Construction method of bidirectional retaining dam of pumped storage power station

Abstract

The invention discloses a construction method of a two-way retaining dam of a pumped storage power station. The two-way retaining dam of the pumped storage power station comprises a dam body and a reservoir surrounding road poured at the top of the dam body. The dam body comprises a main rockfill area formed by filling reservoir basin excavation materials, and further comprises an upstream transition layer, an upstream cushion layer and an upstream face plate which are laid on the upstream of the main rockfill area in sequence, and further comprises a downstream transition layer, a downstream cushion layer and a downstream face plate which are laid on the downstream of the main rockfill area in sequence, and a drainage system filled below the main rockfill area. The main rock-fill area serves as a dam body, the upstream and the downstream of the main rock-fill area are both provided with the concrete panels, the bottom of the dam body is filled with a drainage system composed of the drainage layer, the drainage floral tubes and the drainage galleries, the stability of the two-way water retaining dam is improved, and the two-way water retaining requirement can be met.

Description

Technical Field

[0001] This invention relates to the field of pumped storage engineering, and in particular to a construction method for a bidirectional dam of a pumped storage power station. Background Technology

[0002] Pumped-storage hydroelectric power stations, also known as pumped-storage hydroelectric power stations, utilize electricity generated during periods of low electricity demand to pump water into an upper reservoir, and then release the water into a lower reservoir to generate electricity during periods of high electricity demand. During pumping operation, the water level in the upper reservoir continuously rises, while the water level in the lower reservoir (usually a river channel) remains relatively low. During power generation, the water level in the upper reservoir gradually decreases, while the water level in the downstream river channel gradually rises. This means that the frequent and dramatic fluctuations in water levels in both the upper reservoir and the downstream river channel during the operation of a pumped-storage power station often require the reservoir's water-retaining structures (mostly dams) to impound water in both directions, especially for structures located in river channels, canals, tributaries, and mountain passes.

[0003] Traditional earth-rock dams (such as conventional panel dams or core dams) are typically designed for unidirectional water retention. The downstream slope of such dams has weak seepage resistance and structural stability, making them unable to safely withstand reverse water head. This poses a risk of seepage failure (such as piping and soil erosion) and landslide instability. Therefore, traditional unidirectional earth-rock dams are unsuitable for applications requiring bidirectional water retention. For this reason, pumped-storage power stations typically use concrete gravity dams for their bidirectional water-retaining structures. However, these dams have high foundation requirements, are expensive, and have poor adaptability in mountainous terrain. Furthermore, the excavation of the reservoir basin for pumped-storage power stations generates a large amount of excavated soil and rock waste, and how to environmentally and economically dispose of this waste is a significant challenge. Summary of the Invention

[0004] In view of this, the present invention proposes a construction method for a two-way water-retaining dam of a pumped storage power station.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The construction method of the pumped storage power station bidirectional water-retaining dam according to the present invention, wherein the pumped storage power station bidirectional water-retaining dam includes a dam body and a ring road cast on the top of the dam body; The dam body includes a main rockfill area filled with excavated material from the reservoir basin, an upstream transition layer, an upstream cushion layer, and an upstream face sheet laid sequentially upstream of the main rockfill area, a downstream transition layer, a downstream cushion layer, and a downstream face sheet laid sequentially downstream of the main rockfill area, and a drainage system filled below the main rockfill area. The drainage system includes a drainage layer and drainage units. The drainage units include drainage pipes intermittently buried in the drainage layer and drainage galleries set at the upstream slope toe of the dam body. The drainage pipes are connected to the drainage galleries. The bottom of the downstream panel is connected to a downstream toe plate. A special downstream cushion layer is filled between the downstream toe plate and the downstream cushion layer. The downstream cushion layer is arranged with equal thickness at the top and bottom. The downstream cushion layer expands upstream along the foundation surface. The downstream transition layer is arranged with equal thickness at the top and bottom. The lower part of the downstream cushion layer extends upstream. The drainage layer is laid with equal thickness from downstream to upstream along the foundation surface. The upstream of the drainage layer slopes downward at a certain angle to form an inclined section. The permeable drainage pipe is buried in the inclined section of the drainage layer. An upstream connecting plate is connected to the slope toe of the upstream panel. The upstream panel, upstream connecting plate, downstream panel, and downstream toe plate are all reinforced concrete structures. The upstream subbase is arranged with equal thickness at the top and bottom, and its lower part extends towards the reservoir basin. The upstream connecting plate is laid on the upstream subbase. The construction method includes the following specific construction steps: The first step is to excavate the dam foundation and reservoir basin according to the design requirements, pour the downstream toe slab on the bedrock of the river channel, construct the drainage gallery on the side of the reservoir basin, and pre-embed drainage pipes at intervals while pouring the drainage gallery. The second step is to fill a special downstream cushion layer on the river bedrock. Drainage layer and main rockfill area are filled from bottom to top on the river bedrock, dam foundation and reservoir basin side. During filling, upstream transition layer and upstream cushion layer are filled in sequence on the upstream side of the main rockfill area, and downstream transition layer and downstream cushion layer are filled in sequence on the downstream side of the main rockfill area. Among them, the downstream cushion layer is laid with equal thickness at both the top and bottom, and the downstream transition layer is laid with equal thickness at both the top and bottom. Before filling the drainage layer, the downstream cushion layer and the downstream transition layer are first filled on the bedrock of the river channel from bottom to top, so that the downstream of the drainage layer sinks to the downstream transition layer. Then, the drainage layer is filled with equal thickness from the downstream to the upstream, so that the upstream of the drainage layer extends downward from the dam foundation. When filling the inclined section of the drainage layer, geotextile is wrapped around each drainage pipe and fixed with crushed stone. The third step is to enter the settlement period after the dam body is filled; during the settlement process, curtain grouting is carried out in the bedrock of the river channel below the downstream toe plate to form a downstream water-stopping curtain. The fourth step is to cut and shape the upstream and downstream slopes of the dam after the dam body has settled. The downstream panel is poured on the downstream slope, and copper waterstops are installed at the joints of the downstream panel. The downstream panel and downstream toe plate are poured on the upstream slope, and copper waterstops are installed at the joints of the downstream panel. The upstream panel, downstream panel, upstream connecting plate and downstream toe plate are all reinforced concrete structures. The fifth step is to lay the downstream cover area and the downstream overlay area on the downstream panel in sequence.

[0006] The beneficial effects are as follows: This invention uses the main rockfill area as the main body of the dam, employing concrete panels both upstream and downstream of the main rockfill area. Furthermore, the bottom of the dam body is filled with a drainage system consisting of a drainage layer, drainage pipes, and drainage corridors, improving the stability of the bidirectional dam and meeting the bidirectional water retention requirements. Specifically: When the reservoir basin is at a high water level, the bidirectional dam is in a positive water retention position. The upstream panel and upstream connecting plate work together to stop water ingress. Seepage water enters the drainage layer through the upstream cushion layer and upstream transition zone, then flows through the drainage pipes to the drainage corridor for discharge. When the river channel is at a high water level, the bidirectional dam is in a reverse water retention position. At this time, the seepage prevention system consisting of the downstream panel, downstream toe plate, and water-stop curtain prevents water from intruding into the dam body. A small portion of seepage water enters the drainage layer and is finally guided through the drainage pipes to the drainage corridor for discharge, thus improving the stability of the downstream panel.

[0007] In addition, this invention uses reservoir excavation material as the main filling material, realizing the resource utilization of reservoir excavation material, which not only reduces the engineering cost of pumped storage power stations, but also reduces the environmental burden.

[0008] Furthermore, compared with rigid concrete dams, the combination of double flexible panels and crushed stone main body in this invention has lower requirements for the foundation and is better adapted to the needs of complex mountainous terrain.

[0009] Preferably, the laying width of the lower enlarged section of the upstream cushion layer, the laying width of the lower enlarged section of the downstream cushion layer, and the laying width of the lower enlarged section of the downstream transition layer are all greater than 3.0m.

[0010] Preferably, the upstream cushion layer, downstream cushion layer, and downstream special cushion layer are formed by compacting graded crushed stone, wherein the crushed stone with a particle size of less than 5 mm accounts for 35-55%, and the permeability coefficient after compaction is ≥1×10⁻⁶. -2 ~1×10 -3 cm / s. In actual operation, due to the frequent rise and fall and large fluctuations in the upstream reservoir basin and downstream river channel (or tributary) of the pumped storage power station, the cushion layer and special cushion layer of the present invention have good internal permeability stability and low compressibility, which prevents water accumulation in the cushion layer from acting on the panel in reverse, thereby protecting the panel from damage.

[0011] Preferably, the porosity of the upstream and downstream transition layers is ≤22%, and the permeability coefficient of the upstream and downstream transition layers is 1×10⁻⁶. -1 ~1×10 -2 The speed is cm / s, and the thickness of the upstream and downstream transition layers is 40 cm. In actual construction, the maximum crushed stone particle size of the upstream and downstream transition layers is 300 mm, and the compacted thickness is 40 cm, which gives the transition layer of the present invention good free drainage performance.

[0012] Preferably, both the main rockfill area and the drainage layer are constructed from excavated material from the reservoir basin. The porosity of the main rockfill area is ≤25%, and the permeability coefficients of both the main rockfill area and the drainage layer are >1×10⁻⁶. -1 cm / s.

[0013] The drainage pipes are spaced 2.5 to 4.0 m apart, and are wrapped with geotextile. The perimeter of the drainage pipes is filled with gravel with a particle size of 2 cm to 3 cm. The longitudinal slope of the drainage corridor is 0.1%.

[0014] Compared with the prior art, the advantages of the present invention are as follows: This invention uses the main rockfill area as the dam body, employing concrete panels upstream and downstream of the main rockfill area. The dam body is internally filled with a drainage system consisting of a drainage layer, drainage pipes, and drainage galleries, improving the stability of the bidirectional water-retaining dam and meeting bidirectional water-retaining requirements. Specifically: when the reservoir basin is at a high water level, it acts as a positive water-retaining system. The upstream panel and upstream connecting plate work together to stop water ingress. Seepage water passes through the upstream cushion layer and upstream transition zone, then flows through the drainage pipes to the drainage galleries for discharge. When the river channel is at a high water level, it acts as a reverse water-retaining system. In this case, the downstream panel, downstream toe plate, and water-stop curtain form an anti-seepage system that prevents water from intruding into the dam body. A small portion of seepage water enters the drainage layer and is finally guided through the drainage pipes to the drainage galleries for discharge, thus improving the stability of the downstream panel.

[0015] In addition, this invention uses reservoir excavation material as the main filling material to fill the main rockfill area, drainage layer, subbase layer and transition layer, realizing the resource utilization of reservoir excavation material (such as fresh slightly weathered and weakly weathered rocks excavated), which not only reduces the engineering cost of pumped storage power stations, but also reduces the environmental burden.

[0016] Furthermore, compared with rigid concrete dams, the combination of double flexible panels and crushed stone main body in this invention has lower requirements for the foundation and is better adapted to the needs of complex mountainous terrain. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the bidirectional water-retaining dam described in this invention. Detailed Implementation

[0018] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0019] It should be noted that, in the description of this invention, relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] like Figure 1 As shown, this invention proposes a bidirectional dam for a pumped storage power station, comprising a dam body and a ring road 3 (with wave walls on both the reservoir basin side and the river channel side). The dam body includes a drainage layer 5 constructed from reservoir basin excavated material and a main rockfill area 4. The dam body also includes an upstream transition layer 13, an upstream cushion layer 12, and an upstream panel 11 sequentially laid on the upstream side of the main rockfill area 4, and a downstream transition layer 23, a downstream cushion layer 22, and a downstream panel 21 sequentially laid on the downstream side of the main rockfill area 4. Furthermore, it includes a drainage system constructed beneath the main rockfill area 4, which connects the upstream cushion layer 12 and the downstream cushion layer 22 to allow seepage water to drain promptly, preventing the reverse water pressure generated by accumulated water from acting on the upstream panel 11 and the downstream panel 21, thereby improving stability.

[0022] Combination Figure 1 It can be seen that the drainage system includes drainage layer 5, which is constructed by layering excavated material from the reservoir basin (drainage layer 5 is composed of graded excavated material from the reservoir basin, and its permeability coefficient is >1×10). -1 The drainage unit consists of a drainage channel 16 (located on the reservoir side, and the drainage channel 16 is a gate-shaped structure) cast on the upstream side of the drainage layer 5 and drainage perforated pipes spaced apart in the inclined section of the drainage layer 5. The drainage perforated pipes are wrapped with geotextile and protected around the perimeter with gravel with a particle size of 2 cm to 3 cm. The bottom of the drainage perforated pipes is inserted into the installation hole of the drainage channel 16. The drainage perforated pipes 15 guide the seepage water to the drainage channel 16. The outlet of the drainage channel 16 is connected to the drainage ditch through a water passage, so as to realize the timely drainage of seepage water and reduce the impact of seepage water on the dam body.

[0023] Combination Figure 1It is known that the bottom of the downstream panel 21 is connected to the downstream toe plate 27 for water-stopping. The riverbed rock strata corresponding to the downstream toe plate 27 are grouted to form a water-stopping curtain 28. The downstream panel 21, the downstream toe plate 27 and the water-stopping curtain 28 are connected to form a seepage prevention system, which improves the seepage prevention performance of the downstream of the dam and minimizes seepage. In addition, the lower part of the downstream panel 21 is successively laid with a downstream cover area 24 (i.e., a fine sand cover area) and a heavy cover area 25. The heavy cover area 25 is made of stone chips. The downstream stone chip layer 25 covers the downstream fine sand layer 24 to prevent the fine sand from being washed away or slipped under the action of water level rise and fall or seepage.

[0024] Combination Figure 1 It can be seen that a downstream special cushion layer 26 (preferably made of graded material excavated from the reservoir basin, with a permeability coefficient ≥1×10⁻⁶ after compaction) is filled between the downstream toe slab 27 and the downstream cushion layer 22. -2 ~1×10 -3 cm / s (preferably ≥1×10) -2 The downstream cushion layer 22 is laid with equal thickness at both ends, and its lower part extends upstream on the foundation surface. The downstream transition layer 23 is laid with equal thickness at both ends, and its lower part extends upstream on the upstream cushion layer. The downstream of the drainage layer 5 sinks and is laid on the downstream transition layer 23, so that the downstream special cushion layer 26, the downstream cushion layer 22 and the downstream transition layer 23 above the river bedrock are finally connected to the drainage layer 5, which helps with drainage.

[0025] Combination Figure 1 It can be seen that the upstream of the drainage layer 5 extends downward at a certain slope to the drainage corridor 16, and the drainage pipes 15 are buried intermittently in the inclined section of the drainage layer 5; the bottom of the downstream side of the main riprap area 4 is laid on the lower part of the drainage layer 5, and the main riprap area 4 is filled on the drainage layer 5; the lower part of the upstream cushion layer 12 extends towards the reservoir basin, and the upstream connecting plate 14 is poured at the slope foot of the upstream panel 11. The upstream connecting plate 14 is located on the upstream cushion layer 12, and the upstream cushion layer 12 is connected to the drainage layer 5 through the upstream transition layer 13, so that the seepage water flows through the drainage layer 5 and the drainage pipes 15 to the drainage corridor 16.

[0026] The upstream panel 11, upstream connecting plate 14, downstream panel 21 and downstream toe plate 27 of the present invention are all reinforced concrete structures. Other structural layers and the main rockfill area 4 are preferably made of reservoir excavated material gradation, which not only realizes the resource utilization of reservoir excavated material and reduces the environmental burden, but also reduces the project cost.

[0027] In actual construction, both the upstream panel 11 and the downstream panel 21 have vertical joints, and these joints are staggered. The spacing of the joints can be flexibly adjusted according to the terrain. If the terrain is gentle, the spacing can be controlled between 8-16m; if the slope is steep, the spacing can be appropriately reduced. This allows both the upstream panel 11 and the downstream panel 21 to adapt to dam deformation, thereby reducing the flexural stress of the panels. The flexible panel of this invention, combined with the dam body constructed of crushed stone, improves seismic performance and better adapts to the needs of complex mountainous terrain.

[0028] In actual construction, the upstream cushion layer 12, downstream cushion layer 22, and downstream special cushion layer 26 are constructed by compacting graded crushed stone, with crushed stone with a particle size of less than 5mm accounting for 35-55%. The permeability coefficient after compaction is preferably ≥1×10⁻⁶. -2 The flow rate (cm / s) ensures that both the subbase and the special subbase have good internal permeability stability and low compressibility, preventing water accumulation within the subbase from acting back onto the upstream panel 11 and the downstream panel 21, thus protecting the panels from damage. Furthermore, the horizontal filling width of the downstream subbase 22, the upstream subbase 12, and the downstream transition layer 13 is all greater than 3.0m.

[0029] In actual construction, the upstream transition layer 13 and the downstream transition layer 23 are composed of graded material excavated from the reservoir basin, with a maximum crushed stone size of 300mm, a porosity of ≤22%, and a permeability coefficient of 1×10⁻⁶. -1 ~1×10 -2 The thickness of the upstream transition layer 13 and the downstream transition layer 23 is 40 cm / s, giving the transition layer of the present invention good free drainage performance and low compressibility. In addition, the downstream transition layer 23 has a horizontal filling zone with a width of ≥3 m; the overall laying thickness of the upstream transition layer 13 and the downstream transition layer 23 is controlled at 40 cm.

[0030] In actual construction, both the main rockfill zone 4 and the drainage layer 5 are composed of graded material excavated from the reservoir basin. The main rockfill zone 4, as the main structure bearing and transmitting water load, has a minimum of 20% crushed stone with a particle size less than 5mm and a minimum of 5% crushed stone with a particle size less than 0.075mm during filling. After compaction, the porosity of the main rockfill zone 4 is ≤25%, and the permeability coefficient is >1×10⁻⁶. -1 cm / s; Drainage layer 5 serves as a drainage strip connecting upstream panel 11 and downstream panel 21. During filling, the proportion of crushed stone with a particle size less than 5mm should not exceed 20%, and the proportion of crushed stone with a particle size less than 0.075mm should be ≤5%; The thickness after compaction should be greater than or equal to 3 m, the porosity ≤25%, and the permeability coefficient >1×10 -1 cm / s.

[0031] This invention also proposes a construction method for a two-way dam in a pumped storage power station, comprising the following steps: The first step is to excavate the dam foundation, reservoir basin, and river channel according to the design requirements. After excavation, the downstream toe slab 27 is poured on the bedrock of the river channel (copper waterstops are installed at the joints between the downstream toe slabs 27). The drainage gallery 16 (with construction joints) is constructed on the reservoir basin side. When pouring the drainage gallery 16, drainage pipes 15 are pre-embedded at intervals in the drainage gallery 16. The drainage gallery 16 is a gate-shaped structure with a longitudinal slope of 0.1%, allowing seepage water flowing into the drainage gallery 16 to drain freely. The dam project is usually equipped with a water passage and a drainage ditch connected to the water passage. The outlet of the drainage gallery 16 is connected to the water passage, allowing seepage water flowing into the drainage gallery 16 to be discharged into the downstream river channel through the water passage and drainage ditch. The second step involves filling a downstream special cushion layer 26 on the riverbed rock, and filling a drainage layer 5 and a main rockfill area 4 from bottom to top on the riverbed rock, dam foundation, and reservoir basin side. During filling, an upstream transition layer 13 and an upstream cushion layer 12 are simultaneously filled on the upstream side of the main rockfill area 4 and on the downstream side of the main rockfill area 4. A downstream transition layer 23 and a downstream cushion layer 22 are simultaneously filled on the downstream side of the main rockfill area 4. That is, the upstream cushion layer 12, the upstream transition layer 13, the main rockfill area 4, the downstream cushion layer 22, and the downstream transition layer 23 of this invention are filled on a level surface. Since the downstream cushion layer 22, downstream transition layer 23, and drainage layer 5 all have horizontal filling sections, the downstream cushion layer 22 and downstream transition layer 23 are first filled from bottom to top on the riverbed bedrock before filling the drainage layer 5. The filling width of each is greater than 3.0m. Then, the drainage layer 5 is filled on the downstream transition layer 23. The drainage layer is filled with equal thickness from downstream to upstream on the dam foundation. The upstream of the drainage layer slopes downward at a certain angle to form an inclined section. When filling the inclined section, geotextile is wrapped around the drainage pipe 15 and the drainage pipe 15 is supported and protected with crushed stone. Similarly, the upstream cushion layer 12 has a horizontal filling section. When filling the upstream transition layer 13 on the reservoir basin side, a horizontal filling section should be laid. Then, the upstream cushion layer 12, upstream transition layer 13, main rockfill area 4, downstream cushion layer 22, and downstream transition layer 23 are filled simultaneously from the dam baseline to ensure uniform settlement of the dam body and avoid lateral compression. The third step is to enter the settlement period after the dam body is filled (the settlement period is determined according to the specifications); during the settlement process, curtain grouting is carried out in the bedrock of the river channel below the downstream toe plate 27 to form a water-stopping curtain 28. The water-stopping curtain 28, the downstream toe plate 27 and the downstream panel 21 are combined to form a seepage prevention body to improve the seepage prevention performance on the downstream side. Fourth, after the dam body settlement is completed, the upstream and downstream slopes are trimmed and shaped respectively. The downstream panel 21 is poured on the downstream slope, and copper waterstops are installed at the joints of the downstream panel 21 (it can be one waterstop or two waterstops, with polyurethane material filling between the two copper waterstops). The downstream panel 21 and the downstream toe plate 27 are poured on the upstream slope, and copper waterstops are installed at the joints of the downstream panel 21 (it can be one waterstop or two waterstops, with polyurethane material filling between the two copper waterstops). In actual construction, the upstream panel 11, downstream panel 21, upstream connecting plate 14 and downstream toe plate 27 of the present invention are all reinforced concrete structures. The steel reinforcement configuration in the upstream connecting plate 14 is the same as that in the upstream panel 11, and the steel reinforcement configuration in the downstream toe plate 27 is the same as that in the downstream panel 21. Fifth step, lay downstream fine sand layer 24 and downstream stone slag layer 25 on downstream panel 21 in sequence.

[0032] The present invention uses a drainage layer 5 filled with crushed stone and a main rockfill area 4 as the main body of the dam. Concrete panels are used in the upstream and downstream of the main rockfill area 4. The dam body is filled with a drainage system consisting of drainage layer 5, drainage pipe 15, and drainage gallery 16, which improves the stability of the two-way water-retaining dam and can meet the two-way water-retaining requirements.

[0033] When the reservoir basin is at a high water level, the bidirectional water-retaining dam described in this invention is in the positive water-retaining position. The upstream panel 11 and the upstream connecting plate 14 are combined to stop the water. The seepage water passes through the upstream cushion layer 12 area and the upstream transition area to the drainage layer 5, and then flows through the drainage flower pipe 15 to the drainage gallery 16, and is discharged to the downstream river channel through the water tunnel and drainage ditch. When the river is at a high water level, the bidirectional dam described in this invention acts as a reverse dam. The anti-seepage system consisting of the downstream panel 21, the downstream toe plate 27, and the water-stop curtain 28 prevents water from intruding into the dam body. A small portion of the seepage water enters the drainage layer 5 through the downstream cushion layer and the downstream transition layer, and is then guided by the drainage pipe 15 in the drainage layer 5 to the drainage gallery 16 to achieve the discharge of seepage water and improve the stability of the downstream panel 21.

[0034] This invention uses reservoir excavation material as the main filling material, realizing the resource utilization of reservoir excavation material, which not only reduces the engineering cost of pumped storage power stations, but also reduces the environmental burden.

[0035] Finally, the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for a bidirectional dam of a pumped storage power station, characterized in that: The pumped storage power station's bidirectional dam includes the dam body and a ring road cast on top of the dam body; The dam body includes a main rockfill area filled with excavated material from the reservoir basin, an upstream transition layer, an upstream cushion layer, and an upstream face sheet laid sequentially upstream of the main rockfill area, a downstream transition layer, a downstream cushion layer, and a downstream face sheet laid sequentially downstream of the main rockfill area, and a drainage system filled below the main rockfill area. The drainage system includes a drainage layer and drainage units. The drainage units include drainage pipes intermittently buried in the drainage layer and drainage galleries set at the upstream slope toe of the dam body. The drainage pipes are connected to the drainage galleries. The bottom of the downstream panel is connected to a downstream toe plate. A special downstream cushion layer is filled between the downstream toe plate and the downstream cushion layer. The downstream cushion layer is arranged with equal thickness at the top and bottom. The downstream cushion layer expands upstream along the foundation surface. The downstream transition layer is arranged with equal thickness at the top and bottom. The lower part of the downstream cushion layer extends upstream. The drainage layer is laid with equal thickness from downstream to upstream along the foundation surface. The upstream of the drainage layer slopes downward at a certain angle to form an inclined section. The drainage pipe is buried in the inclined section of the drainage layer. An upstream connecting plate is connected to the slope toe of the upstream panel. The upstream panel, upstream connecting plate, downstream panel, and downstream toe plate are all reinforced concrete structures. The upstream subbase is arranged with equal thickness at the top and bottom, and its lower part extends towards the reservoir basin. The upstream connecting plate is laid on the upstream subbase. The construction method includes the following specific construction steps: The first step is to excavate the dam foundation and reservoir basin according to the design requirements, pour the downstream toe slab on the bedrock of the river channel, construct the drainage gallery on the side of the reservoir basin, and pre-embed drainage pipes at intervals while pouring the drainage gallery. The second step is to fill a special downstream cushion layer on the river bedrock. Drainage layer and main rockfill area are filled from bottom to top on the river bedrock, dam foundation and reservoir basin side. During filling, upstream transition layer and upstream cushion layer are filled in sequence on the upstream side of the main rockfill area, and downstream transition layer and downstream cushion layer are filled in sequence on the downstream side of the main rockfill area. Among them, the downstream cushion layer is laid with equal thickness at both the top and bottom, and the downstream transition layer is laid with equal thickness at both the top and bottom. Before filling the drainage layer, the downstream cushion layer and the downstream transition layer are first filled on the bedrock of the river channel from bottom to top, so that the downstream of the drainage layer sinks to the downstream transition layer. Then, the drainage layer is filled with equal thickness from the downstream to the upstream, so that the upstream of the drainage layer extends downward from the dam foundation. When filling the inclined section of the drainage layer, geotextile is wrapped around each drainage pipe and fixed with crushed stone. The third step is to enter the settlement period after the dam body is filled; during the settlement process, curtain grouting is carried out in the bedrock of the river channel below the downstream toe plate to form a downstream water-stopping curtain. The fourth step is to cut and shape the upstream and downstream slopes of the dam after the dam body has settled. The downstream panel is poured on the downstream slope, and copper waterstops are installed at the joints of the downstream panel. The downstream panel and downstream toe plate are poured on the upstream slope, and copper waterstops are installed at the joints of the downstream panel. The upstream panel, downstream panel, upstream connecting plate and downstream toe plate are all reinforced concrete structures. The fifth step is to lay the downstream cover area and the downstream overlay area on the downstream panel in sequence.

2. The construction method of the bidirectional water-retaining dam of the pumped storage power station according to claim 1, characterized in that: The laying width of the lower enlarged section of the upstream subbase and the laying width of the lower enlarged section of the downstream subbase are both greater than 3.0m; the laying width of the lower enlarged section of the downstream transition layer is greater than 3.0m.

3. The construction method of the bidirectional water-retaining dam of the pumped storage power station according to claim 2, characterized in that: The upstream cushion layer, downstream cushion layer, and downstream special cushion layer are constructed by compacting graded crushed stone, wherein crushed stone with a particle size of less than 5 mm accounts for 35-55%, and the permeability coefficient after compaction is ≥1×10⁻⁶. -2 ~1×10 -3 cm / s.

4. The construction method of the bidirectional dam for a pumped storage power station according to claim 1, characterized in that: The porosity of the upstream and downstream transition layers is ≤22%, and the permeability coefficient of the upstream and downstream transition layers is 1×10⁻⁶. -1 ~1×10 -2 cm / s, the thickness of the upstream transition layer and the downstream transition layer is 40cm.

5. The construction method of the bidirectional dam for a pumped storage power station according to claim 1, characterized in that: Both the main rockfill area and the drainage layer are constructed from excavated material from the reservoir basin. The porosity of the main rockfill area is ≤25%, and the permeability coefficient of the main rockfill area is >1×10⁻⁶. -1 cm / s, the permeability coefficient of the drainage layer is >1×10⁻⁶ -1 cm / s.

6. The construction method of the bidirectional dam for a pumped storage power station according to claim 1, characterized in that: The drainage pipes are spaced 2.5 to 4.0 m apart, and are wrapped with geotextile. The perimeter of the drainage pipes is filled with gravel with a particle size of 2 cm to 3 cm. The longitudinal slope of the drainage corridor is 0.1%.

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