Siphon drainage system for reverse slope construction of water-rich tunnel and construction method of siphon drainage system

Abstract

The invention belongs to the technical field of tunnel construction, and discloses a siphon drainage system for reverse slope construction of a water-rich tunnel and a construction method of the siphon drainage system. The main drainage pipe comprises a first pipe section and a second pipe section, the second pipe section is configured to vertically extend and enable the water outlet end of the main drainage pipe to extend into water in the water collecting tank outside the tunnel, the first pipe section comprises a plurality of sub-pipelines which are connected one by one in the tunneling direction of the tunnel, and the sub-pipelines and the water collecting vertical shafts are arranged in a one-to-one correspondence mode; the end, close to the tunnel face, of each sub-pipeline in the tunneling direction of the tunnel communicates with the corresponding water collecting vertical shaft and is further connected with a water suction pipe, and the water suction pipes are configured to stretch into water in the corresponding water collecting pits; and water in the water collecting pit is configured to be discharged into the water collecting tank outside the tunnel through the main water discharging pipe by utilizing a siphonic effect. The problems of high construction cost, high energy consumption and the like of reverse slope drainage can be solved by utilizing the siphon principle.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a siphon drainage system and its construction method for reverse slope construction of water-rich tunnels. Background Technology

[0002] During tunnel construction, to ensure construction progress, long or ultra-long tunnels often employ bidirectional excavation, which is further divided into downslope excavation and upslope excavation. Drainage during tunnel construction is crucial for ensuring construction safety and progress, especially in water-rich tunnels undergoing upslope excavation, where drainage becomes a key focus and challenge. In downslope construction, water collected along the excavation route and at the tunnel face can naturally drain away under gravity through permanently designed drainage ditches. However, in upslope construction, groundwater converges along the tunnel route towards the tunnel face. As the excavation length increases, groundwater accumulates in both the excavated and ongoing sections. If this accumulated water cannot be effectively drained in a timely manner, it can not only hinder tunnel excavation but also trigger significant construction risks such as large deformations in soft rock and landslides.

[0003] Currently, drainage during tunnel reverse slope construction typically employs tiered collection wells and pumping stations to mechanically pump out concentrated water from the tunnel face in stages until it is discharged outside the tunnel. However, the construction and maintenance of tiered collection wells and pumping stations require significant investment in equipment, materials, and labor costs. Furthermore, the high electricity consumption during mechanical pumping significantly increases the cost of engineering measures. Moreover, as tunnel excavation lengths continue to increase, higher demands are placed on the drainage capacity of pumping machinery. Existing solutions often involve adding pumping equipment or setting up multiple drainage channels, which further exacerbates the construction cost burden.

[0004] Therefore, there is an urgent need to propose a siphon drainage system and its construction method for reverse slope construction of water-rich tunnels in order to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a siphon drainage system and its construction method for reverse slope construction of water-rich tunnels, which can solve the problems of high construction cost and high energy consumption of reverse slope drainage by utilizing the siphon principle.

[0006] Based on the above concept, the technical solution adopted by this invention is as follows:

[0007] In a first aspect, the present invention provides a siphon drainage system for reverse slope construction of water-rich tunnels, comprising a siphon drainage assembly and an external water collection tank, wherein the external water collection tank is disposed outside the tunnel entrance and below the tunnel entrance; the siphon drainage assembly comprises:

[0008] Multiple water collection pits are provided inside the tunnel body, and the multiple water collection pits are spaced apart along the tunnel excavation direction;

[0009] Multiple water collection shafts are provided, each corresponding to one of the multiple water collection pits. The water collection shafts are located above the corresponding water collection pits. The water collection shafts are configured to penetrate the mountain and have their bottoms extending into the water inside the water collection pit.

[0010] The main drainage pipe includes a first pipe section and a second pipe section that are interconnected. The inlet end of the main drainage pipe is located in the first pipe section, and the outlet end of the main drainage pipe is located in the second pipe section. The second pipe section is configured to extend vertically so that the outlet end of the main drainage pipe extends into the water inside the external water collection tank. The first pipe section includes multiple sub-pipes connected one by one along the tunnel excavation direction. The multiple sub-pipes are configured to correspond one-to-one with multiple water collection shafts. The end of each sub-pipe near the tunnel face along the tunnel excavation direction is connected to the corresponding water collection shaft, and this end is also connected to a suction pipe. The suction pipe is configured to extend into the water inside the corresponding water collection pit. The water in the water collection pit is configured to be discharged into the external water collection tank through the main drainage pipe using a siphon effect.

[0011] In some embodiments, a buoyancy ball and a buoyancy valve are provided at the inlet of the water suction pipe. The buoyancy ball can rise or fall under the buoyancy of the water inside the water collection pit. The rise of the buoyancy ball can cause the buoyancy valve to be in an open state, and the fall of the buoyancy ball can cause the buoyancy valve to be in a closed state.

[0012] In some embodiments, a one-way valve is also provided at the inlet of the water suction pipe, the one-way valve being used to prevent water in the main drain pipe from flowing back into the water collection pit through the water suction pipe.

[0013] In some embodiments, the siphon drainage system further includes a water collection trolley, which is movably disposed within the tunnel body. The water collection trolley is used to collect drainage at the tunnel face. The water collection trolley is connected to a water collection pipe, which is used to transport the water in the water collection trolley to a water collection pit adjacent to the water collection trolley in the opposite direction of the tunnel excavation direction.

[0014] In some embodiments, each of the sub-pipes is provided with a three-way valve at one end near the tunnel face along the tunnel excavation direction. The first port of the three-way valve is connected to the sub-pipe, the second port of the three-way valve is connected to the corresponding water collection shaft, and the third port of the three-way valve is reserved for connecting to the next adjacent sub-pipe.

[0015] In some embodiments, a connecting valve is provided at the third interface for connecting with the next adjacent sub-pipe.

[0016] In some embodiments, a vent valve is installed on the sub-pipe for venting air from inside the sub-pipe.

[0017] In some embodiments, the external water collection tank is further provided with an external drain pipe, and the water in the external water collection tank is configured to be discharged through the external drain pipe.

[0018] In some embodiments, the siphon drainage system further includes an external sedimentation tank, and the external drainage pipe is disposed between the external water collection tank and the external sedimentation tank, the external drainage pipe being used to transport water from the external water collection tank to the external sedimentation tank.

[0019] Secondly, the present invention provides a construction method for a siphon drainage system for reverse slope construction of water-rich tunnels, employing the siphon drainage system for reverse slope construction of water-rich tunnels as described in any one of the first aspects; the construction method includes the following steps:

[0020] S1. Drill holes at predetermined locations on the mountain to form water collection shafts according to the design;

[0021] S2. Install an external water collection tank outside the tunnel entrance and excavate the tunnel;

[0022] S3. When the first water collection shaft is dug, the main drainage pipe is erected, the first sub-pipe in the first pipe section is connected to the current water collection shaft, and the water outlet on the second pipe section is extended into the water collection tank outside the tunnel.

[0023] S4. Start the siphon drainage to discharge the water in the first sump into the outside water tank through the main drain pipe.

[0024] S5. Continue excavating the tunnel. When you reach the next water collection shaft, connect the next sub-pipe to the previous sub-pipe and connect the connected sub-pipe to the current water collection shaft. Start the siphon drainage so that the water in the current water collection pit is discharged to the water collection tank outside the tunnel through the main drainage pipe.

[0025] S6. Repeat step S5 until the tunnel excavation is completed.

[0026] The beneficial effects of this invention are:

[0027] The siphon drainage system and its construction method for reverse slope construction of water-rich tunnels provided by this invention eliminate the need for traditional graded collection wells and pumping stations. It can achieve drainage during reverse slope construction by utilizing the siphon principle, which helps to reduce costs and save energy. Moreover, the system can flexibly connect sub-pipes in the main drainage pipe as the tunnel excavation progresses, which can better adapt to the construction needs when the tunnel excavation length continues to increase. This achieves the goal of energy-free reverse slope drainage for ultra-long tunnels, greatly reducing construction costs and construction difficulty. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a siphon drainage system at the initial stage of tunnel excavation from one perspective provided in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the siphon drainage system at the initial stage of tunnel excavation from another perspective provided by an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the siphon drainage system after a tunnel has been excavated to a certain length, provided by an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the siphon drainage system after the tunnel has been excavated to a certain length, provided by another perspective of the embodiments of the present invention.

[0033] In the picture:

[0034] 1. External water collection tank; 11. External drainage pipe;

[0035] 2. Sump pit;

[0036] 3. Water collection shaft;

[0037] 4. Main drainage pipe; 41. First pipe section; 411. Sub-pipe; 42. Second pipe section;

[0038] 5. Suction pipe; 51. Buoyancy ball; 52. Buoyancy valve; 53. Check valve;

[0039] 6. Water collection trolley; 61. Water collection pipe;

[0040] 7. Three-way valve;

[0041] 8. Connecting valves;

[0042] 9. Air vent valve;

[0043] 100. Mountain body; 110. Working face. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] 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.

[0047] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., 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 this invention is in use. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0048] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0051] like Figures 1-4 As shown, this embodiment provides a siphon drainage system for reverse slope construction of water-rich tunnels, including a siphon drainage component and an external water collection tank 1. The external water collection tank 1 is located outside the tunnel entrance and is lower than the tunnel entrance.

[0052] The siphon drainage assembly includes multiple sump pits 2, multiple sump shafts 3, and a main drain pipe 4.

[0053] Multiple water collection pits 2 are installed inside the tunnel body, and are spaced apart along the tunnel excavation direction. Figures 1 to 4 Taking the orientation shown as an example, the direction from right to left in the figure is the tunnel excavation direction.

[0054] Multiple water collection shafts 3 are set up one-to-one with multiple water collection pits 2. The water collection shafts 3 are set above the corresponding water collection pits 2. The water collection shafts 3 are configured to penetrate the mountain body 100 and the bottom of the water collection shafts 3 extends into the water inside the water collection pits 2.

[0055] The main drainage pipe 4 includes a first pipe section 41 and a second pipe section 42 that are interconnected. The inlet end of the main drainage pipe 4 is located in the first pipe section 41, and the outlet end is located in the second pipe section 42. The second pipe section 42 is configured to extend vertically so that the outlet end of the main drainage pipe 4 extends into the water inside the external water collection tank 1. The first pipe section 41 includes multiple sub-pipes 411 connected one by one along the tunnel excavation direction. The multiple sub-pipes 411 are correspondingly arranged with multiple water collection shafts 3. The end of each sub-pipe 411 near the tunnel face 110 along the tunnel excavation direction is connected to the corresponding water collection shaft 3, and this end is also connected to a suction pipe 5. The suction pipe 5 is configured to extend into the water inside the corresponding water collection pit 2. The water in the water collection pit 2 is configured to be discharged into the external water collection tank 1 through the main drainage pipe 4 using the siphon effect.

[0056] Correspondingly, the construction method of the siphon drainage system for reverse slope construction of water-rich tunnels includes the following steps:

[0057] S1. Drill a hole at a predetermined location on the mountain 100 to form a water collection shaft 3. Since the mountain 100 is rich in groundwater, water will accumulate inside the water collection shaft 3.

[0058] S2. Install an external water collection tank 1 outside the tunnel entrance and excavate the tunnel.

[0059] S3. When the first water collection shaft 3 is reached, the main drainage pipe 4 is installed, and the first sub-pipe 411 in the first pipe section 41 is connected to the current water collection shaft 3. The outlet end of the second pipe section 42 is extended into the water collection tank 1 outside the tunnel (e.g., Figure 1 and Figure 2 ).

[0060] S4. Start the siphon drainage to discharge the water in the first water collection pit 2 through the main drain pipe 4 to the water collection tank 1 outside the cave.

[0061] Specifically, after the first sub-pipe 411 is connected to the first water collection shaft 3, the water in the water collection shaft 3 will flow to the main drain pipe 4 under the action of gravity, so that the main drain pipe 4 is filled with water, thereby achieving the starting condition of the siphon effect. At this time, the opening at the top of the water collection shaft 3 is immediately sealed to form a vacuum inside, ensuring the siphon effect. Then, when the water level in the water collection pit 2 rises, a connection can be formed, and the water in the water collection pit 2 can be discharged from the main drain pipe 4 to the water collection tank 1 outside the cave using the siphon effect.

[0062] S5. Continue excavating the tunnel. When you reach the next water collection shaft 3, connect the next sub-pipe 411 to the previous sub-pipe 411 and connect the connected sub-pipe 411 to the current water collection shaft 3. Start the siphon drainage to discharge the water in the current water collection pit 2 through the main drainage pipe 4 to the water collection tank 1 outside the tunnel. The drainage principle after each connection is the same as in step S4, which is to use the siphon effect for drainage.

[0063] S6. Repeat step S5 until the tunnel excavation is completed.

[0064] The siphon drainage system and its construction method for reverse slope construction of water-rich tunnels provided in this embodiment do not require the setting of traditional graded water collection wells and pumping stations. They can achieve drainage during reverse slope construction by utilizing the siphon principle, which helps to reduce costs and save energy. Moreover, the system can flexibly connect the sub-pipes 411 in the main drainage pipe 4 as the tunnel excavation progresses, which can better adapt to the construction needs when the tunnel excavation length continues to increase. This achieves the purpose of reverse slope drainage of ultra-long tunnels without energy consumption, greatly reducing construction costs and construction difficulty.

[0065] like Figure 1 and Figure 2 As shown, in some embodiments, a buoyancy ball 51 and a buoyancy valve 52 are provided at the inlet of the water suction pipe 5. The buoyancy ball 51 can rise or fall under the buoyancy of the water inside the water collection pit 2. The rise of the buoyancy ball 51 can drive the buoyancy valve 52 to be in the open state, and the fall of the buoyancy ball 51 can drive the buoyancy valve 52 to be in the closed state.

[0066] At normal times, the water level in the sump 2 does not exceed the buoyancy ball 51, and the buoyancy valve 52 is closed, causing the suction pipe 5 to close. When the water level in the sump 2 rises, it lifts the buoyancy ball 51, which in turn opens the buoyancy valve 52, connecting the suction pipe 5. Under siphon action, the suction pipe 5 drains the water from the sump 2 until the buoyancy ball 51, as the water level drops, again closes the suction pipe 5. This setup enables automatic activation of the siphon channel, achieving energy-free construction.

[0067] like Figure 1 and Figure 2 As shown, in some embodiments, a one-way valve 53 is also provided at the inlet of the suction pipe 5. The one-way valve 53 is used to prevent water in the main drain pipe 4 from flowing back into the sump 2 through the suction pipe 5. When the sub-pipe 411 is connected to the sump 3, the sump 3, the main drain pipe 4, and the suction pipe 5 are all connected. Therefore, the one-way valve 53 ensures that water can only flow from the inlet of the suction pipe 5 to the main drain pipe 4, avoiding reverse flow and preventing the siphon effect from being activated.

[0068] like Figures 1-4 As shown, in some embodiments, the siphon drainage system also includes a water collection trolley 6, which is movably installed inside the tunnel. The water collection trolley 6 is used to collect drainage at the tunnel face 110. The water collection trolley 6 is connected to a water collection pipe 61, which is used to transport the water in the water collection trolley 6 to a water collection pit 2 adjacent to the water collection trolley 6 in the opposite direction of the tunnel excavation direction.

[0069] There is a distance between two adjacent water collection pits 2. Water excavated at the tunnel face 110 within this distance is discharged into the previous water collection pit 2 through the water collection trolley 6 and the water collection pipe 61, which is conducive to achieving drainage without dead angles throughout the tunnel excavation process.

[0070] like Figure 2 As shown, in some embodiments, each sub-pipe 411 is provided with a three-way valve 7 at one end near the tunnel face 110 along the tunnel excavation direction. The first port of the three-way valve 7 is connected to the sub-pipe 411, the second port of the three-way valve 7 is connected to the corresponding water collection shaft 3, and the third port of the three-way valve 7 is reserved to connect to the next adjacent sub-pipe 411.

[0071] The three-way valve 7 allows for easy connection of sub-pipe 411 and connection to water collection shaft 3 without complicated pipe modification operations.

[0072] like Figure 2 As shown, in some embodiments, a connecting valve 8 is provided at the third interface, which is used to connect with the next adjacent sub-pipe 411. By reserving the connecting valve 8, subsequent connection operations and maintenance are facilitated.

[0073] like Figure 3 and Figure 4 As shown, in some embodiments, a vent valve 9 is installed on the sub-pipe 411 to release air from inside the sub-pipe 411.

[0074] During the extension of the main drain pipe 4, air will inevitably be present in the sub-pipe 411 between the previous sump 2 and the next sump 2. The presence of air will affect the siphon effect and may even cause the siphon effect to fail. Therefore, after the sub-pipe 411 is extended, the air release valve 9 is opened to release air until water flows out of the outlet of the air release valve 9, and then it is closed.

[0075] In some embodiments, a vacuum pump can be installed at the water collection tank 1 outside the cave. When the first sub-pipe 411 and the second pipe section 42 are installed, the vacuum pump can be used to draw out the air inside to keep the inside of the pipe vacuum, so as to ensure the smooth implementation of the subsequent siphon action.

[0076] like Figure 1 As shown, in some embodiments, the external water collection tank 1 is also equipped with an external drain pipe 11, and the water in the external water collection tank 1 is configured to be discharged through the external drain pipe 11. Specifically, when the water level in the external water collection tank 1 is higher than the horizontal section of the external drain pipe 11, the water in the tank can be discharged from the external drain pipe 11, and drainage can be achieved without additional power.

[0077] In some embodiments, the siphon drainage system further includes an external sedimentation tank, and an external drain pipe 11 is disposed between the external water collection tank 1 and the external sedimentation tank. The external drain pipe 11 is used to transport water from the external water collection tank 1 to the external sedimentation tank. The external sedimentation tank is used to treat the tunnel water discharged from the external water collection tank 1, so that the treated water can meet safe discharge standards.

[0078] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A siphon drainage system for reverse slope construction of water-rich tunnels, characterized in that, The system includes a siphon drainage assembly and an external water collection tank (1), wherein the external water collection tank (1) is located outside the tunnel entrance and below the tunnel entrance; the siphon drainage assembly includes: Multiple water collection pits (2) are set inside the tunnel body, and the multiple water collection pits (2) are set at intervals along the tunnel excavation direction; Multiple water collection shafts (3) are provided one-to-one with multiple water collection pits (2). The water collection shafts (3) are located above the corresponding water collection pits (2). The water collection shafts (3) are configured to penetrate the mountain (100) and the bottom of the water collection shafts (3) extends into the water inside the water collection pits (2). The main drainage pipe (4) includes a first pipe section (41) and a second pipe section (42) that are interconnected. The inlet end of the main drainage pipe (4) is located in the first pipe section (41), and the outlet end of the main drainage pipe (4) is located in the second pipe section (42). The second pipe section (42) is configured to extend vertically and allow the outlet end of the main drainage pipe (4) to extend into the water inside the external water collection tank (1). The first pipe section (41) includes a plurality of sub-pipes (411) that are connected one by one along the tunnel excavation direction. Multiple sub-pipes (411) are provided one-to-one with multiple water collection shafts (3). Each sub-pipe (411) is connected to the corresponding water collection shaft (3) at one end near the tunnel face (110) along the tunnel excavation direction, and the end is also connected to a suction pipe (5). The suction pipe (5) is configured to extend into the water inside the corresponding water collection pit (2). The water in the water collection pit (2) is configured to be discharged into the external water collection tank (1) through the main drainage pipe (4) using the siphon effect.

2. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 1, characterized in that, The water suction pipe (5) is equipped with a buoyancy ball (51) and a buoyancy valve (52) at the pipe opening. The buoyancy ball (51) can rise or fall under the buoyancy of the water inside the water collection pit (2). The rise of the buoyancy ball (51) can drive the buoyancy valve (52) to be in the open state, and the fall of the buoyancy ball (51) can drive the buoyancy valve (52) to be in the closed state.

3. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 2, characterized in that, A one-way valve (53) is also provided at the inlet of the water suction pipe (5). The one-way valve (53) is used to prevent water in the main drain pipe (4) from flowing back into the water collection pit (2) through the water suction pipe (5).

4. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 1, characterized in that, The siphon drainage system also includes a water collection trolley (6), which is movably installed inside the tunnel. The water collection trolley (6) is used to collect drainage at the tunnel face (110). The water collection trolley (6) is connected to a water collection pipe (61), which is used to transport the water in the water collection trolley (6) to the water collection pit (2) adjacent to the water collection trolley (6) in the opposite direction of the tunnel excavation direction.

5. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 1, characterized in that, Each of the sub-pipes (411) is provided with a three-way valve (7) at one end near the tunnel face (110) along the tunnel excavation direction. The first port of the three-way valve (7) is connected to the sub-pipe (411), the second port of the three-way valve (7) is connected to the corresponding water collection shaft (3), and the third port of the three-way valve (7) is reserved to connect to the next adjacent sub-pipe (411).

6. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 5, characterized in that, A connecting valve (8) is provided at the third interface, which is used to connect with the next adjacent sub-pipe (411).

7. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 5, characterized in that, A vent valve (9) is installed on the sub-pipe (411) for venting air from inside the sub-pipe (411).

8. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 1, characterized in that, The external water collection tank (1) is also equipped with an external drain pipe (11), and the water in the external water collection tank (1) is configured to be discharged through the external drain pipe (11).

9. The siphon drainage system for reverse slope construction of water-rich tunnels according to claim 8, characterized in that, The siphon drainage system also includes an external sedimentation tank. The external drainage pipe (11) is located between the external water collection tank (1) and the external sedimentation tank. The external drainage pipe (11) is used to transport water from the external water collection tank (1) to the external sedimentation tank.

10. A construction method for a siphon drainage system in reverse slope construction of a water-rich tunnel, characterized in that, A siphonic drainage system for reverse slope construction of water-rich tunnels according to any one of claims 1 to 9; the construction method includes the following steps: S1. Drill holes at the preset position on the mountain (100) according to the design to form a water collection shaft (3); S2. Install an external water collection tank (1) outside the tunnel entrance and excavate the tunnel; S3. When the first water collection shaft (3) is dug, the main drainage pipe (4) is erected, the first sub-pipe (411) in the first pipe section (41) is connected to the current water collection shaft (3), and the water outlet on the second pipe section (42) is extended into the water collection tank (1) outside the tunnel. S4. Start the siphon drainage to discharge the water in the first water collection pit (2) through the main drain pipe (4) to the water collection tank (1) outside the cave. S5. Continue excavating the tunnel. When the next water collection shaft (3) is reached, connect the next sub-pipe (411) to the previous sub-pipe (411) and connect the connected sub-pipe (411) to the current water collection shaft (3). Start the siphon drainage so that the water in the current water collection pit (2) is discharged from the main drainage pipe (4) to the water collection tank (1) outside the tunnel. S6. Repeat step S5 until the tunnel excavation is completed.

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