Air cushion type surge chamber structure

Abstract

The present application relates to a kind of air cushion type surge chamber structure, belong to the technical field of pressure passage in hydraulic engineering.The present application includes diversion tunnel, top air chamber and vertical shaft, top air chamber is long strip structure, the section of top air chamber is semicircular;The lower end of vertical shaft is communicated with diversion tunnel by impedance hole, the upper end of vertical shaft and the bottom plate of top air chamber are directly connected, form the two-stage step type sudden expansion cavity structure of lower vertical upper dome;All structural wall surfaces of top air chamber and the upper end lateral wall of vertical shaft are provided with closed gas structure layer;During the whole process of surge chamber steady state, transient operation, gas-water interface is limited in the interior of vertical shaft, closed gas structure layer and water mat layer located in vertical shaft form gas seal structure.The present application realizes the physical partition of vertical shaft water, top air chamber pure gas storage, can reduce the gas pressure of surge chamber, reduce the volume of air chamber and the area of air chamber sealing, improve system pressure regulation stability.

Description

Technical Field

[0001] This invention relates to an air cushion type pressure regulating chamber structure, belonging to the technical field of pressure channel technology in water conservancy engineering. Background Technology

[0002] Air cushion surge chambers are the core pressure regulating and energy dissipation structures for high-head, long-distance water diversion hydropower stations and inter-basin water diversion projects. Relying on the buffering and pressure stabilizing characteristics of the closed cavity high-pressure air cushion, they can effectively suppress water hammer pressure and surge wave fluctuations in the water conveyance system. Compared with traditional open surge chambers, they have significant advantages such as strong terrain adaptability, small amount of civil engineering work, low construction difficulty, and small ecological disturbance.

[0003] Currently, the air cushion pressure regulating chambers commonly used in domestic and international engineering projects are mainly divided into two categories: horizontal tunnel type and all-steel-clad type. Existing research mainly focuses on optimizing the air closure form, adjusting the structural shape, and improving the sealing materials. Overall, it still follows the traditional design concept of fully coupled water and air operation (i.e., the air-water interface is located inside the main body of the air chamber, and the area of ​​the air-water interface is consistent with the cross-sectional area of ​​the main body of the air chamber along the horizontal plane), and has not fundamentally changed the existing technical framework.

[0004] For example, Chinese patent document CN217325278U discloses a double-layer airtight cushion-type pressure regulating chamber, including a pressure regulating chamber cover and a water inlet channel connected to the pressure regulating chamber cover. The inner wall surface of the pressure regulating chamber cover is covered with a first airtight layer and a second airtight layer, with the second airtight layer located between the first airtight layer and the inner wall surface of the pressure regulating chamber cover. The ends of the first and second airtight layers are located below the lowest surge water level of the pressure regulating chamber. The pressure regulating chamber cover is also provided with a sealing device to seal the ends of the first and second airtight layers. By adding a first and second airtight layer to the inner wall of the pressure regulating chamber cover, the airtight effect inside the pressure regulating chamber is improved. By adding a sealing device to seal the ends of the first and second airtight layers, the ends of the first and second airtight layers can be pressed and fixed to prevent air leakage or water ingress at the ends of the airtight layers, thereby improving the airtight effect inside the pressure regulating chamber cover.

[0005] Chinese patent document CN211171871U discloses an air cushion pressure regulating chamber with a double-layer air-tight structure, including a reinforced concrete lining, an air chamber, and a drainage hole. It features two layers of air-tight structures: a first layer and a second layer. The first layer consists of a steel lining and a water cushion layer; the second layer consists of the water cushion layer and a water layer. The steel lining is fixedly connected to the inner side of the reinforced concrete lining and is separated from it. The water cushion layer is located at the bottom of the reinforced concrete lining. This double-layer air-tight structure utilizes the first layer as the primary means of sealing the high-pressure air in the air chamber, while the second layer continues to function as a sealant even after the first layer develops leaks during long-term operation, resulting in a good air-tight effect.

[0006] The two patent documents mentioned above improved the air-tight structure from different perspectives, but they still follow the traditional design concept of full water-gas coupling operation. When the hydropower station experiences large load fluctuations and water level changes, the full coupling water-gas interface will cause large changes in gas volume and amplify pressure fluctuations. This will not only affect the stability of unit operation, but also place higher demands on the structural strength of the surge tank, increasing construction costs. In addition, the required gas chamber volume is also larger, and the high-pressure sealing construction area is also larger, further increasing construction costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an air cushion type pressure regulating chamber structure that can reduce the gas pressure in the pressure regulating chamber, reduce the volume of the air chamber, reduce the sealing area of ​​the air chamber, and improve the stability of system pressure regulation.

[0008] The technical solution adopted by this invention to solve its technical problem is: an air cushion type pressure regulating chamber structure, including a water diversion tunnel, a top air chamber, and a vertical shaft. The top air chamber is a long strip structure, and its cross-section perpendicular to its length direction is semi-circular. The lower end of the vertical shaft is connected to the water diversion tunnel through an impedance hole, and the upper end of the vertical shaft is directly connected to the bottom plate of the top air chamber, forming a two-stage stepped abrupt expansion cavity structure with a lower vertical and upper dome. The vertical shaft is coaxial with the impedance hole, and the axis of the vertical shaft is located at the center of the width direction of both the water diversion tunnel and the top air chamber. All structural walls of the top air chamber and the upper sidewall of the vertical shaft are provided with an air-tight structure layer. During the steady-state and transient operation of the pressure regulating chamber, the air-water interface is confined inside the vertical shaft, and the air-tight structure layer and the water cushion layer located inside the vertical shaft form a gas-sealed structure.

[0009] A further preferred option is that both the top air chamber and the vertical shaft have reinforced concrete lining layers, the airtight structure layer is an airtight steel plate pre-embedded inside the reinforced concrete lining layer, and the outside of the reinforced concrete lining layer is bonded to the surrounding rock leveling layer.

[0010] A further preferred embodiment is that both the top air chamber and the vertical shaft have reinforced concrete lining layers. An air chamber pressure equalization system is installed in the outer area of ​​the airtight structure layer. The air chamber pressure equalization system includes a pressure equalization pipe network embedded in the reinforced concrete lining layer. The pressure equalization pipe network is connected to the inner cavity of the vertical shaft through several first connecting pipes. The pipe opening at the end of the first connecting pipe connected to the inner cavity of the vertical shaft is lower than the lowest surge water level in the vertical shaft. The pressure equalization pipe network is connected to the outer area of ​​the top air chamber through several second connecting pipes. The end of the second connecting pipe away from the pressure equalization pipe network extends into the bedrock outside the top air chamber.

[0011] A further preferred embodiment is: multiple first connecting pipes are evenly spaced along the circumference of the vertical shaft; the flat pressure network has multiple pipe interfaces for connecting the second connecting pipes on all structural walls of the top air chamber, and each pipe interface is connected to a straight second connecting pipe.

[0012] A further preferred option is that the pressure-reducing pipeline network, the first connecting pipe, and the second connecting pipe are all made of steel pipes.

[0013] The beneficial effects of this invention are as follows: This invention breaks the traditional fully coupled operation mode of water and gas in the same cavity, and adds a vertical shaft to confine the gas-water interface inside the vertical shaft. This achieves physical partitioning of water passage in the vertical shaft and pure gas storage in the top gas chamber, physically isolating the gas storage space from the water passage space. The top gas chamber constantly stores high-pressure buffer gas, forming a stable air cushion buffer layer. When the unit load fluctuates or water hammer pressure is transmitted, only the water in the vertical shaft fluctuates up and down. The position of the gas-water interface is controllable and the fluctuation amplitude is small. The pressure in the gas storage cavity does not oscillate violently, which greatly improves the stability of system pressure regulation, effectively suppresses water disturbance and vortex air mixing in the gas storage cavity, and has a good water hammer protection effect. It can adapt to the operation requirements of frequent start-up and shutdown and large load fluctuation of pumped storage units, and its pressure regulation performance is better than that of the traditional water-gas mixed cavity structure. Furthermore, by employing a vertical shaft, this invention can reasonably reduce the maximum working pressure and volume of the gas chamber. This not only lowers the requirements for surrounding rock geological conditions but also effectively reduces the construction scope of high-pressure sealing, significantly decreasing civil engineering investment and the probability of seal failure. The circular arc structure of the top gas chamber distributes stress evenly, better adapting to high ground stress environments and reducing the risk of rock mass cracking and seal damage. The invention features a simple overall structure and mature construction technology, making it suitable for hydropower and water diversion projects with varying surrounding rock conditions, water heads, and flow rates. It combines structural reliability, operational stability, and economic applicability, demonstrating promising prospects for engineering applications. Attached Figure Description

[0014] Figure 1This is a schematic diagram of the elevation structure of the overall structure of the present invention; Figure 2 yes Figure 1 A schematic diagram of the AA cross-section; Figure 3 yes Figure 2 BB cross-sectional diagram; Figure 4 This is a schematic diagram of the elevation structure of the upper region of the present invention; Figure 5 This is a schematic diagram of the elevation layout of the flat pressure pipeline network and airtight structure layer in the end plate area of ​​the top air chamber of the present invention. Figure 6 This is a schematic diagram of the elevation layout of the flat pressure pipeline network and airtight structure layer in the top plate area of ​​the top air chamber of the present invention.

[0015] The components in the diagram are labeled as follows: water diversion tunnel 1, impedance hole 2, vertical shaft 3, top air chamber 4, airtight structure layer 5, reinforced concrete lining layer 6, flat pressure pipeline network 7, first connecting pipe 8, second connecting pipe 9. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] like Figures 1 to 6As shown, the present invention includes a water diversion tunnel 1, a top air chamber 4, and a vertical shaft 3. The top air chamber 4 has a long strip structure (i.e., it adopts a specific cross-sectional structure and extends along its length). The cross-section of the top air chamber 4 perpendicular to its length direction is semi-circular. That is, the top air chamber 4 of the present invention typically includes a semi-circular air chamber top plate, a horizontally arranged air chamber bottom plate, and two vertically arranged air chamber end plates, which are correspondingly arranged at both ends of the length direction of the top air chamber 4. The lower end of the vertical shaft 3 is connected to the water diversion tunnel 1 through an impedance hole 2, and the upper end of the vertical shaft 3 is directly connected to the bottom plate of the top air chamber 4, forming a two-stage stepped abrupt expansion cavity structure with a lower vertical and an upper dome (i.e., on a horizontal reference plane, the area of ​​the horizontal cross-section of the inner cavity of the top air chamber 4 is larger than the area of ​​the radial cross-section of the inner cavity of the vertical shaft 3). The vertical shaft 3 is coaxial with the impedance hole 2, and the axis of the vertical shaft 3 is... Simultaneously located at the center of the width direction of the water diversion tunnel 1 and the center of the width direction of the top air chamber 4; all structural walls of the top air chamber 4 and the upper sidewall of the vertical shaft 3 are provided with airtight structure layers 5, that is, the top plate, bottom plate and end plate of the top air chamber 4 are provided with airtight structure layers 5, and the transition section of the vertical shaft 3 used to connect the top air chamber 4 is also provided with airtight structure layers 5; throughout the steady-state and transient operation of the pressure regulating chamber, the gas-water interface is confined inside the vertical shaft 3, that is, the top air chamber 4 is a dedicated sealed gas storage space, and there is no water retention inside the top air chamber 4 at any time, realizing complete physical separation of water passage function and gas storage function; the airtight structure layer 5 and the water cushion layer located in the vertical shaft 3 form a gas sealing structure, that is, throughout the steady-state and transient operation of the pressure regulating chamber, the lowest point of the airtight structure layer 5 should always be lower than the top surface of the water cushion layer. The vertical shaft 3 refers to a structure with a vertical axis and a conventional circular cross-section. In this invention, the vertical shaft 3 mainly serves as a dedicated water passage area for water flow and buffering of water level fluctuations. The impedance hole 2 refers to the throttling channel at the bottom of the vertical shaft 3, which can consume energy and attenuate water hammer fluctuations in the water intake channel through local hydraulic resistance, thereby reducing the volume of the pressure regulating chamber. The inner diameter of the impedance hole 2 should be smaller than the inner diameter of the vertical shaft 3. The phrase "the air-water interface is confined within the vertical shaft 3" actually refers to the positional relationship between the water cushion layer and the vertical shaft 3 and the top air chamber 4, and also represents a specific structural improvement of the pressure regulating chamber. In specific implementation, the radius and length of the top air chamber 4 are determined based on the stable gas volume determined by hydraulic calculations of the air cushion pressure regulating chamber. Combined with the design of the air pressure inside the air chamber through hydraulic calculations, the surge water level can be kept below the top of the vertical shaft 3. It is understood that hydraulic calculation methods are common knowledge to those skilled in the art, and the present invention only claims protection for the specific layout and structure of the pressure regulating chamber involved in the above embodiments.

[0018] This invention, through the above-mentioned structural combination, adds a vertical shaft 3, which confines the gas-water interface within the vertical shaft 3. This breaks the traditional fully coupled operation mode of water and gas in the same cavity, and realizes the physical partitioning of the vertical shaft 3 for water passage and the top gas chamber 4 for pure gas storage. The gas storage space is physically isolated from the water passage space. The top gas chamber 4 constantly stores high-pressure buffer gas, forming a stable air cushion buffer layer. When the unit load fluctuates or water hammer pressure is transmitted, only the water in the vertical shaft 3 fluctuates up and down. The position of the gas-water interface is controllable and the fluctuation amplitude is small. The pressure in the gas storage cavity does not oscillate violently, which greatly improves the stability of system pressure regulation, effectively suppresses water disturbance and vortex air mixing in the gas storage cavity, and has a good water hammer protection effect. It can adapt to the operation requirements of frequent start-up and shutdown and large load fluctuation of pumped storage units, and its pressure regulation performance is better than that of traditional water-gas mixed cavity structures. In addition, by setting up a vertical shaft 3, the present invention can reasonably reduce the maximum working pressure and volume of the gas chamber, which can not only reduce the requirements for the geological conditions of the surrounding rock, but also effectively reduce the construction scope of high-pressure sealing, significantly reduce civil engineering investment and the probability of sealing failure; the arc structure of the top gas chamber 4 is uniformly stressed, which can better adapt to the high ground stress environment and reduce the hidden dangers of rock mass cracking and sealing damage.

[0019] In practical implementation, the sealing system of this invention can be designed according to the different functions of the gas storage space and the water passage space. The arrangement of the airtight structure layer 5 can refer to the existing technology. In order to make the structure simple and reliable and reduce the overall construction cost, one embodiment is as follows: both the top gas chamber 4 and the vertical shaft 3 have reinforced concrete lining layers 6. The airtight structure layer 5 is an airtight steel plate pre-embedded inside the reinforced concrete lining layer 6. The outside of the reinforced concrete lining layer 6 is in contact with the surrounding rock leveling layer. That is, in the area where the gas storage space is located (the area corresponding to all structural walls of the top gas chamber 4 and the upper side wall of the vertical shaft 3), its side wall is a multi-layer composite airtight sealing structure. The multi-layer composite airtight sealing structure consists of the surrounding rock leveling layer, the reinforced concrete lining layer 6, the airtight steel plate, and the reinforced concrete lining layer 6 from the outside to the inside. The multi-layer structure works together to adapt to long-term high-pressure gas infiltration, temperature stress, and micro-deformation of the surrounding rock, and prevents the sealing layer from cracking and leaking gas. The vertical shaft 3 primarily serves as a dedicated water passage area for water flow and buffering water level fluctuations; therefore, it only requires a corresponding water seepage prevention structure. This invention addresses the differentiated protection requirements of the high-pressure gas storage area and the water flow passage area under different working conditions. The gas chamber area with high leakage risk employs a multi-layer composite airtight sealing structure, while the vertical shaft area with low leakage risk has a simplified lining structure (without airtight steel plates). This significantly reduces the high-pressure sealing construction area and lowers the probability of sealing failure caused by surrounding rock deformation, while ensuring airtight reliability.

[0020] It is understood that, in some embodiments, the main bodies of the top air chamber 4 and the vertical shaft 3 are generally constructed of reinforced concrete, and both have at least a reinforced concrete lining layer 6. In some preferred embodiments, the present invention may also provide an air chamber pressure equalization system in the outer region of the airtight structure layer 5. The air chamber pressure equalization system includes a pressure equalization pipe network 7 embedded inside the reinforced concrete lining layer 6. The pressure equalization pipe network 7 is connected to the inner cavity of the vertical shaft 3 through several first connecting pipes 8. The pipe opening at one end of the first connecting pipe 8 connected to the inner cavity of the vertical shaft 3 is lower than the lowest surge water level in the vertical shaft 3. The pressure equalization pipe network 7 is connected to the outer region of the top air chamber 4 through several second connecting pipes 9. The end of the second connecting pipe 9 away from the pressure equalization pipe network 7 extends into the bedrock outside the top air chamber 4. The air chamber pressure equalization system is mainly used to balance the water pressure difference between the outside and the air pressure difference of the air chamber structure, ensuring that the pressure inside and outside the air chamber structure is always in dynamic equilibrium when the surge wave fluctuates in the pressure regulating chamber, thus ensuring structural stability. To improve the pressure equalization effect of the air chamber pressure equalization system, in a preferred embodiment, multiple first connecting pipes 8 are evenly spaced along the circumference of the vertical shaft 3; the pipe interfaces of the pressure equalization network 7 for connecting the second connecting pipes 9 are arranged on all structural walls of the top air chamber 4, and each pipe interface corresponds to a straight second connecting pipe 9, meaning that the entire outer area of ​​the top air chamber 4 can be connected to the pressure equalization network 7 through the second connecting pipes 9. The pipe openings of the second connecting pipes 9, at the end furthest from the pressure equalization network 7, are located throughout the entire outer area of ​​the top air chamber 4 (including the outer area of ​​the top plate of the top air chamber 4, the area below the bottom plate of the air chamber, and the outer area of ​​the end plate of the air chamber). In some further preferred embodiments, a second connecting pipe 9 may also be added to the top area of ​​the vertical shaft 3.

[0021] To ensure a simple and reliable structure and reduce overall construction costs, in the preferred embodiment, the pressure-reducing pipeline 7, the first connecting pipe 8, and the second connecting pipe 9 are all made of steel pipe.

Claims

1. A cushion-type pressure regulating chamber structure, comprising a water diversion tunnel (1) and a top air chamber (4), wherein the top air chamber (4) is a long strip structure, characterized in that: The top air chamber (4) has a semi-circular cross section perpendicular to its length direction; it includes a vertical shaft (3), the lower end of which is connected to the water diversion tunnel (1) through an impedance hole (2), and the upper end of which is directly connected to the bottom plate of the top air chamber (4), forming a two-stage stepped abrupt expansion cavity structure with a lower vertical and upper dome; the vertical shaft (3) is coaxial with the impedance hole (2), and the axis of the vertical shaft (3) is located at the center of the width direction of the water diversion tunnel (1) and the center of the width direction of the top air chamber (4); all structural walls of the top air chamber (4) and the upper side wall of the vertical shaft (3) are provided with a gas-sealing structure layer (5); during the entire steady-state and transient operation of the pressure regulating chamber, the gas-water interface is confined inside the vertical shaft (3), and the gas-sealing structure layer (5) and the water cushion layer located in the vertical shaft (3) form a gas-sealed structure.

2. The air cushion pressure regulating chamber structure as described in claim 1, characterized in that: Both the top air chamber (4) and the vertical shaft (3) have reinforced concrete lining (6), and the air-tight structure layer (5) is an air-tight steel plate pre-embedded inside the reinforced concrete lining (6). The outside of the reinforced concrete lining (6) is in contact with the surrounding rock leveling layer.

3. The air cushion pressure regulating chamber structure as described in claim 1, characterized in that: Both the top air chamber (4) and the vertical shaft (3) have reinforced concrete lining layers (6). An air chamber pressure equalization system is set in the outer area of ​​the air-tight structure layer (5). The air chamber pressure equalization system includes a pressure equalization network (7) pre-embedded in the reinforced concrete lining layer (6). The pressure equalization network (7) is connected to the inner cavity of the vertical shaft (3) through several first connecting pipes (8). The pipe opening of the first connecting pipe (8) connected to the inner cavity of the vertical shaft (3) is lower than the lowest surging wave water level in the vertical shaft (3). The pressure equalization network (7) is connected to the outer area of ​​the top air chamber (4) through several second connecting pipes (9). The end of the second connecting pipe (9) away from the pressure equalization network (7) extends into the bedrock outside the top air chamber (4).

4. The air cushion pressure regulating chamber structure as described in claim 3, characterized in that: Multiple first connecting pipes (8) are evenly spaced along the circumference of the vertical shaft (3); the pipe interfaces of the flat pressure network (7) used to connect the second connecting pipes (9) are arranged on all structural walls of the top air chamber (4), and each pipe interface is connected to a straight second connecting pipe (9).

5. The air cushion pressure regulating chamber structure as described in claim 3, characterized in that: The pressure-reducing pipeline (7), the first connecting pipe (8), and the second connecting pipe (9) are all steel pipes.

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