Safe and intelligent pressure reduction system for vertical pressure reduction well of tailing pond dam

Abstract

According to the safe and intelligent pressure reduction system for the vertical pressure reduction well of the tailing pond dam, the pressure reduction well system is arranged, and when the water pressure in the pond dam rises under the action of vibration loads or earthquakes and the water pressure in the pressure reduction well exceeds a threshold value, part of water enters the pressure reduction well. Active water pumping is carried out through the layered water seepage pipe, so that layered pressure reduction is carried out on underground water, and accidents caused by liquefaction instability of the tailing pond dam body due to the too high seepage line are prevented. According to the technical scheme, an external water seepage pipe is driven into a tailing pond dam, the lower end of the external water seepage pipe is arranged below a seepage line, a plurality of external water seepage holes are formed in the external water seepage pipe, a water pressure sensor is installed at the bottom of the external water seepage pipe, and a plurality of water seepage nets are vertically arranged in the external water seepage pipe at intervals; water pumps are installed below each water seepage net and above the water seepage net at the uppermost end, the water pumps are communicated to the outside of the water seepage pipe through drainage pipes, and the water pumps and the pressure reduction sensors are connected into an electric control box arranged outside the water seepage pipe.

Description

Technical Field

[0001] This invention relates to the field of tailings dam safety technology, and in particular to a safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams. Background Technology

[0002] Tailings are waste generated during mineral processing, containing non-recoverable metals and mixtures of different chemical components. Tailings ponds are used to store discharged tailings. my country is a major mining country, and the provinces with the largest number of tailings ponds are: Hebei, Liaoning, Yunnan, Hunan, Henan, Inner Mongolia, Jiangxi, Shanxi, Shaanxi, and Gansu. These provinces account for approximately 75% of the country's total number of tailings ponds. Within these provinces, there are 1,112 "overhead tailings ponds" (tailings ponds with residents or important facilities within 1 kilometer downstream). Currently, many enterprises are restarting and expanding some small and medium-sized or temporarily shut-down tailings ponds. Without sufficient demonstration of the safety and stability of tailings dams, engineering accidents are highly likely to occur, and even dam failures may be induced.

[0003] The seepage line is the free water level line formed within the dam body when water seeps downstream from the reservoir. The seepage line is a critical element for the safety of tailings dams, and its elevation directly affects the stability of the dam body. Therefore, the seepage line is an indispensable factor in studying the seepage stability of tailings dam bodies, and it is essential for the overall stability of the tailings dam.

[0004] Guo Tingting, Zhao Zhouneng, et al. published "Analysis of the Disaster-Causing Mechanism and Prevention Strategies of Tailings Dam Accidents in my country" [J]. Chemical Minerals and Processing, 2022, 51(04): 31-34, which analyzed the disaster-causing mechanism of tailings dam accidents in my country. The main influencing factors are seepage failure, flooding, dam instability, and earthquake disasters, among which seepage failure and earthquake disasters have the greatest impact. Since the phreatic line is related to the water level in the dam body, under the action of vibration loads, such as when an earthquake occurs, the pore water below the phreatic line is prone to form excess pore water pressure, which can easily cause liquefaction of sandy dam bodies. If no control measures are taken, it will induce dam instability and even lead to serious dam failure events. Summary of the Invention

[0005] The purpose of this invention is to provide a safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams. By setting up a pressure relief well system, this invention uses layered permeation pipes. When an earthquake occurs, the water pressure rises, and overpressured pore water enters the pressure relief well, causing the water level in the well to rise. When the water pressure detection device in the pressure relief well exceeds the threshold, the pumping and drainage device can be actively activated to pump out water and reduce the pressure of groundwater in layers, preventing the dam from becoming unstable due to excessive pore water pressure and reducing the accident rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a safe and intelligent pressure reduction system for a vertical pressure relief well in a tailings dam, comprising an external seepage pipe driven into the tailings dam, the lower end of the external seepage pipe being positioned below the phreatic line, characterized in that the external seepage pipe has multiple external seepage holes, a water pressure sensor is installed at the bottom of the external seepage pipe, multiple seepage nets are vertically spaced inside the external seepage pipe, a water pump is installed below each seepage net and above the uppermost seepage net, the water pump is connected to the outside of the seepage pipe via a drain pipe, and the water pump and the pressure relief sensor are connected in an electrical control box located outside the seepage pipe. Preferably, the bottom of the external seepage pipe reaches the bottom of the dam body.

[0007] Preferably, at least one inner seepage pipe is coaxially inserted through the outer seepage pipe from the outside to the inside, and the inner seepage pipe has multiple inner seepage holes. The water pump is placed in the innermost inner seepage pipe, and the diameter of the outer seepage hole is larger than that of the inner seepage hole.

[0008] Preferably, the drainage pipe is wrapped with geotextile and mesh in sequence.

[0009] Preferably, a groove and rail structure is provided between two adjacent seepage pipes, allowing the inner seepage pipe to be slid into the outer seepage pipe during installation. The cooperation of the rail and groove also provides support for the inner and outer seepage pipes.

[0010] Preferably, the slide groove is composed of a stepped groove with a smaller outer diameter and a larger inner diameter, and the shape of the slide rail is adapted to the slide groove.

[0011] Preferably, the internal seepage pipe is composed of multiple vertical pipe sections, each pipe section is equipped with a lifting lug, and adjacent lifting lugs are connected by a pull rope. A pull rope extending outward from the uppermost lifting lug is fixed to the seepage pipe.

[0012] Preferably, two adjacent tubes are connected together via a tube connector.

[0013] Preferably, both the external and internal seepage holes are located below the wetting line.

[0014] Preferably, an external seepage pipe is installed on each stage of the dam, and multiple external seepage pipes are spaced apart in the longitudinal direction of each stage of the dam. This longitudinal direction is the direction perpendicular to the seepage line.

[0015] Preferably, the diameter of the multi-layer internal seepage holes decreases sequentially from the outside to the inside.

[0016] This invention uses a drilling rig to make holes, and then the outer permeation pipes are installed in sequence. The holes should be drilled to the base of the tailings dam.

[0017] The seepage pipe is wrapped in geotextile and mesh in sequence. The mesh is made of stainless steel and the geotextile is permeable geotextile.

[0018] The beneficial effects of this invention are: 1. The external and internal infiltration pipes form a loop, with multiple loops. The water first passes through the large-diameter external infiltration pipe and then through the small-diameter internal infiltration pipe. Since the large holes are not easily blocked, and the water is filtered again by the filter screen and geotextile at the large holes when it reaches the small holes, the blockage can be effectively reduced.

[0019] 2. The water level is detected by a water level sensor, and the degree of earthquake response is judged by the surge in water level. The sudden fluctuation and change in water level triggers the start of the water pump to extract water from the pressure relief well.

[0020] 3. When an earthquake occurs, groundwater is prone to excess pore water pressure under vibration, which can cause sandy dams to liquefy. During the vibration, some groundwater enters the pressure relief well, causing the water level in the pressure relief well to rise. Therefore, multi-stage pumps can extract groundwater in time to reduce the pressure of the groundwater.

[0021] 4. Multiple seepage nets are vertically installed inside the seepage pipe. When water is rapidly pumped out from the lower part of the seepage net, the rate at which the seepage net replenishes water downwards is lower than the rate at which the pump pumps outwards. This creates a negative pressure in the pipe below the seepage net due to rapid extraction, allowing groundwater in this layer to collect more quickly. Without multiple seepage nets, the seepage pipe is not designed as a completely unobstructed conduit. Even with multiple pumps installed inside the seepage pipe, groundwater within the dam body is difficult to quickly collect at the pump locations, hindering the rapid reduction of water pressure in the tailings dam. Due to earthquake vibrations, the groundwater pressure in the upper strata does not change significantly. Failure to promptly reduce the pressure of groundwater in deeper strata poses a significant risk to the stability of the dam. Furthermore, the multi-layer seepage net of this invention, when not pumping, maintains a continuous flow of water within the seepage pipe due to its slow seepage function, and the water level can be detected by a water level sensor. When dewatering is required, the water pumps can be started to quickly pump water, so that the groundwater at each part of the seepage network is extracted in time. This allows the water pumps and the seepage network to work well together, thereby achieving simultaneous depressurization of multiple layers of groundwater.

[0022] 5. The internal seepage pipe consists of multiple sections in the vertical direction, and each section has at least two "ears" (two adjacent pipes are sealed together by a pipe connector). The "ears" of the multiple pipe sections are strung together with steel wire rope in the vertical direction, which makes it easier to lift.

[0023] 6. If water is pumped from the lowest pump, the surrounding groundwater will quickly seep in and replenish that section of the pipe (due to the presence of a seepage net, the water level above the seepage pipe drops more slowly, creating a negative pressure zone at the lower pumping section). Once the surrounding groundwater flows into the pipe, the water in the upper soil layer will change its seepage direction and seep downwards into the soil layer corresponding to the pumping pipe, and then into the well, thereby changing the seepage field and contributing to the stability of the dam. Attached Figure Description

[0024] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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.

[0025] Figure 1 This is a schematic diagram of the external seepage pipe of the present invention installed on the tailings dam body; Figure 2 This is a front view schematic diagram of the connection structure between the external seepage pipe and the internal seepage pipe of the present invention; Figure 3 This is a top sectional view of the connection between the internal and external seepage pipes of the present invention; Figure 4 This is a schematic diagram showing the two sections of the drainage pipe of the present invention connected together by a pipe connector. Figure 5 This is a schematic diagram of the permeable geotextile layer installed on the upper part of the perforated stainless steel plate of the present invention. Figure 6 This is a schematic diagram illustrating the process of groundwater seeping into each vertical layer of the seepage pipes according to the present invention. (The seepage pipes are divided into multiple layers by a seepage network, and multiple water pumps are pumping water simultaneously.) Explanation of reference numerals in the attached drawings: 1. External seepage pipe; 2. External seepage hole; 3. Water pressure sensor; 4. Seepage net; 5. Water pump; 6. Drainage pipe; 7. Internal seepage pipe; 8. Internal seepage hole; 9. Geotextile; 10. Mesh net; 11. Slide chute; 12. Slide rail; 13. Lifting lug; 14. Pull rope; 15. Pipe body; 16. Pipe connector; 17. Immersion line; 18. Electrical control box; 19. Stainless steel plate. Detailed Implementation

[0026] The following will refer to the appendices in the embodiments of the present invention. Figure 1-6 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention relates to a safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams. Multiple holes are installed on the initial dam and various sub-dams of the tailings dam, extending to the bottom of the dam. An external seepage pipe 1 is installed within each hole, and an internal seepage pipe 7 is installed inside the external seepage pipe 1. Both the external seepage pipe 1 and the internal seepage pipe 7 are composed of multiple pipe sections 15, connected together by a pipe connector 16. To ensure the stability of the external seepage pipe 1 and the internal seepage pipe 7, a stepped groove 11 (smaller on the outside, larger on the inside) is installed on the external seepage pipe 1, and a stepped slide rail 12 is installed on the outside of the internal seepage pipe 7. The slide rail 12 and the groove 11 cooperate to interlock, ensuring the stability of both.

[0028] In the embodiment with only an external seepage pipe 1, multiple layers of seepage nets 4 are vertically spaced inside the external seepage pipe 1. In this case, the seepage net 4 is a single piece, and its shape is adapted to the internal cavity shape of the external seepage pipe 1. In the embodiment where at least one internal seepage pipe 7 is coaxially arranged from the outside to the inside of the external seepage pipe 1, multiple layers of seepage nets 4 are still provided. Each layer of the seepage net is divided into multiple parts. Specifically, a ring-shaped seepage net connects the external seepage pipe 1 and its adjacent internal seepage pipe 7; a ring-shaped seepage net connects two connected internal seepage pipes; and a seepage net adapted to the inner diameter of the innermost internal seepage pipe is connected inside the innermost internal seepage pipe.

[0029] Multiple layers of permeable mesh 4 are vertically spaced between the external and internal permeable pipes 7, between adjacent internal permeable pipes, and within the internal permeable pipe 7. The external permeable pipes have external permeable holes 2, and the internal permeable pipes 7 have internal permeable holes 8. The permeable mesh 4 consists of a perforated stainless steel plate 19 and a permeable geotextile 9 covering the stainless steel plate. The permeable geotextile 9 is placed on top of the perforated stainless steel plate, enabling the permeable mesh 4 to function as a permeable surface. Both the external and internal permeable pipes 1 and 7 are wrapped from the inside out with geotextile 9 and mesh 10. The mesh 10 not only serves a filtering function but also provides support and protection for the geotextile 9 layers. The permeable holes of the permeable pipes are located below the phreatic line 17 to allow groundwater to infiltrate. The permeable mesh 4 is also placed below the phreatic line 17. When only the external seepage pipe 1 is present, the seepage net 4 is fixed inside the external seepage pipe 1 with detachable screws. The seepage net 4 has through holes for drainage pipes and wiring to pass through. In another embodiment, when an internal seepage pipe 7 is installed inside the external seepage pipe 1, each layer of the external seepage net 4 has two parts: one part is disc-shaped inside the internal seepage pipe 7, and the other part is annular between the internal seepage pipe 7 and the external seepage pipe 1. Both have through holes and are detachable and fixed with screws. The inner disc-shaped through holes are used for drainage pipes and wiring to pass through, while the outer annular seepage net's through holes are used for the pull rope 14 to pass through. Water seeps sequentially into the seepage pipe from the mesh 10, geotextile 9, and seepage holes.

[0030] Pumps 5 are installed in the space below the seepage net 4 and above the uppermost seepage net 4. The pumps 5 are installed in the innermost seepage pipe 7 (in the embodiment with only an outer seepage pipe, the pumps 5 are installed in the outer seepage pipe). The pumps 5 can pump water out of the seepage pipe through the drain pipe. A water pressure sensor 3 is installed at the bottom of the lowest seepage net 4. When an earthquake occurs, the vibration load can easily cause the groundwater to form excess pore water pressure, which can easily cause the sandy dam below the groundwater to liquefy. During the vibration, some groundwater enters the pressure relief well, causing the water level in the pressure relief well to rise. Therefore, our multi-stage pumps 5 are used to pump out the groundwater in time to reduce the groundwater pressure. The reason for using a multi-stage seepage network 4 and multi-stage pumps 5 is that if it were a single, permeable seepage pipe with pumps 5 installed at the bottom, due to water flow, even if the lower pumps 5 start pumping, the water level at the top of the seepage pipe would drop first, while the bottom would still be full of water. This would cause the water pressure at the bottom to decrease as the water level at the top decreases. Because the water level at the top drops directly, the groundwater in that area would more easily seep into the seepage pipe, while the water in the bottom would seep in more slowly, resulting in insufficient pressure reduction in the lower groundwater layer. Our intelligent pressure reduction system includes the aforementioned multi-stage pumps 5 and one or more water pressure sensors 3. The pumps 5 and water pressure sensors 3 are connected to an electrical control box 18 fixed to the upper part of the dam. A wireless transmitter can also be installed in the electrical control box 18 to transmit the relevant parameters of the pumps 5 and water pressure sensors 3 to a remote control center.

[0031] When an earthquake occurs, pressurized groundwater continues to flow into the seepage pipe under dynamic load, causing the water level to rise. Water pressure sensor 3 detects this increase. Once the water level reaches a set threshold, the controller in electrical control box 18 activates the multi-stage pumping pumps 5 to begin pumping water until the water pressure drops to a reasonable range. During pumping, due to the multi-stage seepage network 4, when a pump 5 pumps water, the water level in that section drops rapidly. Figure 6 The diagram shows the flow of groundwater into the pipe 15 at each layer. When the pumping speed exceeds the seepage speed of the seepage network 4 above the pump, the downward seepage from the network cannot keep up with the water pumped out by the pump. This creates a negative pressure between the water level in that area and the network above, significantly reducing the pressure and causing surrounding groundwater to rush into the negative pressure zone. This results in multiple pumps 5 simultaneously depressurizing multiple groundwater layers, greatly reducing the risk of liquefaction or dam failure due to earthquakes. In non-earthquake conditions, because the seepage network 4 has seepage capabilities, the entire seepage pipe below the phreatic line 17 is filled with water and can be used as a piezometer to monitor the height of the phreatic line 17.

[0032] During normal operation, if the phreatic line 17 continues to rise and needs to be lowered, the lowest pump 5 can be activated to create a negative pressure zone at the bottom. This causes groundwater at the bottom to flow into the seepage pipe. As the groundwater pressure at the bottom decreases, the upper groundwater will seep downwards. During this downward seepage, the downward force of the seepage helps stabilize the soil or dam. Once the phreatic line 17 has been lowered to a safe position, pump 5 can be shut off.

[0033] In this invention, the internal seepage pipe 7, composed of multiple pipe sections 15, is relatively long and prone to breakage or falling during maintenance or replacement. Therefore, two symmetrical lifting lugs 13 are provided on each pipe section 15, and a pull rope 14 is connected between two adjacent lifting lugs 13. The uppermost lifting lug 13 is connected to a pull rope 14 with its free end outside the seepage pipe. As an embodiment, when there is only one internal seepage pipe 7, the annular seepage net between the internal seepage pipe 7 and the external seepage pipe 1 is detachably connected to the internal seepage pipe 1, and the entire internal seepage pipe can be placed into the external seepage pipe. When a sliding groove 11 is provided inside the external seepage pipe 1, and a sliding rail 12 that cooperates with the sliding groove is provided outside the internal seepage pipe, a clearance opening can be opened on the outside of the annular seepage net to allow the sliding groove to pass smoothly through the clearance groove, ensuring that the internal seepage pipe can be smoothly placed into the external seepage pipe 1. As another embodiment, when multiple coaxial inner seepage pipes 7 are sequentially arranged from the outside to the inside of the outer seepage pipe 1, the diameter of the multiple inner seepage pipes 7 decreases sequentially from the outside to the inside. The annular seepage net between two adjacent inner seepage pipes can be detachably fixed to the outside of the inner seepage net located in the inner layer. The annular seepage net between the outermost inner seepage pipe and the outer seepage pipe 1 can be detachably fixed to the outermost inner seepage pipe. In use, the inner seepage pipe with the annular seepage net can be placed in the seepage pipe on its outer side in sequence. The circular seepage net of the innermost seepage pipe can be detachably fixed to the innermost seepage pipe. When a sliding groove 11 is provided on the outer seepage pipe between two adjacent seepage pipes and a sliding rail 12 is provided on the inner seepage pipe, a clearance opening can be opened on the outside of the annular seepage net so that the sliding groove can pass smoothly through the clearance groove, ensuring that the inner seepage pipe can be smoothly put into the outer seepage pipe.

[0034] If the drain pipe breaks when pulled upwards, a rope can be used to ensure that the drain pipe can be removed smoothly.

[0035] The above embodiment provides an example of an external seepage pipe 1 and an internal seepage pipe 7. There can also be multiple internal seepage pipes 7, for example, a first internal seepage pipe 7 installed inside the external seepage pipe 1, and a second internal seepage pipe 7 installed inside the first internal seepage pipe 7. Their structural function is consistent with the interaction between the external and internal seepage pipes 1 described above.

Claims

1. A safe and intelligent pressure reduction system for a vertical pressure relief well in a tailings dam, comprising an external seepage pipe (1) driven into the tailings dam, wherein the lower end of the external seepage pipe (1) is positioned below the phreatic line (17), characterized in that, The external seepage pipe (1) has multiple external seepage holes (2), and a water pressure sensor (3) is installed at the bottom of the external seepage pipe (1). Multiple seepage nets (4) are arranged vertically at intervals inside the external seepage pipe (1). A water pump (5) is installed below each seepage net (4) and above the uppermost seepage net (4). The water pump (5) is connected to the outside of the seepage pipe through a drain pipe (6). The water pump (5) and the pressure reducing sensor are connected in an electrical control box (18) placed outside the seepage pipe.

2. The intelligent safety depressurization system for vertical pressure relief wells in tailings dams according to claim 1, characterized in that, The external seepage pipe (1) has at least one internal seepage pipe (7) coaxially inserted from the outside to the inside. The internal seepage pipe (7) has multiple internal seepage holes (8). The water pump (5) is placed inside the innermost internal seepage pipe (7). The diameter of the external seepage hole (2) is larger than that of the internal seepage hole (8).

3. A safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams according to claim 1 or 2, characterized in that, The seepage pipe is wrapped with geotextile (9) and mesh (10) in sequence.

4. The intelligent safety depressurization system for vertical pressure relief wells in tailings dams according to claim 3, characterized in that, A groove (11) and a rail (12) structure are provided between two adjacent seepage pipes, so that during installation, the inner seepage pipe can be slid into the outer seepage pipe through the rail (12) and groove (11) structure.

5. The intelligent safety depressurization system for vertical pressure relief wells in tailings dams according to claim 4, characterized in that, The slide groove (11) is composed of a stepped groove with a smaller outer diameter and a larger inner diameter, and the slide rail (12) is adapted to the shape of the slide groove (11).

6. The intelligent safety depressurization system for vertical pressure relief wells in tailings dams according to claim 1, characterized in that, The internal seepage pipe is composed of vertical multi-section pipe body (15), each pipe body (15) is equipped with a lifting lug (13), and two adjacent lifting lugs (13) are connected by a pull rope (14). A pull rope (14) extending outward from the uppermost lifting lug (13) is fixed on it.

7. A safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams according to claim 6, characterized in that, Two adjacent tubes (15) are connected together via a tube connector (16).

8. The intelligent safety depressurization system for vertical pressure relief wells in tailings dams according to claim 1, characterized in that, Both the external seepage hole (2) and the internal seepage hole (8) are located below the wetting line.

9. A safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams according to claim 1 or 2, characterized in that, Each dam body is equipped with an external seepage pipe (1), and multiple external seepage pipes (1) are spaced apart in the longitudinal direction of each dam body.

10. A safe and intelligent pressure reduction system for vertical pressure relief wells in tailings dams according to claim 2, characterized in that, The diameter of the multi-layer internal seepage holes (8) decreases sequentially from the outside to the inside.

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