A Multi-Point Distributed Underground Engineering Structure and Design Method for Pumped Storage Power Stations in Karst Areas

Abstract

This invention provides a multi-point decentralized underground engineering structure and design method for pumped storage power stations in karst areas, relating to the field of water conservancy and hydropower engineering technology. It includes upper and lower reservoirs arranged at varying elevations on a mountainside, connected by a water conveyance tunnel. The power plant of the pumped storage power station is functionally zoned and dispersed within the mountainside between the upper and lower reservoirs. The power plant includes several generator sets located on the water conveyance tunnel. The generator sets are connected to a access tunnel via shafts, which connects to the control center and serves as the entrance and exit for the power plant. This invention employs a multi-point decentralized layout strategy, subdividing the power plant into several smaller spaces, thus achieving flexibility in layout. This design helps avoid adverse geological conditions such as karst and caves; it not only reduces the difficulty and workload of seepage prevention treatment but also saves on project investment.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering technology, and in particular to a multi-point decentralized underground engineering structure and design method for pumped storage power stations in karst areas. Background Technology

[0002] Pumped storage power stations typically consist of four parts: an upper reservoir, a water diversion system, a power plant system, and a lower reservoir. Among these, the power plant system is the core of the pumped storage power station, forming its central brain.

[0003] Currently, most pumped storage power stations under construction or already completed utilize underground power plant systems. The location of the power plant is significantly influenced by geological and construction conditions, with priority given to designing power plants within rock strata with relatively intact bedrock and stable surrounding rock. However, in current pumped storage power station designs, underground power plant systems often occupy a large space. For example, a pumped storage power station with an installed capacity of approximately 1.2 million kWa requires a power plant system with dimensions of approximately 500 meters long, 200 meters wide, and 100 meters high. The area with intact and stable surrounding rock strata is limited. Adopting existing underground power plant design types often necessitates additional engineering measures, leading to increased project investment.

[0004] The design of underground powerhouses for pumped storage power stations is usually located about 100 meters below the normal water level of the lower reservoir. On the one hand, there is a risk of water leakage from the lower reservoir; on the other hand, the construction period is long. To make the underground powerhouse ready for construction, it is often necessary to build a construction access tunnel about 2.0 km long from the ground to reach the underground powerhouse, which results in a long construction period and a large increase in investment for pumped storage power stations.

[0005] In southwestern my country, such as Guizhou, Sichuan, Yunnan, and Guangxi Zhuang Autonomous Region, the design of pumped storage power stations is significantly affected by karst geological development. This is particularly true when designing pumped storage power stations for existing reservoirs, where karst conduits, fissures, and faults exist, posing significant challenges to the seepage prevention design of the underground power plant, increasing construction safety risks, and resulting in substantial project investment. For example, in the design of a pumped storage power station in Guizhou Province, the lower reservoir is located within the area of ​​an existing large hydropower station. The underground power plant system is located on the left bank of the reservoir, approximately 800 meters from the water surface. The elevation of the underground power plant installation area is about 100 meters below the normal reservoir level. The access tunnel winds along the left bank mountain to the power plant installation area, with a length of approximately 2.0 km. Geological findings from the underground power plant tunnel indicate that the area suitable for the underground power plant location contains large karst caves and cavities, with karst conduits connecting to the reservoir water. Underground power plant construction carries extremely high safety risks, a long construction period, and significant design challenges, particularly in seepage prevention design. It also presents high safety risks during operation and maintenance, and requires substantial investment. Summary of the Invention

[0006] This invention provides a design method for multi-point decentralized underground powerhouses in pumped storage power stations in karst areas. It primarily addresses the challenges of constructing pumped storage power stations in karst regions, including issues such as stable surrounding rock within the caverns, difficulties in preventing reservoir leakage, high construction safety risks, long construction periods, and substantial project investments. This invention is particularly applicable to the design and construction of underground powerhouse systems in pumped storage power stations where the layout requires a large spatial area, the range of stable surrounding rock within the caverns is limited, karst geology is developed, and the karst is connected to the reservoir water.

[0007] The present invention provides the following technical solution to achieve the above objectives:

[0008] A multi-point decentralized design method for pumped storage power stations in karst areas includes upper and lower reservoirs arranged at varying heights on a mountainside, connected by a water conveyance tunnel. The method is characterized by: the power plant buildings of the pumped storage power station are functionally zoned and dispersed within the mountainside between the upper and lower reservoirs. Each power plant building includes several generator rooms located on the water conveyance tunnel. The generator rooms are connected to a access tunnel via shafts. The access tunnel is connected to the control center and serves as the entrance and exit for the power plant buildings.

[0009] Furthermore, the water conveyance tunnel is arranged in a stepped manner according to the drop between the upper and lower reservoirs, and the generator rooms are all located on the lowest level of the water conveyance tunnel.

[0010] Furthermore, the generator room is connected to the control center via a cable.

[0011] Furthermore, the control center and the traffic tunnel are both located at elevations above the highest operating water level of the lower reservoir.

[0012] Furthermore, each well shaft is equipped with several generator rooms.

[0013] Furthermore, the wellbore has a circular cross-section.

[0014] Furthermore, the wellbore has a circular cross-section.

[0015] A design method for a multi-point decentralized underground engineering structure for pumped storage power stations in karst areas includes the following steps:

[0016] Step 1: Divide the power plant into functional sections including generator room, control center, access tunnel and shaft, and conduct geological survey of the proposed dam area;

[0017] Step 2: Based on the geological survey results, select an area with stable and intact surrounding rock and relatively undeveloped karst as the location for the generator room;

[0018] Step 3: Design the route of the water conveyance tunnel according to the location of the generator room. The water conveyance tunnel can be arranged in a way that one generator room is set up for one water conveyance tunnel or several generator rooms are set up for one water conveyance tunnel.

[0019] Step 4: Based on the geological conditions of the area where the generator room is located, adopt an arrangement method of setting up one generator room for one shaft or setting up several generator rooms for one shaft.

[0020] Step 5: Arrange the control center and access tunnel according to the location of the generator room, with the principle that the control center is close to the generator room and the access tunnel is connected to both the generator room and the control center, in order to reduce the length of cable laying.

[0021] Beneficial effects

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention adopts a multi-point decentralized layout strategy, subdividing the power plant building into several smaller spaces, thereby achieving flexibility in layout. This design helps to avoid unfavorable geological areas such as karst and caverns; it not only reduces the difficulty and workload of seepage prevention treatment, but also saves on project investment. At the same time, this design also helps to ensure the stability of the surrounding rock of the underground cavern.

[0024] 2. By placing the control center and traffic tunnel above the highest water level of the lower reservoir, this invention can effectively avoid the safety risks to personnel and equipment caused by reservoir water leakage during construction and operation.

[0025] 3. Compared to existing underground power plant access tunnel designs, the total length of the access tunnel in this invention can be reduced by more than 50%. When designing the excavation and support for the control center and access tunnel, seepage prevention measures are simplified, resulting in a reduction of project investment by more than 70%. Simultaneously, the shorter access tunnel length allows for earlier construction of the generator rooms; through spatial division, each generator room is relatively independent, enabling simultaneous construction of multiple generator rooms and significantly shortening the construction period. Under the same installed capacity conditions, compared to existing underground power plant designs, the total construction period can be shortened by more than 6 months.

[0026] 3. By setting the cross-section of the well shaft to be circular, this invention makes full use of the soil's self-supporting capacity, transforms the soil pressure into circumferential pressure, reduces stress concentration, and thus improves the overall stability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0028] Figure 1 This is a floor plan of the power plant for this invention;

[0029] Figure 2 Wellbore structure arrangement of the present invention Figure 1 ;

[0030] Figure 3 Wellbore structure arrangement of the present invention Figure 2 .

[0031] Attached diagram labels: 1-Lower reservoir, 2-Mountain, 3-Upper reservoir, 4-Water conveyance tunnel, 5-Keloid cave / unfavorable geological body, 6-Impering curtain, 7-Generator unit, 8-Control center, 9-Traffic tunnel, 10-Drainage hole, 11-Elevator, 12-Grouting gallery, 13-Well shaft, 14-Circular ladder. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0033] It should be noted that in this invention: the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices; the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," "longitudinal," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. The terminology used is primarily for the purpose of better describing the invention and its embodiments, and is not intended to limit the indicated devices, elements, or components to having a specific orientation, or to construct and operate in a specific orientation. Terms such as "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Terms such as "installed," "set," "equipped with," "connected," "linked," "socketed," etc., should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, elements, or components. Furthermore, some terms, in addition to indicating orientation or positional relationships, may also have other meanings; for example, the term "above" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0034] Example 1. A multi-point decentralized underground engineering structure for pumped storage power stations in karst areas, with structural reference... Figure 1 and 2 The pumped storage power station comprises an upper reservoir (3) and a lower reservoir (1) arranged at varying elevations on hillside 2. These reservoirs are connected by a water conveyance tunnel (4). The power plant buildings are functionally zoned and dispersed within hillside 2 between the upper and lower reservoirs. Each power plant building includes several generator rooms (7) located on the water conveyance tunnel (4). These generator rooms are connected to a access tunnel (9) via a shaft (13). The access tunnel (9) connects to the control center (8) and serves as the entrance and exit for the power plant buildings. The control center (8) can be strategically located either inside or outside hillside 2, depending on the specific project requirements. Locating it outside hillside 2 would reduce the amount of excavation work.

[0035] The water conveyance tunnel 4 is arranged in a stepped manner according to the drop between the upper and lower reservoirs, and the generator rooms 7 are all located on the lowest level section of the water conveyance tunnel 4. Placing the generator set 7 on the lowest level water conveyance tunnel 4 maximizes the water level difference and ensures the power generation capacity of the generator set 7.

[0036] The generator room 7 is connected to the control center 8 via a cable. This cable connection facilitates monitoring of the generator room 7 by the control center 8.

[0037] The control center 8 and the traffic tunnel 9 are both located above the highest operating water level of the lower reservoir 1. Positioning the control center 8 and the traffic tunnel 9 above the highest water level of the lower reservoir 1 effectively mitigates the safety risks to personnel and equipment caused by reservoir water leakage during construction and operation.

[0038] Each wellbore 13 is equipped with several generator sets 7. (Structural reference) Figure 2 The system adopts a configuration where one generator set 7 is installed in relation to one shaft 13. For example, if four generator sets 7 are designed, four independent shafts 13 are required. Each shaft 13 is designed with seepage prevention and drainage features, arranged around its circumference. Each shaft 13 contains an elevator and a manual ladder, serving as the operating passage for the generator room and an escape route for personnel. The cross-section of each shaft 13 is circular. By making the cross-section of the shaft 13 circular, the self-supporting capacity of the soil is fully utilized, converting soil pressure into circumferential pressure, reducing stress concentration, and thus improving overall stability.

[0039] Example 2. In Example 1, each generator unit 7 is relatively independent, ensuring high safety for personnel and equipment, and facilitating unit hoisting. However, the overall geological space occupied by the cavern is large, the probability of encountering karst caves is high, the excavation of the shaft and the anti-seepage curtain work are extensive, and a large number of elevators need to be installed, resulting in significant project investment. Therefore, this example adjusts the setting of the shaft 13 based on Example 1, with the structure referenced... Figure 3 The method of setting up multiple generator sets 7 in one shaft 13 is adopted. The number and location of the generator sets 7 are determined according to the layout location of the shaft 13 and the geological conditions. This ensures that one shaft 13 radiates multiple generator sets 7 through the tunnel. Compared with the embodiment 1, this method occupies less geological space in the overall cavern, has a lower probability of encountering karst caves, requires less shaft excavation and anti-seepage curtain engineering, requires fewer elevators, and has a relatively lower project investment.

[0040] A design method for a multi-point decentralized underground engineering structure for pumped storage power stations in karst areas includes the following steps:

[0041] Step 1: The power plant is divided into functional sections including generator room 7, control center 8, access tunnel 9, and shaft 13, and a geological survey is conducted on the proposed dam area.

[0042] Step 2: Based on the geological survey results, select an area with stable and intact surrounding rock and relatively undeveloped karst as the location for generator room 7;

[0043] Step 3: Design the route of the water conveyance tunnel 4 according to the location of the generator room 7. The water conveyance tunnel 4 can be arranged in a way that one generator room 7 is set up for one water conveyance tunnel 4 or several generator rooms 7 are set up for one water conveyance tunnel 4; the specific arrangement will be determined based on a comprehensive economic and technical comparison.

[0044] Step four: Based on the geological conditions of the area where the generator room 7 is located, adopt an arrangement of one generator room 7 corresponding to one shaft 13 or several generator rooms 7 corresponding to one shaft 13; the specific arrangement shall be determined based on a comprehensive economic and technical comparison.

[0045] Step 5: Arrange the control center 8 and the access tunnel 9 according to the location of the generator room 7. The principle is to make the control center 8 close to the generator room 7 and to make the access tunnel 9 interconnected with the generator room 7 and the control center 8, so as to reduce the length of cable laying. The access tunnel is interconnected with the control center and the generator room. The design of the access tunnel should fully consider the transportation needs during the construction period and the convenience of passage during the later operation period.

[0046] This invention has been tested in actual engineering projects. In the design of a pumped storage power station in Southwest China, the existing large hydropower station reservoir was used as the lower reservoir. The underground powerhouse was located on the left bank of the reservoir, with its generating units installed at an elevation approximately 100 meters below the highest water level of the reservoir. Geological exploration of the underground powerhouse revealed karst and fault development on the left bank of the reservoir, primarily characterized by large, concentrated karst caves. These caves were connected to the reservoir water, but the surrounding rock strata between them were relatively intact. Using the existing underground powerhouse layout design required a large spatial dimension, making it difficult to avoid the caves, increasing the probability of encountering them, posing significant challenges to the underground powerhouse's seepage prevention design, posing extremely high construction safety risks, and resulting in substantial project investment.

[0047] This pumped storage power station adopts the multi-point decentralized underground powerhouse design method provided by this invention. The underground powerhouse is divided into multiple spatial layouts, each with a small size and flexible arrangement. This effectively avoids adverse geological conditions such as underground karst caves and faults on the left bank, thereby optimizing a large amount of excavation, support, and seepage prevention work. Using this invention, important facilities such as the powerhouse control center, access tunnel, and main transformer room are located in the mountain on the left bank of the reservoir, all above the highest water level of the reservoir. The length of the access tunnel is shortened from the original design of 2km to 1.2km, and the construction period is shortened by about 6 months. At the same time, it avoids safety risks such as reservoir water leakage during the construction and operation of the underground powerhouse, ensuring the safety of personnel and equipment.

[0048] Obviously, the above description is only a part of the embodiments of the present invention, and not all of the embodiments. The above embodiments are not intended to limit the present invention, and various modifications and variations can be made to the present invention by those skilled in the art. Any combination, modification, equivalent substitution, improvement, and all other embodiments that can be made by those skilled in the art within the spirit and principles of the present invention should be within the protection scope of the present invention.

Claims

1. A multi-point distributed underground engineering structure of a pumped storage power station in a karst area, comprising an upper reservoir (3) and a lower reservoir (1) arranged in a staggered manner on a mountain (2), and a water conveyance tunnel (4) connecting the upper reservoir (3) and the lower reservoir (1), characterized in that: The power plant of the pumped storage power station is divided into a generator room (7), a control center (8), a traffic tunnel (9) and a shaft (13) according to functions, and the generator room (7), the control center (8), the traffic tunnel (9) and the shaft (13) are arranged dispersedly in a mountain (2) between an upper reservoir (3) and a lower reservoir (1), the power plant comprises a plurality of generator rooms (7), the generator rooms (7) are arranged on a water conveyance tunnel (4), the generator rooms (7) are connected with the traffic tunnel (9) through the shaft (13), the traffic tunnel (9) is connected with the control center (8) and is arranged as an entrance and exit of the power plant; the control center (8) and the traffic tunnel (9) are arranged above the highest operating water level of the lower reservoir (1).

2. The multi-point distributed underground engineering structure of a karst area pumped storage power station according to claim 1, characterized in that: The water conveyance tunnel (4) is arranged in a stepped mode according to the difference between the upper reservoir and the lower reservoir, and the generator rooms (7) are arranged on the lowest level section of the lowest stage of the water conveyance tunnel (4).

3. The multi-point distributed underground engineering structure of a karst area pumped storage power station according to claim 1, characterized in that: The generator rooms (7) are connected with the control center (8) through cables.

4. The multi-point distributed underground engineering structure of a karst area pumped storage power station according to claim 1, characterized in that: One shaft (13) corresponds to a plurality of generator rooms (7).

5. The karst region pumped storage power plant multi-point dispersed underground engineering structure according to any one of claims 1 and 4, characterized in that: The shaft (13) is arranged in a circular cross section.

6. The method for designing a multi-point distributed underground engineering structure of a karst region pumped storage power station according to claim 1, characterized in that: The method comprises the following steps: step one, dividing the power plant into a generator room (7), a control center (8), a traffic tunnel (9) and a shaft (13) according to functions, and carrying out geological survey on the region of the proposed dam; Step three, according to the arrangement position of the generator room (7), the route of the water conveyance tunnel (4) is designed, the water conveyance tunnel (4) adopts an arrangement mode that one water conveyance tunnel (4) corresponds to one generator room (7) or one water conveyance tunnel (4) corresponds to a plurality of generator rooms (7); Step four, according to the geological condition of the arrangement region of the generator room (7), an arrangement mode that one shaft (13) corresponds to one generator room (7) or one shaft (13) corresponds to a plurality of generator rooms (7) is adopted; Step five, according to the arrangement position of the generator room (7), the control center (8) and the traffic tunnel (9) are arranged, the control center (8) is close to the generator room (7), the traffic tunnel (9) is communicated with the generator room (7) and the control center (8), and the length of the cable is reduced.

Images