Water-filling method for drainage tunnel and lifting and removing method for cap

Abstract

The present application relates to nuclear power drainage system construction technical field, specifically relates to a kind of drainage tunnel water filling method and jacking cap removal method, wherein the drainage tunnel water filling method includes the following steps: SA1, water is injected into siphon well until the water level in siphon well is higher than the highest point of tunnel entrance;Continue to inject water into siphon well until the water level in siphon well reaches the preset water level, the preset water level is higher than sea level;SA2, hole is opened on jacking cap or the pipeline reserved on jacking cap is opened, wait for the water level in siphon well to be flush with sea level, complete the water filling of tunnel.The present application can overcome the deficiency that there is still a large pressure difference on both sides of jacking cap after the tunnel is water-filled by the existing tunnel water filling method, and there is a hidden danger that a diver or diving equipment is sucked into the inside of tunnel by negative pressure.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant drainage system construction technology, and in particular to a method for filling drainage tunnels with water and a method for removing the jacking cap. Background Technology

[0002] Existing nuclear power plant drainage systems typically employ a combination of vertical siphon wells, undersea shield tunnels, and drainage risers. One end of the drainage riser connects to the top of the tunnel, while the other end extends upwards through the seabed and connects to the ocean. To minimize underwater construction, drainage risers are often constructed using a jacking method. This involves pre-reserving a jacking opening at the top of the tunnel, dividing the drainage riser into multiple segments, and then using a jacking device to push each segment out sequentially from the jacking opening. To prevent seawater from entering the tunnel during jacking, a temporary jacking cap needs to be installed on the top of the uppermost segment to isolate the tunnel interior from the marine environment. Therefore, after the jacking is completed, the jacking cap needs to be removed to install drainage cylinders or drainage grids.

[0003] However, since the lifting cap is located underwater and the tunnel interior is connected to the surrounding atmosphere, the pressure difference between the two sides of the lifting cap is extremely large. To avoid the extreme pressure difference threatening the safety of underwater operations, existing technology involves filling the tunnel with water through a siphon well before removing the lifting cap. Theoretically, when the tunnel is full of water and the water level in the siphon well is equal to the sea level, the pressure on both sides of the lifting cap can be balanced. However, in practice, even after applying this water filling method, there is still a large pressure difference between the two sides of the lifting cap, which may still lead to accidents where divers or diving equipment are sucked into the tunnel during the removal of the lifting cap. Therefore, it is urgent to develop a new method for filling tunnels with water and a corresponding method for removing the lifting cap. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing tunnel filling methods, which still have a large pressure difference on both sides of the lifting cap after filling the tunnel with water, posing a risk that divers or diving equipment may be sucked into the tunnel by negative pressure. This invention provides a drainage tunnel filling method and a lifting cap removal method.

[0005] In a first aspect, the present invention provides a method for filling a drainage tunnel with water, comprising the following steps: SA1. Inject water into the siphon well until the water level in the siphon well is higher than the highest point of the tunnel entrance; continue to inject water into the siphon well until the water level in the siphon well reaches the preset water level, which is higher than the sea level. SA2. Make a hole in the lifting cap or open the pre-installed pipe on the lifting cap, wait for the water level in the siphon well to be level with the sea level, and complete the filling of the tunnel with water.

[0006] Preferably, the preset water level is obtained through the following steps: The gas content inside the tunnel was measured when the water level in the siphon well was level with the highest point at the tunnel entrance. The target pressure is determined based on the water pressure on the outside of the lifting cap, and the equilibrium water level in the tunnel is determined based on the target pressure and the gas content when the gas in the tunnel reaches the target pressure. Based on the equilibrium water level, the additional water filling height required in the siphon well is determined according to the target pressure, and the preset water level is obtained based on the equilibrium water level and the additional water filling height.

[0007] Preferably, the target pressure is higher than the water pressure on the outside of the lifting cap.

[0008] Preferably, the method further includes the following steps: An exhaust pipe is installed on the lifting cap to expel some of the air from inside the tunnel.

[0009] Preferably, a one-way valve is installed inside the exhaust pipe, which opens in one direction away from the tunnel interior.

[0010] Preferably, when injecting water into the siphon well, the water injection operation is divided into multiple stages, with a specified pause between two adjacent stages.

[0011] Preferably, the rate at which water is injected into the siphon well is less than or equal to 2,000 cubic meters per hour.

[0012] Preferably, the diameter of the opening on the lifting cap is greater than or equal to 10 centimeters and less than or equal to 20 centimeters.

[0013] Preferably, the method further includes the following steps: A water level line is set inside the siphon well to monitor the water level.

[0014] In a second aspect, the present invention provides a method for removing a lifting cap, comprising the following steps: SB1. Filling a tunnel with water using the drainage tunnel filling method of the present invention; SB2, Remove the lifting cap.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for filling a drainage tunnel with water. By raising the water level in the siphon well to above sea level during filling, additional compression can be generated in the gas in the tunnel air chamber, increasing the pressure inside the lifting cap. This further reduces or even completely eliminates the pressure difference between the two sides of the lifting cap based on the existing technology, or makes the pressure inside the lifting cap greater than the pressure outside, thereby ensuring the safety of subsequent lifting cap removal operations.

[0016] 2. This invention provides a method for removing a lifting cap. By using the drainage tunnel filling method of this invention to fill the tunnel with water, the safety of the lifting cap removal operation can be ensured, and the safety of divers or diving equipment can be avoided by instantaneous large pressure differences. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the steps of a drainage tunnel filling method according to the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the steps of a drainage tunnel filling method according to the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the steps of a drainage tunnel filling method according to the present invention. Figure 3 ; Figure 4 This is a schematic diagram of the steps of a drainage tunnel filling method according to the present invention. Figure 4 ; icon: 1-Siphon well; 2-Tunnel; 3-Drainage riser; 4-Lifting cap. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0019] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0020] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0021] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0022] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0023] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0024] Example 1 like Figures 1 to 4 As shown, a method for filling a drainage tunnel with water includes the following steps: SA1. Fill siphon well 1 with water until the water level in siphon well 1 is higher than the highest point at the entrance of tunnel 2, for example, reaching the following level: Figure 2 The water level shown is h1; continue injecting water into siphon well 1 until the water level in siphon well 1 reaches the preset water level, which is higher than sea level, for example, reaching h1. Figure 4 The water level shown is h3.

[0025] SA2. Use divers or diving equipment to make holes in the lifting cap 4, or open the pre-installed pipes on the lifting cap 4, so that the internal environment of tunnel 2 is connected with the marine environment, thereby allowing seawater to replace the remaining gas inside tunnel 2; wait for the water level in the siphon well 1 to be level with the sea level to complete the filling of tunnel 2 with water.

[0026] It is important to note that Figures 2 to 3 The water level shown is only a simplified illustration. In actual filling, h1, h2, and h3 should be calculated based on the actual structure of tunnel 2 and the target pressure.

[0027] After studying existing water filling methods, the inventors of this invention discovered that, due to interference from various factors such as the tunnel 2 alignment, the shape of the lifting cap 4, gas dissolution and precipitation, no matter how the water filling process of the tunnel 2 is optimized, it is extremely difficult to completely evacuate the air inside the tunnel 2. The remaining gas will form an air cavity at the top of the drainage riser 3. The air cavity causes the pressure on the inner side of the lifting cap 4 (the side facing the inside of the tunnel 2) to not directly depend on the water pressure inside the tunnel 2, but is also affected by the gas compressibility inside the air cavity. Furthermore, due to the long length of the tunnel 2, various frictional resistances and local resistances inside the tunnel 2 will cause further pressure drop. Therefore, if the water level in the siphon well 1 is controlled to be level with the sea level, it is not enough to eliminate the risk of pressure difference on both sides of the lifting cap 4. This will result in the risk that divers or diving equipment will still be sucked into the tunnel 2 by the pressure difference when removing the lifting cap 4.

[0028] Based on the above analysis, in this embodiment, when injecting water into tunnel 2, the water level is first raised to the highest point of tunnel 2 entrance to seal the entrance of tunnel 2, so that subsequent water injection can compress the remaining gas in tunnel 2; then the water level in siphon well 1 is raised further, so that the water level in siphon well 1 is not only raised to sea level, but also raised further above sea level. The additional water can generate additional compression of the gas in the air chamber of tunnel 2, increasing the pressure inside the lifting cap 4. Depending on the height of the additional water, this embodiment can further reduce or even completely eliminate the pressure difference between the two sides of the lifting cap 4 on the basis of the prior art, or make the pressure inside the lifting cap 4 greater than the pressure on the outside (the side away from tunnel 2), thereby ensuring the safety of the subsequent removal operation of the lifting cap 4.

[0029] In an optional implementation, the height difference between the preset water level and the sea level is determined according to the actual construction requirements, so as to reduce the pressure difference on both sides of the lifting cap 4 to an allowable value. The specific value of the preset water level can be obtained by theoretical calculation or fluid simulation calculation, or by real-time pressure monitoring of the air chamber during water injection and continuous adjustment of the water level accordingly.

[0030] In an optional implementation, the preset water level can be obtained through the following steps: When the water level in siphon well 1 is level with the highest point of the tunnel entrance 2, obtain the gas content (volume or molecular weight) in tunnel 2.

[0031] The target pressure is determined based on the water pressure on the outside of the lifting cap 4. The equilibrium water level in tunnel 2 is determined based on the target pressure and the gas content when the gas in tunnel 2 reaches the target pressure. Based on the equilibrium water level, the additional water filling height required in siphon well 1 is determined according to the target pressure, and the preset water level is obtained based on the equilibrium water level and the additional water filling height.

[0032] This embodiment provides one specific method for obtaining the preset water level, which can quantitatively calculate the corresponding water level in the siphon well 1 when the gas in the tunnel 2 reaches the target pressure. This avoids the situation where the water level in the siphon well 1 is insufficient, resulting in low air pressure inside the lifting cap 4, which could lead to the risk of divers or diving equipment being sucked into the tunnel 2; or the air pressure inside the lifting cap 4 is too high, which could lead to the risk of divers or diving equipment being overturned by the airflow.

[0033] In an optional implementation, the target pressure is higher than the water pressure on the outside of the lifting cap 4, thereby ensuring that when divers make an opening in the lifting cap 4, only air bubbles will overflow from the opening and there will be no negative pressure backflow, thus fully ensuring the safety of the subsequent removal operation of the lifting cap 4.

[0034] In an optional implementation, the gas content inside the tunnel 2 can be determined based on the remaining cavity volume inside the tunnel 2 when the water level in the siphon well 1 is level with the highest point of the tunnel 2 entrance, in order to simplify subsequent calculations.

[0035] In an optional implementation, the gas content within tunnel 2 can be considered a fixed quantity, and the equilibrium water level can be determined using the ideal gas law to simplify subsequent calculations. For example, if the gas pressure and volume within tunnel 2 are measured to be P1 and V1 respectively when the water level in siphon well 1 is level with the highest point of tunnel 2's inlet, and the target pressure is P2, then P1*V1 = P2*V2 can be set. This allows calculation of the compressed gas volume V2 within tunnel 2 when the gas pressure reaches P2. Furthermore, the equilibrium water level within tunnel 2 when the gas pressure reaches P2 can be deduced from V2. Figure 3 The water level shown is h2.

[0036] In an optional implementation, the additional water filling height can be determined using the hydrostatic pressure formula; for example, if the target pressure is P2, then the additional water filling height H = P2 / (ρg), where ρ is the density of water and g is the acceleration due to gravity. Adding the additional water filling height to the equilibrium water level height yields the preset water level. Figure 4 The water level shown is h3.

[0037] In an optional implementation, the preset water level is at least 1m above sea level.

[0038] In an optional implementation, the following steps are also included: An exhaust pipe is installed on the lifting cap 4 to discharge some of the air in the tunnel 2, thereby filling the tunnel 2 with water as much as possible; at the same time, this embodiment can adjust the equilibrium water level in the tunnel 2 while keeping the target pressure constant, and avoid the situation where the equilibrium water level is too low due to too much residual gas in the tunnel 2.

[0039] Remote valves can be installed inside the exhaust pipe, allowing workers to remotely control the opening and closing of the exhaust pipe according to the construction progress, thereby improving the safety of water filling construction.

[0040] In an optional embodiment, a one-way valve is installed inside the exhaust pipe. The one-way valve opens in one direction away from the interior of the tunnel 2, thereby preventing seawater from rushing into the interior of the tunnel 2 from threatening the safety of the jacking operation during the jacking process.

[0041] In an optional implementation, when injecting water into the siphon well 1, the water injection operation is divided into multiple stages, with a specified pause between two adjacent stages, to allow sufficient time for the gas inside the tunnel 2 to escape or gather at a higher position, so as to avoid the gas being trapped at a position other than the top of the tunnel 2 and the top of the drainage riser 3, which would cause the pressure inside the lifting cap 4 to deviate from the expected situation; the specified time depends on the actual situation, such as several minutes or several hours.

[0042] In optional implementations, such as Figure 1 As shown, some existing tunnels 2 adopt a profile that is higher in the middle and lower at both ends. For this type of tunnel 2, when filling water into the siphon well 1, the filling can be carried out in stages as follows to avoid the formation of large air pockets due to sudden air compression: Phase 1: Fill siphon well 1 with water until the water level in siphon well 1 is higher than the highest point at the entrance of tunnel 2, thus achieving the desired result. Figure 2 The water level h1 shown indicates that subsequent water filling can compress the remaining gas in tunnel 2.

[0043] Phase 2: Continue injecting water into siphon well 1 until the water level in siphon well 1 is higher than the highest point of the bottom of tunnel 2, allowing the water to flow over tunnel 2. Figure 1 The reverse slope point shown continues to compress the remaining gas inside tunnel 2.

[0044] Stage 3: Continue injecting water into siphon well 1 until the water level in siphon well 1 reaches the preset water level, i.e., as shown in the figure. Figure 4 The water level shown is h3.

[0045] In an optional implementation, the rate at which water is injected into the siphon well 1 is less than or equal to 2,000 cubic meters per hour, in order to avoid sudden changes in local pressure inside the tunnel 2.

[0046] In an optional embodiment, the diameter of the opening on the lifting cap 4 is greater than or equal to ten centimeters and less than or equal to twenty centimeters.

[0047] Since the lifting cap 4 is located on the seabed, if the diameter of the opening is too small, it will not only result in a low exhaust velocity of the lifting cap 4, but also easily cause air blockage. However, if the diameter of the opening is too large, it will result in excessive water flow impact, which may easily damage the tunnel 2 structure near the opening. Therefore, this embodiment recommends a specific diameter range for the opening, which can avoid air blockage and reduce the disturbance of water flow impact on the tunnel 2 structure.

[0048] In an optional implementation, the lifting cap 4 has at least two openings.

[0049] This embodiment can increase the exhaust speed of the lifting cap 4 without increasing the opening diameter.

[0050] In an optional implementation, the following steps are also included: A water level line is set inside the siphon well 1, and the water level height inside the siphon well 1 is monitored through the water level line.

[0051] Since the water level in the siphon well 1 is directly related to the inner pressure of the lifting cap 4, this embodiment recommends setting a water level line in the siphon well 1 so that staff can monitor the water level in the siphon well 1 in real time.

[0052] Example 2 A method for removing a lifting cap includes the following steps: SB1. Fill tunnel 2 with water using a drainage tunnel filling method as described in Example 1; SB2, Remove the lifting cap 4.

[0053] This embodiment uses the drainage tunnel filling method in Embodiment 1 to fill the tunnel 2 with water, which can ensure the safety of the lifting cap 4 removal operation and avoid the threat to the safety of divers or diving equipment caused by instantaneous large pressure difference.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for filling a drainage tunnel with water, characterized in that, The steps include the following: SA1. Pour water into the siphon well (1) until the water level in the siphon well (1) is higher than the highest point of the tunnel (2) entrance; continue to pour water into the siphon well (1) until the water level in the siphon well (1) reaches the preset water level, which is higher than the sea level. SA2. Make a hole in the lifting cap (4) or open the pipeline reserved in the lifting cap (4), wait for the water level in the siphon well (1) to be level with the sea level, and complete the filling of the tunnel (2) with water. in: Obtain the preset water level by following these steps: Obtain the gas content in the tunnel (2) when the water level in the siphon well (1) is level with the highest point of the tunnel entrance (2); determine the target pressure based on the water pressure on the outside of the lifting cap (4); determine the equilibrium water level height in the tunnel (2) when the gas in the tunnel (2) reaches the target pressure based on the target pressure and the gas content; determine the additional water filling height required in the siphon well (1) based on the equilibrium water level height and the target pressure; obtain the preset water level based on the equilibrium water level height and the additional water filling height.

2. The method for filling a drainage tunnel with water according to claim 1, characterized in that, The target pressure is higher than the water pressure on the outside of the lifting cap (4).

3. The method for filling a drainage tunnel with water according to claim 1, characterized in that, It also includes the following steps: An exhaust pipe is installed on the lifting cap (4) to discharge some of the air inside the tunnel (2).

4. The method for filling a drainage tunnel with water according to claim 3, characterized in that, The exhaust pipe is equipped with a one-way valve, which opens in one direction away from the inside of the tunnel (2).

5. A method for filling a drainage tunnel with water according to any one of claims 1 to 4, characterized in that, When injecting water into the siphon well (1), the water injection operation is divided into multiple stages, with a specified pause between two adjacent stages.

6. A method for filling a drainage tunnel with water according to any one of claims 1 to 4, characterized in that, The rate at which water is injected into the siphon well (1) is less than or equal to 2,000 cubic meters per hour.

7. A method for filling a drainage tunnel with water according to any one of claims 1 to 4, characterized in that, The diameter of the opening on the lifting cap (4) is greater than or equal to 10 cm and less than or equal to 20 cm.

8. A method for filling a drainage tunnel with water according to any one of claims 1 to 4, characterized in that, It also includes the following steps: A water level line is set inside the siphon well (1) to monitor the water level height inside the siphon well (1).

9. A method for removing a lifting cap, characterized in that, The steps include the following: SB1. Fill the tunnel (2) with water using a drainage tunnel filling method according to any one of claims 1 to 8; SB2, Remove the lifting cap (4).

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