A diversion tunnel alternative flow staging gate closing water storage structure and method

Abstract

The application discloses a diversion tunnel alternating flow staging gate closing water storage structure and method, relates to the technical field of water conservancy and hydropower construction, and comprises a first diversion tunnel, a second diversion tunnel and a three-face stoplog gate, the first diversion tunnel is provided with a first water inlet and a first water outlet at two ends, and is further provided with a third water inlet, the setting height of the third water inlet is higher than that of the first water inlet; the first diversion tunnel is further provided with a first gate slot and a third gate slot, and the first gate slot and the third gate slot are located at the front and rear of the third water inlet respectively; the second diversion tunnel is provided with a second water inlet and a second water outlet at two ends, the setting height of the second water inlet is higher than that of the first water inlet and is lower than that of the third water inlet; the second diversion tunnel is vertically provided with a second gate slot at the second water inlet; and the stoplog gate is formed by parallel and coplanar splicing of a plurality of baffles. The application can solve the problem that the downstream river channel cannot be effectively prevented from being dehydrated and cut off under the premise of ensuring economy and safety.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower construction technology, specifically to a phased impoundment structure and method for alternating flow through a diversion tunnel. Background Technology

[0002] In the construction of water conservancy and hydropower projects, diversion is a core element to ensure the smooth construction of dams on dry land. For rivers with large flow rates, two or more diversion tunnels are often arranged to form a group of diversion tunnels. After the diversion tunnels have completed their diversion tasks during the construction period, they must be closed or rebuilt to allow the reservoir water level to gradually rise to the normal storage level required for power generation or water supply.

[0003] The impoundment of water in a reservoir is a crucial transition point from the construction phase to the operational phase of a water conservancy and hydropower project. Diversion tunnel gates typically feature low elevation, large orifice size, and high sealing head, resulting in relatively large gate sizes. After the diversion tunnel gates are closed, but before the water level rises to the overflow elevation of the permanent spillway, upstream water cannot flow downstream, potentially causing the downstream river to dry up. Therefore, during the impoundment period, it is essential to ensure the basic ecological flow of the downstream river channel to prevent dehydration and flow interruption.

[0004] To address the issue of phased water storage and ensuring ecological flow, existing technologies have proposed several solutions: The first type is the diversion bottom outlet scheme. High arch dams typically have diversion bottom outlets installed at lower elevations within the dam body to reduce the safety risks of dam closure, while simultaneously meeting the downstream ecological water supply needs during mid-to-late stage diversion and initial impoundment. However, arranging diversion bottom outlets within the dam body complicates the dam structure and stress distribution, occupies a significant portion of the dam construction period, and results in substantial investment.

[0005] The second type is the phased closure and sealing scheme of diversion tunnel groups. Multiple diversion tunnels are closed in batches, with the remaining diversion tunnels remaining to continue the flow during the flood season after the first batch is closed. However, this scheme requires high water head at the sealing gates, large hoisting capacity, and high investment. For projects with complex inlet geological conditions, the safety risk of the inlet structure during high water head operation is significant.

[0006] The third category is the ecological flow release scheme within the diversion tunnel. The flow through the diversion tunnel meets the requirements for ecological flow and water level connection downstream of the dam, and an additional tunnel plug is installed for energy dissipation. However, the hydraulic risks are significant during high-head operation, and the energy dissipation problem at the outlet is particularly prominent.

[0007] The fourth type is a stepped structure scheme for continuous release of ecological flow. A bypass tunnel is constructed between the diversion tunnel and the spillway tunnel, with the gate sill elevations of the three sections increasing sequentially. This stepped arrangement allows for continuous release of ecological flow. However, this scheme requires the excavation of a dedicated bypass tunnel, increasing the amount of engineering work and investment. Furthermore, the control system for coordinating the operation of multiple gates is more complex.

[0008] In summary, the existing technologies described above have the following drawbacks and shortcomings: First, the contradiction between impounding water and releasing ecological flow has not been systematically resolved. In traditional schemes, the downstream river faces the risk of flow interruption after the diversion tunnel gates are closed and before the water level rises to the overflow elevation of the permanent spillway structure. The pre-buried ecological pipeline scheme has a limited flow regulation range; the bypass tunnel scheme involves large-scale engineering, high investment, and additional construction time. At the same time, when using the bypass tunnel to release ecological flow, there are problems such as excessively high flow velocity inside the tunnel, water flow impacting the diversion tunnel sidewall structure, turbulent flow, and severe splashing, which have a certain impact on the structural safety of the diversion tunnel.

[0009] Second, there is a lack of systematic solutions for precise control of reservoir water levels during phased impoundment. Existing solutions mostly rely on the fixed inlet elevation of the diversion tunnel and the fully open / fully closed state of the gates to control the water level: if flat steel gates are used, the flow conditions in the gate slot are poor when partially opened under dynamic water conditions, which can easily induce gate vibration and cavitation, resulting in high technical risks; if arc-shaped gates are used, although they can adapt to partial opening operations, the controlled discharge operation time is limited and the investment is high.

[0010] Third, traditional blocking gates have high water head and require large investments. In conventional blocking schemes for diversion tunnel groups, the upstream water level needs to be raised to a certain elevation after all diversion tunnels are closed to meet the discharge requirements. This results in the blocking gates having to withstand extremely high water head, requiring large hoist capacity and investment, and posing high safety risks to the inlet structure.

[0011] Therefore, this application is hereby submitted. Summary of the Invention

[0012] The purpose of this invention is to provide a phased sluice gate impoundment structure and method for alternating flow through diversion tunnels, which solves the problem of downstream river channel dehydration and flow interruption under the premise of ensuring economy and safety.

[0013] This invention is achieved through the following technical solution: A phased impoundment structure with alternating flow through diversion tunnels includes: a first diversion tunnel, one end of which has a first inlet and the other end has a first outlet; a third inlet is located at the end of the first diversion tunnel with the first inlet, the height of the third inlet being higher than that of the first inlet; the first diversion tunnel has a vertically formed first gate slot and a third gate slot, the first gate slot and the third gate slot being located in front of and behind the third inlet, respectively; and a second diversion tunnel, which is connected to the first diversion tunnel... The tunnels are arranged in parallel. At each end of the second diversion tunnel, a second water inlet and a second water outlet are respectively opened. The second water inlet is located on the same side as the first water inlet. The height of the second water inlet is higher than that of the first water inlet and lower than that of the third water inlet. The second diversion tunnel has a vertically opened second door slot, which is located at the second water inlet. There are three stacked beam doors, which are detachably connected to the first door slot, the second door slot and the third door slot respectively. The stacked beam doors are composed of multiple parallel and coplanar baffles spliced ​​together.

[0014] In another preferred embodiment, both the first inlet and the second inlet are horizontally opened and are opened along the length direction of the first diversion tunnel or the length direction of the second diversion tunnel.

[0015] In another preferred embodiment, the dimensions of the first inlet and the second inlet gradually decrease from the outside to the inside to form a funnel shape, and the outer dimensions of the first inlet and the second inlet are larger than the inner dimensions of the first diversion tunnel and the second diversion tunnel.

[0016] In another preferred embodiment, the third inlet is opened longitudinally and is located at the top of the first diversion tunnel.

[0017] In another preferred embodiment, a vertical shaft is vertically installed at the top of the end of the first diversion tunnel where the first inlet is located, so as to form the third inlet at the top of the shaft; the top of the shaft is installed at a height higher than the top of the first diversion tunnel.

[0018] In another preferred embodiment, the first door slot and the third door slot are respectively opened on opposite sides of the vertical shaft, so that the vertical shaft is sandwiched between the first door slot and the third door slot; the first door slot is located near the first water inlet, and the third door slot is located near the first drain outlet.

[0019] In another preferred embodiment, the first gate slot, the second gate slot, and the third gate slot are all U-shaped slots; the first gate slot and the third gate slot are excavated in the side wall and bottom wall of the first diversion tunnel and penetrate through the top wall of the first diversion tunnel; the second gate slot is excavated in the side wall and bottom wall of the second diversion tunnel and penetrates through the top wall of the second diversion tunnel.

[0020] In another preferred embodiment, the stacked beam door is detachably plugged into the first door slot, the second door slot, and the third door slot in the vertical direction.

[0021] In another preferred embodiment, the baffle is rectangular, and adjacent baffles are stacked parallel to each other. Each baffle is detachably inserted into the first door slot, the second door slot, or the third door slot in the vertical direction.

[0022] A method for staged impoundment of water with alternating flow through diversion tunnels, applicable to any of the aforementioned staged impoundment structures with alternating flow through diversion tunnels, includes the following steps: S1. Install the baffles sequentially in the first door slot and begin water storage; S2. When the reservoir water level rises above the set height of the second inlet, the first gate slot is completely closed through the stacked beam gate. S3. Construct a temporary plug inside the first diversion tunnel; S4. After the temporary plug in the first diversion tunnel is completed, the baffle is installed in the second portal slot one by one. S5. When the reservoir water level rises above the set height of the third inlet, the second gate slot is completely closed through the stacked beam gate. S6. Construct a permanent plug at one end of the second diversion tunnel near the second drainage outlet; S7. After the permanent plug in the second diversion tunnel is completed, construct the permanent spillway structure of the dam. S8. After the construction of the permanent spillway structure of the dam is completed, the baffle is installed sequentially in the third gate slot; S9. Once the discharge flow of the dam's permanent spillway structure meets the downstream ecological flow requirements, the third gate slot will be completely closed through the stacked beam gate. S10. Construct a permanent plug at one end of the first diversion tunnel near the first drainage outlet.

[0023] The present invention, by adopting the above-mentioned technical solution, has the following positive effects compared with the prior art: This invention discloses a phased impoundment structure for alternating flow through a diversion tunnel: (1) By combining the overflow at the top of the stacked beam gate with the alternating flow of the double holes, water can be continuously discharged in each water storage stage, eliminating the risk of downstream flow interruption caused by the closure of the gate for water storage. There is no time window when there is no water discharge downstream, thus ensuring the downstream ecological flow during the closure of the gate for water storage and avoiding the dehydration and flow interruption of the river. (2) By using the combination method of embedding the baffles of the stacked beam gate into the gate slot one by one, the elevation of the water-blocking top can be flexibly adjusted by increasing or decreasing the number of baffles, so that the reservoir water level can be locked at the predetermined elevation and remain stable at each stage, forming a water-blocking system that can be controlled in stages, thereby realizing the refined staged control of the reservoir water level and reducing the engineering risk of one-time gate closure and water storage. (3) The use of a stacked beam gate structure made of baffles to replace the large integral steel gate as the sealing equipment at each stage eliminates the need to install a large-capacity fixed winch or hydraulic hoist in the inlet tower, which simplifies the structural size and stress system of the inlet tower, saves project investment, and simplifies the inlet structure of the diversion tunnel, reducing equipment investment and construction difficulty. (4) After the phased water storage and flow-through task is completed, the third inlet of the first diversion tunnel can be retained and transformed into a permanent flood discharge facility as needed for the project, so as to further leverage the long-term benefits of the existing structure and improve the efficiency of structural reuse. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 A top view schematic diagram of a phased impoundment structure for alternating flow through a diversion tunnel, provided by the present invention; Figure 2 A side sectional view of the first diversion tunnel in a phased impoundment structure with alternating flow through diversion tunnels provided by the present invention. Figure 3 This is a side sectional view of the second diversion tunnel in a phased impoundment structure for alternating flow through diversion tunnels, as provided by the present invention.

[0025] The attached diagram shows the markings and corresponding component names: 10-First diversion tunnel; 11-First inlet; 12-First outlet; 13-Third inlet; 14-First portal; 15-Third portal; 20-Second diversion tunnel; 21-Second inlet; 22-Second outlet; 23-Second portal; 30-Stacked beam portal; 40-Temporary plug; 41-First permanent plug; 42-Second permanent plug. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "lateral", and "vertical" are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0028] It should be noted that the terms "horizontal" and "vertical" in this invention are used to describe approximate positional relationships, and not strictly "horizontal plane" or "vertical plane". Example

[0029] Please refer to Figures 1 to 3 As shown, this embodiment provides a phased sluice gate impoundment structure with alternating flow through diversion tunnels, including: a first diversion tunnel 10, with a first inlet 11 at one end and a first outlet 12 at the other end; a third inlet 13 at the end of the first diversion tunnel 10 with the first inlet 11, the third inlet 13 being positioned at a higher height than the first inlet 11; the first diversion tunnel 10 having a first gate slot 14 and a third gate slot 15 vertically, the first gate slot 14 and the third gate slot 15 being located in front of and behind the third inlet 13, respectively; and a second diversion tunnel 20, the second diversion tunnel 20 being connected to the first diversion tunnel 10. The diversion tunnel 10 is arranged in parallel. The two ends of the second diversion tunnel 20 are respectively opened with a second inlet 21 and a second outlet 22. The second inlet 21 is located on the same side as the first inlet 11. The setting height of the second inlet 21 is higher than that of the first inlet 11 and lower than that of the third inlet 13. The second diversion tunnel 20 has a vertically opened second door slot 23, which is located at the second inlet 21. The third includes a three-sided stacked beam door 30. The three sides of the stacked beam door 30 are respectively detachably connected to the first door slot 14, the second door slot 23 and the third door slot 15. The stacked beam door 30 is composed of multiple baffles that are parallel and coplanar spliced ​​together.

[0030] The phased impoundment structure with alternating flow through the diversion tunnel disclosed in this embodiment, through the combination of top overflow of the stacked beam gate 30 and alternating flow through the two tunnels, ensures continuous water discharge in each impoundment stage, eliminating the risk of downstream flow interruption caused by impoundment. There are no time windows of no downstream water discharge throughout the entire process, thus guaranteeing downstream ecological flow and preventing river dehydration and flow interruption during impoundment. Utilizing the method of embedding the baffles of the stacked beam gate 30 piece by piece into the gate slot, the elevation of the water-retaining top can be flexibly adjusted by increasing or decreasing the number of baffles, ensuring that the reservoir water level can be locked at a predetermined elevation and remain stable in each stage. This constitutes a graded and controllable backwater system, thereby achieving reservoir... The refined, phased control of water levels reduces the engineering risks associated with a single impoundment. The use of a stacked beam gate structure (30mm) made of baffles instead of a large integral steel gate for each stage of sealing eliminates the need for a large-capacity fixed winch or hydraulic hoist within the inlet tower, simplifying the inlet tower's structural dimensions and stress system, saving on project investment, and thus simplifying the inlet structure of the diversion tunnel, reducing equipment investment and construction difficulty. After completing the phased impoundment and flow control, the third inlet of the first diversion tunnel can be retained and converted into a permanent flood discharge facility as needed, further maximizing the long-term benefits of the existing structure and improving structural reuse efficiency.

[0031] In order to limit the opening direction of the first inlet 11 and the second inlet 21 and ensure the diversion effect, the first inlet 11 and the second inlet 21 are both opened horizontally and along the length direction of the first diversion tunnel 10 or the length direction of the second diversion tunnel 20.

[0032] In order to further improve the confluence effect of the first inlet 11 and the second inlet 21, the size of the first inlet 11 and the second inlet 21 gradually decreases from the outside to the inside to form a funnel shape, and the size of the outer end of the first inlet 11 and the second inlet 21 is larger than the internal size of the first diversion tunnel 10 and the second diversion tunnel 20.

[0033] To further explain the arrangement of the third inlet 13, the third inlet 13 is opened longitudinally and is located at the top of the first diversion tunnel 10.

[0034] To further explain the specific structure of the third inlet 13, a vertical shaft is vertically installed at the top of the end of the first diversion tunnel 10 where the first inlet 11 is located, so that the third inlet 13 is formed at the top of the shaft; the height of the top of the shaft is higher than the height of the top of the first diversion tunnel 10.

[0035] To further explain the location of the first door slot 14 and the third door slot 15, the first door slot 14 and the third door slot 15 are respectively opened on opposite sides of the vertical shaft, so that the vertical shaft is sandwiched between the first door slot 14 and the third door slot 15; the first door slot 14 is located near the first water inlet 11, and the third door slot 15 is located near the first drain outlet 12.

[0036] To further explain the specific structure of the first gate slot 14, the second gate slot 23, and the third gate slot 15, the first gate slot 14, the second gate slot 23, and the third gate slot 15 are all U-shaped slots; the first gate slot 14 and the third gate slot 15 are excavated in the side wall and bottom wall of the first diversion tunnel 10 and penetrate through the top wall of the first diversion tunnel 10; the second gate slot 23 is excavated in the side wall and bottom wall of the second diversion tunnel 20 and penetrates through the top wall of the second diversion tunnel 20.

[0037] The above configuration creates a U-shaped slot, which facilitates the insertion and fixing of the baffle of the stacked beam door 30.

[0038] To further optimize the insertion structure between the stacked beam door 30 and the door slot, the stacked beam door 30 is detachably inserted into the first door slot 14, the second door slot 23 and the third door slot 15 in the vertical direction.

[0039] With the above setup, gravity is used to allow the 30-panel door to naturally slide into the door groove, and fits tightly.

[0040] To further explain the specific shape of the baffle, the baffle is rectangular and adjacent baffles are stacked in parallel and tightly. Each baffle is detachably inserted into the first door slot 14, the second door slot 23, or the third door slot 15 in the vertical direction.

[0041] This embodiment also provides a staged impoundment method for alternating flow through diversion tunnels, applicable to the staged impoundment structure for alternating flow through diversion tunnels described in any of the above embodiments, comprising the following steps: S1. Install the baffles sequentially in the first door slot 14 and start storing water; During this stage, the number of baffles embedded in the first gate slot 14 is adjusted according to the rising water level of the reservoir. By controlling the overflow elevation at the top of the stacked beam gate 30, the water level and water demand are precisely regulated, while ensuring that the water exceeding the top of the stacked beam gate 30 is discharged to protect the downstream ecological flow.

[0042] S2. When the reservoir water level rises above the set height of the second inlet 21, the first gate slot 14 is completely closed through the stacked beam gate 30. After closure, the water will be discharged through the second diversion tunnel 20, creating dry conditions for the construction of a temporary plug 40 inside the first diversion tunnel 10.

[0043] S3. Construct a temporary plug 40 inside the first diversion tunnel 10; S4. After the temporary plug 40 in the first diversion tunnel 10 is constructed, the baffle is installed in the second gate slot 23 one by one. At the same time, the number of baffles in the stacked beam gate 30 is adjusted to control the water level and water storage capacity. As the reservoir water level continues to rise, the water exceeding the top of the stacked beam gate 30 is discharged through the second diversion tunnel to ensure downstream ecological flow.

[0044] S5. When the reservoir water level rises above the set height of the third inlet 13, the second gate slot 23 is completely closed through the stacked beam gate 30. Once closed, the entire flow of the second diversion tunnel 20 will be cut off, providing dry conditions for the construction of the second permanent plug 42 inside the second diversion tunnel 20. Subsequently, the downstream ecological flow will be discharged from the third inlet 13 of the first diversion tunnel 10.

[0045] S6. Construct a second permanent plug 42 at one end of the second diversion tunnel 20 near the second drainage outlet 22; S7. After the second permanent plug 42 in the second diversion tunnel 20 is completed, construct the permanent spillway structure of the dam. S8. After the construction of the permanent spillway structure of the dam is completed, the baffle is installed sequentially in the third gate slot 15; S9. When the discharge flow of the permanent spillway structure of the dam meets the downstream ecological flow requirements, the third gate slot 15 is completely closed through the stacked beam gate 30. After closure, the entire flow of the first diversion tunnel 10 can be cut off, thus providing dry conditions for the construction of the first permanent plug 41 within the first diversion tunnel 10.

[0046] S10. Construct a first permanent plug 41 at one end of the first diversion tunnel 10 near the first drainage outlet 12.

[0047] After the completion of the first permanent plug 41, the diversion phase of water storage was completed, and the reservoir entered the permanent operation and scheduling phase.

[0048] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A phased impoundment structure for alternating flow through a diversion tunnel, characterized in that, include: A first diversion tunnel (10) has a first inlet (11) at one end and a first outlet (12) at the other end. A third inlet (13) is located at the end of the first diversion tunnel (10) where the first inlet (11) is located. The height of the third inlet (13) is higher than that of the first inlet (11). The first diversion tunnel (10) has a first gate slot (14) and a third gate slot (15) vertically. The first gate slot (14) and the third gate slot (15) are located in front of and behind the third inlet (13), respectively. The second diversion tunnel (20) is arranged parallel to the first diversion tunnel (10). The second diversion tunnel (20) has a second inlet (21) and a second outlet (22) at its two ends. The second inlet (21) is located on the same side as the first inlet (11). The height of the second inlet (21) is higher than that of the first inlet (11) and lower than that of the third inlet (13). The second diversion tunnel (20) has a vertical second door slot (23) located at the second inlet (21). The three-sided stacked beam door (30) is detachably connected to the first door slot (14), the second door slot (23) and the third door slot (15) respectively. The stacked beam door (30) is made of multiple parallel and coplanar baffles spliced ​​together.

2. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 1, characterized in that, Both the first inlet (11) and the second inlet (21) are opened horizontally and along the length of the first diversion tunnel (10) or the second diversion tunnel (20).

3. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 2, characterized in that, The dimensions of the first inlet (11) and the second inlet (21) gradually decrease from the outside to the inside to form a funnel shape, and the outer dimensions of the first inlet (11) and the second inlet (21) are larger than the inner dimensions of the first diversion tunnel (10) and the second diversion tunnel (20).

4. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 3, characterized in that, The third inlet (13) is opened longitudinally and is located at the top of the first diversion tunnel (10).

5. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 4, characterized in that, A vertical shaft is vertically installed at the top of one end of the first diversion tunnel (10) where the first water inlet (11) is located, so that the third water inlet (13) is formed at the top of the shaft. The top of the shaft is set at a height higher than the top of the first diversion tunnel (10).

6. The staged impoundment structure with alternating flow through the diversion tunnel according to claim 5, characterized in that, The first door slot (14) and the third door slot (15) are respectively opened on opposite sides of the vertical shaft, so that the vertical shaft is sandwiched between the first door slot (14) and the third door slot (15); The first door slot (14) is located near the first water inlet (11), and the third door slot (15) is located near the first drain outlet (12).

7. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 6, characterized in that, The first door groove (14), the second door groove (23) and the third door groove (15) are all U-shaped grooves; The first gate slot (14) and the third gate slot (15) are excavated on the side wall and bottom wall of the first diversion tunnel (10) and penetrate the top wall of the first diversion tunnel (10); The second gate slot (23) is excavated on the side wall and bottom wall of the second diversion tunnel (20) and penetrates the top wall of the second diversion tunnel (20).

8. The staged impoundment structure with alternating flow through the diversion tunnel as described in claim 7, characterized in that, The stacked beam door (30) is detachably plugged into the first door slot (14), the second door slot (23) and the third door slot (15) in the vertical direction.

9. The staged impoundment structure for alternating flow through the diversion tunnel according to claim 8, characterized in that, The baffle is rectangular in shape, and the adjacent baffles are stacked in parallel and tightly. Each baffle is detachably inserted into the first door slot (14), the second door slot (23), or the third door slot (15) in the vertical direction.

10. A method for staged impoundment of water using alternating flow through a diversion tunnel, characterized in that, The staged impoundment structure for alternating flow through diversion tunnels as described in any one of claims 1-9 includes the following steps: S1. Install the baffles one by one in the first door slot (14) and start storing water; S2. When the reservoir water level rises above the set height of the second inlet (21), the first gate slot (14) is completely closed through the stacked beam gate (30); S3. Construct a temporary plug inside the first diversion tunnel (10); S4. After the temporary plug in the first diversion tunnel (10) is completed, the baffle is installed in the second gate slot (23) one by one. S5. When the reservoir water level rises above the setting height of the third inlet (13), the second gate slot (23) is completely closed through the stacked beam gate (30); S6. Construct a permanent plug at one end of the second diversion tunnel (20) near the second drainage outlet (22); S7. After the permanent plug in the second diversion tunnel (20) is completed, construct the permanent spillway structure of the dam. S8. After the construction of the permanent spillway structure of the dam is completed, the baffle is installed in the third gate slot (15) one by one; S9. When the discharge flow of the permanent spillway structure of the dam meets the downstream ecological flow requirements, the third gate slot (15) is completely closed through the stacked beam gate (30); S10. Construct a permanent plug at one end of the first diversion tunnel (10) near the first drainage outlet (12).

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