Layout structure of flood discharge and sediment discharge tunnel of pumped storage reservoir project

Abstract

The utility model discloses a flood discharge and sand discharge hole arrangement structure of pumped storage reservoir engineering and construction diversion method in the technical field of water conservancy and hydropower engineering. The flood discharge and sand discharge hole arrangement structure of pumped storage reservoir engineering of sand not entering the reservoir, containing the reservoir main dam, still contains the sand retaining dam and the flood discharge and sand discharge hole, the sand retaining dam is located the upstream of reservoir main dam, the flood discharge and sand discharge hole import section is located the upstream of sand retaining dam, the flood discharge and sand discharge hole body section is through the mountain, and the flood discharge and sand discharge hole export section is located the downstream of reservoir main dam, the sand retaining dam still is provided with sand retaining dam water delivery hole, is used for the water delivery to sand retaining dam and reservoir main dam interval reservoir area. Through setting up sand retaining dam and retaining water in the upstream, and utilize flood discharge and sand discharge hole to arrange flood and sand to the downstream of reservoir main dam, utilize sand retaining dam water delivery hole to carry out initial water storage and operation period water supplement to the lower reservoir, make the lower reservoir become the special use reservoir, thereby avoid the influence of sand, form the new type pivot arrangement mode of sand not entering the reservoir pumped storage power station reservoir.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower engineering technology, specifically to a flood discharge and sediment flushing tunnel layout structure for a pumped storage reservoir project. Background Technology

[0002] Hydropower turbines in high-head, especially ultra-high-head, mountain rivers are highly sensitive to sediment. High sediment content in the water flow often causes severe erosion of the turbines and other structures, leading to frequent shutdowns for major repairs or replacements. This not only seriously affects the normal operation of the power station but also increases maintenance costs. In actual engineering projects, mountain river hydropower stations frequently encounter unfavorable conditions such as narrow river channels, large sediment loads, small reservoir capacity, and high sediment particle size.

[0003] To reduce the sediment content in high-head hydropower stations in mountainous areas, sedimentation basins are often installed upstream of the intake to reduce turbine wear and tear. However, this often results in high investment, increased engineering workload, and greater construction difficulty. Furthermore, narrow mountain rivers typically lack sufficient space for surface sedimentation basins, while underground basins pose significant geological risks, require substantial investment, and are not particularly effective at sedimentation. Some hydropower projects reduce the number of operating units during periods of high sedimentation to decrease the size of the sedimentation basin, but this reduces power generation.

[0004] Currently, the common method for diverting water during the construction of conventional pumped-storage power station reservoirs is to design a bypass diversion tunnel next to the permanent spillway tunnel of the main dam, combining the bypass diversion tunnel with the permanent spillway tunnel. However, this diversion arrangement has the following drawbacks: First, it still requires the separate construction of the bypass diversion tunnel, which alters the structural layout of the original permanent spillway tunnel and increases construction complexity; second, the flow through the bypass diversion tunnel inevitably carries solid impurities, causing some wear and tear on the permanent spillway tunnel structure, requiring comprehensive overhaul after sealing, increasing the repair construction period and cost; third, after the bypass diversion tunnel completes its diversion function, it still needs to be sealed and rebuilt, posing certain construction difficulties and safety hazards. Utility Model Content

[0005] To overcome the technical problems of existing high-head power stations using underground sedimentation basins, such as high geological risks and insignificant sedimentation effects, and pumped storage power stations with increased construction costs, long construction periods, and inconvenient construction due to the need for additional buildings, this utility model provides a flood discharge and sediment flushing tunnel layout structure for pumped storage reservoir projects.

[0006] The technical solution adopted by this utility model to solve its technical problem is:

[0007] The layout of the flood discharge and sediment flushing tunnel in the pumped storage reservoir project includes the main dam of the reservoir, as well as a sediment trap and a flood discharge and sediment flushing tunnel. The sediment trap is located upstream of the main dam, the inlet section of the flood discharge and sediment flushing tunnel is located upstream of the sediment trap, the tunnel body passes through the mountain, and the outlet section of the flood discharge and sediment flushing tunnel is located downstream of the main dam. The sediment trap is also equipped with a sediment trap water conveyance tunnel, which is used to convey water to the reservoir area between the sediment trap and the main dam.

[0008] In this invention, by setting up a silt-blocking dam upstream to block water and using a flood discharge tunnel to discharge floodwater and sediment downstream of the main dam of the reservoir, and using the silt-blocking dam's water conveyance tunnel to initially store water and replenish water during operation, the lower reservoir becomes a dedicated reservoir, thereby avoiding the impact of sediment and forming a new type of hub layout where sediment does not enter the pumped storage power station reservoir. Compared with existing technologies, this implementation has lower geological risks and better sediment prevention effect.

[0009] In some embodiments, a construction drainage tunnel is also included, with the inlet section of the construction drainage tunnel located in the reservoir area between the silt trap and the main dam, and the outlet section of the construction drainage tunnel connected to the flood discharge and silt removal tunnel section.

[0010] In some embodiments, the angle between the construction drainage tunnel and the flood discharge and sand discharge tunnel is greater than or equal to 50°.

[0011] In some embodiments, a permanent plug is provided at the connection point between the construction drainage tunnel and the flood discharge and sediment flushing tunnel to prevent water from flowing into the flood discharge and sediment flushing tunnel.

[0012] In some embodiments, both the construction drainage tunnel and the flood discharge and sediment flushing tunnel are in the form of unpressurized tunnels, and the cross-sections of both the construction drainage tunnel and the flood discharge and sediment flushing tunnel are in the shape of city gates.

[0013] In some embodiments, the bottom elevation of the outlet section of the construction drainage tunnel is higher than the flood level at the corresponding location connected to the construction drainage tunnel during the main flood season when the flood discharge and sediment discharge tunnel discharges a 20-year flood; it is also higher than the flood level at the corresponding location connected to the construction drainage tunnel during the 20-year flood season when the construction drainage tunnel is closed.

[0014] The beneficial effects of this utility model are:

[0015] By setting up a silt-blocking dam upstream to block water and using flood discharge tunnels to discharge floodwater and sediment downstream of the main dam of the reservoir, and using the silt-blocking dam's water conveyance tunnel to initially impound water and replenish water during operation, the lower reservoir becomes a dedicated reservoir, thus avoiding the impact of sediment and forming a new type of hub layout where sediment does not enter the pumped storage power station reservoir. Compared with existing technologies, this method has lower geological risks and better sediment prevention effect.

[0016] By strategically placing a construction drainage tunnel at a suitable location within the key section, the tunnel can serve different functions at different stages. During the construction phase of the flood discharge and sediment flushing tunnel, it acts as a transportation channel for construction. During the construction phase of the main dam, the designed drainage tunnel structure guides the flow during construction. During dam operation, sealing the drainage tunnel prevents water from the silt trap and the main dam from entering the flood discharge and sediment flushing tunnel, thus meeting the normal operation requirements of the tunnel. Compared to traditional layouts, this method eliminates the need for excavating and constructing a separate bypass diversion tunnel, shortens the construction period, and offers significant economic and time advantages.

[0017] Taking full advantage of the fact that the construction period of pumped storage power stations is generally longer than that of dam construction, the entire construction diversion was cleverly divided into two phases. In the first phase, the water diversion was carried out using the silt-retaining dam's water conveyance tunnel to divert and discharge the water coming from above the silt-retaining dam, meeting the diversion requirements for silt-retaining dam construction. In the second phase, the water diversion was carried out using the flood discharge and sediment flushing tunnel to discharge the water coming from above the silt-retaining dam, and the construction drainage tunnel to divert the water flow in front of the main dam of the reservoir. The flood discharge and sediment flushing tunnel and the construction drainage tunnel jointly diverted the water, meeting the diversion requirements for dam construction and realizing the multi-purpose function of the construction drainage tunnel.

[0018] The location where the construction drainage tunnel connects with the flood discharge and sediment flushing tunnel is such that the outlet of the construction drainage tunnel is higher than the greater of the design water level during the closure period and the flood season flow level. Firstly, being higher than the design water level during the closure period meets the requirements for closure before water impoundment, facilitates construction, and ensures construction safety. Secondly, being higher than the flood season flow level of the flood discharge and sediment flushing tunnel allows the water diverted by the construction drainage tunnel to smoothly merge with the flood discharge and sediment flushing tunnel. This significantly reduces wear on the permanent lining structure of the flood discharge and sediment flushing tunnel upon reaching the water surface, overcoming the shortcomings of previous methods where bypass diversion tunnels carrying solid materials could damage the permanent flood discharge tunnel. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the plan layout of the construction diversion structure disclosed in this utility model;

[0020] Figure 2 for Figure 1 A partially enlarged schematic diagram of the central silt-trapping dam;

[0021] Figure 3 for Figure 1 A partially enlarged schematic diagram of the main dam of the Zhongshui Reservoir.

[0022] The diagram is marked as follows: 1-1: Inlet section of flood discharge and sediment flushing tunnel; 1-2: Tunnel body section of flood discharge and sediment flushing tunnel; 1-3: Outlet section of flood discharge and sediment flushing tunnel; 2-1: Inlet section of construction drainage tunnel; 2-2: Tunnel body section of construction drainage tunnel; 2-3: Outlet section of construction drainage tunnel; 3: Sediment retaining dam; 4: Main dam of reservoir; 5: Water conveyance tunnel of sediment retaining dam; 6: Permanent flood discharge tunnel of main dam of reservoir. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0025] Combination Figures 1-3 As shown, this utility model provides a flood discharge and sediment flushing tunnel layout structure for a pumped storage reservoir project.

[0026] The layout structure of the flood discharge and sediment flushing tunnel of the pumped storage reservoir project includes the main dam 4 of the reservoir, as well as the sediment trap 3 and the flood discharge and sediment flushing tunnel. The sediment trap 3 is located upstream of the main dam 4 of the reservoir. The inlet section 1-1 of the flood discharge and sediment flushing tunnel is located upstream of the sediment trap 3. The tunnel body section 1-2 of the flood discharge and sediment flushing tunnel passes through the mountain. The outlet section 1-3 of the flood discharge and sediment flushing tunnel is located downstream of the main dam 4 of the reservoir. The sediment trap 3 is also equipped with a sediment trap water conveyance tunnel 5, which is used to convey water to the reservoir area between the sediment trap 3 and the main dam 4 of the reservoir.

[0027] In this utility model, by setting up a silt-blocking dam 3 upstream to block water, and using a flood discharge and silt-discharge tunnel to discharge floodwater and sediment to the downstream of the main dam 4 of the reservoir, and using the silt-blocking dam water conveyance tunnel 5 to initially store water and replenish water during operation, the lower reservoir becomes a dedicated reservoir, thereby avoiding the impact of sediment and forming a new type of hub layout where sediment does not enter the pumped storage power station reservoir. Compared with the existing technology, this implementation has lower geological risks and better sediment prevention effect.

[0028] In this embodiment, a construction drainage tunnel is included. The inlet section 2-1 of the construction drainage tunnel is located in the reservoir area between the silt trap 3 and the main dam of the reservoir. The outlet section 2-3 of the construction drainage tunnel is connected to the tunnel body section 1-2 of the flood discharge and silt removal tunnel.

[0029] In this embodiment, the angle between the construction drainage tunnel and the flood discharge and sediment flushing tunnel is 50°. Preferably, it should be greater than or equal to 50°. This arrangement avoids affecting traffic flow and facilitates its use as a construction passage for the flood discharge and sediment flushing tunnel.

[0030] In this embodiment, a permanent plug is installed at the connection point between the construction drainage tunnel and the flood discharge and sediment flushing tunnel to prevent water flow from entering the flood discharge and sediment flushing tunnel during the operation of the main dam of the reservoir.

[0031] In this embodiment, both the construction drainage tunnel and the flood discharge and sediment flushing tunnel are in the form of unpressurized tunnels. The 2-2 section of the construction drainage tunnel and the 1-2 section of the flood discharge and sediment flushing tunnel are both in the shape of city gates. The size of the cross-sections is designed to meet both the construction needs and the requirements for flood diversion.

[0032] In some embodiments, the bottom elevation of the outlet section 2-3 of the construction drainage tunnel is higher than the flood level at the corresponding connection point of the flood discharge tunnel and the construction drainage tunnel when the main flood season discharges a 20-year flood; it is also higher than the flood level at the corresponding connection point of the flood discharge tunnel and the construction drainage tunnel when the construction drainage tunnel is closed for a 20-year flood.

[0033] This configuration places the construction drainage tunnel at the junction with the flood discharge and sediment flushing tunnel, with the outlet of the construction drainage tunnel higher than the greater of the design water level during the closure period and the flood season flow level. Firstly, being higher than the design water level during the closure period meets the requirements for closure before water storage, facilitating construction and ensuring construction safety. Secondly, being higher than the flood season flow level of the flood discharge and sediment flushing tunnel allows the water diverted by the construction drainage tunnel to smoothly merge with the flood discharge and sediment flushing tunnel. The water falling onto the water surface significantly reduces wear on the permanent lining structure of the flood discharge and sediment flushing tunnel, overcoming the shortcomings of previous methods where bypass diversion tunnels carrying solid materials could damage the permanent flood discharge tunnel.

[0034] The construction diversion method used in the aforementioned pumped storage reservoir project includes the following steps:

[0035] Step S1. During the construction diversion preparation period, the construction drainage tunnel is constructed first. The inlet section 2-1 of the construction drainage tunnel is located in the reservoir area between the silt retention dam 3 and the main dam 4. The flood discharge and silt removal tunnel is excavated at the outlet section 2-3 of the construction drainage tunnel.

[0036] The construction drainage tunnel comprises the inlet section 2-1, the tunnel body section 2-2, and the outlet section 2-3. In practice, the locations of the sediment trap 3, the main reservoir dam 4, and the flood discharge and sediment flushing tunnel are always pre-designed based on the mountain range in which they are located. Here, the construction drainage tunnel is selected based on the pre-designed location.

[0037] After the construction of the drainage tunnel is completed in this stage, it will be used as a construction passage for the flood discharge and sediment flushing tunnel. Construction personnel and equipment will enter through the drainage tunnel to carry out the construction of the flood discharge and sediment flushing tunnel.

[0038] After the flood discharge and sediment flushing tunnel is completed and the flow conditions are met in step S1, the construction diversion period begins. The construction diversion period is divided into two phases: the construction diversion period of the sediment-blocking dam 3 and the construction diversion period of the main reservoir dam 4.

[0039] Step S20. During the construction and diversion period of the silt barrier 3, the water flows through the silt barrier dam water conveyance tunnel 5.

[0040] After the completion of the silt-trapping dam 3, the second diversion period will begin, which is the diversion period for the construction of the main dam 4.

[0041] During the diversion period of the main dam 4 construction, the water flow in front of the silt barrier 3 is blocked by the silt barrier 3 and discharged through the flood discharge and silt removal tunnel; the water flow of the main dam 4 is discharged through the construction drainage tunnel connected to the flood discharge and silt removal tunnel.

[0042] Specifically, the diversion period for the construction of the main dam of the reservoir includes:

[0043] Step S21. Initial diversion period: The water in front of the silt-retaining dam 3 is blocked by the silt-retaining dam 3 and discharged to the downstream through the flood discharge and sediment flushing tunnel; the water in the section in front of the main dam 4 of the reservoir is blocked by the cofferdam and discharged through the construction drainage tunnel connected to the flood discharge and sediment flushing tunnel to meet the design flow requirements of the flood in the section. The focus of this stage is on the excavation of the dam foundation and the filling of the dam body.

[0044] Step S22. Mid-to-late stage of diversion: After the main dam 4 of the reservoir is filled beyond the cofferdam, it enters the mid-to-late stage of diversion. The water in front of the silt-blocking dam 3 is blocked by the silt-blocking dam 3 and discharged to the downstream through the flood discharge and sediment flushing tunnel. It is required to meet the flood discharge requirements of the design flood in front of the silt-blocking dam 3. The water in the section in front of the main dam 4 of the reservoir is blocked by the temporary section of the dam and discharged through the construction drainage tunnel connected to the flood discharge and sediment flushing tunnel. It meets the design flow requirements of the flood in the section and the dam body filling continues.

[0045] Step S3. Before water impoundment, the construction drainage tunnel is sealed. During the sealing period, a temporary water-retaining cofferdam is built at the entrance of the construction drainage tunnel. Construction personnel and equipment enter from the entrance to the exit of the construction drainage tunnel to carry out the sealing construction. The design length of the sealing body must meet the water-retaining requirements of the normal water level. During the sealing period, the water flow is pumped to the permanent flood discharge tunnel 6 of the main dam of the reservoir and then discharged downstream, thereby ensuring the safety of the sealing construction in the construction drainage tunnel.

[0046] Step S4. During the water storage period, after the construction of the drainage tunnel is completed, water is released into the section through the upstream silt-blocking dam water conveyance tunnel 5, so that the reservoir is filled to the normal water level to meet the needs of the pumped storage power station.

[0047] Step S5. During the dam operation period, the construction drainage tunnel is in a blocked state. The construction drainage tunnel plug blocks the flood in the reservoir area to prevent the reservoir water from entering the flood discharge and sediment discharge tunnel, so as to meet the needs of the normal operation of the flood discharge and sediment discharge tunnel.

[0048] In this invention, by arranging a construction drainage tunnel at a suitable location within the hub section, the construction drainage tunnel can serve different functions at different stages. During the construction period of the flood discharge and sediment flushing tunnel, the construction drainage tunnel serves as a traffic channel for the construction of the flood discharge and sediment flushing tunnel; during the construction period of the main dam of the reservoir, the designed construction drainage tunnel structure plays a role in guiding the flow during construction; during the dam operation period, by sealing the construction drainage tunnel, the water flow from the reservoir area between the sediment trap 3 and the main dam is prevented from entering the flood discharge and sediment flushing tunnel, thus meeting the normal operation and flow requirements of the flood discharge and sediment flushing tunnel. Compared with the traditional arrangement, it eliminates the need to excavate and pour a separate bypass diversion tunnel structure, shortens the construction period, and has good economic benefits and time advantages.

[0049] The construction diversion method disclosed in this utility model fully utilizes the characteristic that the construction period of a pumped storage power station is controlled during the powerhouse construction, not the dam construction. It cleverly divides the entire construction diversion period into two stages. The first stage meets the construction diversion requirements of the silt-retaining dam 3; the second stage fully utilizes the drainage function of the flood discharge and silt-removal tunnel, making it also serve as a diversion channel for dam construction, thus achieving a multi-purpose function of one tunnel and eliminating the need to construct a new dam diversion tunnel. This method offers significant economic and time efficiency benefits.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. The layout structure of the flood discharge and sediment discharge tunnel of the pumped storage reservoir project, comprising a reservoir main dam (4), characterized in that, It also includes a silt-retaining dam (3) and a flood discharge and sediment flushing tunnel. The silt-retaining dam (3) is located upstream of the main dam (4) of the reservoir. The inlet section (1-1) of the flood discharge and sediment flushing tunnel is located upstream of the silt-retaining dam (3). The tunnel body section (1-2) of the flood discharge and sediment flushing tunnel passes through the mountain. The outlet section (1-3) of the flood discharge and sediment flushing tunnel is located downstream of the main dam (4) of the reservoir. The silt-retaining dam (3) is also equipped with a silt-retaining dam water conveyance tunnel (5) for conveying water to the reservoir area between the silt-retaining dam (3) and the main dam (4).

2. The layout of the flood discharge and sediment discharge tunnel of the pumped storage power station according to claim 1, wherein, It also includes a construction drainage tunnel. The inlet section (2-1) of the construction drainage tunnel is located in the reservoir area between the silt-blocking dam (3) and the main dam (4). The outlet section (2-3) of the construction drainage tunnel is connected to the tunnel body section (1-2) of the flood discharge and silt removal tunnel.

3. The layout of the flood discharge and sediment discharge tunnel of the pumped storage power station according to claim 2, wherein, The angle between the construction drainage tunnel and the flood discharge and sand removal tunnel is greater than or equal to 50°.

4. The layout of the flood discharge and sediment discharge tunnel of the pumped storage power station according to claim 2, wherein, Permanent plugs are installed at the connection points between the construction drainage tunnel and the flood discharge and sediment flushing tunnel to prevent water from flowing into the flood discharge and sediment flushing tunnel.

5. The flood discharge and sediment flushing tunnel layout structure of the pumped storage reservoir project as described in claim 2, characterized in that, Both the construction drainage tunnel and the flood discharge and sand discharge tunnel are in the form of unpressurized tunnels. The cross-section of the construction drainage tunnel section (2-2) and the cross-section of the flood discharge and sand discharge tunnel section (1-2) are both in the shape of a city gate.

6. The flood discharge and sediment flushing tunnel layout structure of the pumped storage reservoir project as described in any one of claims 1-5, characterized in that, The bottom elevation of the drainage tunnel outlet section is higher than the flood level at the connection point between the drainage tunnel and the construction drainage tunnel during the main flood season when the drainage tunnel discharges a 20-year flood; it is also higher than the flood level at the connection point between the drainage tunnel and the construction drainage tunnel during the closure period of the construction drainage tunnel when the drainage tunnel discharges a 20-year flood.

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