided construction within a hole depth of 150m. Directional drilling rigs are used for boreholes with a depth greater than 150m to ensure the verticality of the borehole, which is conducive to the installation and drainage of drainage equipment such as water pumps.

[0048] In one embodiment of the present invention, the step of monitoring the change of water accumulation in the goaf includes: Step S510, determining a flow rate and time curve, a water level and time curve, and a flow rate and water level curve according to the acquired water level in the borehole and the flow rate of the drainage pipe; Step S520, obtaining the water accumulation change in the goaf based on the flow rate and time curve, the water level and time curve, and the flow rate and water level curve.

[0049] The monitoring and analysis of drainage volume and water level data in the borehole is an important means of effect evaluation. A water level monitoring sensor is installed in the drainage borehole to measure the water level in the borehole. A pipeline flow monitoring device is installed on the drainage pipeline to measure the flow in the drainage pipeline. In terms of analysis methods, the collected data is processed using statistical analysis software to draw flow-time curves and water level-time curves, and the relationship between flow and water level drop (QS curve) is calculated to grasp the changes in water accumulation in the goaf in real time and evaluate the drainage effect. At the same time, a liquid level electromagnetic automatic start-stop control device is installed on the drainage pump in the hole to realize remote real-time monitoring and automatic control, thereby improving the pumping efficiency. Combined with the actual situation on site, the authenticity and reliability of the monitoring data are guaranteed through regular field investigations and data verification.

[0050] 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. An efficient method for solving the problem of water accumulation in a closed goaf with a large-diameter ground borehole, characterized in that: include: Determine the overburden failure height D, and determine the static water accumulation volume Q of the goaf based on the overburden failure height D 积 and the dynamic recharge of the aquifer Q 动补 ; Determining a drilling point for large-diameter extraction, and determining a drilling depth based on the drilling point; Determine the parameters of the water pump and the number of water pumps to be equipped; Setting a large-diameter borehole at the drilling point; Monitor the changes in water accumulation in the goaf.

2. The method for efficiently solving the problem of water accumulation in closed goaf with large-diameter ground drilling according to claim 1 is characterized in that: The step of determining the overburden damage height D comprises: The cracking ratio C is calculated by dividing the measured damage height of the overburden in the goaf under the same coal seam, the same geological mining conditions and the same mining parameters by the mining height. Based on the crack-mining ratio C obtained by analyzing the measured data, the overburden failure height D is determined by analogy according to the actual mining thickness M of the goaf to be drained.

3. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to claim 1 is characterized in that: The static water volume Q of the goaf is determined based on the overburden damage height D 积 and the dynamic recharge of the aquifer Q 动补 The steps include: The static water volume Q of the goaf is determined based on the water outflow volume, water level, water filling coefficient, mining height and coal seam inclination of the goaf. 积 ; The dynamic recharge Q of the aquifer is determined by analytical methods and hydrogeological analogy 动补 .

4. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to claim 1 is characterized in that: The step of determining the drilling point for large-diameter drainage comprises: According to the bottom plate elevation of the working face tunnel and the goaf space in the goaf, the water accumulation parameters are determined, and based on the water accumulation parameters, the relatively low water collection point is determined as the drilling point; wherein the water accumulation parameters include the distribution range of water accumulation in the goaf, the water accumulation depth and the dynamic recharge amount.

5. The method for efficiently solving the problem of water accumulation in closed goaf with large-diameter ground drilling according to claim 4 is characterized in that: Determining the drilling depth based on the drilling point comprises: Determining the ground elevation of the drilling point; The drilling depth is obtained according to the difference between the ground elevation and the elevation of the bottom plate of the goaf.

6. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to any one of claims 1 to 5, characterized in that: The step of setting a large diameter borehole at the drilling point comprises: A primary casing is arranged in the loose sand layer or the topsoil layer at the drilling point, and the lower end of the primary casing is arranged below the top interface of the bedrock; Fixing the primary casing by cement slurry; A secondary casing is arranged in the large-diameter borehole, and the lower end of the secondary casing is arranged below the bottom plate of the goaf.

7. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to claim 6 is characterized in that: The lower end of the primary casing is arranged 5-10m below the top interface of the bedrock.

8. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to claim 6 is characterized in that: The lower end of the secondary casing is arranged 5-10m below the bottom plate of the goaf, and the inner diameter of the secondary casing is at least 150mm larger than the outer diameter of the water pump.

9. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to claim 6 is characterized in that: The secondary casing from 5m above the top boundary of the water-conducting fracture zone to the hole mouth is a solid pipe, and the secondary casing from 5m above the top boundary of the water-conducting fracture zone to the hole bottom is a screen pipe.

10. The method for efficiently solving the problem of water accumulation in a closed goaf with large-diameter ground drilling according to any one of claims 1 to 5, characterized in that: The step of monitoring the change of water accumulation in the goaf includes: Determine the flow rate and time curve, the water level and time curve, and the flow rate and water level curve according to the acquired water level in the borehole and the flow rate of the drainage pipe; The water accumulation change in the goaf is obtained based on the flow rate and time curve, the water level and time curve, and the flow rate and water level curve.

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