Warehouse-out drainage gallery of pumped storage power station with soil foundation and construction method of warehouse-out drainage gallery

Abstract

The invention discloses an ex-warehouse drainage gallery of a pumped storage power station with a soil foundation and a construction method of the ex-warehouse drainage gallery, and belongs to the technical field of water conservancy and hydropower engineering. The warehouse-out drainage gallery comprises a composite foundation arranged in a soil foundation, a bottom plate is arranged on the composite foundation and is of a stepped structure, and water stop grooves are formed in the two sides of the bottom plate; the water stop groove is connected with a side wall in a matched mode, and the side wall is of a counterfort type retaining wall structure. A top plate is buckled to the tops of the side walls. The construction method comprises the steps that foundation pit groove digging is conducted on a warehouse-out drainage gallery area in a soil foundation, and a foundation pit foundation surface and a side slope are rolled to eliminate collapsibility; cast-in-place piles are arranged at the bottom of the treated foundation pit according to the designed row spacing; a bottom plate is poured above the cast-in-place pile; a water stop groove is formed in the bottom plate; a side wall is poured in the water stop groove of the bottom plate; the side wings of the top plate are clamped to the tops of the side walls, and mounting of the top plate is completed; and dam body materials are backfilled in the area above the top plate.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and hydropower engineering technology, and relates to an outlet drainage corridor for a pumped storage power station on soil foundation and its construction method. Background Technology

[0002] Driven by both energy structure transformation and the construction of new power systems, pumped storage power stations have become a key area of ​​energy infrastructure construction due to their multiple core functions, including peak shaving and valley filling, energy storage and supply guarantee, frequency and phase regulation, and emergency backup. As a crucial component of the pumped storage power station's main structure, the outflow drainage channel plays a vital role in discharging excess water from the reservoir bottom, ensuring stable water levels in the reservoir area, and preventing seepage damage to the dam and foundation. Its structural stability and construction efficiency directly affect the safe operation and project benefits of the entire power station. Currently, most of the pumped storage power station sites that have been completed or are under construction are located in mountainous rocky terrain, and the outflow drainage channel is generally constructed using tunnel excavation technology. This technology is mature in rock foundations, and thanks to the good bearing capacity and stability of rock, it can effectively control the risk of construction collapse. Furthermore, the structure is stable after tunnel excavation, resulting in lower later operation and maintenance costs, which can better meet the project requirements. However, with the continuous expansion of pumped storage power station construction, in order to adapt to the energy demands and terrain conditions of different regions, a number of pumped storage power station projects relying on deep soil foundations have been gradually planned and constructed in some hilly areas with thick overburden. These areas have flat terrain and lack natural rock formations as reservoir basins, which brings new challenges to the design and construction of reservoir drainage corridors.

[0003] Given the unique topographical characteristics of deep soil foundations, these power stations typically employ a dam-based construction method, creating a closed reservoir basin to ensure the required water head. However, due to terrain conditions and engineering layout limitations, the vertical distance between the dam foundation and the bottom slab of the outflow drainage gallery is only a few meters to a dozen meters, creating a unique engineering environment of shallow burial and close proximity to the dam. Under these conditions, traditional tunnel excavation techniques are completely unsuitable: firstly, the bearing capacity of the soil is far lower than that of rock, and the cohesion between soil particles is weak, making it highly susceptible to geological disasters such as sidewall collapse and crown subsidence during tunnel excavation. This not only leads to construction interruptions but may also cause disturbance to the dam foundation, threatening the structural safety of the dam; secondly, to control the risk of collapse, tunnel excavation requires complex measures such as advanced support and phased excavation, which significantly increases construction procedures, extends the construction period, and substantially raises project costs, failing to meet the requirements of economic efficiency and timeliness.

[0004] Currently, the industry has explored some construction technologies for shallow-buried soil foundation projects. Among them, the trenching-joining-backfilling construction method is considered suitable for the construction of drainage corridors in shallow-buried soil foundations due to its advantages such as convenient construction and fast tunnel formation. However, existing technologies lack specialized structural designs adapted to the characteristics of soil foundations and the functional requirements of drainage corridors for pumped storage power stations, and a systematic and mature set of supporting construction methods has not yet been formed. For example, existing trenching-joining structures are difficult to effectively cope with uneven soil settlement and lateral pressure, and are prone to structural cracking and leakage; the selection of backfill materials and construction technology lack specificity, failing to ensure the coordinated deformation and overall stability of the corridor and the surrounding soil. These technological gaps make it difficult to effectively guarantee the construction quality and safety stability of drainage corridors in soil foundations. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of traditional tunnel excavation technology in soil foundations and shallow buried adjacent dam environments, such as easy collapse, difficulty in tunnel construction, high construction costs, and poor safety. The invention provides an outlet drainage corridor for pumped storage power stations in soil foundations and its construction method.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention discloses an outlet drainage corridor for a pumped storage power station on a soil foundation, comprising a composite foundation set in a soil foundation, a base plate set on the composite foundation, the base plate having a stepped structure and water-stopping grooves set on both sides; the water-stopping grooves are connected to side walls, the side walls having a buttress-type retaining wall structure; and a top plate is fastened to the top of the side walls.

[0007] Further improvements are made in the following aspects: The composite foundation includes cast-in-place piles and soil between the piles; the top plate has side wings on both sides, which are engaged with the top of the side wall; the water-stop groove forms a mortise and tenon interlocking structure with the side wall.

[0008] The diameter of the cast-in-place pile is 50cm to 100cm, and the depth is 5 to 15m.

[0009] The side wall includes a wall panel; a side wall heel plate perpendicular to the lower end of the wall panel is provided on one side, and a wall toe plate is provided on the other side, the side wall heel plate and the wall toe plate are located on the same horizontal plane; a buttress is provided between the side wall and the side wall heel plate; a water-stop tenon is provided at the bottom of the side wall, and the water-stop tenon is embedded in the water-stop groove.

[0010] The buttresses are arranged at intervals along the length of the side wall; a straight wall section is reserved on the side wall above the buttresses, and the top plate is inverted and placed on the straight wall section.

[0011] The width of the water-stop tenon is 20cm~30cm and the depth is 15~20cm; the size of the water-stop groove is adapted to the size of the water-stop tenon; the thickness of the buttress is 40~80cm and the spacing is 1.5~2.0m; the slope ratio of the buttress is 1:(0.3~0.6).

[0012] The base plate includes a low section on both sides and a high section in the middle; the water-stop groove is provided on the low section; a drainage ditch is provided on the high section, and a grid is provided on the top of the drainage ditch.

[0013] The thickness of the lower stage of the base plate is 45-60cm, and the thickness of the upper stage is 70-80cm; the size of the drainage ditch is 30×20cm.

[0014] The thickness of the top slab is 50-75cm, the thickness of the side wings of the top slab is 20-30cm, and the length is 30-50cm; the net width of the drainage corridor formed between the top slab, the bottom slab, and the side walls on both sides is 2.5-3.5m, and the net height is 3.0-4.5m; the longitudinal slope of the bottom slab is 0.30%-3%.

[0015] Secondly, this invention discloses a construction method for the outflow drainage corridor of the aforementioned soil-based pumped storage power station, comprising: Excavate foundation pits in the drainage corridor area of ​​the soil foundation, and compact the foundation surface and slope of the foundation pit to eliminate collapsibility. At the bottom of the treated foundation pit, cast-in-place piles are arranged according to the designed spacing. A base plate is poured on top of the cast-in-place pile; a water-stopping groove is provided on the base plate. The side wall is cast in the water-stop groove of the base plate; The top plate side wing is snapped onto the top of the side wall to complete the top plate installation; Backfill the area above the top slab with dam material.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an outlet drainage corridor for a pumped storage power station with soil foundation. First, by setting a composite foundation in the soil foundation, the bearing capacity and uniformity of the deep soil foundation can be effectively improved, the risk of uneven settlement of the foundation can be greatly reduced, and the corridor structure can be prevented from cracking, leakage and other defects caused by foundation deformation. This ensures the long-term stable operation of the outlet drainage system. It is especially suitable for soil foundation scenarios with weak bearing capacity and high deformation sensitivity, such as deep soft soil and silty clay, and fills the gap in the adaptability of traditional corridor structures to soil foundations. Secondly, the base slab adopts a stepped structural design. On the one hand, this better conforms to the topographical undulations and stress distribution characteristics of the soil foundation, improving the fit between the base slab and the foundation and enhancing the overall load-bearing stability of the structure. On the other hand, the water-stop grooves on both sides form a precise fit with the side walls, constructing an efficient water-stop sealing system. Compared with the conventional flat-joint water-stop structure, this significantly improves the corridor's anti-seepage capability, effectively preventing water seepage into the foundation during drainage and the chain reaction of problems such as foundation softening and reduced bearing capacity, ensuring the water conveyance efficiency and structural safety of the drainage corridor. In addition, the top of the side walls and the top slab are connected by a snap-fit ​​joint, which not only simplifies the construction process and reduces on-site assembly difficulty, but also facilitates rapid construction organization and shortens the construction period. At the same time, the snap-fit ​​structure ensures the sealing and firmness of the connection between the top slab and the side walls, further improving the overall airtightness of the corridor. In summary, through the collaborative design of its various structures, this invention not only achieves precise adaptation to the characteristics of the soil foundation, ensuring the long-term effectiveness and stability of the outflow drainage system from the source, but also has significant advantages such as low cost and simple construction. It eliminates the need for complex foundation treatment processes and large construction equipment, effectively reducing engineering construction and operation and maintenance costs. It is easy to promote and apply in various soil foundation pumped storage power station projects, and has extremely high engineering practical value and economic value.

[0017] Furthermore, the side walls adopt a buttress-type retaining wall structure. This structure can make full use of the supporting effect of the buttress on the wall, significantly improving the side walls' ability to resist soil pressure and water pressure. In environments where the soil foundation is prone to lateral deformation, it can effectively resist the damage of the lateral thrust of the foundation to the corridor structure. At the same time, compared with solid retaining walls, the buttress-type structure significantly reduces the amount of material used while ensuring structural strength, achieving a balance between structural strength and economy.

[0018] This invention discloses a construction method for the outflow drainage corridor of a pumped-storage power station on a soil foundation. First, after excavating the foundation pit in the drainage corridor area during the initial construction phase, the foundation surface and slopes of the pit are specifically compacted. This effectively eliminates the collapsibility of the soil foundation, preventing structural settlement and cracking caused by foundation subsidence during subsequent operation, and laying a stable and reliable foundation for subsequent construction procedures. Simultaneously, compaction increases the density of the foundation surface and slopes, enhancing the stability of the foundation pit slopes and reducing safety risks such as slope collapse and landslides during construction, ensuring the safety and controllability of the construction process. Second, cast-in-place piles are arranged at the designed spacing at the bottom of the treated foundation pit. This process precisely constructs a composite foundation structure. Through the synergistic bearing effect of the cast-in-place piles and the soil, the overall bearing capacity and uniformity of the foundation are significantly improved, adapting to the characteristics of soil foundations with weak bearing capacity and high deformation sensitivity. This fundamentally solves the core problem that soil foundations cannot support the drainage corridor structure, providing a solid guarantee for subsequent foundation slab pouring and overall structural stability. Furthermore, a base slab with a water-stop groove is poured above the cast-in-place piles, and then the side walls are poured within the water-stop groove. This process design achieves precise positioning and tight connection between the base slab and the side walls. The pre-set water-stop groove not only provides precise template guidance for the side wall pouring but also allows the side walls and base slab to form an embedded connection, significantly improving the sealing and structural integrity of the connection, effectively blocking water seepage channels, and strengthening the corridor's anti-seepage performance. Compared to the traditional construction method of pouring the side walls first and then treating the connection, this process avoids quality problems such as gaps and hollow areas at the connection, improving construction quality while simplifying the construction difficulty of the water-stop structure. In addition, the top slab is installed by snapping it to the top of the side walls using the side wings of the top slab. This snap-fit ​​installation method eliminates the need for complex welding or bolt tightening procedures, simplifying the construction process, reducing the technical threshold and labor intensity of on-site construction, facilitating rapid completion of the top slab assembly, and shortening the construction period. At the same time, the snap-fit ​​structure ensures the firmness and sealing of the connection between the top slab and the side walls, preventing loosening and leakage at the connection due to vibration and settlement during subsequent use. Finally, after the top slab is installed, dam material is backfilled into the area above. This serves two purposes: firstly, the self-weight of the dam material provides stable ballast to the top slab, enhancing the overall structure's resistance to buoyancy and deformation; secondly, the backfill provides comprehensive protection for the corridor, reducing external environmental erosion and damage, and extending its service life. In summary, this construction method features a scientifically sound and rationally designed process, with each step tailored to the soil foundation characteristics and drainage corridor structural requirements. It not only ensures construction quality and long-term structural stability but also offers advantages such as ease of construction, high efficiency, and low cost. It eliminates the need for complex construction techniques and large-scale specialized equipment, facilitating standardized operations and widespread application. This significantly improves the construction benefits and practical value of drainage corridor projects for pumped-storage power stations in soil-based foundations. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the outflow drainage corridor of a pumped storage power station on a soil foundation according to an embodiment of the present invention. Figure 2 for Figure 1 AA cross-section; Figure 3 This is a schematic diagram of the side wall structure of the outflow drainage corridor of a pumped storage power station on a soil foundation, according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the connection structure between the top slab and the side wall of the outflow drainage corridor of a pumped storage power station on soil foundation, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the bottom slab structure of the outflow drainage corridor of a pumped storage power station on a soil foundation, according to an embodiment of the present invention.

[0021] The components are: 1. Original ground line; 2. Reservoir bottom; 3. Reservoir perimeter drainage corridor; 4. Outflow drainage corridor; 5. Top slab; 6. Side walls; 7. Bottom slab; 8. Cast-in-place piles; 9. Wall panels; 10. Water-stop tenon; 11. Buttress; 12. Side wall heel plate; 13. Top slab side wing; 14. Water-stop groove; 15. Drainage ditch; 16. Wall toe plate. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 and Figure 2 This invention discloses an outlet drainage corridor for a pumped-storage power station on an earthen foundation, comprising a composite foundation set in an earthen foundation. The composite foundation includes cast-in-place piles 8 and soil between the piles; the diameter of the cast-in-place piles 8 is 50cm~100cm, and the depth is 5~15m. Top plate wing 13 is provided on both sides of the top plate 5, and the top of the top plate wing 13 is engaged with the top of the side wall 6; the water-stop groove 14 forms a mortise and tenon interlocking structure with the side wall 6. A bottom plate 7 is provided on the composite foundation. The bottom plate 7 has a stepped structure and water-stop groove 14 is provided on both sides; the water-stop groove 14 is engaged with the side wall 6, and the side wall 6 is a buttress-type retaining wall structure; the top of the side wall 6 is fastened to the top of the top plate 5. The thickness of the top plate 5 is 50-75cm, the thickness of the side wing 13 of the top plate is 20-30cm, and the length is 30-50cm; the net width of the drainage corridor formed by the top plate 5, the bottom plate 7, and the side walls 6 on both sides is 2.5-3.5m, and the net height is 3.0-4.5m; the longitudinal slope of the bottom plate 7 is 0.30%-3%.

[0029] See Figure 3 and Figure 4 The side wall 6 includes a wall panel 9; a side wall heel plate 12 perpendicular to the lower end of the wall panel 9 is provided on one side, and a wall toe plate 16 is provided on the other side, with the side wall heel plate 12 and the wall toe plate 16 located on the same horizontal plane; a buttress 11 is provided between the side wall 6 and the side wall heel plate 12; a water-stop tenon 10 is provided at the bottom of the side wall 6, and the water-stop tenon 10 is embedded in the water-stop groove 14. The buttresses 11 are arranged at intervals along the length of the side wall 6; a straight wall section is reserved above the buttresses 11 on the side wall 6, and the top plate 5 is overturned on the straight wall section. The width of the water-stop tenon 10 is 20cm~30cm and the depth is 15~20cm; the dimensions of the water-stop groove 14 are adapted to the dimensions of the water-stop tenon 10; the thickness of the buttresses 11 is 40~80cm, the spacing is 1.5~2.0m, and the slope ratio of the buttresses 11 is 1:(0.3~0.6). The side walls adopt a buttress-type retaining wall structure. This structure can make full use of the supporting role of the buttresses on the wall, significantly improving the side walls' ability to resist soil pressure and water pressure. In environments where soil foundations are prone to lateral deformation, it can effectively resist the damage of the corridor structure to the lateral thrust of the foundation. At the same time, compared with solid retaining walls, the buttress-type structure significantly reduces the amount of materials used while ensuring structural strength, achieving a balance between structural strength and economy.

[0030] See Figure 5 The base plate 7 includes low sections on both sides and a high section in the middle; the water-stop groove 14 is disposed on the low section; a drainage ditch 15 is disposed on the high section, and a grid mesh is disposed on the top of the drainage ditch 15. The thickness of the low section of the base plate 7 is 45~60cm, and the thickness of the high section is 70~80cm; the size of the drainage ditch 15 is 30×20cm.

[0031] This invention discloses an outlet drainage corridor for a pumped storage power station with soil foundation. First, by setting a composite foundation in the soil foundation, the bearing capacity and uniformity of the deep soil foundation can be effectively improved, the risk of uneven settlement of the foundation can be greatly reduced, and the corridor structure can be prevented from cracking, leakage and other defects caused by foundation deformation. This ensures the long-term stable operation of the outlet drainage system. It is especially suitable for soil foundation scenarios with weak bearing capacity and high deformation sensitivity, such as deep soft soil and silty clay, and fills the gap in the adaptability of traditional corridor structures to soil foundations. Secondly, the base slab adopts a stepped structural design. On the one hand, this better conforms to the topographical undulations and stress distribution characteristics of the soil foundation, improving the fit between the base slab and the foundation and enhancing the overall load-bearing stability of the structure. On the other hand, the water-stop grooves on both sides form a precise fit with the side walls, constructing an efficient water-stop sealing system. Compared with the conventional flat-joint water-stop structure, this significantly improves the corridor's anti-seepage capability, effectively preventing water seepage into the foundation during drainage and the chain reaction of problems such as foundation softening and reduced bearing capacity, ensuring the water conveyance efficiency and structural safety of the drainage corridor. In addition, the top of the side walls and the top slab are connected by a snap-fit ​​joint, which not only simplifies the construction process and reduces on-site assembly difficulty, but also facilitates rapid construction organization and shortens the construction period. At the same time, the snap-fit ​​structure ensures the sealing and firmness of the connection between the top slab and the side walls, further improving the overall airtightness of the corridor. In summary, through the collaborative design of its various structures, this invention not only achieves precise adaptation to the characteristics of the soil foundation, ensuring the long-term effectiveness and stability of the outflow drainage system from the source, but also has significant advantages such as low cost and simple construction. It eliminates the need for complex foundation treatment processes and large construction equipment, effectively reducing engineering construction and operation and maintenance costs. It is easy to promote and apply in various soil foundation pumped storage power station projects, and has extremely high engineering practical value and economic value.

[0032] This invention also discloses a construction method for the outflow drainage corridor of a pumped storage power station on a soil foundation, comprising: Step 1: Excavate the foundation pit in the drainage corridor area of ​​the soil foundation, and compact the foundation surface and slope of the foundation pit to eliminate collapsibility. Step 2: Arrange cast-in-place piles at the designed spacing at the bottom of the treated foundation pit; Step 3: Cast a base plate on top of the cast-in-place pile; a water-stop groove is provided on the base plate; Step 4: Cast the side wall within the water-stop groove of the base plate; Step 5: Attach the top panel side wing of the top panel to the top of the side wall to complete the top panel installation; Step 6: Backfill the area above the top plate with dam material.

[0033] This invention discloses a construction method for the outflow drainage corridor of a pumped-storage power station on a soil foundation. First, after excavating the foundation pit in the drainage corridor area during the initial construction phase, the foundation surface and slopes of the pit are specifically compacted. This effectively eliminates the collapsibility of the soil foundation, preventing structural settlement and cracking caused by foundation subsidence during subsequent operation, and laying a stable and reliable foundation for subsequent construction procedures. Simultaneously, compaction increases the density of the foundation surface and slopes, enhancing the stability of the foundation pit slopes and reducing safety risks such as slope collapse and landslides during construction, ensuring the safety and controllability of the construction process. Second, cast-in-place piles are arranged at the designed spacing at the bottom of the treated foundation pit. This process precisely constructs a composite foundation structure. Through the synergistic bearing effect of the cast-in-place piles and the soil, the overall bearing capacity and uniformity of the foundation are significantly improved, adapting to the characteristics of soil foundations with weak bearing capacity and high deformation sensitivity. This fundamentally solves the core problem that soil foundations cannot support the drainage corridor structure, providing a solid guarantee for subsequent foundation slab pouring and overall structural stability. Furthermore, a base slab with a water-stop groove is poured above the cast-in-place piles, and then the side walls are poured within the water-stop groove. This process design achieves precise positioning and tight connection between the base slab and the side walls. The pre-set water-stop groove not only provides precise template guidance for the side wall pouring but also allows the side walls and base slab to form an embedded connection, significantly improving the sealing and structural integrity of the connection, effectively blocking water seepage channels, and strengthening the corridor's anti-seepage performance. Compared to the traditional construction method of pouring the side walls first and then treating the connection, this process avoids quality problems such as gaps and hollow areas at the connection, improving construction quality while simplifying the construction difficulty of the water-stop structure. In addition, the top slab is installed by snapping it to the top of the side walls using the side wings of the top slab. This snap-fit ​​installation method eliminates the need for complex welding or bolt tightening procedures, simplifying the construction process, reducing the technical threshold and labor intensity of on-site construction, facilitating rapid completion of the top slab assembly, and shortening the construction period. At the same time, the snap-fit ​​structure ensures the firmness and sealing of the connection between the top slab and the side walls, preventing loosening and leakage at the connection due to vibration and settlement during subsequent use. Finally, after the top slab is installed, dam material is backfilled into the area above. This serves two purposes: firstly, the self-weight of the dam material provides stable ballast to the top slab, enhancing the overall structure's resistance to buoyancy and deformation; secondly, the backfill provides comprehensive protection for the corridor, reducing external environmental erosion and damage, and extending its service life. In summary, this construction method features a scientifically sound and rationally designed process, with each step tailored to the soil foundation characteristics and drainage corridor structural requirements. It not only ensures construction quality and long-term structural stability but also offers advantages such as ease of construction, high efficiency, and low cost. It eliminates the need for complex construction techniques and large-scale specialized equipment, facilitating standardized operations and widespread application. This significantly improves the construction benefits and practical value of drainage corridor projects for pumped-storage power stations in soil-based foundations.

[0034] The working principle of this invention is as follows: This invention provides an outlet drainage gallery for a pumped storage power station on a soil foundation and its construction method, aiming to adapt to uneven settlement of deep soil foundations and ensure the smooth operation and long-term use of the outlet drainage system. Figure 1 As shown in the diagram, the area includes the original ground line 1, the bottom of the pumped storage reservoir 2, the drainage corridor around the bottom of the pumped storage reservoir 3, and the outflow drainage corridor 4. The outflow drainage corridor 4 adopts a combination of a top slab 5, side walls 6, and a bottom slab 7. The foundation is deep loess, using cast-in-place piles 8 and the soil between the piles to form a composite foundation, effectively reducing uneven settlement of the foundation. Simultaneously, the bottom slab 7 effectively disperses the pressure from the overlying dam body, reducing stress concentration. The net width L1 of the outflow drainage corridor is generally 2.5~3.5m, and the net height h1 is generally 3.0~4.5m. Considering both drainage efficiency and construction feasibility, the longitudinal slope of the bottom slab is typically 0.30%~3%. The concrete grade used is C30. The top slab 5 of the drainage corridor has side wings 13 on both sides, which are fastened to the wall panels 9 of the side walls 6, effectively suppressing the lateral movement of the top slab and enhancing overall stability and safety. The top slab is 50-75cm thick, and the side wings 13 are 20-30cm thick. The concrete grade used is C30. Side wall 6 adopts a buttress-type retaining wall structure, which reduces the amount of concrete used compared to gravity retaining walls, effectively lowering costs. It mainly consists of wall panels 9, buttresses 11, water-stop tenons 10, and side wall heel plates 12. The concrete grade is C30. The wall panel 9 is 50-75cm thick, the buttresses are 40-80cm thick, and the heel plate 12 is 50-60cm thick. The water-stop tenons 10 are 20-30cm wide and 15-20cm deep, with pre-reserved water-stop grooves 14 corresponding to the base plate 7, achieving a tenon-and-mortise interlocking water-stop structure, enhancing the joint's impermeability, reducing the amount of waterstop strip used, and lowering investment.

[0035] Base plate 7, such as Figure 5 As shown, the pre-reserved groove 14 and the water-stop tenon 10 of the side wall form a mortise and tenon structure. This serves two purposes: water prevention and enhancing the anti-slip ability of the side wall's base plate. The base plate adopts a stepped design, lower on both sides and higher in the middle, which can hold the side wall in place, preventing it from moving inward under external active earth pressure, thus enhancing the side wall's anti-slip stability. The thickness h2 on both sides is 45~60cm, and the thickness h3 in the middle is 70~80cm. A drainage ditch 15 with dimensions of 30×20cm is pre-reserved in the middle of the base plate, and a grating is installed on the top. Cast-in-place piles 8, typically 50cm-100cm in diameter and 5-15m in depth, with specific dimensions calculated based on pile bearing capacity; wall panels 9, 50-75cm thick, using C30 concrete; side wall water-stop tenons 10 (20cm-30cm wide, 15-20cm deep), with corresponding water-stop grooves in the base plate 7, achieving a tenon-and-mortise interlocking water-stop structure, enhancing joint impermeability, reducing the amount of waterstop strip used, and lowering investment; buttresses 11, 40-80cm thick, spaced 1.5-2.0m apart, with a 30-50cm straight wall section reserved at the top for the inverted side wing 13 of the top plate. The slope ratio of the buttresses is 1:n, where n is typically 0.3-0.6, determined based on stability calculations. The concrete grade is C30; the wall heel slab 12 is 50-60cm thick and uses C30 concrete; the top slab side wing 13 is 20-30cm thick and 30-50cm long, increasing the seepage path length, and uses C30 concrete; the water-stop groove 14 is 20-30cm wide and 15-20cm deep; the drainage ditch 15 is 30×20cm in size, with a grid mesh on top and a longitudinal slope of 0.30%-3%, for gravity drainage. The wall toe slab 16 has the same thickness as the wall heel slab 12, and a width of 50-60cm, using C30 concrete.

[0036] The construction steps are as follows: Step 1: According to Figure 1 Since the burial depth is only a few meters to a dozen meters, the first step is to excavate the foundation pit for the drainage corridor. Then, the foundation surface and slope are compacted to eliminate collapsibility. Generally, a 25t to 32t vibratory roller is used to compact the surface 4 to 8 times. Step 2: Bottom design: Arrange 8 cast-in-place piles according to the designed spacing; Step 3: Pour the base slab 7; Step 4: Pour the side walls 6 of the buttress-type structure on both sides; Step 5: Pour the top slab (5 mm). Step 6: Backfill the top of the dam body with material.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A drainage channel for a pumped-storage power station on an earthen foundation, characterized in that, The composite foundation is set in the soil foundation, and a base plate (7) is set on the composite foundation. The base plate (7) is a stepped structure and water-stop grooves (14) are set on both sides. The water-stop grooves (14) are connected to side walls (6), and the side walls (6) are buttress-type retaining wall structures. A top plate (5) is fastened to the top of the side walls (6).

2. The outflow drainage corridor of the pumped storage power station on soil foundation according to claim 1, characterized in that, The composite foundation includes cast-in-place piles (8) and soil between the piles; the top plate (5) is provided with top plate side wings (13) on both sides, and the top plate side wings (13) are engaged with the top of the side wall (6); the water-stop groove (14) and the side wall (6) form a mortise and tenon interlocking structure.

3. The outflow drainage corridor of the pumped storage power station on soil foundation according to claim 2, characterized in that, The diameter of the cast-in-place pile (8) is 50cm~100cm and the depth is 5~15m.

4. The outflow drainage corridor of the pumped storage power station on soil foundation according to claim 1, characterized in that, The side wall (6) includes a wall panel (9); a side wall heel plate (12) perpendicular to the lower end of the wall panel (9) is provided on one side, and a wall toe plate (16) is provided on the other side. The side wall heel plate (12) and the wall toe plate (16) are located on the same horizontal plane. A buttress (11) is provided between the side wall (6) and the side wall heel plate (12). A water-stop tenon (10) is provided at the bottom of the side wall (6), and the water-stop tenon (10) is embedded in the water-stop groove (14).

5. The outflow drainage corridor of the pumped storage power station on soil foundation according to claim 4, characterized in that, The buttresses (11) are arranged at intervals along the length of the side wall (6); a straight wall section is reserved on the side wall (6) above the buttresses (11), and the top plate (5) is upside down on the straight wall section.

6. The outflow drainage corridor of the pumped storage power station on soil foundation according to claim 4, characterized in that, The width of the water-stop tenon (10) is 20cm~30cm and the depth is 15~20cm; the size of the water-stop groove (14) is adapted to the size of the water-stop tenon (10); the thickness of the buttress (11) is 40~80cm and the spacing is 1.5~2.0m; the slope ratio of the buttress (11) is 1:(0.3~0.6).

7. The outflow drainage corridor of a pumped storage power station on soil foundation according to claim 1, characterized in that, The base plate (7) includes a low stage on both sides and a high stage in the middle; the water-stop groove (14) is provided on the low stage; a drainage ditch (15) is provided on the high stage, and a grid is provided on the top of the drainage ditch (15).

8. The outflow drainage corridor of a pumped storage power station on soil foundation according to claim 7, characterized in that, The thickness of the lower stage of the base plate (7) is 45~60cm, and the thickness of the upper stage is 70~80cm; the size of the drainage ditch (15) is 30×20cm.

9. The outflow drainage corridor of a pumped storage power station on soil foundation according to claim 1, characterized in that, The thickness of the top plate (5) is 50~75cm, the thickness of the side wing (13) of the top plate is 20~30cm, and the length is 30~50cm; the net width of the drainage corridor formed between the top plate (5), the bottom plate (7) and the side walls (6) on both sides is 2.5~3.5m, and the net height is 3.0~4.5m; the longitudinal slope of the bottom plate (7) is 0.30%~3%.

10. The construction method of the outlet drainage gallery of a pumped storage power station with soil foundation according to any one of claims 1-9, characterized in that, include: Excavate foundation pits in the drainage corridor area of ​​the soil foundation, and compact the foundation surface and slope of the foundation pit to eliminate collapsibility. At the bottom of the treated foundation pit, cast-in-place piles are arranged according to the designed spacing. A base plate is poured on top of the cast-in-place pile; a water-stopping groove is provided on the base plate. The side wall is cast in the water-stop groove of the base plate; The top plate side wing is snapped onto the top of the side wall to complete the top plate installation; Backfill the area above the top slab with dam material.

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