A construction method for tailings top filling of downward approach road using artificial overflow trough

Abstract

This invention provides a method for constructing tailings backfill in a downward-entry stope using artificial overflow channels. After ore is extracted from the rock-drilled and blasted stope, the remaining ore on the stope floor is leveled to make it smooth both longitudinally and laterally, and then backfilling is carried out. The main backfilling pipeline is connected to the stope backfilling return air shaft, and then backfilling is carried out in the stope. Considering the conditions of the lower-level stope, artificial overflow channels are constructed at appropriate locations within that level. Woven bags are used to fill the crushed ore, and then the woven bags are stacked into a suitable cube on the floor at the appropriate location. The outside is then tightly wrapped with plastic film to solidify the interior, forming an artificial overflow channel. Constructing artificial overflow channels improves the smoothness of the backfill surface and increases its compressive strength. After the lower-level stope is exposed, a backfilling cavity forms on the roof, facilitating the hanging of backfilling pipelines during the lower-level backfilling process and ensuring proper backfilling of the stope in the downward-entry stope.

Description

Technical Field

[0001] This invention relates to the field of mining technology, specifically to a method for constructing a bottom-entry tailings top filling system using an artificial overflow trough. Background Technology

[0002] With increasing demands for mining operations and growing environmental awareness, backfilling mining methods have seen significant development and widespread application in longwall mining. However, existing deep, fractured orebody mining technologies are increasingly hampered by the fact that single upward horizontal backfilling methods are no longer sufficient for safe and efficient longwall mining as mining depth increases. Furthermore, the increasing ground pressure leads to highly fractured ore bodies, greater mining difficulty, higher support costs, higher ore loss rates, and higher roof safety risks, making the exploration and practice of downward horizontal layered backfilling increasingly important.

[0003] For underground metal / non-metal mineral mining with high grade and value, but poor ore stability and high original rock stress, the downward-sloping approach with backfilling is generally used. In this backfilling method, the direct roof of the downward-sloping mining face is an artificial false roof constructed by backfilling after the upper-sloping approach mining is completed. Compared with the high-stress, soft, and fractured ore roof, the artificial backfill provides a safe and controllable stable roof for the mining operations of the lower-sloping approach. Existing downward-sloping tailings backfilling construction has disadvantages such as incomplete roof contact, limited overflow chute construction location, inability to be changed according to actual production conditions, slow construction progress, high cost, and poor flexibility. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for constructing tailings backfill in a downward-entry stope using artificial overflow channels. This method improves the flatness and compressive strength of the backfill surface by constructing artificial overflow channels. By constructing artificial overflow channels at appropriate locations within each layer, a backfilling pit is formed in the roof after the lower layer of the stope is exposed. This facilitates the hanging of backfilling pipelines during the lower layer's backfilling process, ensuring successful backfilling of the downward-entry stope.

[0005] The method includes the following steps:

[0006] S1. Filling of filling slurry: After the ore is extracted from the rock drilling and blasting stope, the stope is filled with filling slurry C material as cementing material and graded tailings as filling aggregate.

[0007] S2. Installation of filling pipeline: Using the filling pits reserved in advance during the laying of the previous layer of false bottom, ensure top filling. The air outlet and filling pipe are tied in the reserved filling pits, and two signal pipes are installed at the same time.

[0008] S3. Cutting of filling pipeline: Cut along one side of the filling pipeline and drill several notches to release sand, forming multiple points for uniform sand discharge.

[0009] S4. Leveling and laying crushed ore bedding layer: After the stope is mined out, the remaining residual ore on the stope floor is leveled and the floor is leveled in both horizontal and vertical directions.

[0010] S5. Install chain link fence: When the side wall of the mining room is filled with ore, chain link fence shall be installed for protection.

[0011] S6. Laying plastic film: After the chain link fence is installed, a layer of plastic film is laid on the bottom plate of the crushed ore bedding layer, close to the perimeter of the mine.

[0012] S7. Construction of artificial overflow channel: Based on the conditions of the lower-level mining area, fill woven bags with crushed ore and pile them into a cube at the pre-set position of the layer, and wrap the stacked material with plastic film.

[0013] S8. Laying bottom reinforcement mesh: When the sidewalls of the retreating ore chamber are the upper and lower wall surrounding rock, install round steel bars, then place wooden blocks on plastic sheeting, and construct the bottom reinforcement mesh above the wooden blocks; when the sidewalls of the retreating ore chamber are the ore body, reserve the main reinforcement bars and erect them tightly against the ore body, then cover the reserved main reinforcement bars with plastic film; when the sidewalls of the second-stage ore chamber are the filling body, first expose all the reserved steel bars of the false bottom of the first-stage ore chamber, then straighten the reserved steel bars horizontally and weld them continuously to the newly laid main reinforcement bars;

[0014] S9. Reinforcing bar suspension: The suspension bars are arranged vertically, with the upper end connected to the top slab reinforcement mesh and the lower end connected to the bottom slab reinforcement mesh.

[0015] S10. Erection of the filling retaining wall: Drill holes on both sides of the access road and the top slab, insert round steel into the holes, put steel pipes on the round steel, hang the mesh, fix the geotextile on the mesh, and use diagonal braces to support the holes.

[0016] S11. Stope backfilling: The interval between each backfilling of the downward stope is ≥8h, and the end of the backfilling tee entering the stope is connected to a straight valve.

[0017] It should be further noted that in step S1, the mass concentration of the filling slurry used shall not be less than 72%. During filling, it shall first be connected to the return air shaft of the stope via the main filling pipeline, and then filled into the stope.

[0018] It should be further noted that in step S2, the vent pipe is installed at a high position, the filling pipe is slightly lower than the vent pipe, the first signal pipe is set at a position 0.5m below the false ceiling, and the second signal pipe is slightly lower than the upper layer of artificial false ceiling.

[0019] It should be further noted that in step S3, the distance between any point in the mining area and the sand discharge port shall not exceed 5m.

[0020] It should be further noted that in step S4, the thickness of the bottom plate crushed ore cushion layer shall not be less than 200mm, the particle size of the crushed ore used for leveling shall not be greater than 2cm, the diameter of the crushed ore used for leveling shall not exceed 3cm, and the ore cushion layer shall not be less than 20cm.

[0021] It should be further noted that in step S5, the height of the chain link fence protection is 0.5m-2.5m below the top layer of false bottom.

[0022] It should be further noted that step S7 also includes: by combining the conditions of the lower-level mining area, filling crushed ore with woven bags at appropriate locations in the layer, and stacking the woven bags at appropriate locations to form a square with a height of 1.5m and a length and width of 1.5m, wrapping the stacked material with plastic film to solidify the inside, forming an artificial overflow trough.

[0023] It should be further explained that in step S8, when the sidewalls of the mining chamber are the upper and lower walls, firstly, at a height of more than 1m above the bottom plate of the cushion layer, a downward inclined hole with a depth of 0.9m is drilled every 0.9m, and No. 36 round steel is installed with 0.1m of the rod exposed. Then, wooden blocks are placed on the plastic sheet as bottom reinforcement mesh pads with a height of 200mm. The bottom reinforcement mesh is constructed above the bottom reinforcement mesh pads.

[0024] When the side wall of the mining chamber is the ore body, a 0.5m main reinforcement bar is reserved and erected tightly against the ore body. Then, the reserved main reinforcement bar is covered with a 0.8m wide plastic film, and the upper edge of the plastic film is fixed with cement nails.

[0025] When the side wall of the second-stage mining room is filled, the reserved steel bars are straightened horizontally and continuously welded to the newly laid main bars. The straight weld length is not less than 10cm, and the bottom reinforcement mesh must be raised by 20cm.

[0026] The lap welding length of the reinforcing bars shall not be less than 10cm. The main and secondary reinforcing bars shall be tied or welded in a cross shape with No. 8 iron wire at the intersection. 0.5m of reinforcing bars shall be reserved at the wall position.

[0027] It should be further noted that in step S9, the main reinforcement bars of the bottom reinforcement mesh are at the bottom and the secondary reinforcement bars are at the top. The main reinforcement bars are made of No. 12 round steel and the secondary reinforcement bars are made of No. 10 round steel. One round steel bar is welded for every three main reinforcement bars.

[0028] It should be further noted that step S11 also includes stope filling: the concentration of the filling slurry going down into the stope is not less than 72%, and the interval between each filling is ≥8h. One end of the filling tee entering the stope is connected to a straight valve.

[0029] The filling is carried out in three stages. The first stage is the base filling, which forms a stable artificial false bottom.

[0030] The second stage is ordinary filling, which is carried out after the base filling and curing are completed;

[0031] The third step is to fill the top layer by using the filling pits artificially reserved during the previous layer of false bottom laying.

[0032] As can be seen from the above technical solutions, the present invention has the following advantages:

[0033] The present invention provides a method for constructing tailings backfilling in a downward approach using artificial overflow channels. After ore extraction from the rock-drilled and blasted stope, the remaining ore on the stope floor is leveled to ensure longitudinal and transverse flatness. Backfilling is then carried out, with the main backfilling pipeline connected to the stope backfilling return air shaft before filling the stope. Considering the conditions of the lower-level stope, artificial overflow channels are constructed at appropriate locations within that level. Woven bags are used to fill the ore fragments, and then these bags are stacked into a suitable cube on the floor at the appropriate location. The cube is then tightly wrapped with plastic film to solidify the interior, forming the artificial overflow channel. Constructing artificial overflow channels improves the flatness and compressive strength of the backfill surface. After the lower-level stope is exposed, a backfilling depression forms on the roof, facilitating the hanging of backfilling pipelines during the lower-level backfilling process and ensuring proper backfilling of the downward-approaching stope. Attached Figure Description

[0034] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the distribution structure of the filling pipeline and artificial overflow channel provided by the present invention;

[0036] Figure 2 A schematic diagram of the distribution structure of the filling pipeline and artificial overflow channel provided by the present invention;

[0037] Figure 3 This is a schematic diagram of the bottom reinforcement mesh structure provided by the present invention;

[0038] Figure 4 This is a schematic diagram of the retaining wall structure provided by the present invention;

[0039] Figure 5 A side view of the retaining wall provided by the present invention;

[0040] Figure 6 This is a schematic diagram of the steel pipe connection provided by the present invention;

[0041] Figure 7 This is a schematic diagram of the material stacking for the artificial overflow trough provided by the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Vent pipe; 2. Filling pipe; 3. Signal pipe 1; 4. Signal pipe 2; 5. Artificial overflow trough stacking material; 6. Inlet; 7. Upper layer artificial overflow trough; 8. Chain link fence fixing wooden blocks; 9. Chain link fence; 10. No. 36 round steel; 11. Main reinforcement; 12. Rooting hook; 13. No. 8 iron wire; 14. Bottom reinforcement mesh pad block; 15. Secondary reinforcement; 16. Plastic film; 17. Pipe clamp; 18. Mesh; 19. Steel pipe; 20. Round steel; 21. Vertical support. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Please see Figures 1 to 7 The method for bottom-entry tailings top filling using an artificial overflow trough provided in this embodiment includes the following steps:

[0046] S1. Filling of filling slurry: After the ore is extracted from the rock drilling and blasting stope, the stope is filled. The filling slurry C material is used as the cementing material and the graded tailings are used as the filling aggregate. The mass concentration of the filling slurry used shall not be less than 72%. Before filling, it is connected to the stope filling return air shaft through the main filling pipeline and then filled into the stope.

[0047] S2. Installation of filling pipeline: With the help of the artificial overflow trough 7 reserved in advance when laying the upper layer of false bottom, ensure the filling of the top. The air outlet and the filling pipe are tied to the reserved artificial overflow trough 7 in the upper layer. At the same time, the signal pipe 3 and the signal pipe 4 are installed. Among them, the air outlet 1 is the highest, and the filling pipe 2 is slightly lower than the air outlet 1. The first signal pipe is installed at a position 0.5m below the false top, and the second signal pipe is slightly lower than the artificial false top of the upper layer.

[0048] S3. Cutting of filling pipes: Cut the side of filling pipe 2 every 3m, or drill a notch for sand discharge, with a diameter of 2-4cm, so as to form multiple points of uniform sand discharge, thereby improving the flatness of the filling surface. The distance between any point in the stope and the sand discharge port (including the pipe opening) shall not exceed 5m to ensure that the false bottom filling does not segregate.

[0049] S4. Leveling and Laying Crushed Ore Subbase: After the stope is mined out, the remaining residual ore on the stope floor is leveled, and the floor is leveled in both horizontal and vertical directions. The thickness of the crushed ore subbase on the floor should not be less than 200mm. The particle size of the crushed ore used for leveling should not be greater than 2cm. The diameter of the crushed ore used for leveling should not exceed 3cm. When leveling, it is necessary to ensure that the floor is flat and the crushed ore on the sidewalls or the bottom of the upper and lower plates is cleaned up. There should be no triangular areas. In order to avoid water accumulation in the floor of the stope after leveling, the ore subbase should not be less than 20cm. Leveling should only be carried out after the floor of the stope has passed the acceptance inspection during the mining process.

[0050] S5. Install chain link mesh: When the side wall of the mining room is ore, chain link mesh 9 needs to be installed for protection. The protection height of chain link mesh 9 is 0.5m-2.5m below the upper layer false bottom. For the protection of chain link mesh, attention should be paid to the construction sequence. First install the chain link mesh, and then lay the bottom reinforcement mesh.

[0051] S6. Laying plastic film: After the chain link fence 9 is installed, a layer of plastic film 16 is laid on the bottom plate of the crushed ore bedding layer. The edges of the plastic film 16 are folded up 0.2m and tightly attached to the perimeter of the mine.

[0052] S7. Construction of artificial overflow trough: Based on the conditions of the lower mining layer, fill crushed ore with woven bags at a suitable location in the layer, and stack the woven bags at a suitable location to form a square with a height of 1.5m and a length and width of 1.5m. Wrap the stacked material 5 tightly with plastic film 16 to solidify the inside, thereby forming an artificial overflow trough. The location of the filling pit can be determined according to the design plan of the next layer, and a suitable pipeline layout method should be selected to start filling.

[0053] S8. Laying the bottom reinforcement mesh: When the sidewalls of the mining stop are the hanging wall and footwall, firstly, at a height of 1m above the bottom plate of the cushion layer, drill a downward inclined hole (10~20°) with a depth of 0.9m every 0.9m, and install No. 36 round steel 10 (round steel length 1.0m), with 0.1m of the rod exposed. Then, place wooden blocks as bottom reinforcement mesh pads 14 on the plastic sheet, with a height of 200mm. Construct the bottom reinforcement mesh above the bottom reinforcement mesh pads 14. When the sidewalls of the mining stop are the ore body, reserve 0.5m of main reinforcement 11 and erect it vertically close to the ore body. Then, cover the reserved main reinforcement with a 0.8m wide plastic film 16, and fix the upper edge of the plastic film 16 with cement nails. To prevent the filling slurry from submerging the reserved main reinforcement bars 11, the reserved main reinforcement bars 11 are not easily exposed during the second-stage mining. When the side walls of the second-stage mining chamber are filled, all the reserved main reinforcement bars 11 of the false bottom laid in the first-stage mining chamber are exposed. Then, the reserved steel bars are straightened horizontally and continuously welded to the newly laid main reinforcement bars 11. The straight weld length is not less than 10cm. The bottom reinforcement mesh is raised by 20cm so that the slurry can wrap the steel bars during filling, improving the integrity and strength. The lap weld length of the steel bars is not less than 10cm. The intersection of the main and secondary reinforcement bars is tied or welded with No. 8 iron wire in a cross shape. 0.5m of steel bars must be reserved at the plate wall position so that the reserved steel bars can be dug out and welded when the inter-column is recovered.

[0054] S9. Reinforcing bar hanging: The hanging bars are arranged vertically, with the upper end connected to the top slab reinforcing mesh and the lower end connected to the bottom slab reinforcing mesh. The mesh size is 2.0m×2.0m. The main bars 11 are at the bottom and the secondary bars 15 are at the top. The main bars 11 use No. 12 round steel and the secondary bars 15 use No. 10 round steel. The mesh size is 300mm×300mm. The intersection of the main and secondary bars is reinforced with No. 8 iron wire or welded. The exposed part of the main bars 11 and No. 36 round steel 10 in the bottom reinforcing mesh is welded along the direction. The continuous welding length is not less than 10cm. Every three main bars 11 are welded with one round steel 10 to improve the overall strength of the artificial false ceiling. After the bottom reinforcing mesh construction is completed, the anchoring hooks 12 are hung on the bottom reinforcing mesh. The mesh size of the rooting hook 12 is 2.0m×2.0m. The rooting hook 12 must penetrate the plastic film 16 and be inserted into the bottom of the crushed ore cushion layer. After the artificial false roof of the lower layer mining area is exposed, the rooting hook 12 is partially exposed, which facilitates the construction of the bottom reinforcement mesh between the upper and lower layers.

[0055] S10. Erection of the infill retaining wall: Drill holes 50cm deep on both sides of the road and the top slab. Insert round steel 20 into the holes and put steel pipe 19 on top of the round steel 20. The steel pipe 19 can be fixed between each other with pipe clamp 17. Hang the mesh 18 and fix the geotextile on the mesh. Use vertical support 21 to support the drilled holes to ensure the firmness and stability of the retaining wall. The second retaining wall is 3-4m outside the first retaining wall. Drill holes on both sides and the top slab in the same way. After connecting with steel pipe 19, hang the mesh 18 and seal the geotextile. The infill retaining wall can be disassembled and reused.

[0056] S11. Stope backfilling: The concentration of the backfill slurry in the downward stope shall not be less than 72%, and the interval between each backfilling shall be ≥8 hours. A straight valve must be connected to one end of the backfill tee entering the stope. It is strictly forbidden to introduce water or low-concentration slurry into the stope before backfilling. Backfilling shall be carried out in three stages. The first stage is the underfilling, which forms a stable artificial false bottom to ensure the safety of the lower layer's access road mining. The second stage is ordinary backfilling, which is carried out after the underfilling has been cured. The third stage is the roof filling, which uses the backfilling pits artificially reserved during the laying of the false bottom of the previous layer to ensure the roof filling.

[0057] In the method provided by this invention, the No. 36 round steel, No. 12 round steel, No. 8 iron wire, No. 10 round steel, pipe clamp 17, No. 33 round steel 20 and various filling materials are all materials that can be easily obtained within the mining area, and the material parameters are all within the variable range. The grid steel frame reusable panel wall adopted in this system is composed of pipe clamp 17, grid 18, steel pipe 19, round steel 20 and vertical support 21. The grid is welded from steel bars with a diameter of 12mm, the pipe clamp is made of No. 14 channel steel, the steel pipe has a diameter of 60mm, the wooden board is 300cm long, 24~26cm wide, and 2~4cm thick, and the round steel has a diameter of 36mm.

[0058] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0059] Based on the above method, the flatness of the filling surface and the compressive strength of the filling surface can be improved by constructing artificial overflow channels. During the filling process, it is essential to ensure that the filling is connected to the roof. Artificial overflow channels can be constructed at appropriate locations in the lower-level stopes or stopes, depending on their layout. After the lower-level stopes are exposed, the roof forms a filling pit, which facilitates the hanging of filling pipelines during the filling of the lower-level stopes, ensuring that the filling of the lower-level stopes is connected to the roof.

[0060] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0061] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0062] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the expression within this document. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that, when used in this specification, the term “comprising” means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a bottom-entry tailings backfill using an artificial overflow trough, characterized in that, The method includes the following steps: S1. Filling of filling slurry: After the ore is extracted from the rock drilling and blasting stope, the stope is filled with filling slurry C material as cementing material and graded tailings as filling aggregate. S2. Installation of filling pipeline: Using the filling pits reserved in advance during the laying of the previous layer of false bottom, ensure top filling. The air outlet and filling pipe are tied in the reserved filling pits, and two signal pipes are installed at the same time. S3. Cutting of filling pipeline: Cut along one side of the filling pipeline and drill several notches to release sand, forming multiple points for uniform sand discharge. S4. Leveling and laying crushed ore bedding layer: After the stope is mined out, the remaining residual ore on the stope floor is leveled and the floor is leveled in both horizontal and vertical directions. S5. Install chain link fence: When the side wall of the mining room is filled with ore, chain link fence shall be installed for protection. S6. Laying plastic film: After the chain link fence is installed, a layer of plastic film is laid on the bottom plate of the crushed ore bedding layer, close to the perimeter of the mine. S7. Construction of artificial overflow channel: Based on the conditions of the lower-level mining area, fill woven bags with crushed ore and pile them into a cube at the pre-set position of the layer, and wrap the stacked material with plastic film. S8. Laying bottom reinforcement mesh: When the sidewalls of the retreating ore chamber are the upper and lower wall surrounding rock, install round steel bars, then place wooden blocks on plastic sheeting, and construct the bottom reinforcement mesh above the wooden blocks; when the sidewalls of the retreating ore chamber are the ore body, reserve the main reinforcement bars and erect them tightly against the ore body, then cover the reserved main reinforcement bars with plastic film; when the sidewalls of the second-stage ore chamber are the filling body, first expose all the reserved steel bars of the false bottom of the first-stage ore chamber, then straighten the reserved steel bars horizontally and weld them continuously to the newly laid main reinforcement bars; When the side walls of the mining chamber are the upper and lower walls, firstly, at a height of more than 1m above the bottom plate of the cushion layer, drill a downward inclined hole with a depth of 0.9m every 0.9m and install No. 36 round steel, with 0.1m of the rod exposed. Then, place wooden blocks on the plastic sheet as bottom reinforcement mesh pads, with the wooden blocks being 200mm high. Construct the bottom reinforcement mesh above the bottom reinforcement mesh pads. When the side wall of the mining chamber is the ore body, a 0.5m main reinforcement bar is reserved and erected tightly against the ore body. Then, the reserved main reinforcement bar is covered with a 0.8m wide plastic film, and the upper edge of the plastic film is fixed with cement nails. When the side wall of the second-stage mining room is filled, the reserved steel bars are straightened horizontally and continuously welded to the newly laid main bars. The straight weld length is not less than 10cm, and the bottom reinforcement mesh must be raised by 20cm. The lap welding length of the reinforcing bars shall not be less than 10cm. The main and secondary reinforcing bars shall be tied or welded in a cross shape with No. 8 iron wire at the intersection. 0.5m of reinforcing bars shall be reserved at the wall position. S9. Reinforcing bar suspension: The suspension bars are arranged vertically, with the upper end connected to the top slab reinforcement mesh and the lower end connected to the bottom slab reinforcement mesh. S10. Erection of the filling retaining wall: Drill holes on both sides of the access road and the top slab, insert round steel into the holes, put steel pipes on the round steel, hang the mesh, fix the geotextile on the mesh, and use diagonal braces to support the holes. S11. Stope backfilling: The interval between each backfilling of the downward stope is ≥8h, and the end of the backfilling tee entering the stope is connected to a straight valve.

2. The method for constructing a bottom-entry tailings backfill using an artificial overflow trough according to claim 1, characterized in that, In step S1, the mass concentration of the filling slurry used shall not be less than 72%. During filling, it shall first be connected to the return air shaft of the stope via the main filling pipeline, and then filled into the stope.

3. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, In step S2, the vent pipe is installed at a high position, the filling pipe is slightly lower than the vent pipe, the first signal pipe is set at a position 0.5m below the false ceiling, and the second signal pipe is slightly lower than the upper layer of artificial false ceiling.

4. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, In step S3, the distance between any point in the mining area and the sand discharge port shall not exceed 5m.

5. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, In step S4, the thickness of the bottom plate crushed ore cushion layer shall not be less than 200mm, the particle size of the crushed ore used for leveling shall not be greater than 2cm, the diameter of the crushed ore used for leveling shall not exceed 3cm, and the ore cushion layer shall not be less than 20cm.

6. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, In step S5, the height of the chain link fence protection is 0.5m-2.5m below the top layer of false bottom.

7. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, Step S7 further includes: by combining the conditions of the lower-level mining area, filling crushed ore with woven bags at appropriate locations in the layer, and stacking the woven bags at appropriate locations to form a square with a height of 1.5m and a length and width of 1.5m, wrapping the stacked material with plastic film to solidify the inside, forming an artificial overflow trough.

8. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, In step S9, the main reinforcement bars of the bottom reinforcement mesh are at the bottom and the secondary reinforcement bars are at the top. The main reinforcement bars are made of No. 12 round steel and the secondary reinforcement bars are made of No. 10 round steel. Every three main reinforcement bars are welded with one round steel bar.

9. The method for constructing a bottom-entry tailings top filling system using an artificial overflow trough according to claim 1, characterized in that, Step S11 also includes stope filling: the concentration of the filling slurry going down into the stope is not less than 72%, and the interval between each filling is ≥8h. One end of the filling tee entering the stope is connected to a straight valve. The filling is carried out in three stages. The first stage is the base filling, which forms a stable artificial false bottom. The second stage is ordinary filling, which is carried out after the base filling and curing are completed; The third step is to fill the top layer by using the filling pits artificially reserved during the previous layer of false bottom laying.

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