Construction method of river valley type tailing pond flood discharge and drainage system

Abstract

The invention provides a construction method of a river valley type tailing pond flood discharge and drainage system, which comprises the following steps: determining a construction influence area of an existing river according to the positions and operation conditions of a to-be-constructed tailing pond, a retaining dam, an initial dam and an environment-friendly dam; based on the construction influence area, the burying position and length of the drainage pipe are determined; a temporary riverway is constructed on the upstream of the retaining dam, and river water flows to the temporary riverway from the existing riverway; burying a drainage tube; and after the tunnel outside the reservoir is completed, the drainage tube is cut off and plugged. The existing river is temporarily changed, the drainage pipe and the existing river channel form the continuous drainage channel, the drainage channel is used for discharging river water, the flow direction of the existing river can be recovered in time, meanwhile, construction of a tailing pond, a water retaining dam, an initial dam and an environment-friendly dam can be conducted in advance, and the construction efficiency is improved. And the construction can be carried out without finishing the construction of the tunnel outside the reservoir and introducing water, so that the construction progress is obviously accelerated.

Description

Technical Field

[0001] This invention belongs to the field of tailings dam engineering technology, and in particular relates to a method for constructing a river channel diversion and flood diversion system for a valley-type tailings dam. Background Technology

[0002] Tailings dam projects are an important component of mining engineering, used to store tailings or other industrial waste discharged after ore beneficiation in metal or non-metal mines. Tailings dam projects built in valleys typically involve diverting water from existing rivers, and face harsh construction environments and limited space. Current technologies often employ a method of releasing water through an external tunnel after its completion, allowing dam construction to begin only after the existing river water has been drained. However, the external tunnel's narrow cross-section makes mechanical operations difficult, and the stringent requirements for ventilation, electricity, and water pipelines result in excessively long construction periods, severely delaying dam construction. This directly impacts the construction time of subsequent works such as the extraction yard and intercepting ditches, leading to overall project delays and compromised safety and reliability. To address these technical problems, a rapid and effective method for diverting water from existing rivers in valleys is urgently needed, simultaneously providing the necessary conditions for dam construction and accelerating the overall construction progress. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for constructing a valley-type tailings dam flood discharge and diversion system, enabling the construction of the tailings dam, water-retaining dam, initial dam, and environmental protection dam to be carried out in advance, thereby accelerating the construction progress.

[0004] The technical solution adopted in this invention is: a method for constructing a valley-type tailings dam flood discharge and diversion system, comprising the following steps:

[0005] Based on the location and operating conditions of the proposed tailings dam, water-retaining dam, initial dam, and environmental protection dam, the construction impact zone of the existing river is determined;

[0006] Based on the construction impact area, determine the burial location and length of the drainage pipe;

[0007] A temporary waterway is constructed upstream of the dam to allow river water to flow from the existing waterway to the temporary waterway.

[0008] The drainage pipe is installed;

[0009] After the tunnel outside the reservoir is completed, the drainage pipe is cut off and sealed.

[0010] Furthermore, determining the burial location and length of the drainage pipe based on the construction impact area includes:

[0011] The length of the diversion section of the dam body is determined based on the location of the water-blocking dam and the environmental protection dam;

[0012] Based on the location of the tailings dam and the initial dam and the construction impact zone, the length of the diversion section outside the dam is determined;

[0013] The diversion section of the dam body, the diversion section outside the dam, and the existing river channel are connected to form a diversion channel.

[0014] Furthermore, the distance between the inlet of the diversion section of the dam and the upstream toe of the dam body is not less than 12m.

[0015] Furthermore, the outlet location of the diversion section of the dam body in the water-blocking dam area corresponds to the entrance of the tunnel outside the reservoir.

[0016] Furthermore, the outlet of the diversion section of the dam body in the environmental protection dam area is located more than 15m downstream of the dam toe.

[0017] Furthermore, the embedding of the drainage tube includes:

[0018] Construction diversion pipe foundation: The foundation of the diversion section of the dam body is set on the bearing layer of the dam body; the foundation of the diversion section outside the dam body is set on the hard base layer.

[0019] Furthermore, the diversion pipe includes a main diversion pipe and a backup pipe. The main diversion pipe is located below the existing river channel, and the backup pipe is parallel to the main diversion pipe and located below the riverbank on one side of the existing river channel.

[0020] Furthermore, the main diversion pipe and the backup pipe of the dam body diversion section are set on the same diversion pipe base, and the inlet of the main diversion pipe is higher than the inlet of the backup pipe.

[0021] Furthermore, the main diversion pipe and the backup pipe of the diversion section outside the dam are set on the same diversion pipe base, and the inlet of the main diversion pipe and the inlet of the backup pipe are set at the same height.

[0022] Furthermore, a two-stage sedimentation tank is provided at the front end of the water inlet of the diversion section of the dam, and a debris barrier is provided at the front end of the sedimentation tank.

[0023] The advantages and positive effects of this invention are:

[0024] (1) This application temporarily diverts the existing river and sets up a diversion pipe to form a continuous diversion channel with the existing river channel. The diversion channel is used to discharge the river water. This can restore the existing river flow direction in a timely manner and allow the construction of tailings ponds, water-blocking dams, initial dams and environmental protection dams to be carried out in advance, without having to wait for the tunnel outside the reservoir to be completed and water to be put into operation. This significantly speeds up the construction progress.

[0025] (2) By rationally setting the location and length of the main diversion pipe, backup pipe and diversion branch pipe, and making full use of the existing river channel, a smooth diversion channel was formed, which reduced the amount of construction work, reduced the construction difficulty and improved the construction efficiency.

[0026] (3) Using corrugated steel pipes as the main and backup pipes can effectively adapt to the displacement caused by tailings dam foundation settlement, seismic load or frost heave, while facilitating transportation and installation, further accelerating the construction progress.

[0027] (4) By setting up the foundation of the drainage pipe and the sedimentation tank in a reasonable manner, the safety and reliability of the overall structure are ensured. Attached Figure Description

[0028] Figure 1 This is a plan view of a specific embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the basic structure of the dam diversion section according to a specific embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the foundation structure of the diversion section outside the dam according to a specific embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the basic structure of the spare pipe according to a specific embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the foundation structure of a ditch branch pipe according to a specific embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of a sedimentation tank structure according to a specific embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of a specific embodiment of the trash rack structure of the present invention.

[0035] In the picture:

[0036] 1. Tailings dam; 2. Initial dam; 3. Environmental protection dam; 4. Water-retaining dam; 5. Sedimentation basin; 5-1. I-beam; 6. Interception ditch; 7. Main diversion pipe; 8. Branch pipe of gully; 9. Existing river; 10. Existing road; 11. External tunnel; 12. External tunnel measures tunnel; 13. Diversion pipe trench; 14. Sand cushion layer; 15. Crushed stone layer; 16. Backfill soil and rock layer; 17. Compacted soil and rock layer; Detailed Implementation

[0037] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0038] like Figure 1As shown, this invention proposes a method for constructing a flood discharge and diversion system for a valley-type tailings dam. After temporarily diverting the existing river, a diversion pipe is buried along the existing river channel in the tailings dam area, forming a diversion channel with the existing river. The river water is then discharged from the construction impact area through this channel. Subsequently, the existing river is restored, allowing it to flow along the diversion channel to avoid affecting dam construction. After the external tunnel is filled with water, the diversion pipe is cut off and sealed, and flood discharge is carried out through the external tunnel. By adopting the flood discharge and diversion system construction method proposed in this application, the dam can be constructed simultaneously with the external tunnel, without having to construct the dam after the external tunnel is completed. This ensures the safety and reliability of the construction while accelerating the construction progress.

[0039] like Figure 1 As shown in the figure, this embodiment of the invention provides a method for constructing a valley-type tailings dam flood discharge and diversion system. The proposed tailings dam 1 is located in a valley, and there is an existing river 9 in the valley. The tailings dam 1 is constructed along the existing river channel, with a water-retaining dam 4 upstream and an initial dam 2 and an environmental protection dam 3 downstream. Based on the impact of the existing river 9 on the construction of the water-retaining dam 4, the initial dam 2, the environmental protection dam 3, and the tailings dam 1, the existing river channel is divided into a construction impact zone and a non-construction impact zone. The construction impact zone is the area where the flowing river water will affect construction operations such as material extraction, material transportation, foundation clearing, anchoring platform excavation, and dam filling. The non-construction impact zone is the area that will not affect the above-mentioned construction operations.

[0040] The flood discharge and diversion system includes an existing river channel located in the non-construction impact zone, an external tunnel 11, and several diversion pipes. Interception ditches 6 are located on both sides of the existing river channel, and the external tunnel 11 is situated on the other side of one of these ditches 6. The diversion pipes connect with the existing river channel in the non-construction impact zone to form a diversion channel, used to drain water from the existing river channel before the external tunnel is filled with water, facilitating the construction of the tailings dam, dam, initial dam, and environmental protection dam. By burying the diversion pipes at designated locations in the existing river channel before the construction of the tailings dam 1, dam 4, initial dam 2, and environmental protection dam 3, connecting them with the existing river channel in the non-construction impact zone to form a diversion channel, and draining water through this channel, the construction impact zone meets the construction conditions, allowing the tailings dam 1, dam 4, initial dam 2, and environmental protection dam 3 to be constructed before the external tunnel 11 is filled with water, thus accelerating the overall construction progress.

[0041] This invention provides a method for constructing a valley-type tailings dam flood discharge and diversion system, comprising the following steps:

[0042] S1. Based on the proposed tailings dam 1, water-blocking dam 4, initial dam 2 and environmental protection dam 3 areas and operating conditions, determine the construction impact zone of the existing river 9.

[0043] like Figure 1As shown, the areas for the proposed tailings dam 1, dam 4, initial dam 2, and environmental protection dam 3 are determined according to the plan layout. The working conditions include the terrain in the valley, the construction technology, construction sequence, and construction equipment of each dam, as well as the location of material storage yards and transportation channels corresponding to different construction progress. The area where the existing river 9 will affect the construction of tailings dam 1, dam 4, initial dam 2, and environmental protection dam 3 is determined, which is the construction impact area.

[0044] S2. Based on the construction impact area, determine the burial location and length of the drainage pipe;

[0045] In this embodiment, the diversion pipe includes a dam body diversion section and an external dam diversion section, depending on its burial location.

[0046] Specifically, the location and length of the drainage tube are determined using the following method:

[0047] S201. Based on the locations of the water-blocking dam 4 and the environmental protection dam 3, determine the length of the diversion section of the dam body;

[0048] Since the proposed dam 4 and environmental protection dam 3 are located on the existing river channel, the existing river channel corresponding to the areas of dam 4 and environmental protection dam 3 is the construction impact zone, and the diversion pipes set at the locations of dam 4 and environmental protection dam 3 are the diversion sections of the dam body.

[0049] Furthermore, in this embodiment, the diversion section of the dam body in the area of ​​the dam 4 is set along the existing river channel in the area and passes through the dam 4, extending from the upstream to the downstream of the dam 4; the distance between the inlet of the diversion section and the upstream toe of the dam body is not less than 12m, and the outlet position corresponds to the entrance of the tunnel 11 outside the reservoir; the length of the diversion section can be determined according to the position of its inlet and outlet.

[0050] Furthermore, in this embodiment, the diversion section of the dam body in the environmental protection dam 3 area is set along the existing river channel in the area and runs through the environmental protection dam 3, extending from the upstream of the environmental protection dam 3 to the downstream; the inlet of the diversion section is at least 12m away from the upstream toe of the dam body, and the outlet is located more than 15m away from the downstream toe of the dam body; the length of the diversion section can be determined according to the location of its inlet and outlet.

[0051] S202. Based on the construction impact zone of tailings dam 1 and initial dam 2, determine the length of the diversion section outside the dam;

[0052] Depending on the scope of the construction impact zone, the diversion pipe set outside the dam body area is called the external diversion section. The dam body diversion section and the external diversion section can be directly connected or indirectly connected. For example, the external diversion section set in the construction impact zone between two non-construction impact zones and outside the dam body area is connected to the dam body diversion section through an existing river channel within the non-construction impact zone.

[0053] In this embodiment, the existing river 9 in the tailings dam 1 area affects the construction of ancillary facilities (wells, etc.) of tailings dam 1. A portion of the existing river channel within the tailings dam 1 area is designated as a construction impact zone, therefore an external diversion section is constructed at its corresponding location. Simultaneously, due to the narrow valley area between the dam 4 and tailings dam 1, an external diversion section is directly constructed downstream of the diversion section of the dam 4. This external diversion section is constructed along the existing river channel, with its inlet connected to the outlet of the dam diversion section. Its outlet is located at the edge of the construction impact zone within the tailings dam 1 area. The length of the external diversion section can be determined based on the positions of its inlet and outlet.

[0054] In this embodiment, the existing river 9 in the area of ​​the initial dam 2 is not affected by construction, so open drainage through the existing river channel is sufficient.

[0055] Through the above technical solution, the dam body diversion section, the external diversion section and the existing river channel are connected to form a diversion channel. The river water enters from the dam body diversion section of the dam 4, flows through the external diversion section and enters the existing river channel in the tailings pond 1 area. It then flows through the existing river channel to the dam body diversion section of the environmental protection dam 3 and flows out of the valley area through the diversion pipe.

[0056] S3. Construct a temporary waterway upstream of the dam 4 to allow the river water to flow from the existing waterway to the temporary waterway;

[0057] By constructing a temporary river channel, the existing river 9 is diverted, preventing river water from entering the valley. This facilitates the construction of a flood discharge and diversion system, which will then drain the original river water from the valley.

[0058] S4. Lay out the drainage pipe;

[0059] Specifically, the drainage pipe is installed in the following manner:

[0060] S401. Determine the number and diameter of the drainage tubes;

[0061] In this embodiment, the number and diameter of the drainage pipes are determined by calculation, specifically including calculating the maximum flood discharge based on the flood control calculation, determining the number of drainage pipes based on the maximum flood discharge, and calculating the minimum inner diameter of the drainage pipes according to the Manning formula; the calculation method is existing technology and will not be described in detail here; for example, through the above calculation, the number of drainage pipes is determined to be two, and the diameter is DN1.2m.

[0062] In one specific embodiment, the drainage pipe adopts a DN1.2m corrugated steel pipe. Its corrugated structure has axial flexibility and radial deformation resistance, which can effectively adapt to displacement caused by foundation settlement, seismic loads, or frost heave of tailings dam 1. Compared with rigid concrete pipes, it allows for greater deformation, avoiding the risk of pipe breakage due to uneven foundation settlement. The corrugated structure achieves a high strength-to-weight ratio through geometric strengthening effect. The weight of the same pipe diameter is only 1 / 10 of that of a concrete pipe, which is convenient for transportation and rapid installation in mountainous areas. It is especially suitable for the complex terrain of tailings dam 1, saving foundation treatment costs, maintenance costs, and construction time costs. The overall cost can be reduced by about 25%. Furthermore, the corrugated steel pipe can be prefabricated and assembled, and the flange interface design can achieve rapid assembly. The modular assembly process can shorten the construction period by more than 50%.

[0063] In the above embodiment, two diversion pipes are provided, including a main diversion pipe 7 and a backup pipe. The main diversion pipe 7 is located below the existing river channel, and the backup pipe is parallel to the main diversion pipe 7 and located below the riverbank on one side of the existing river channel. For example, when there is an existing road 10 on one side of the existing river channel, the backup pipe is preferably located below the existing road 10.

[0064] S402, Excavation of drainage pipe trench 13;

[0065] Specifically, excavators are used for excavation. For trench excavation that may affect the overall stability of the slope during construction, a segmented excavation method is adopted, where pipes are laid in sections of the excavated section, and then backfilled in sections of the excavated section.

[0066] When the diversion pipe is buried at a deep depth, necessary monitoring measures should be taken on the trench slope. For the diversion section of the dam body, due to its deeper excavation, it should be excavated in layers and combined with the dam foundation clearing and trenching work. During the excavation process, depending on the groundwater level, open drainage or diversion measures should be adopted; for open drainage, a sump pit or open ditch should be set up along the trench edge and pumped out with water. According to the site soil conditions, the trench slope should be sloped during the trench excavation process. The longitudinal slope of the trench should meet the design requirements. When encountering local soft soil layers, it is necessary to replace them with gravel or crushed stone.

[0067] S403, Foundation for construction diversion pipe;

[0068] In this embodiment of the application, two drainage pipes are provided, including a main drainage pipe 7 and a backup pipe. The main drainage pipe 7 is used for drainage and flood discharge under normal conditions, and the backup pipe is used for emergency backup drainage pipes. The main drainage pipe 7 and the backup pipe can be set on separate drainage pipe foundations, or they can be set on the same drainage pipe foundation. Preferably, the main drainage pipe 7 and the backup pipe are set on the same drainage pipe foundation.

[0069] like Figure 2As shown, the foundation of the diversion pipe in the dam's diversion section is set on the bearing layer of the dam body, including a sand cushion layer 14, a crushed stone layer 15, and a compacted soil and rock layer 17 arranged from bottom to top within the diversion pipe trench 13. Both the main diversion pipe 7 and the backup pipe are located on the crushed stone layer 15, and the inlet of the main diversion pipe 7 is higher than the inlet of the backup pipe. Preferably, the main diversion pipe 7 is located near the upper edge of the crushed stone layer 15. In one specific embodiment, the height difference between the two is 6m.

[0070] like Figure 3 As shown, the foundation of the diversion pipe in the diversion section outside the dam is set on a hard base layer, including a sand cushion layer 14, a crushed stone layer 15, and a backfill soil and rock layer 16 arranged from bottom to top in the diversion pipe trench 13. The main diversion pipe 7 and the spare pipe are both set in the crushed stone layer 15, and the inlet of the main diversion pipe 7 and the inlet of the spare pipe are set at the same height. Preferably, they are set in the middle of the thickness direction of the crushed stone layer 15, with a set distance between them and the upper surface of the backfill soil and rock layer 16 to form a sufficient cover layer thickness. The backfill soil and rock layer 16 is backfilled after the diversion pipe is installed in place.

[0071] When the main drainage pipe 7 and the backup pipe are each equipped with independent drainage pipe foundations, the drainage pipe foundation structure of the backup pipe is as follows: Figure 4 As shown, the drainage pipe trench 13 includes a sand cushion layer 14, a gravel layer 15, and a backfill soil and rock layer 16 arranged from bottom to top. The spare pipe is located in the middle of the gravel layer 15 in the thickness direction, and there is a set distance between it and the upper surface of the backfill soil and rock layer 16 to form a sufficient cover layer thickness. The backfill soil and rock layer 16 is backfilled after the spare pipe is installed in place.

[0072] Furthermore, in this embodiment of the application, the diversion pipe also includes a gully branch pipe 8, which is set in the gullies on both sides of the existing river channel and located inside the intercepting ditch 6; the gully branch pipes 8 in the gullies on both sides are connected to the main diversion pipe 7, and after the completion of the external tunnel 11 measures opening, they are connected to the external tunnel 11 measures opening to discharge the river water in the gullies; a temporary collection pool is also provided at the inlet of the gully branch pipe 8.

[0073] In the above embodiments, the ditch branch pipe 8 is a small-diameter corrugated pipe. The ditch branch pipe 8 can be installed on the same drainage pipe foundation as the main drainage pipe 7 and the spare pipe, or it can be installed on an independent drainage pipe foundation; for example... Figure 5 As shown, the gully branch pipe 8 is installed on an independent drainage pipe foundation. The drainage pipe foundation of the gully branch pipe 8 includes a sand cushion layer 14, a gravel layer 15, and a backfill soil and rock layer 16, arranged from bottom to top within the drainage pipe trench 13. The gully branch pipe 8 is located in the middle of the gravel layer 15 in the thickness direction, and there is a set distance between it and the upper surface of the backfill soil and rock layer 16 to form a sufficient cover layer thickness. The backfill soil and rock layer 16 is backfilled after the gully branch pipe 8 is installed in place.

[0074] Before installing the drainage pipe, it is necessary to check the flatness, elevation, and pre-camber of the drainage pipe foundation, and determine the location, center axis, and midpoint of the drainage pipe.

[0075] S404, pipe section hoisting;

[0076] The aforementioned main drainage pipe 7, spare pipe, and ditch branch pipe 8 each consist of several pipe sections, each of which is hoisted into place. When the site conditions allow for the installation of a crane, a truck crane is used to hoist the pipe sections; when the site conditions do not allow for the installation of a crane, an excavator or loader is used to hoist the pipe sections. To prevent the hoisting ropes from squeezing and deforming the pipe sections, discarded vehicle tire pads are placed at the contact points between the hoisting ropes and the pipe walls.

[0077] S405, Pipe section installation and connection;

[0078] During the installation of the main drainage pipe 7 and the spare pipe, corrugated steel pipe sections are laid out according to the actual site conditions. The first pipe section is laid out from one side, ensuring its centerline aligns with the longitudinal centerline of the foundation. This first corrugated pipe section is then positioned, and the installation extends outwards from this point. When the gap between adjacent flanges of two pipes is 3-5 cm, a small pry bar is used to align the bolt holes on the flanges, ensuring the bolts on both flanges are aligned. Then, from the other end of the second pipe section, a pry bar is used to move the section longitudinally towards the corrugated pipe. When the gap between the two flanges is approximately 2 cm, all bolts are inserted into the bolt holes, and nuts are fitted and slightly tightened, but not fully tightened.

[0079] S406, Pipe sections are fitted with sealing gaskets;

[0080] When installing the main drainage pipe 7 and the spare pipe, if the distance between the two flanges of adjacent pipe sections is small, use a hammer and chisel to create a gap of about 1 cm between the two flanges, and then use a screwdriver to insert the gasket between the two flanges. If the distance between the two flanges at the top of the pipe section is large, making it difficult to insert the gasket, use binding wire to tie the gasket to the bolts for fixation, and then the workers begin to tighten the nuts symmetrically. Continue until the gap between the two flanges is only 2-5 mm when viewed from the outside.

[0081] S407. Tighten the nut;

[0082] After all pipe sections are assembled, tighten the nuts one by one. The torque of each nut must not be less than 135.6 N·m and must not exceed 203.4 N·m. When using a power wrench, the tightening time should be 2 to 5 seconds. Continue connecting the sections in this manner.

[0083] S408, Trench backfilling;

[0084] After the diversion section of the dam is completed, passes inspection, and the concealed works are inspected, backfilling can begin. Before backfilling, debris such as garbage and formwork supports should be removed from the foundation, water in the foundation trench should be pumped out, silt should be removed, and the foundation elevation should be inspected. The soil quality, gradation, and moisture content of the backfill soil should meet the design requirements.

[0085] In one specific embodiment, the backfill soil and rock layer 16 adopts a "sandwich" layered backfilling method, consisting of three layers: bottom, middle, and top. The materials used are graded crushed stone (5-20mm) + 3% cement, gravelly soil (containing 30% coarse sand), and undisturbed soil (passed through a 10mm sieve), respectively. The compaction standards can be implemented according to ≥95% Protodyakonov, ≥93% modified AASHTO, and ≥90% standard compaction, respectively. The functions of the three backfill soil layers are respectively positioned as capillary rise prevention, stress buffer layer, and ecological restoration foundation. A "nano-silicon-based waterproofing agent" can be added to the bottom layer to reduce the permeability coefficient to 1×10⁻⁶. -6 For the middle layer, a "vibration + static pressure alternating compaction process" (3 passes of vibration + 2 passes of static pressure) can be used. During construction, it is important to note that if dump trucks are used to unload backfill material, it should be dumped at a distance of more than one diameter on both sides of the drainage pipe, and then small machinery or manual labor should be used to spread the backfill gravel and other materials into place. When backfilling on both sides of the drainage pipe, a road roller can be used for compaction 50cm away from the maximum diameter of the pipe, and a vibratory rammer should be used within 50cm to avoid impact from large machinery on the corrugated pipe. The number of passes for the vibratory rammer can be determined according to the actual situation. Within 0.5 meters of the pipe, no hard objects such as stones larger than 50mm are allowed.

[0086] During backfilling, layers should be filled and compacted in stages, with each layer compacted to a thickness of 20cm. The next layer can only be filled after the compaction degree meets the specifications. Backfilling must be carried out symmetrically and simultaneously on both sides of the diversion pipe, with the height difference between the backfill on both sides not exceeding 20cm. When the backfill thickness above the corrugated pipe is less than 50cm, a hand-held vibratory roller or a static roller with a capacity of less than 6t should be used for compaction, and the compaction degree should meet the specifications. Heavy rollers should not be used for backfill thicknesses less than 0.5m above the pipe; heavy rollers can only be used for backfill thicknesses exceeding 0.5m. When using a heavy roller, two static compactions should be performed first, followed by careful vibratory compaction as needed, until the required compaction degree is achieved.

[0087] For diversion pipes that pass over heavy vehicles at the top and diversion pipes located below the material receiving area, the thickness of the dense covering layer on top of the pipes should be no less than 1m or as required by the design. All heavy vehicles are strictly prohibited from passing through when the corrugated pipes have not reached the minimum backfill height (0.5m).

[0088] If backfilling is required in areas with high water levels, the "airbag-assisted drainage backfilling method" can be used. This involves pre-burying a permeable pipe (DN200 HDPE) at the bottom of the pipe, installing an expandable rubber airbag (pressure resistant 1MPa), injecting water and venting air during backfilling, and simultaneously pumping out groundwater to achieve backfilling of the pipe trench. If backfilling is required in areas with frozen soil, "composite saline-modified soil" can be used to achieve frost heave prevention. This involves using sandy silt as the base soil and adding CaCl2 (5%) + glass fiber (0.3%) to reduce the frost heave rate of the backfill soil at -20℃ to below 0.5%.

[0089] In this embodiment of the application, after steps S1-S4 are completed, the diversion pipe forms a continuous diversion channel with the existing river channel, and the river water is discharged through the diversion channel. This can restore the flow direction of the existing river 9 in a timely manner, and at the same time make the construction impact area meet the construction conditions, so that the tailings dam 1, the water-blocking dam 4, the initial dam 2 and the environmental protection dam 3 can be constructed. This allows the above construction operations to be carried out simultaneously with the tunnel 11 outside the dam, or before the construction of the tunnel 11 outside the dam, which significantly speeds up the construction progress.

[0090] Furthermore, a 2m long concrete pier is poured at the junction of the diversion pipe and the dam slope to achieve sealing and pipe stabilization.

[0091] S5. After the tunnel 11 outside the reservoir is completed, cut off and seal the drainage pipe.

[0092] After water is introduced into the external tunnel 11, the connection between the diversion pipe and the dam body is cut according to the slope of the dam body. The outlet of the diversion pipe is sealed with a steel plate flange, and C25 concrete is poured into the diversion pipe for sealing. After the sealing is completed and the concrete has reached a certain strength, a seepage-proof layer is laid at the connection between the upper diversion pipe and the dam body.

[0093] In one specific embodiment, the branch pipe 8 of the ditch can be removed after the intercepting ditch 6 is filled with water, or it can be left untreated.

[0094] Furthermore, in this embodiment of the application, a two-stage sedimentation tank 5 is provided at the front end of the inlet of the dam diversion section, and a debris-blocking grid is provided at the front end of the sedimentation tank 5. Figure 6 As shown, the sedimentation tank 5 is constructed using mortar-grouted masonry, which can quickly reduce the flow velocity and decrease the subsequent water flow load. This helps ensure the engineering quality and construction efficiency of the tailings dam 1 and the dam body, while also guaranteeing the safety and reliability of the construction. The specific structure of the trash rack is as follows: Figure 7 As shown, it includes a concrete foundation and several longitudinally intersecting I-beams 5-1 set on the concrete foundation, forming an arc-shaped structure.

[0095] Furthermore, in this embodiment of the application, in order to facilitate the maintenance and repair of the drainage pipe, a drainage pipe inspection well is also provided in a flat area.

[0096] The advantages and positive effects of this invention are:

[0097] (1) This application temporarily diverts the existing river and sets up a diversion pipe to form a continuous diversion channel with the existing river channel. The diversion channel is used to discharge the river water. This can restore the existing river flow direction in a timely manner and allow the construction of tailings ponds, water-blocking dams, initial dams and environmental protection dams to be carried out in advance, without having to wait for the tunnel outside the reservoir to be completed and water to be put into operation. This significantly speeds up the construction progress.

[0098] (2) By rationally setting the location and length of the main diversion pipe, backup pipe and diversion branch pipe, and making full use of the existing river channel, a smooth diversion channel was formed, which reduced the amount of construction work, reduced the construction difficulty and improved the construction efficiency.

[0099] (3) Using corrugated steel pipes as the main and backup pipes can effectively adapt to the displacement caused by tailings dam foundation settlement, seismic load or frost heave, while facilitating transportation and installation, further accelerating the construction progress.

[0100] (4) By setting up the foundation of the drainage pipe and the sedimentation tank in a reasonable manner, the safety and reliability of the overall structure are ensured.

[0101] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for constructing a valley-type tailings dam flood discharge and diversion system, characterized in that, Includes the following steps: Based on the location and operating conditions of the proposed tailings dam, water-retaining dam, initial dam, and environmental protection dam, the construction impact zone of the existing river is determined; Based on the construction impact area, determine the burial location and length of the drainage pipe; A temporary waterway is constructed upstream of the dam to allow river water to flow from the existing waterway to the temporary waterway. The drainage pipe is installed; After the tunnel outside the reservoir is completed, the drainage pipe is cut off and sealed.

2. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 1, characterized in that: The determination of the burial location and length of the drainage pipe based on the construction impact area includes: The length of the diversion section of the dam body is determined based on the location of the water-blocking dam and the environmental protection dam; Based on the location of the tailings dam and the initial dam and the construction impact zone, the length of the diversion section outside the dam is determined; The diversion section of the dam body, the diversion section outside the dam, and the existing river channel are connected to form a diversion channel.

3. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 2, characterized in that: The distance between the inlet of the diversion section of the dam and the upstream toe of the dam body shall not be less than 12m.

4. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 2 or 3, characterized in that: The outlet of the diversion section of the dam body in the water-blocking dam area corresponds to the entrance of the tunnel outside the reservoir.

5. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 2 or 3, characterized in that: The outlet of the diversion section of the dam body in the environmental protection dam area is located more than 15m downstream of the dam toe.

6. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 2, characterized in that: The installation of the drainage tube includes: Construction diversion pipe foundation: The foundation of the diversion section of the dam body is set on the bearing layer of the dam body; the foundation of the diversion section outside the dam body is set on the hard base layer.

7. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 6, characterized in that: The diversion pipe includes a main diversion pipe and a backup pipe. The main diversion pipe is located below the existing river channel, and the backup pipe is parallel to the main diversion pipe and located below the riverbank on one side of the existing river channel.

8. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 7, characterized in that: The main diversion pipe and the backup pipe of the dam body diversion section are set on the same diversion pipe base, and the inlet of the main diversion pipe is higher than the inlet of the backup pipe.

9. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 7 or 8, characterized in that: The main diversion pipe and the backup pipe of the diversion section outside the dam are set on the same diversion pipe base, and the inlet of the main diversion pipe and the inlet of the backup pipe are set at the same height.

10. The method for constructing a valley-type tailings dam flood discharge and diversion system according to claim 2, characterized in that: Two-stage sedimentation tanks are installed at the front end of the water inlet of the diversion section of the dam, and the front end of the sedimentation tanks is equipped with a debris barrier.

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