Urban deep-tunnel arrangement structure capable of forward drainage and reverse water replenishment, and operating method

Abstract

Disclosed in the present invention are an urban deep-tunnel arrangement structure capable of forward drainage and reverse water replenishment, and an operating method. The arrangement structure comprises water inlets, a deep tunnel, an outlet hub and a reverse water-replenishment and water-purification facility, wherein the water inlets are arranged in low-lying areas along the deep tunnel and are connected to urban riverways; the outlet hub is arranged at the tail end of the deep tunnel to communicate the deep tunnel with a receiving water area; and the reverse water-replenishment and water-purification facility is arranged at the outlet hub. In the present invention, water is delivered through the underground deep tunnel; during forward drainage, urban accumulated water is discharged into the receiving water area through the deep tunnel, thereby achieving the waterlogging drainage and flood control function; and during reverse water replenishment, purified water in the receiving water area is supplied to the urban riverways through the deep tunnel, thereby achieving the function of ecological water replenishment.

Description

A layout structure and operation method for urban deep tunnels with forward drainage and reverse water replenishment Technical Field

[0001] This invention belongs to the field of deep tunnel engineering layout for drainage in water conservancy projects, and particularly relates to a layout structure and operation method for urban deep tunnels with forward drainage and reverse water replenishment. Background Technology

[0002] Urban deep tunnels refer to large and extra-large drainage, storage, or water supply tunnels built deep underground in urban built-up areas. They are an important engineering means to solve urban flooding problems.

[0003] Deep tunnels have a long history of research and engineering practice abroad, with numerous deep tunnel projects completed in countries such as the United States, Europe, Malaysia, and Japan. In recent years, my country has also been actively exploring the application of deep tunnels to address urban water pollution and flooding issues. Overall, deep tunnel engineering developed earlier and its technology is relatively mature abroad, while China started later but has developed more rapidly. Each city's deep tunnel project has its own unique characteristics; the functions and layouts of deep tunnels are very similar, each possessing unique technical features and challenges, and there is no unified technical system.

[0004] To address the challenges of complex deep tunnel layout schemes in urban built-up areas and ecologically sensitive areas, and to overcome the shortcomings of low utilization and single function in traditional deep tunnel layout methods, this application proposes a forward drainage and reverse water replenishment urban deep tunnel layout structure. This structure can achieve the dual functions of forward drainage and flood control and reverse ecological water replenishment when facing various complex hydrogeological conditions and engineering tasks in different regions. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of complex deep tunnel layout schemes in different urban built-up areas and ecologically sensitive areas, and to propose a forward drainage and reverse water replenishment urban deep tunnel layout structure and operation method.

[0006] The present invention is achieved through the following technical solution.

[0007] On one hand, the present invention provides a layout structure for a deep urban tunnel with forward drainage and reverse water replenishment. The layout structure includes an inlet, a deep tunnel, an outlet hub, and a reverse water replenishment purification facility. The inlet is located in a low-lying area along the deep tunnel and connects to an urban river. The outlet hub is located at the end of the deep tunnel, connecting the deep tunnel to the receiving water area. The reverse water replenishment purification facility is located at the outlet hub. Its characteristic is that:

[0008] The inlet includes an inlet forebay, a top cover, diversion piers, a trash rack, a gate, and an inlet shaft. The inlet forebay is connected to the urban river. The inlet shaft is located in the inlet forebay. Multiple diversion piers are located above the inlet shaft and are distributed circumferentially around the inlet shaft. The tail of each diversion pier tapers into a pointed angle. The inlet opening is located between adjacent diversion piers. The trash rack and the gate are arranged sequentially from the outside to the inside of the inlet opening. The top cover is located above the diversion piers and covers the inlet shaft.

[0009] Forward drainage uses pumping stations for pumping, while reverse water replenishment uses gravity flow. During both forward drainage and reverse water replenishment operations, the inlet shaft (1-6), deep tunnel (2), and outlet shaft (3-1) maintain pressurized water delivery throughout the entire process. During non-operation periods, the inlet shaft (1-6), deep tunnel (2), and outlet shaft (3-1) also remain in a static water state filled with water.

[0010] The water receiving areas include, but are not limited to, reservoirs, flood channels, lakes, and rivers.

[0011] Furthermore, the number of diversion piers is four to eight.

[0012] Furthermore, the number of diversion piers is six.

[0013] Furthermore, the water inlets are arranged symmetrically in a radial pattern.

[0014] Furthermore, the top cover plane is circular, with its upper surface being a plane and its lower surface being an approximately conical guide cone.

[0015] Furthermore, the outlet hub includes an outlet shaft, a pump station forebay, and a forced drainage pump station. The pump station forebay is located above the outlet shaft, and the deep tunnel is connected to the pump station forebay through the outlet shaft. The forced drainage pump station forcefully discharges the floodwater in the pump station forebay to the receiving water area.

[0016] Furthermore, the forced drainage pumping station includes multiple mixed-flow pumps.

[0017] Furthermore, the reverse water replenishment and purification facility includes a first water intake culvert, a second water intake culvert, and a high-efficiency clarifier. The first and second water intake culverts are located between the pump station forebay and the receiving water area. The first water intake culvert is connected to the pump station forebay, and the second water intake culvert is connected to the high-efficiency clarifier. The high-efficiency clarifier is also connected to the pump station forebay. When the turbidity of the receiving water area is low and does not require treatment, the water flows by gravity to the pump station forebay through the first water intake culvert. When purification treatment is required, the water is introduced into the high-efficiency clarifier through the second water intake culvert and then enters the pump station forebay after purification.

[0018] On the other hand, the present invention also provides an operation method for a deep urban tunnel for positive drainage and reverse water replenishment, which utilizes the above-mentioned deep urban tunnel layout structure, including: burying a deep tunnel underground, the deep tunnel penetrating the city and leading to a receiving water area, the deep tunnel connecting to urban waterways along its route, and its end connecting to the receiving water area, so that during positive drainage, floodwater from the urban waterway is discharged into the receiving water area through the inlet via the deep tunnel, and during reverse water replenishment, purified water from the receiving water area is replenished into the urban waterway through the deep tunnel via the reverse water replenishment purification facility.

[0019] In the application scenarios targeted by this invention, the elevation of urban waterways is low while the elevation of the receiving water area is high. This invention is a technical solution for drainage hydraulic facilities based on the principle of "low inside" and "high outside". In terms of elevation, the inlet (1) is low, while the receiving water area is high. The hydraulic facilities of this invention are based on the following purpose: to drain "floodwater" from low-lying areas. Urban deep tunnels refer to large and extra-large drainage, storage, or water supply tunnels built in the deep underground space of urban built-up areas. For such drainage deep tunnels, their length is long, the amount of engineering work is large, and the volume of deep tunnels is huge.

[0020] Due to the technical effects of this invention, the beneficial effects of this invention are:

[0021] This invention employs underground deep tunnel water conveyance. During the forward drainage period, urban floodwater can be discharged into the receiving water area through the deep tunnel to achieve the function of drainage and flood control. During the reverse water replenishment period, the water in the receiving water area can be purified and then transported back to the river network in the urban area to achieve the function of ecological water replenishment. Thus, the urban deep tunnel layout method and structure proposed in this invention have the dual functions of forward drainage and flood control and reverse ecological water replenishment. Attached Figure Description

[0022] Figure 1 is a longitudinal cross-sectional view of the urban deep tunnel layout structure proposed in this invention.

[0023] Figure 2 is a plan view of the inlet of the present invention;

[0024] Figure 3 is a cross-sectional view of the inlet of the present invention;

[0025] Figure 4 is a schematic diagram of the structure of the export hub of the present invention;

[0026] Figure 5 is a schematic diagram of the reverse water replenishment water purification device of the present invention;

[0027] Figure 6 is a three-dimensional schematic diagram of the urban deep tunnel layout structure proposed in this invention.

[0028] In the diagram: Inlet 1, Inlet forebay 1-1, Top cover 1-2, Diversion pier 1-3, Trash rack 1-4, Gate 1-5, Inlet shaft 1-6, Inlet orifice 1-7, Deep tunnel 2, Outlet hub 3, Outlet shaft 3-1, Pump station forebay 3-2, Forced drainage pump station 3-3, Reverse water supply purification facility 4, First water intake box culvert 4-1, Second water intake box culvert 4-2, High-efficiency clarifier 4-3. Detailed Implementation

[0029] The following description further illustrates the structures involved in this invention and the technical terms used therein. These descriptions are merely illustrative of how the invention is implemented and do not constitute any limitation on the invention.

[0030] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, unless otherwise explicitly specified and limited, terms such as "connection" and "fixation" should be interpreted broadly. For example, "fixation" can mean a fixed connection, a detachable connection, or an integral part; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] Example 1:

[0033] This embodiment introduces a deep tunnel layout structure for forward drainage and reverse water replenishment in urban areas, as shown in Figures 1-5. This structure includes an inlet 1, a deep tunnel 2, an outlet hub 3, and a reverse water replenishment purification facility 4. The inlet 1 is located in a low-lying area along the deep tunnel 2 and connects to the urban river. The outlet hub 3 is located at the end of the deep tunnel 2, connecting the deep tunnel 2 to the receiving water area. The reverse water replenishment purification facility 4 is located at the outlet hub 3. The urban river refers to a river within the urban built-up area, and the receiving water area refers to reservoirs, flood channels, lakes, rivers, and other water bodies capable of receiving large volumes of floodwater. This layout structure involves burying a deep tunnel 2 underground, which runs from the urban river to the receiving water area. The deep tunnel 2 runs along the urban river and connects to the receiving water area at its end. During forward drainage, urban floodwater is discharged into the receiving water area via the deep tunnel 2. During reverse water replenishment, purified water from the receiving water area is replenished into the urban river via the deep tunnel 2.

[0034] Forward drainage is achieved by pumping, while reverse water replenishment is achieved by gravity flow.

[0035] As shown in Figure 2-3, the inlet 1 includes an inlet forebay 1-1, a top cover 1-2, diversion piers 1-3, a trash rack 1-4, a gate 1-5, and an inlet shaft 1-6. The inlet forebay 1-1 is connected to the urban river. The inlet shaft 1-6 is located inside the inlet forebay 1-1. Multiple diversion piers 1-3 are located above the inlet shaft 1-6 and are distributed circumferentially around the inlet shaft 1-6. The tail of each diversion pier 1-3 tapers into a pointed angle. Between adjacent diversion piers 1-3 is the inlet opening 1-7. From the outside to the inside, the trash rack 1-4 and the gate 1-5 are installed in the inlet opening 1-7. The top cover 1-2 is located above the diversion piers 1-3 and covers the inlet shaft 1-6.

[0036] In this embodiment, the water conveyance route of Deep Tunnel 2 should be as short and straight as possible. Under the condition of meeting the overall layout requirements, the route should be selected through technical and economic comparison, taking into account factors such as topography, geology, ecological environment, soil and water conservation, hydraulics, construction and traffic, operation, buildings along the route, and overall project layout. The water conveyance route should minimize the crossing of environmentally sensitive areas. The route should be selected in areas with simple geological structures, intact and stable rock masses, moderate overlying rock layer thickness, favorable hydrogeological conditions, and convenient construction. The route layout should have a large angle with the direction of rock layers, structural fault surfaces, and major weak zones, and avoid gullies that may cause strong surface water replenishment. The environmental impact and soil and water conservation requirements of permanent land occupation, temporary land occupation, vegetation destruction and restoration, construction pollution, and groundwater level changes during operation should be considered to ensure that the tunnel has a certain vertical and lateral overburden thickness.

[0037] The bottom elevation of the inlet forebay 1-1 is approximately -6.5m. The top cover 1-2 is circular in plan, with a flat upper surface and a nearly conical guide cone on the lower surface. To ensure uniform water flow, inlet 1 has six inlet holes, divided by six diversion piers 1-3 arranged radially. Each diversion pier 1-3 is 2.5m thick, tapering to a pointed end, and its plan is approximately fan-shaped. The cross-sectional dimensions of each inlet hole 1-7 are 4×4m (width×height). A trash rack 1-4 can be installed in front of the six-hole flow channel to intercept debris such as tree branches. A gate 1-5 is installed behind the trash rack 1-4, followed by a vertical shaft section, specifically a circular, straight-cylinder inlet shaft 1-6.

[0038] The number of inlet orifices 1-7 was determined after comprehensive comparison. Water from the inlet forebay 1-1 flows into the lower inlet shaft 1-6 through inlet orifices 1-7. Gates 1-5 are used for bidirectional water blocking. During forward drainage, the flow into the inlet shaft 1-6 is controlled by opening or closing the gates. During maintenance or dredging of the deep tunnel 2, gates 1-5 are closed to block water and allow the deep tunnel 2 to be emptied. During reverse water replenishment, inlet orifices 1-7, which do not require water distribution, can be closed to block water from the deep tunnel 2. Inlet 1 is distributed in low-lying areas of the urban river system. Floodwater can be collected at inlet 1 through main waterways and connecting water systems, and then enter the deep tunnel 2 from inlet 1.

[0039] As shown in Figure 4, an outlet hub 3 is arranged at the outlet end of deep tunnel 2. Outlet hub 3 includes an outlet shaft 3-1, a pump station forebay 3-2, and a forced-flow pumping station 3-3. The pump station forebay 3-2 is located above and connected to the outlet shaft 3-1, and deep tunnel 2 is connected to the pump station forebay 3-2 through the outlet shaft 3-1. The forced-flow pumping station 3-3 is equipped with six mixed-flow pumps. Floodwater enters the pump station forebay 3-2 through deep tunnel 2 and is then forced-flowed to the receiving area by the mixed-flow pumps.

[0040] As shown in Figure 4-5, the outlet hub 3 is equipped with a reverse water replenishment and purification facility 4. This facility 4 includes a first water intake culvert 4-1, a second water intake culvert 4-2, and a high-efficiency clarifier 4-3. The first and second water intake culverts 4-1 and 4-2 are located between the pump station forebay 3-2 and the Qiantang River. The first water intake culvert 4-1 is connected to the pump station forebay 3-2, and the second water intake culvert 4-2 is connected to the high-efficiency clarifier 4-3. The high-efficiency clarifier 4-3 is also connected to the pump station forebay 3-2. When the turbidity of the water in the receiving area is low and no treatment is required, the water flows by gravity through the first water intake culvert 4-1 to the pump station forebay 3-2. When purification is required, the water is introduced into the high-efficiency clarifier 4-3 through the second water intake culvert 4-2, purified, and then enters the pump station forebay 3-2. Finally, utilizing the water level difference, the water flows by gravity through the deep tunnel 2 back to the urban built-up area river channel, thus achieving the reverse ecological water replenishment function.

[0041] The first and second water intake culverts 4-1 and 4-2 are constructed of reinforced concrete and can introduce water from one location to another, thus achieving water transportation. The high-efficiency clarifier 4-3 employs a sand-added high-efficiency clarifier process, including three stages: mixing, flocculation, and sedimentation, which can remove suspended solids and colloids from the water, thereby purifying it. Both the water intake culverts and the high-efficiency clarifier 4-3 are existing technologies and will not be described in detail here.

[0042] Example 2

[0043] This embodiment introduces an operation method for a deep urban tunnel with forward drainage and reverse water replenishment, utilizing the layout structure described in Embodiment 1, as shown in Figure 1. The operation method includes an inlet 1, a deep tunnel 2, an outlet hub 3, and a reverse water replenishment purification facility 4. The deep tunnel 2 is buried underground, penetrating the city and leading to the receiving water area. The inlet 1 is located in a low-lying area along the deep tunnel 2 and connects with the urban river. The outlet hub 3 is located at the end of the deep tunnel 2, connecting the deep tunnel 2 with the receiving water area. The reverse water replenishment purification facility 4 is located at the outlet hub 3, so that during forward drainage, floodwater from the urban river is discharged into the receiving water area through the deep tunnel 2 via the inlet 1. During reverse water replenishment, purified water from the receiving water area is replenished into the urban river through the deep tunnel 2 via the reverse water replenishment purification facility 4.

[0044] During both forward drainage and reverse water replenishment operations, the inlet shafts 1-6, deep tunnel 2, and outlet shaft 3-1 maintain pressurized water conveyance throughout the entire process. During non-operational periods, the inlet shafts 1-6, deep tunnel 2, and outlet shaft 3-1 also remain in a static state filled with water, and the internal water is only discharged when large-scale maintenance or dredging is required.

[0045] The inlet shafts 1-6, deep tunnel 2, and outlet shaft 3-1 adopt pressurized full-flow water conveyance operation. While maintaining the water head inside the tunnel, they are less affected by the water surface line and can be flexibly arranged to avoid environmentally sensitive areas and geologically complex areas. At the same time, the flow inside the pressurized tunnel is always pressurized, and the water flow pattern is stable.

[0046] Deep Tunnel 2, Inlet Shafts 1-6, and Outlet Shaft 3-1 remain fully filled with water during non-operation periods, saving the time required for low-flow, long-term water filling when restarting the deep tunnel. This allows for rapid conversion between dynamic and static water, enabling fast drainage and efficient reverse water replenishment, thus improving water conveyance efficiency. At the same time, it avoids the problems of huge impact and violent internal pressure fluctuations caused by high-speed water flow from the top of the inlet shaft during high-flow drainage operation.

[0047] Example 3

[0048] Taking the expanded western channel of the Hangjiahu South Drainage Project in Hangzhou, Zhejiang Province as an example, its deep tunnel drainage system uses a "Y"-shaped layout with multiple inlets to transport water through underground deep tunnels and connects the flood discharge channel from the west of Hangzhou to the Qiantang River.

[0049] As shown in Figure 6, a deep tunnel 2 is constructed underground, running from the west of Hangzhou city to the Qiantang River. Tunnel 2 connects to the waterways of western Hangzhou city along its route, and its final end connects to the Qiantang River. Inlets 1 are distributed in low-lying areas along tunnel 2 and connect to the waterways of western Hangzhou city. Floodwater is collected at inlets 1 via main waterways and connecting water systems. An outlet hub 3 is located at the end of tunnel 2, connecting tunnel 2 to the Qiantang River. A reverse water replenishment and purification facility 4 is located at outlet hub 3. During the forward drainage period, urban floodwater is discharged from inlets 1 through tunnel 2 into the Qiantang River. During the reverse water replenishment period, purified water from the Qiantang River is replenished into the waterways of western Hangzhou city through tunnel 2. Tunnel 2 is approximately 29 km long and 50 m deep, reaching a depth of 370 m when passing through mountains. It does not affect major urban buildings, traverses the southwestern edge of the West Lake scenic area, and extends south to the Qiantang River. Using this deep tunnel, floodwaters can be discharged into the Qiantang River during floods; while during non-flood seasons, when drainage is not carried out, the water from the Qiantang River can be purified and then transported by gravity through the deep tunnel 2 to the river network in the western part of Hangzhou, thus realizing the reverse ecological water replenishment function.

[0050] In this embodiment, the urban deep tunnel layout structure with forward drainage and reverse water replenishment can be used to quickly drain floodwater from the western part of Hangzhou into the Qiantang River during floods, thereby improving the flood control capacity of western Hangzhou. During non-flood seasons, high-quality water from the Qiantang River can be purified and discharged into the river network of western Hangzhou, improving the water ecological environment of the urban river network and effectively improving the flood control and drainage standards of western Hangzhou.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forward drainage and reverse water replenishment urban deep tunnel layout structure, the layout structure comprising an inlet (1), a deep tunnel (2), an outlet hub (3), and a reverse water replenishment purification facility (4), wherein the inlet (1) is located in a low-lying area along the deep tunnel (2) and connects to an urban river, the outlet hub (3) is located at the end of the deep tunnel (2) connecting the deep tunnel (2) to the receiving water area, and the reverse water replenishment purification facility (4) is located at the outlet hub (3), characterized in that: The inlet (1) includes an inlet forebay (1-1), a top cover (1-2), diversion piers (1-3), a trash rack (1-4), a gate (1-5), and an inlet shaft (1-6). The inlet forebay (1-1) is connected to the urban river. The inlet shaft (1-6) is located inside the inlet forebay (1-1). Multiple diversion piers (1-3) are located above the inlet shaft (1-6) and are distributed circumferentially at intervals in the inlet shaft (1-6). The tail of each diversion pier (1-3) tapers into a pointed angle. Between adjacent diversion piers (1-3) is an inlet opening (1-7). The trash rack (1-4) and the gate (1-5) are arranged sequentially from the outside to the inside of the inlet opening (1-7). The top cover (1-2) is located above the diversion piers (1-3) and covers the inlet shaft (1-6). Forward drainage uses pumping stations for pumping, while reverse water replenishment uses gravity flow. During both forward drainage and reverse water replenishment operations, the inlet shaft (1-6), deep tunnel (2), and outlet shaft (3-1) maintain pressurized water delivery throughout the entire process. During non-operation periods, the inlet shaft (1-6), deep tunnel (2), and outlet shaft (3-1) also remain in a static water state filled with water.

2. The urban deep tunnel layout structure with forward drainage and reverse water replenishment according to claim 1, characterized in that, The number of diversion piers (1-3) is four to eight.

3. The urban deep tunnel layout structure with forward drainage and reverse water replenishment according to claim 2, characterized in that, The number of diversion piers (1-3) is six.

4. A city deep tunnel arrangement structure for positive flood drainage and reverse water replenishment according to claim 1, characterized in that, The water inlet ports (1-7) are arranged radially and symmetrically.

5. A city deep tunnel arrangement structure for positive flood drainage and reverse water replenishment according to claim 1, characterized in that, The top cover (1-2) has a circular plane, with its upper surface being a plane and its lower surface being an approximately conical guide cone.

6. A city deep tunnel arrangement structure for positive flood drainage and reverse water replenishment according to claim 1, characterized in that: The outlet hub (3) includes an outlet shaft (3-1), a pump station forebay (3-2), and a forced drainage pump station (3-3). The pump station forebay (3-2) is located above the outlet shaft (3-1). The deep tunnel (2) is connected to the pump station forebay (3-2) through the outlet shaft (3-1). The forced drainage pump station (3-3) forcibly discharges the floodwater in the pump station forebay (3-2) to the receiving water area.

7. A city deep tunnel arrangement structure for positive flood drainage and reverse water replenishment according to claim 6, characterized in that: The forced drainage pumping station (3-3) includes multiple mixed-flow pumps.

8. A city deep tunnel arrangement structure for positive flood drainage and reverse water replenishment according to claim 6, characterized in that: The reverse water supply purification facility (4) includes a first water intake culvert (4-1), a second water intake culvert (4-2), and a high-efficiency clarifier (4-3). The first water intake culvert (4-1) and the second water intake culvert (4-2) are located between the forebay (3-2) of the pumping station and the receiving water area. The first water intake culvert (4-1) is connected to the forebay (3-2) of the pumping station, and the second water intake culvert (4-2) is connected to the high-efficiency clarifier (4-3). The high-efficiency clarifier (4-3) is connected to the forebay (3-2) of the pumping station. When the turbidity of the receiving water area is low and does not require treatment, the water flows by gravity to the forebay (3-2) of the pumping station through the first water intake culvert (4-1). When purification treatment is required, the water is introduced into the high-efficiency clarifier (4-3) through the second water intake culvert (4-2) and then enters the forebay (3-2) of the pumping station after purification.

9. A method for forward drainage and reverse water replenishment in urban deep tunnels using the forward drainage and reverse water replenishment arrangement structure described in any one of claims 1-8. Method for operating an urban deep tunnel, characterized in that: A deep tunnel (2) is buried underground, which runs through the city to the receiving water area. The deep tunnel (2) connects to the city's waterways along its route and connects to the receiving water area at its end. This allows the floodwater from the city's waterways to be discharged into the receiving water area through the deep tunnel (2) during the positive drainage period, and the clean water from the receiving water area to be replenished into the city's waterways through the deep tunnel (2) during the reverse water replenishment period.

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