A large-diameter drainage sand well structure for a tailings pond and its construction application method

Abstract

The present invention discloses a large-diameter drainage sand well structure for a tailings pond, which includes a sand well body and a pneumatic extraction drainage device. A geotextile mat, a first geotextile, a steel reinforcement cage, a gravel backfill layer, a second geotextile, and a screen pipe are fixedly arranged inside the sand well body. The aperture of the sand well is 800 - 1200 mm. The outside of the steel reinforcement cage is wrapped with the geotextile mat and the first geotextile, which play a role in filtering and reinforcement. The gap between the geotextile mat and the first geotextile effectively improves the permeability. The screen pipe is arranged at the innermost side of the sand well body, and the outside of the screen pipe is wrapped with the second geotextile. A gravel backfill layer is arranged between the pipe wall of the screen pipe and the sand well wall. The drainage of the tailings pond is carried out through the cooperation of the sand well body and the pneumatic extraction drainage device. The large-diameter drainage sand well structure for the tailings pond of the present invention has a large aperture and good drainage effect, and because pneumatic pumping is adopted and automated control is used, the energy consumption and maintenance cost can be significantly reduced, which is extremely practical. The present invention also provides a construction application method for the above-mentioned large-diameter drainage sand well of the tailings pond.

Description

Technical Field

[0001] The present invention belongs to the field of tailings pond seepage drainage and consolidation, and particularly relates to a large-diameter seepage sand well structure and construction method for a tailings pond. Background Art

[0002] Currently, there are more than 7,000 tailings ponds in China, and about 25% of them are operating in an environment where safety cannot be guaranteed, affecting the safety of downstream facilities and residents. With the continuous improvement of the beneficiation plant grinding process, the tailings discharged from the tailings pond are becoming finer and finer. Coupled with the fact that most tailings ponds use the upstream dam construction method, it is easy for the tailings pond to have a problem that the position of the phreatic line is too high and exceeds the control requirements, bringing certain hidden dangers to the operation of the tailings pond. To ensure the safe operation of the tailings pond, seepage drainage facilities can be added to accelerate the seepage drainage and consolidation of the tailings, thereby improving the stability of the dam body. The current main seepage drainage technologies mainly include blind ditch seepage drainage, pipe well seepage drainage, siphon seepage drainage, and radiation well technology.

[0003] The blind ditch seepage drainage of the flexible permeable pipe is to embed a blind ditch gravel body wrapped with geotextile on the deposition beach surface, and a flexible permeable pipe is arranged in the blind ditch. The seepage water is drained to the dam external drainage ditch through the flexible permeable pipe blind ditch. This seepage drainage method has a good initial seepage drainage effect, but it is easy to be blocked in the later stage, resulting in the failure of seepage drainage;

[0004] The pipe well seepage drainage is to set a seepage water vertical shaft below the phreatic line along the axis direction of the tailings stacking dam, and use a water pump to pump the seepage water in the pipe well. The pipe well is composed of a wellhead pipe, a well wall pipe, a filter pipe and a sand settling pipe section. Since the content in the tailings pond is basically tailings sand, its working conditions are significantly different from those of ordinary civil engineering working conditions. The tailings pond is in a saturated state due to hydraulic filling and has not been deposited and consolidated. After the pore diameter becomes large, it is difficult to ensure the stability of the hole wall by using the traditional slurry wall protection, and the cost of using the steel casing wall protection is too high and the construction difficulty is large. Therefore, there is currently no large-diameter sand well with a well diameter greater than 1000 mm built in the tailings pond. And for the sand well with a well diameter of 110 - 250 mm, due to the particularity of the tailings, the water collection and seepage effect is very poor. At present, it is basically not applied or only used as a temporary and small-scale facility in the tailings pond seepage drainage technology. At the same time, due to the small permeability of the tailings, the pump water system of the pipe well cannot meet the requirements of long-term and slow water flow, so the water pump needs to be frequently started and stopped to ensure that a precipitation funnel is formed around the seepage well to achieve precipitation. And each seepage drainage well needs to be equipped with a separate water pump, and the water pump needs to be frequently started and stopped during operation, which is inconvenient for maintenance and management;

[0005] Siphon drainage applies the siphon principle to siphon and drain seepage water. Such a drainage system mainly consists of a water seal groove, a siphon well, a siphon pipeline, and an observation well. The water seal groove mainly ensures the vacuum degree required by the siphon system, that is, to ensure that the outlet of the drain pipe is always below the corresponding water level after the siphon system is started. The siphon well is a key dewatering facility in this system, and there are certain standards and requirements for the quality of well completion. Affected by atmospheric pressure, the drainage depth is generally limited within 7 - 8 meters, which is of little significance for the drainage of tailing ponds;

[0006] The radiation well technology for drainage is to set one or more layers of radially arranged drainage pipes in the embankment dam. The tailing seepage water is self - flowingly collected into the water - collecting vertical shaft through the drainage pipes, and then the seepage water is self - flowingly discharged from the dam through the water - guiding pipe connected to the vertical shaft. According to the direction of seepage flow, the radiation well mainly consists of radially arranged drainage pipes, a vertical water - collecting well, and a water - guiding pipe leading to the dam slope. It has the disadvantages of long construction period, high cost, high construction risk, and easy failure and siltation;

[0007] Therefore, it is necessary to design a large - diameter drainage sand well structure and construction method for tailing ponds to effectively drain the tailing ponds. Summary of the Invention

[0008] Aiming at the deficiencies of the above - mentioned existing technologies, the present invention provides a large - diameter drainage sand well structure and construction application method for tailing ponds. This drainage sand well has a large diameter, easy water intake for the filter, good drainage effect, and the well wall is not easy to collapse.

[0009] Specifically, the present invention relates to the following technical solutions:

[0010] The present invention provides a large - diameter drainage sand well structure for tailing ponds, including a sand well body and a pneumatic extraction drainage device. A geotextile mat, a first geotextile, a steel reinforcement cage, a gravel backfill layer, a second geotextile, and a screen pipe are fixedly arranged in the sand well body. The aperture of the sand well is 800 - 1200 mm. The outside of the steel reinforcement cage is wrapped with a geotextile mat and a first geotextile, which play a role in filtering and reinforcement. The gap between the geotextile mat and the first geotextile effectively improves the permeability. The screen pipe is arranged on the innermost side of the sand well body, and the outside of the screen pipe is wrapped with a second geotextile. A gravel backfill layer is arranged between the pipe wall of the screen pipe and the sand well wall. The tailing pond is drained through the cooperation of the sand well body and the pneumatic extraction drainage device.

[0011] Preferably, the pneumatic extraction and drainage device includes a drainage tank, a control pipe, an air pipe, a drain pipe, and a controller. The drainage tank is arranged in the well hole of the sand drain body. A one-way valve is provided at the bottom of the drainage tank. One end of the drain pipe extends below the liquid level and the other end is connected to the controller. One end of the air pipe is above the liquid level and the other end is connected to the controller through an air compressor. One end of the control pipe is communicated with the controller, and a plugging component is provided at the other end of the control pipe to control the liquid level. The other end of the drain pipe at the wellhead position is set as a Venturi tube structure to jointly control the pressure in the controller to realize the working control of the air compressor. According to the change of the liquid level in the tank, the air pressure difference in the controller changes, so as to realize the working control of the air compressor. Specifically, when the pneumatic pumping device works, when the liquid passes through the Venturi device, if the water level in the drainage tank is higher than the control value, the control pipe will form a plug, and then a negative pressure will be formed in the controller, causing the inner sealing piece to deform and extending the working time of the air compressor until the water level is lower than the control value. Air enters the controller from the control pipe to form a negative pressure compensation, and the inner sealing piece is restored, and the air compressor stops working.

[0012] Preferably, the plugging component includes a float chamber and a float. The plugging component includes a float chamber and a float. The bottom of the floating chamber is hollowed out. The size of the float matches the size of the control pipe diameter. The float chamber is integrally formed with the control pipe and is arranged at the bottom of the control pipe in a flared shape. If the liquid level in the tank is higher than the float chamber, the float in the chamber will block the bottom of the control pipe. The inner sealing piece in the controller deforms due to the negative pressure. A first metal sheet is provided at the bottom of the inner sealing piece, and the first metal sheet can deform with the deformation of the inner sealing piece. A second metal sheet is provided below the first metal sheet. The contact or disconnection of the first metal sheet and the second metal sheet conducts the signal circuit for controlling the air compressor, and finally realizes the start and stop of the air compressor. When the first metal sheet at the bottom contacts the second metal sheet, the continuous start signal of the air compressor is triggered, and air is filled and drained at the same time until the liquid level drops below the floating chamber. The float drops and air enters from the bottom of the control pipe to compensate the negative pressure inside the controller. The inner sealing piece is restored and the first metal sheet is disconnected from the second metal sheet, and the air compressor stops working. By paralleling the signals of the air compressor and the controller, the air compressor can be automatically started and stopped according to the water level in the drainage tank.

[0013] Preferably, a sand and gravel cushion layer is provided at the bottom inside the sand drain body.

[0014] The present invention also provides a construction application method for the above-mentioned large-diameter drainage and seepage sand drain, including the following steps:

[0015] S1. Bury steel coiled pipes for all well holes as orifice casings;

[0016] S2. Dig a mud pit near the drill rig, connect the well holes, mud ditches, and mud pits, and dig ditches according to the mud flow direction;

[0017] S3. Configure the slurry. The slurry consists of the following raw materials in parts by mass: 6 - 9 parts of bentonite, 63 - 73 parts of water, 20 - 30 parts of tailings, 2 - 3 parts of asbestos, 0.002 parts of externally added polyacrylamide. During drilling, carry out slurry wall protection to prevent hole collapse, effectively ensuring the successful implementation of large-diameter sand wells in the tailings stratum.

[0018] S4. After wrapping the outside of the steel reinforcement cage with geotextile mat and geotextile in sequence, install the steel reinforcement cage.

[0019] S5. Backfill a small amount of gravel for bedding.

[0020] S6. Install the screen pipe. Wrap the screen pipe with geotextile and tie it tightly with iron wire.

[0021] S7. Fill the space between the screen pipe wall and the well wall with gravel. Control the well diameter between 800 - 1200 mm.

[0022] S8. After completing the pipeline assembly of the pneumatic extraction drainage device outside the well, install the device into the well and check the air tightness.

[0023] S9. Complete the installation of the air compressor and air storage tank, and set the start time of the air compressor according to the water volume.

[0024] S10. After the water in the tailings pond seeps into the drainage tank and reaches the set time, start the air compressor.

[0025] S11. Compressed air enters the drainage tank through the air inlet pipe, the pressure in the tank increases, and under the action of the pressure, the one-way valve at the bottom of the tank closes.

[0026] S12. The water stored in the pipe is discharged outside the well through the drain pipe. When the water flows through the Venturi tube structure, due to the change in flow rate, a negative pressure is formed in the controller, the flexible inner sealing piece deforms, and the metal piece in the control device contacts to give a continuous operation signal, causing the air compressor to continue running.

[0027] S13. When the liquid level in the tank continuously drops below the control pipe, the float in the floating chamber drops, gas enters the control pipe, the air pressure in the controller is compensated, the metal piece disconnects, gives a stop operation signal, stops pressing air into the tank, the air pressure inside and outside the drainage tank gradually balances, and the water in the tailings pond continues to seep into the drainage tank. When the liquid level in the tank is higher than the floating chamber, the float in the chamber will block the bottom of the control pipe. The sealing piece in the controller deforms due to the negative pressure, and the first metal piece at the bottom contacts the second metal piece, sending a continuous start signal for the air compressor until the liquid level drops below the floating chamber, and the cycle repeats to complete the drainage task.

[0028] Preferably, in S6, holes are provided on the screen pipe wall, the hole pitch is 12 - 17 cm, and the hole diameter is 12 - 19 mm.

[0029] Preferably, 5 - 10 mm gravel is filled in S7.

[0030] Compared with the prior art, the beneficial effects of the large-diameter seepage sand well structure and construction application method for tailing ponds of the present invention are as follows:

[0031] 1. Aiming at the problem that it is difficult to form holes in tailing ponds because they are hydraulically filled, not deposited and consolidated, and are in a saturated state, the slurry wall protection of the present invention is adopted. The static pressure of the slurry on the groove wall and the mud feeling formed by the slurry on the groove wall can effectively prevent the collapse of the hole wall. In addition, the slurry also has the functions of carrying slag, cooling and lubrication. The slurry with a certain roughness can carry the mud slag out together, and can effectively stabilize the quicksand layer of the tailings.

[0032] 2. Compared with small-diameter sand wells, the large-diameter sand well filter of the present invention is easy to admit water, has good seepage effect, is not easily blocked during use, and has a larger drainage capacity. It is more convenient for water inlet and drainage. At the same time, it also reduces the drainage frequency and energy consumption.

[0033] 3. Adopting the pneumatic drainage scheme of the present invention, there is no need to arrange water pumps, circuits and signal sensors underground. It can be directly installed after being integrally assembled outside the well, which is convenient for installation and maintenance and has no risk of electric leakage.

[0034] 4. Adopting the pneumatic drainage scheme of the present invention can control multiple single wells by one air compressor through the control of the gas storage tank valve, reducing the operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0036] Figure 2 It is Figure 1 Top view.

[0037] Figure 3 It is Figure 2 A-A cross-sectional view of

[0038] Figure 4 It is a schematic structural diagram of the upper part of the pneumatic extraction drainage device of the present invention.

[0039] Figure 5 It is a schematic structural diagram of the pneumatic extraction drainage device of the present invention.

[0040] Figure 6 It is Figure 3 Partial view b of

[0041] Figure 7 It is Figure 3 Partial view c of

[0042] Figure 8 It is a schematic structural diagram of the float chamber.

[0043] Figure 9 It is a cross-sectional view of the sand drain body.

[0044] In the figure: geotextile mat 101, first geotextile 102, steel reinforcement cage 103, gravel backfill layer 104, second geotextile 105, screen pipe 106, tailings 107, slurry pond 108, slurry ditch 109, gravel bedding 110;

[0045] Drainage tank 201, control pipe 202, air pipe 203, drain pipe 204, one-way valve 205, Venturi tube structure 206, controller 207, float chamber 208;

[0046] Inner sealing piece 2061, first metal piece 2062, second metal piece 2063;

[0047] Float 2081. Specific implementation mode

[0048] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0050] The technical solution of the first embodiment is a large-diameter drainage sand well structure for a tailings pond. Refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , the present invention provides a large-diameter drainage sand well structure for a tailings pond, including a sand well body 1 and a pneumatic extraction drainage device 2. The sand well main body (refer to Figure 9 ), which is composed of a geotextile mat 101, a first geotextile 102, a steel reinforcement cage 103, a gravel backfill layer 104, a second geotextile 105, and a screen pipe 106. The well diameter of the sand well body is controlled between 800 and 1200 mm. The outside of the steel reinforcement cage is wrapped with a geotextile mat and the first geotextile, which plays a role in filtration and reinforcement. The innermost part is a DN315 screen pipe. The screen pipe uses a special pipe with a diameter of DN315, and holes are drilled around the pipe wall. The hole distance is 12 - 17 cm and the hole diameter is 12 - 19 mm. After drilling, 200 - 400 g / m 2Wrap the non-woven geotextile around for one and a half turns and tie it tightly with iron wire. Dig a mud pit 108 in the tailings 107 near the drill rig, connect the well hole, mud ditch 109 and mud pit, and dig a trench according to the mud flow direction. Select a special mud. The mass parts of the main components of the mud are: 6-9 parts of bentonite, 63-73 parts of water, 20-30 parts of tailings, 2-3 parts of asbestos, and 0.002 parts of polyacrylamide added externally. During the hole cleaning process, continuously replace the mud until gravel is filled. This slurry has a good wall protection effect, can effectively stabilize the tailings quicksand layer, and overcome the difficulty of easy hole collapse in the construction of large-diameter sand wells. Finally, fill the space between the pipe wall and the well wall with 5-10 mm gravel. Set a small amount of sand cushion layer 110 at the bottom.

[0051] The pneumatic extraction and drainage device is composed of a drainage tank 201, a control pipe 202, an air pipe 203, a drainage pipe 204, and a controller 207. The length of the control pipe can be adjusted according to the design. The drainage pipe needs to extend below the liquid level, and the air pipe needs to be arranged above the liquid level. When pumping water, use a PLC to control the air compressor to start regularly and inflate the drainage tank through the air pipe 203. At this time, the one-way valve 205 at the bottom of the drainage tank closes under the internal pressure, making the drainage tank 201 in an airtight state and preventing the liquid in the tank from flowing back to the tailings pond. Groundwater is discharged through the drainage pipe under the action of pressure. The drainage pipe 204 is set as a Venturi tube structure 206 at the wellhead, which can form a negative pressure in the controller 207. The inside of the controller is a cavity and is connected to the drainage pipe 204 and the control pipe 202. A flexible sealing piece 2061 is arranged on the upper part. A first metal piece 2062 is arranged at the bottom of the sealing piece 2061. A second metal piece is fixed on the pipe wall of the controller below the first metal piece. A float chamber 208 is arranged at the bottom of the control pipe 202 (see Figure 8 ), the float chamber is in a flared shape with a hollow bottom, and there is a float 2081 in the float chamber (see Figure 7 ); when the liquid flows through below the controller 202, if the liquid level in the tank is higher than the floating chamber 208, the float in the chamber will block the bottom of the control pipe, and the sealing piece 2061 in the controller 207 will deform due to the negative pressure, and the first metal piece 2062 will contact the second metal piece 2063, sending a signal for the air compressor to start continuously until the liquid level drops below the floating chamber 208, and air enters from the bottom of the control pipe to compensate for the negative pressure inside the controller 202, and the first metal piece 2062 disconnects from the second metal piece 2063, and the air compressor stops working. By paralleling the signals of the air compressor and the controller, the air compressor can be made to start and stop automatically according to the water level in the drainage tank 201. Further, one air compressor can also control multiple single wells through an air storage tank, and control by starting and stopping the air valve of the air storage tank. Due to the large pipe diameter of the present invention, the water filter is easy to intake water and has a good drainage effect, and because pneumatic pumping is adopted and automated control is used, the energy consumption and maintenance cost can be significantly reduced, which is very practical.

[0052] The technical solution of the second embodiment of the present invention is to provide a construction application method for the above-mentioned large-diameter drainage sand well structure in the tailings pond, including the following steps:

[0053] S1: Bury steel coiled pipes as hole mouth casings for all well holes, dig and bury them according to the measured pile hole center. The inner diameter of the casing is 200 - 400 mm larger than the pile diameter, the embedding depth is 1 - 2 m, it is 20 cm higher than the natural ground surface, and the gap between it and the outside of the pit is filled with muck to ensure the stability and verticality of the casing;

[0054] S2: Dig a mud pit near the drill rig, connect the well hole, mud ditch 109, and mud pit 108, and dig trenches according to the mud flow direction;

[0055] S3: Configure mud. The mass fractions of the main components of the mud are: 6 - 9 parts of bentonite, 63 - 73 parts of water, 20 - 30 parts of tailings, 2 - 3 parts of asbestos, and 0.002 parts of externally added polyacrylamide. During the tunneling process, every 3 m of tunneling, it is necessary to convert according to the density of different types of tailings. Based on the mass of the tailings, the slurry is modulated according to the above ratio. Among them, the tailings do not need to be added separately and can utilize the tailings during the drilling process. During the hole cleaning process, the mud should be continuously replaced until the hole formation is completed. The subsequent process flow should be completed within 5 hours after the hole formation is completed to prevent the hole from collapsing;

[0056] S4: After wrapping the outside of the steel reinforcement cage with a geotextile mat and the first geotextile in sequence, install the steel reinforcement cage;

[0057] S5: Backfill a small amount of gravel at the bottom to prevent the tailings from entering the sand well from the bottom and forming blockages, reducing the seepage efficiency;

[0058] S6: Install the screen pipe. The screen pipe uses a special pipe with a diameter of DN315. Drill holes around the pipe wall, with a hole distance of 12 - 17 cm and a hole diameter of 12 - 19 mm. After drilling, wrap it with 200 - 400 g / m 2 non-woven geotextile 2105 and tie it tightly with iron wire;

[0059] S7: Fill the space between the well pipe wall and the well wall with 5 - 10 mm gravel;

[0060] S8: After assembling the pneumatic pumping system pipeline outside the well, install the pneumatic pumping device into the well and check the air tightness;

[0061] S9: Complete the installation of the air compressor and air storage tank, and set the start time of the air compressor according to the water volume;

[0062] S10: After the water in the tailings pond seeps into the pumping tank and reaches the set time, the air compressor starts;

[0063] S11: Compressed air enters the pumping tank through the air inlet pipe, the pressure in the tank increases, and it closes under the action of the pressure;

[0064] S12: The water stored in the pipe is discharged out of the well through the outlet pipe. When the water flows through the Venturi device, due to the change in flow velocity, a negative pressure is formed inside the controller, causing the flexible sealing sheet to deform. The metal sheet inside the control device contacts to give a continuous operation signal, enabling the air compressor to operate continuously.

[0065] S13: When the liquid level in the tank continuously drops below the control pipe, the float in the floating chamber drops, and gas enters the control pipe. The air pressure inside the controller is compensated, the metal sheet disconnects, giving a stop operation signal, and stopping the air injection into the tank. The air pressure inside and outside the pumping tank gradually balances, and the accumulated water in the reservoir continues to seep into the pumping tank, repeating the process to complete the drainage task.

[0066] Applying the large-diameter sand well structure of the present invention to the seepage drainage of the tailings pond, the seepage drainage sand well can have the characteristics of large diameter, easy water inlet of the filter, good seepage drainage effect, non-collapse of the well wall, low energy consumption, simple operation and maintenance, etc., which is of great engineering practical significance for promoting its application.

[0067] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A large-diameter drainage sand well structure for a tailings pond, characterized in that, It includes a sand drain body and a pneumatic extraction and drainage device. Inside the sand drain body, a geotextile mat, a first geotextile, a steel reinforcement cage, a gravel backfill layer, a second geotextile, and a screen pipe are fixedly arranged. The aperture of the sand drain is 800 - 1200 mm. The outside of the steel reinforcement cage is successively wrapped with the first geotextile and the geotextile mat. The screen pipe is arranged away from the inner wall of the sand drain, and the outside of the screen pipe is wrapped with the second geotextile. A gravel backfill layer is arranged between the pipe wall of the screen pipe and the inner wall of the sand drain. The sand drain body conducts seepage drainage of the tailings pond through the pneumatic extraction and drainage device. The pneumatic extraction and drainage device includes a drainage tank, a control pipe, an air pipe, a drainage pipe, and a controller. The drainage tank is arranged inside the screen pipe, and a one-way valve is arranged at the bottom of the drainage tank. One end of each of the control pipe, the air pipe, and the drainage pipe is arranged inside the drainage tank, and the other end extends to the wellhead. One end of the drainage pipe extends into the liquid surface, and the other end of the drainage pipe at the wellhead position is set as a Venturi tube structure. One end of the air pipe is above the liquid surface, and one end of the control pipe is provided with a plugging component to control the liquid surface. The plugging component includes a float chamber and a float. The size of the float matches the size of the control pipe diameter. The bottom of the control pipe is provided with a float chamber. The float chamber is in a flared shape with a hollow bottom. A float capable of plugging the bottom of the control pipe is arranged inside the float chamber. The controller is placed at the wellhead position. One end of the controller is connected to the control pipe, and the other end is connected to the reduced-diameter pipe in the Venturi tube structure. The other end of the air pipe is connected to an air compressor, and the air compressor is electrically connected to the controller. An internally sealed sheet capable of elastic deformation is arranged at the top of the controller. A first metal sheet is arranged at the bottom of the internally sealed sheet, and a second metal sheet is arranged below the first metal sheet. The change of the liquid level in the tank causes the change of the air pressure difference inside the controller, which deforms the internally sealed sheet, thereby causing the contact or disconnection of the first metal sheet and the second metal sheet to control the start and stop of the air compressor, and finally realizing the control of the operation of the air compressor.

2. The large-diameter drainage sand well structure for tailing ponds according to claim 1, characterized in that, A gravel cushion layer is arranged at the bottom inside the sand drain body.

3. The large-diameter drainage sand well structure for tailing ponds according to claim 2, characterized in that, The pneumatic extraction and drainage device further includes an air storage tank, and one end of the air storage tank is connected to the air compressor.

4. A construction application method for the large-diameter seepage sand well structure of a tailings pond as described in any one of claims 1-3, characterized in that, The construction application method includes the following steps: S1, bury steel coiled pipes as wellhead casing for all well holes; S2, dig a mud pit near the drill rig, connect the well hole and the mud pit through hook grooves, and dig a trench according to the mud flow direction; S3, prepare mud. The mud includes the following raw materials in parts by mass: 6 - 9 parts of bentonite, 63 - 73 parts of water, 20 - 30 parts of tailings, 2 - 3 parts of asbestos, 0.002 parts of polyacrylamide, and carry out mud wall protection while drilling; S4, after the drilling is completed, after successively wrapping the outside of the steel reinforcement cage with the first geotextile and the geotextile mat, install the steel reinforcement cage in the drill hole; S5, backfill a small amount of gravel for bedding; S6, install the screen pipe. The screen pipe is wrapped with the second geotextile and tied tightly with iron wire; S7, fill the space between the screen pipe wall and the well wall with gravel, and control the well diameter between 800 - 1200 mm; S8, after completing the pipeline assembly in the pneumatic extraction and drainage device outside the well, install the device into the well and check the air tightness; S9, complete the installation of the air compressor and the air storage tank, and set the start time of the air compressor according to the water volume; S10, after the water in the tailings pond seeps into the drainage tank and reaches the set time, the air compressor starts; S11. Compressed air enters the drainage tank through the intake pipe, increasing the pressure inside the tank. Under the action of the pressure, the one-way valve at the bottom of the tank closes. S12. The water stored in the tank is discharged outside the well through the drain pipe. When the water flows through the Venturi tube structure, due to the change in flow velocity, a negative pressure is formed inside the controller, the inner sealing piece deforms, and the two metal pieces come into contact, and the air compressor continues to operate. S13. When the liquid level in the tank continuously drops below the control pipe, the float in the floating chamber drops, and gas enters the control pipe, compensating the air pressure inside the controller. The inner sealing piece disconnects, and the air compressor stops pressing air into the tank. The air pressure inside and outside the drainage tank gradually balances. The accumulated water in the tailings pond continues to seep into the drainage tank. When the liquid level in the tank is higher than the floating chamber, the float in the chamber blocks the bottom of the control pipe. The inner sealing piece of the controller deforms due to the negative pressure and conducts the circuit, sending a signal for the air compressor to continuously start until the liquid level drops below the floating chamber. This cycle repeats to complete the drainage task.

5. The construction application method of the large-diameter seepage sand well structure in the tailings pond according to claim 4, characterized in that, In step S6, holes are provided on the wall of the screen pipe, the hole pitch is 12 - 17 cm, and the hole diameter is 12 - 19 mm.

6. The construction application method of the large-diameter drainage sand well structure in the tailings pond according to claim 5, characterized in that In step S7, 5 - 10 mm gravel is filled.

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