Reservoir bypass desilting system and method with high-sand-content branches and hydropower station

Abstract

The invention provides a reservoir bypass desilting system and method with high-sand-content branches and a hydropower station, and relates to the technical field of hydraulic engineering, the reservoir bypass desilting system with the high-sand-content branches is applied to the hydropower station, the hydropower station comprises a main reservoir area and a branch river channel, the branch river channel is communicated with the main reservoir area, and an afflux area is formed at the communication position of the branch river channel and the main reservoir area; the opposite bank mountain is located on the side, away from the branch river channel, of the main reservoir area; the reservoir bypass desilting system with the high-sand-content branch comprises a water inlet structure, a desilting hole and a gate shaft assembly, the water inlet structure is arranged in an afflux area, one end of the desilting hole is communicated with the water inlet structure, the end, away from the water inlet structure, of the desilting hole is communicated with a downstream leakage bearing area, and the gate shaft assembly is communicated with the desilting hole. The control module is used for controlling connection or disconnection between the two ends of the desilting hole. According to the invention, high-silt-content water flow of the tributary river channel is prevented from occupying the effective storage capacity of the reservoir, the abrasion of silt to the hydraulic turbine set is reduced, and the service life of the reservoir and the hydraulic turbine set is prolonged.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, and more specifically, to a reservoir bypass sediment discharge system, method, and hydropower station with a high sediment load tributary. Background Technology

[0002] If a reservoir built on a sandy river has siltation problems, it will affect the service life of the hydropower station.

[0003] In the relevant technologies, high sediment-laden tributaries first enter the confluence area or main reservoir area with the inflow flood, and then migrate towards the front of the dam with the flood. Later, dredging (sand discharge and sand hauling operation) is carried out through the existing flood discharge and sand discharge facilities of the hub.

[0004] However, after entering the inflow area, sediment gradually accumulates at the tributary outlet, forming a delta. It forms a sediment bed or barrier sandbar in the inflow area and gradually advances towards the dam. This not only encroaches on the effective storage capacity of the reservoir, but also causes the inlets of the flood discharge and water supply facilities of the hydropower station to be blocked by sediment. The amount of sediment passing through the generator units increases, the wear and tear on the units intensifies, and seriously affects the comprehensive benefits of the reservoir in flood control, power generation, and water supply. Summary of the Invention

[0005] The problem solved by this invention is how to not only prevent the high sediment load of tributary rivers from encroaching on the effective storage capacity of reservoirs, but also reduce the siltation of the inlet of the flood discharge and water supply facilities of hydropower stations and the wear of turbine units.

[0006] To address the aforementioned problems, this invention provides a reservoir bypass sediment discharge system, method, and hydropower station with a high sediment load tributary.

[0007] In a first aspect, the present invention provides a reservoir bypass sediment discharge system with a high sediment-laden tributary, applied to a hydropower station. The hydropower station includes a main reservoir area and a tributary channel for transporting high sediment-laden water. The tributary channel is connected to the main reservoir area, and the connection point between the two forms a confluence area with density currents. The hydropower station also includes a mountain on the opposite bank, located on the side of the main reservoir area away from the tributary channel. The reservoir bypass sediment discharge system with a high sediment-laden tributary includes an intake structure, a sediment discharge tunnel, and a gate well assembly disposed within the mountain on the opposite bank. The intake structure is disposed in the confluence area and is opposite to and spaced from the tributary channel. One end of the sediment discharge tunnel is connected to the intake structure, and the end of the sediment discharge tunnel away from the intake structure is used to connect to a downstream discharge area. The gate well assembly is connected to the sediment discharge tunnel and is used to control the connection or disconnection between the two ends of the sediment discharge tunnel.

[0008] Optionally, the sand discharge tunnel includes a temporary water-retaining structure and a tunnel body. The temporary water-retaining structure is located at the front edge of the inlet structure. One end of the tunnel body is connected to the end of the temporary water-retaining structure away from the confluence area, and the other end of the tunnel body is used to connect to the downstream discharge area.

[0009] Optionally, the main body of the tunnel includes a connecting tunnel and a first tunnel section. One end of the connecting tunnel is connected to the end of the temporary water-retaining structure away from the inflow area, and one end of the first tunnel section is connected to the end of the connecting tunnel away from the temporary water-retaining structure. The end of the first tunnel section away from the connecting tunnel is used to connect to the downstream discharge area. The gate well assembly includes an inlet gate well assembly, which is disposed at the connection between the connecting tunnel and the first tunnel section.

[0010] Optionally, the main body of the tunnel further includes a second tunnel section, the end of the first tunnel section away from the connecting tunnel being connected to the downstream discharge area through the second tunnel section; the gate well assembly further includes an outlet gate well assembly, the outlet gate well assembly being disposed at the connection between the first tunnel section and the second tunnel section.

[0011] Optionally, the temporary water-blocking structure is a cofferdam that can be detachably installed on the side of the inlet structure near the confluence area, and the cofferdam is used to isolate the confluence area from the main body of the tunnel.

[0012] Optionally, the temporary water-blocking structure is a rock plug, which is located on the side of the inlet structure near the confluence area. The main body of the tunnel also includes a slag collection pit, which is located on the side of the rock plug away from the confluence area and is used to store the rock debris formed after the rock plug is blasted. The inlet structure is connected to the connecting tunnel through the top of the slag collection pit.

[0013] Optionally, the height from the top of the slag collection pit to the end of the connecting hole near the first hole section gradually increases.

[0014] Optionally, the height of the first hole section gradually decreases from the end near the connecting hole to the end away from the connecting hole.

[0015] Secondly, the present invention provides a method for bypassing sediment discharge from a reservoir with a high sediment-laden tributary, based on the above-described bypass sediment discharge system for a reservoir with a high sediment-laden tributary, comprising the following steps: When a tributary enters the flood season, high-sediment-laden water flows into the confluence area along the tributary. Under the influence of gravity, it sinks to the bottom of the less dense water body in the confluence area and continues to move downstream along the bottom of the confluence area to form a high-sediment-laden density flow. The high-sediment-laden density current moves to the inlet structure located in the opposite mountain. The inlet structure is located on the path of the high-sediment-laden density current. The tunnel axis of the inlet structure is consistent with the direction of movement of the high-sediment-laden density current and captures the high-sediment-laden density current. Open the gate well assembly to connect the two ends of the sand discharge tunnel. The high-sand density flow passes through the sand discharge tunnel and the gate well assembly in sequence and is discharged to the downstream receiving area, ensuring that the high-sand density flow does not enter the main reservoir area.

[0016] Thirdly, the present invention provides a hydropower station, including a main reservoir area and a tributary river channel, as well as the above-mentioned reservoir bypass sediment discharge system with a high sediment content tributary, and also includes a turbine unit, wherein the end of the main reservoir area away from the confluence area is connected to the turbine unit.

[0017] The beneficial effects of the reservoir bypass sediment removal system, method, and hydropower station with high sediment-laden tributaries of the present invention are as follows: An intake structure is constructed within the mountainside opposite the density current formation area (convergence area) and connected to an independent sediment discharge tunnel. After the high-sediment-laden water flows into the confluence area along the tributary, a high-sediment-laden density current naturally forms due to the density difference. This high-sediment-laden density current then flows submerged along the bottom of the confluence area. The intake structure is positioned along the path of the density current, with its tunnel axis aligned with the direction of flow and located within the mountainside opposite the tributary in the confluence area. The bottom elevation of the intake structure is typically within the bottom layer of the density current. Therefore, before the density current arrives and spreads and deposits further into the main reservoir area, the intake structure directly "draws in" the high-sediment-laden density current from the bottom, effectively "intercepting" it and preventing it from entering and accumulating in the main reservoir area. In other words, by "diverting" the high-sediment-laden water flow from tributaries into the confluence area, the amount of sediment entering the main reservoir is significantly reduced or even completely avoided, thus ensuring the effective storage capacity of the main reservoir.

[0018] Because the two ends of the sediment discharge tunnel connect the intake structure and the downstream discharge area respectively, most of the sediment is drawn in by the intake structure and flows along the sediment discharge tunnel. When the gate well assembly is opened, the sediment is discharged through the sediment discharge tunnel to the downstream discharge area, thus effectively blocking it from the main reservoir area. In other words, the bypass sediment discharge system of a reservoir with high sediment content tributaries can act as a "barrier" to physically isolate the high sediment content water flow in the tributary from the main reservoir area, the water supply facility inlet, and the turbine inlet in terms of space and flow path. This keeps the water in the main reservoir area at a low sediment content due to the interception of the sediment source (i.e., the high sediment content water flow in the tributary), thereby reducing the amount of sediment entering the main reservoir area. This reduces the amount of sediment encroaching on the effective reservoir capacity, blocking the inlets of flood discharge and water supply facilities, and entering the turbines of the hydropower station. Consequently, it extends the service life of the reservoir and turbines and ensures the comprehensive benefits of flood control, power generation, and water supply in the main reservoir area. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the hydropower station in an embodiment of the present invention; Figure 2 This is a partial structural diagram of the inflow area and the sand discharge tunnel in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the inflow area and the sand discharge tunnel in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1-Main reservoir area; 2-Tributary channel; 3-Confluence area; 4-Inlet structure; 5-Desand discharge tunnel; 51-Rock plug (temporary water-retaining structure); 52-Main tunnel body; 521-Connecting tunnel; 522-First tunnel section; 523-Second tunnel section; 524-Slag collection pit; 6-Gate well assembly; 61-Inlet gate well assembly; 62-Outlet gate well assembly; 7-Turbine unit; 8-Downstream discharge area. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0022] In the attached diagram, the X-axis represents left and right position, with the positive direction of the X-axis representing the right side and the negative direction representing the left side; the Y-axis represents front and back position, with the positive direction of the Y-axis representing the front and the negative direction representing the back; the Z-axis represents up and down position, with the positive direction of the Z-axis representing up and the negative direction representing down. It should be noted that the aforementioned representations of the X, Y, and Z axes are merely for the convenience of describing the invention and for 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 limiting the invention.

[0023] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0024] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0025] like Figure 1 As shown in the figure, an embodiment of the present invention provides a reservoir bypass sediment discharge system with a high sediment load tributary, applied to a hydropower station. The hydropower station includes a main reservoir area 1 and a tributary channel 2 for conveying high sediment load water. The tributary channel 2 is connected to the main reservoir area 1, and the connection between the two forms a confluence area 3 with density current. The hydropower station also includes a mountain on the opposite bank, which is located on the side of the main reservoir area 1 away from the tributary channel 2. The reservoir bypass sediment discharge system with a high sediment load tributary includes an inlet structure 4, a sediment discharge tunnel 5, and a gate well assembly 6 disposed in the mountain on the opposite bank. The inlet structure 4 is disposed in the confluence area 3 and is opposite to and spaced from the tributary channel 2. One end of the sediment discharge tunnel 5 is connected to the inlet structure 4, and the end of the sediment discharge tunnel 5 away from the inlet structure 4 is used to connect to a downstream discharge area 8. The gate well assembly 6 is connected to the sediment discharge tunnel 5 and is used to control the connection or disconnection between the two ends of the sediment discharge tunnel 5.

[0026] Specifically, the main reservoir area 1 is the main area through which the water flows in the reservoir. The reservoir bypass sediment discharge system with high sediment content tributaries can be set up as a bypass channel on the opposite bank of the inflow area 3, and is used to directly draw high sediment content density flow out of the inflow area 3.

[0027] The inlet structure 4 can be the connection point between the inflow area 3 and the sand discharge tunnel 5, or the inlet structure 4 can be the inlet port connecting the sand discharge tunnel 5 and the inflow area 3.

[0028] When it is necessary to discharge the silt accumulated in the sand discharge tunnel 5, the gate well assembly 6 is opened to make the two ends of the sand discharge tunnel 5 connected; when it is not necessary to discharge the silt in the sand discharge tunnel 5, the gate well assembly 6 is closed to make the two ends of the sand discharge tunnel 5 disconnected.

[0029] The downstream discharge area can be the downstream river channel of the dam, or a non-inflow river channel.

[0030] In this embodiment, an inlet structure 4 is installed in the mountain opposite the confluence area 3 of the density current, and is connected to an independent sediment discharge tunnel 5. After the high sediment-laden water flows into the confluence area 3 along the tributary channel 2, it naturally forms a high sediment-laden density current due to the density difference. The high sediment-laden density current will flow along the bottom of the confluence area 3. The inlet structure 4 is located on the movement path of the density current. The tunnel axis of the inlet structure 4 is consistent with the movement direction of the density current, and it is located in the mountain opposite the tributary channel 2 of the confluence area 3. Its bottom elevation is usually located within the bottom layer of the density current. Therefore, before the density current arrives and spreads and accumulates in the main reservoir area 1, the inlet structure 4 can directly "suck in" the high sediment-laden density current from the bottom, realizing "pre-interception" of the high sediment-laden water flow, preventing it from entering and accumulating in the main reservoir area 1. In other words, by "diverting" the high-sediment-laden water flow from tributary 2 into the confluence area 3, the amount of sediment entering the main reservoir 1 is significantly reduced or even completely avoided, thus ensuring the effective storage capacity of the main reservoir 1.

[0031] Since the two ends of the sand discharge tunnel 5 are connected to the inlet structure 4 and the downstream discharge area 8 respectively, most of the sediment is sucked in by the inlet structure 4 and flows along the sand discharge tunnel 5. When the gate well assembly 6 is opened, the sediment is discharged through the sand discharge tunnel 5 to the downstream discharge area 8, thus being effectively blocked outside the main reservoir area 1. In other words, the reservoir bypass sediment discharge system with a high sediment-laden tributary can act as a "barrier" to physically isolate the high sediment-laden water flow in the tributary channel 2 from the main reservoir area 1, the water supply facility inlet, and the turbine inlet in both space and flow path. This ensures that the water in the main reservoir area 1 remains in a low sediment-laden state due to the interception of the sediment source (i.e., the high sediment-laden water flow in the tributary channel 2), thereby reducing the amount of sediment entering the main reservoir area 1. This reduces the amount of sediment encroaching on the effective reservoir capacity, blocking the inlets of flood discharge and water supply facilities, and entering the turbine unit 7 of the hydropower station. Consequently, it extends the service life of the reservoir and turbine unit 7 and ensures the comprehensive benefits of the main reservoir area 1 in terms of flood control, power generation, and water supply.

[0032] Optionally, combined Figure 1 As shown, the sand discharge tunnel 5 includes a temporary water-blocking structure and a tunnel body 52. ​​The temporary water-blocking structure is located at the front edge of the water inlet structure 4. One end of the tunnel body 52 is connected to the end of the temporary water-blocking structure away from the confluence area 3, and the other end of the tunnel body 52 is used to connect to the downstream discharge area 8.

[0033] Specifically, the temporary water-retaining structure refers to the structure used during the construction of the main tunnel 52 to block the high-sediment density flow from the confluence area 3 from entering the main tunnel 52 through the inlet structure 4, so as to ensure that the main tunnel 52 and the gate well assembly 6 are constructed in a relatively dry and safe environment. After the main tunnel 52 and the gate well assembly 6 are completed and the entire reservoir bypass sand discharge system with high-sediment tributaries is ready for water flow, the temporary water-retaining structure is dismantled or blasted at once to make the sand discharge tunnel 5 unobstructed. This is a key technical means to achieve "non-stop production transformation" of the existing reservoir.

[0034] The main body 52 can serve as an underground tunnel (unpressurized or pressurized) for the opposite mountain, used to transport sediment with a certain flow velocity.

[0035] In this optional embodiment, a temporary water-blocking structure is set inside the inlet structure 4 that penetrates the opposite mountain to physically isolate the main body 52 of the desilting tunnel 5 from the water in the external main reservoir area or the inflow area during the construction period. This not only creates a completely dry and safe working environment for the construction of the main body 52 of the desilting tunnel 5, but also avoids the influence of water level fluctuations and inflow of water in the main reservoir area 1. Furthermore, it greatly reduces construction safety risks, significantly improves the construction quality and long-term durability of the main body of the project, and makes the construction schedule more certain and efficient.

[0036] After the construction period, the temporary water-retaining structure can serve as an initial, precisely controllable water-retaining facility. Before the first use of the bypass sediment discharge system of a reservoir with a high sediment content tributary, the temporary water-retaining structure can be removed in a controlled manner (such as underwater blasting) to achieve a precise "first water passage".

[0037] Optionally, combined Figure 2 and Figure 3 As shown, the main body 52 of the tunnel includes a connecting tunnel 521 and a first tunnel section 522. One end of the connecting tunnel 521 is connected to the end of the temporary water-retaining structure away from the inflow area 3. One end of the first tunnel section 522 is connected to the end of the connecting tunnel 521 away from the temporary water-retaining structure. The end of the first tunnel section 522 away from the connecting tunnel 521 is used to connect to the downstream discharge area 8. The gate well assembly 6 includes an inlet gate well assembly 61, which is disposed at the connection between the connecting tunnel 521 and the first tunnel section 522.

[0038] Specifically, the two ends of the connecting hole 521 are connected to the downstream side of the temporary water-retaining structure and the first hole section 522, respectively. Therefore, the connecting hole 521 is used to connect the downstream side of the temporary water-retaining structure and the first hole section 522.

[0039] One end of the first tunnel section 522 is connected to the connecting tunnel 521, and the other end can be used to connect to the downstream drainage area 8.

[0040] The inlet gate well assembly 61 is located at the connection between the connecting tunnel 521 and the first tunnel section 522. The inlet gate well assembly 61 may include an inlet gate well and a first control gate located inside the inlet gate well. The first control gate can be used to control the connection or disconnection between the connecting tunnel 521 and the first tunnel section 522.

[0041] In this optional embodiment, the main tunnel body 52 can be divided into a connecting tunnel 521 and a first tunnel section 522, and the key inlet gate well assembly 61 is precisely set at the connection between the two. The connecting tunnel 521 serves as a "transition section" adjacent to the pressure front of the reservoir area, the first tunnel section 522 serves as a "sand conveying section" of the main tunnel body 52, and the inlet gate well assembly 61 becomes the core "control node" for separating and controlling these two sections. This forms a clear and modular hydraulic boundary and structural system of "inlet - connecting tunnel 521 - gate well - main tunnel - downstream", providing a precise operating interface for construction, operation and maintenance.

[0042] The inlet gate well assembly 61 is located at the end of the connecting tunnel 521. When it is necessary to inspect the first tunnel section 522, simply closing the inlet gate well assembly 61 will isolate the connecting tunnel 521 from the downstream first tunnel section 522 and the downstream discharge area. Only the limited water in the first tunnel section 522 needs to be drained to create safe dry conditions for inspection.

[0043] Optionally, combined Figure 3 As shown, the main body 52 of the tunnel also includes a second tunnel section 523, and the end of the first tunnel section 522 away from the connecting tunnel 521 is connected to the downstream discharge area 8 through the second tunnel section 523; the gate well assembly 6 also includes an outlet gate well assembly 62, which is disposed at the connection between the first tunnel section 522 and the second tunnel section 523.

[0044] Specifically, the two ends of the second tunnel section 523 are connected to the first tunnel section 522 and the downstream drainage area 8, respectively. Therefore, the second tunnel section 523 is used to connect the downstream side of the first tunnel section 522 and the downstream drainage area 8.

[0045] The outlet gate well assembly 62 is located at the connection between the first tunnel section 522 and the second tunnel section 523. The outlet gate well assembly 62 may include an outlet gate well and a second control gate located inside the outlet gate well. The second control gate can be used to control the connection or disconnection between the first tunnel section 522 and the second tunnel section 523.

[0046] In this optional embodiment, the outlet gate well assembly 62 is located at the junction of the two tunnel sections, isolating downstream fluctuations outside the second tunnel section 523. By adjusting the opening of the second control gate of the outlet gate well assembly 62, a stable outlet pressure and flow condition undisturbed by external factors can be actively created and maintained at the end of the first tunnel section 522, ensuring that the main tunnel body 52 is always in a state of efficient sediment transport with open flow or predetermined pressurized flow.

[0047] Furthermore, the inlet gate well assembly 61 serves as a safety isolation valve between the first tunnel section 522 and the connecting tunnel 521. When the first tunnel section 522, the outlet gate well assembly 62, and the second tunnel section 523 (terminal outlet section) require maintenance due to external impact, wear, or siltation, simply closing this inlet gate well assembly 61 will completely isolate the first tunnel section 522 from the upstream side, such as the connecting tunnel 521 and the main reservoir area 1 of the reservoir. Subsequently, drainage, inspection, and repair of the first tunnel section 522, the outlet gate well assembly 62, and the second tunnel section 523 can be safely carried out.

[0048] By adjusting the opening of the outlet gate well assembly 62, the flow rate and velocity of the sand discharge tunnel 5 can be precisely controlled, allowing it to operate at the optimal sand transport velocity. This avoids excessive wear or low-speed siltation, effectively protecting the structural safety of the connecting tunnel 521, the first tunnel section 522, and the second tunnel section 523, reducing long-term erosion damage from high-speed sand-laden water flow, and extending the service life of the main body of the sand discharge tunnel 5.

[0049] The second tunnel section 523 can serve as an energy dissipation transition section. For example, energy dissipation structures (such as a widening section or a stilling sill) can be installed in the second tunnel section 523 to change pressurized flow into unpressurized flow, convert some potential energy into kinetic energy, and form a high-speed water flow. A spillway and a flow-dissipating sill are installed at the end, and the flow-dissipating energy is used to enter the center of the downstream discharge area 8. That is, the discharged water dissipates energy through friction with the air, collision with the riverbed water cushion, submerged turbulence, and collision with the riverbed.

[0050] Optionally, the temporary water-blocking structure is a cofferdam that can be detachably installed on the side of the inlet structure 4 near the confluence area 3, and the cofferdam is used to isolate the confluence area 3 from the main tunnel body 52.

[0051] Specifically, a cofferdam is a temporary water-retaining structure built in a body of water to create dry construction conditions during the construction of water conservancy, bridge, port and other water-related projects.

[0052] Cofferdams can be made of earth and rock, steel sheet piles, concrete, or double-walled steel, and are easy to dismantle later.

[0053] The cofferdam can be temporarily installed inside the intake structure 4 using bolts, anchors, or other means.

[0054] In this optional embodiment, a cofferdam is installed inside the already completed and stably supported intake structure 4, changing the working environment from "underwater in the field" to "dry indoor ground". The size and stress conditions of the cofferdam can be precisely designed, and the installation process is not affected by weather or hydrology, completely eliminating the major hydrogeological risks in traditional cofferdam construction, making the safety, schedule and quality of the water-blocking process completely controllable.

[0055] Optionally, combined Figure 3 As shown, the temporary water-blocking structure is a rock plug 51, which is located on the side of the inlet structure 4 near the confluence area 3. The main body of the tunnel 52 also includes a slag collection pit 524, which is located on the side of the rock plug 51 away from the confluence area 3 and is used to store the rock debris formed after the rock plug 51 is blasted. The inlet structure 4 is connected to the connecting tunnel 521 through the top of the slag collection pit 524.

[0056] Specifically, Rock Plug 51 is a rock barrier designed and reserved in advance to achieve a specific engineering goal for temporary water retention. It is not a permanent natural structure, but rather a product of artificial design and construction processes.

[0057] During the construction of the intake structure 4, before the main tunnel 52 is excavated and connected, a section of original rock with a certain safety thickness is reserved at the designed location of the intake structure 4 to serve as a rock plug 51. During construction, it is used to isolate the inflow area 3 from the main tunnel 52. It acts as a natural and reliable temporary water-retaining structure, isolating the reservoir water and ensuring the safety of the downstream main tunnel 52 construction. After construction is completed, it is demolished in one go by underwater blasting to form the intake structure 4 with the designed cross-section.

[0058] In this optional embodiment, the pre-set slag collection pit 524 is located directly behind the rock plug 51 and below the water flow channel. After blasting, most of the rock debris falls directly into the slag collection pit 524 under the influence of gravity and water flow, effectively being "captured" and stored. The water flows away through the channel at the top of the slag collection pit 524 (i.e., the connecting hole 521). This arrangement not only avoids severe erosion and wear of the connecting hole 521 and subsequent tunnel sections by high-speed rock debris, but also protects the safety of the permanent structure.

[0059] Optionally, combined Figure 3 As shown, the height from the top of the slag collection pit 524 to the end of the connecting hole 521 near the first hole section 522 gradually increases.

[0060] Specifically, the end of the connecting tunnel 521 near the first tunnel section 522 refers to the downstream end of the connecting tunnel 521; the top elevation of the slag collection pit 524 is lower than the downstream elevation of the connecting tunnel 521.

[0061] In this optional embodiment, the top of the slag collection pit 524 gradually rises to the downstream end of the connecting hole 521. This gradual structure not only guides the water flow to transition smoothly and effectively suppresses the generation of eddies and violent turbulence, but also creates a more stable and undisturbed storage environment for the sediment in the slag collection pit 524. This significantly reduces the risk of secondary activation of the sediment by the water flow during operation and ensures the long-term stable slag storage function of the slag collection pit 524.

[0062] The elevation gradually increases from the slag collection pit 524 to the connecting tunnel 521, which makes it difficult for the rock debris in the slag collection pit 524 to move upward to the connecting tunnel 521 and its downstream end under the action of gravity. This can further reduce the wear of the rock debris on the concrete lining of the connecting tunnel 521 and its downstream end.

[0063] Optionally, combined Figure 2 and Figure 3As shown, the height of the first hole section 522 gradually decreases from the end near the connecting hole 521 to the end away from the connecting hole 521.

[0064] Specifically, the end of the first hole segment 522 closest to the connecting hole 521 refers to the upstream end of the first hole segment 522; the end of the first hole segment 522 furthest from the connecting hole 521 refers to the downstream end of the first hole segment 522. Therefore, the upstream end of the first hole segment 522 is higher than the downstream end of the first hole segment 522.

[0065] In this optional embodiment, the vertical height of the first tunnel section 522 gradually decreases from the upstream end (the side connecting tunnel 521) to the downstream end (the second tunnel section 523 or the outlet side), forming a flow channel with a decreasing elevation along the flow direction. By utilizing the gradually downward slope from the upstream end to the downstream end of the first tunnel section 522, and taking advantage of the gravity and inertia of the sediment in the water flow, the sediment discharge efficiency of the first tunnel section 522 is increased, the risk of siltation in the first tunnel section 522 is reduced, and the long-term smooth operation and functional reliability of the sediment discharge system are ensured. Moreover, it significantly enhances the overall sediment carrying capacity of the first tunnel section 522, enabling the system to transport higher concentrations of sediment under the same head, or to effectively discharge sediment at lower flow rates, thereby improving the overall level of the sediment discharge ratio and operational flexibility.

[0066] The present invention provides a hydropower station including a main reservoir area 1, a tributary river channel 2, and a reservoir bypass sediment discharge system with a high sediment load tributary as described above, and also includes a turbine unit 7, wherein the end of the main reservoir area 1 away from the confluence area 3 is connected to the turbine unit 7.

[0067] Specifically, the main reservoir area 1 is the main reservoir area, which is mainly used to provide sufficient flood control and flood retention capacity for floods, provide sufficient clean water for industry and agriculture, and provide water source power for the turbine unit 7 to generate electricity.

[0068] Because the sediment entering the main reservoir area 1 from tributary 2 is largely intercepted by the reservoir bypass sediment discharge system of the tributary with high sediment content, the sediment content of the water in the main reservoir area 1 will be maintained at an extremely low level for a long time.

[0069] (1) With the existing sediment discharge facilities of the reservoir continuing to function, the bypass sediment discharge system and method of the present invention are used to intercept most of the high sediment content water flow in the tributary 2 outside the main sediment discharge reservoir area 1, so that the effective storage capacity of the reservoir can be gradually restored, the flood retention and flood control capacity of the reservoir can be improved, and the service life of the reservoir can be extended. (2) The sediment content of the reservoir is significantly reduced to a low level, the water quality is improved, and it can provide a valuable clean water source for industrial, agricultural and residential production and life. (3) When the sediment content of the water in the main reservoir 1 is maintained at an extremely low level for a long time, especially the coarse sediment content that has an abrasive effect on the turbine unit 7 is maintained at an extremely low level for a long time, this clear water is transported to the turbine unit 7 through the water diversion system, which has at least the following effects: for example, it greatly reduces the abrasion and damage of the sediment passing through the turbine unit 7 to the runner, guide vanes and other components; it significantly extends the overhaul interval and service life of the turbine unit 7; it reduces the efficiency decline caused by the wear of the turbine unit 7 and maintains the long-term stability of power generation efficiency; and it reduces the operation and maintenance costs and safety risks of the hydropower station.

[0070] The beneficial effects of the hydropower station in this embodiment compared to the prior art are the same as those of the above-mentioned reservoir bypass sediment discharge system with high sediment content tributaries, and will not be repeated here.

[0071] This invention provides a method for bypassing sediment removal from a reservoir with a high sediment-laden tributary, based on the aforementioned bypass sediment removal system for a reservoir with a high sediment-laden tributary, and includes the following steps: S1. When the tributary channel 2 enters the flood season, the high sediment load water flows into the confluence area 3 along the tributary channel 2. Under the action of gravity, it sinks into the bottom of the less dense water body in the confluence area 3 and continues to move downstream along the bottom of the confluence area 3 to form a high sediment load density flow.

[0072] Before step S1 above, the following construction work is also carried out. For example, at the inlet structure 4, a rock plug 51 is reserved to temporarily block water. Its thickness is determined by calculation to meet the water blocking requirements for construction safety. First, construction adits are excavated, such as the connecting tunnel 521 of the main tunnel 52, the first tunnel section 522 and the second tunnel section 523, as well as the inlet gate well assembly 61 and the outlet gate well assembly 62. Then, the emergency maintenance gate in the inlet gate well, the working arc gate of the second tunnel section 523, and all opening and closing equipment can be installed.

[0073] Once everything is ready, the underwater rock plug 51 is blasted open in one go using underwater rock plug blasting technology, so that the main reservoir area 1 or the inflow area can be connected to the connecting tunnel 521 through the inlet structure 4. The rock debris formed after the blast falls into the pre-dug slag collection pit 524. At this time, the entire sand discharge tunnel 5 is fully connected.

[0074] S2. The high-sediment-content density current moves to the mountain on the opposite bank. The inlet structure 4 is located on the path of the high-sediment-content density current. The tunnel axis of the inlet structure 4 is consistent with the direction of movement of the high-sediment-content density current and captures the high-sediment-content density current.

[0075] S3. Open the gate well assembly 6 to make the two ends of the sand discharge tunnel 5 connected. The high sand content density flow passes through the sand discharge tunnel 5 and the gate well assembly 6 in sequence and is discharged to the downstream receiving area 8, ensuring that the high sand content density flow does not enter the main reservoir area 1.

[0076] The beneficial effects of the reservoir bypass sediment discharge method with high sediment-laden tributaries in this embodiment compared to the prior art are the same as those of the reservoir bypass sediment discharge system with high sediment-laden tributaries described above, and will not be repeated here.

[0077] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A reservoir bypass sediment discharge system with a high sediment-laden tributary, applied to a hydropower station, the hydropower station comprising a main reservoir area (1) and a tributary channel (2) for transporting high sediment-laden water flow, the tributary channel (2) being connected to the main reservoir area (1), and the connection point between the two forming a confluence area (3) with density current, characterized in that, The hydropower station also includes a mountain on the opposite bank, which is located on the side of the main reservoir area (1) away from the tributary channel (2); the reservoir bypass sediment discharge system with a high sediment content tributary includes an inlet structure (4), a sediment discharge tunnel (5) and a gate well assembly (6) set in the mountain on the opposite bank. The inlet structure (4) is set in the confluence area (3) and is opposite to and spaced apart from the tributary channel (2). One end of the sediment discharge tunnel (5) is connected to the inlet structure (4). The end of the sediment discharge tunnel (5) away from the inlet structure (4) is used to connect to the downstream discharge area (8). The gate well assembly (6) is connected to the sediment discharge tunnel (5) and is used to control the connection or disconnection between the two ends of the sediment discharge tunnel (5).

2. The reservoir bypass sediment discharge system with a high sediment load tributary as described in claim 1, characterized in that, The sand discharge tunnel (5) includes a temporary water-blocking structure and a tunnel body (52). The temporary water-blocking structure is located at the front edge of the inlet structure (4). One end of the tunnel body (52) is connected to the end of the temporary water-blocking structure away from the confluence area (3). The other end of the tunnel body (52) is used to connect to the downstream discharge area (8).

3. The reservoir bypass sediment discharge system with a high sediment load tributary according to claim 2, characterized in that, The main body of the tunnel (52) includes a connecting tunnel (521) and a first tunnel section (522). One end of the connecting tunnel (521) is connected to the end of the temporary water-retaining structure away from the inflow area (3). One end of the first tunnel section (522) is connected to the end of the connecting tunnel (521) away from the temporary water-retaining structure. The end of the first tunnel section (522) away from the connecting tunnel (521) is used to connect to the downstream discharge area (8). The gate well assembly (6) includes an inlet gate well assembly (61). The inlet gate well assembly (61) is located at the connection between the connecting tunnel (521) and the first tunnel section (522).

4. The reservoir bypass sediment discharge system with a high sediment load tributary as described in claim 3, characterized in that, The main body of the tunnel (52) also includes a second tunnel section (523), the end of the first tunnel section (522) away from the connecting tunnel (521) is connected to the downstream discharge area (8) through the second tunnel section (523); the gate well assembly (6) also includes an outlet gate well assembly (62), the outlet gate well assembly (62) is disposed at the connection between the first tunnel section (522) and the second tunnel section (523).

5. The reservoir bypass sediment discharge system with a high sediment load tributary according to claim 2, characterized in that, The temporary water-blocking structure is a cofferdam that can be detachably installed on the side of the inlet structure (4) near the confluence area (3). The cofferdam is used to isolate the confluence area (3) from the main body of the tunnel (52).

6. The reservoir bypass sediment discharge system with a high sediment load tributary according to claim 3, characterized in that, The temporary water-blocking structure is a rock plug (51). The rock plug (51) is located on the side of the inlet structure (4) near the confluence area (3). The main body of the tunnel (52) also includes a slag collection pit (524). The slag collection pit (524) is located on the side of the rock plug (51) away from the confluence area (3) and is used to store the rock slag formed after the rock plug (51) is blasted. The inlet structure (4) is connected to the connecting tunnel (521) through the top of the slag collection pit (524).

7. The reservoir bypass sediment discharge system with a high sediment load tributary according to claim 6, characterized in that, The height from the top of the slag collection pit (524) to the end of the connecting hole (521) near the first hole section (522) gradually increases.

8. The reservoir bypass sediment discharge system with a high sediment load tributary according to claim 3, characterized in that, The height of the first hole section (522) gradually decreases from the end near the connecting hole (521) to the end away from the connecting hole (521).

9. A method for bypassing sediment discharge from a reservoir with a high sediment-laden tributary, based on the bypass sediment discharge system for a reservoir with a high sediment-laden tributary as described in any one of claims 1 to 8, characterized in that, Includes the following steps: When the tributary channel (2) enters the flood season, the high sediment load water flows into the confluence area (3) along the tributary channel (2). Under the action of gravity, it sinks into the bottom of the water body with lower density in the confluence area (3) and continues to move downstream along the bottom of the confluence area (3) to form a high sediment load density flow. The high-sediment-laden density current moves to the inlet structure (4) located in the opposite mountain, and the inlet structure (4) captures the high-sediment-laden density current. Open the gate well assembly (6) to make the two ends of the sand discharge tunnel (5) connected. The high sand content density flow passes through the sand discharge tunnel (5) and the gate well assembly (6) in sequence and is discharged to the downstream receiving area (8) to ensure that the high sand content density flow does not enter the main reservoir area (1).

10. A hydroelectric power station, characterized in that, The system includes a main reservoir area (1) and a tributary channel (2) as well as a reservoir bypass sediment discharge system with a high sediment load tributary as described in any one of claims 1 to 8, and also includes a turbine unit (7), wherein the end of the main reservoir area (1) away from the confluence area (3) is connected to the turbine unit (7).

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