Segmented Drainage and Segmented Maintenance System and Method for Urban Long-Distance Water Conveyance Tunnel Project

Abstract

The present invention discloses a segmented drainage and segmented maintenance system and method for a long-distance water conveyance tunnel project in a city. It includes arranging maintenance drainage equipment at positions along the water conveyance tunnel that can absorb the drainage water volume, and setting maintenance butterfly valves and / or bypass pipes upstream and downstream of the water diversion branch line that diverts water to the water plant along the water conveyance tunnel. The present invention avoids problems such as large amounts of raw water pumping and drainage, serious waste of raw water, and long maintenance time existing in the case of draining and maintaining one section of the entire length of the water conveyance tunnel at a time; significantly improves the water supply guarantee rate of the water plants along the line; and discharges the maintenance drainage water to the adjacent river section to achieve ecological water replenishment.

Description

Technical Field

[0001] The present invention relates to the technical field of urban water conveyance tunnel engineering, and more specifically, it is a segmented drainage and segmented maintenance system and method for urban long-distance water conveyance tunnel engineering. Background Art

[0002] With the rapid development of urban construction, the population has increased sharply, and the water consumption for urban production and living is getting larger and larger. The construction of urban water network projects has become the main measure to solve the urban water demand.

[0003] In addition to undertaking the task of water volume allocation, long-distance water conveyance tunnel projects also need to supply water to the corresponding water plants in the water receiving area. To meet the needs of urban development and reserve precious surface and shallow underground spaces, more and more water conveyance tunnel projects are located 50m or even deeper below the ground surface.

[0004] At present, the urban long-distance water conveyance tunnel project adopts the design of one-section drainage and one-section maintenance for the entire length of the tunnel, that is, by closing the maintenance gates at the water intake at both ends of the water conveyance tunnel and pumping out all the water in the tunnel, the tunnel is maintained. The main technical defects include: (1) The amount of pumped drainage water is large, the raw water is wasted seriously, and the maintenance time is long; (2) It affects the normal water supply of all water plants along the line, and it is difficult to guarantee the water supply guarantee rate of the water plants.

[0005] Therefore, it has become an urgent and important task to develop a segmented drainage and segmented maintenance system for urban long-distance water conveyance tunnel engineering. Summary of the Invention

[0006] The purpose of the present invention is to make up for the technical defects existing in the existing water conveyance tunnel project that adopts one-section drainage and one-section maintenance for the entire length of the tunnel, and to provide a segmented drainage and segmented maintenance system and method for urban long-distance water conveyance tunnel engineering.

[0007] The technical solution adopted by the present invention is: A segmented drainage and segmented maintenance system for urban long-distance water conveyance tunnel engineering, in which maintenance drainage equipment is arranged at the parts along the water conveyance tunnel that can accommodate the drainage water volume, and maintenance butterfly valves and / or bypass pipes are set upstream and downstream of the water diversion branch line that diverts water to the water plant along the water conveyance tunnel.

[0008] At the first surface river or lake and the second surface river or lake along the water conveyance tunnel where the drainage volume can be absorbed, a lower point of the tunnel is set, and the entire length of the water conveyance tunnel is divided into three sections: the first section of the water conveyance tunnel, the second section of the water conveyance tunnel, and the third section of the water conveyance tunnel; a maintenance drainage well is set in the first section of the water conveyance tunnel, a first maintenance drainage device is set in the maintenance drainage well, and the first maintenance drainage device is connected to the first surface river or lake through a maintenance drainage pipe; a water distribution well is set between the first section of the water conveyance tunnel and the second section of the water conveyance tunnel, and a first section maintenance butterfly valve of the water conveyance tunnel and a second section maintenance butterfly valve of the water conveyance tunnel are respectively set in the water distribution well; a maintenance drainage and water distribution well is set between the second section of the water conveyance tunnel and the third section of the water conveyance tunnel, and a third section maintenance butterfly valve of the water conveyance tunnel is set on the water conveyance tunnel in the maintenance drainage and water distribution well.

[0009] The water conveyance tunnel in the water distribution well is connected to a first water distribution branch line, a first water distribution branch line maintenance butterfly valve is set on the first water distribution branch line, and the first water distribution branch line is connected to a first water treatment plant.

[0010] The water conveyance tunnel in the maintenance drainage and water distribution well is respectively connected to a second water distribution branch line and a bypass pipe of the water distribution branch line, and a second water distribution branch line maintenance butterfly valve is set on the second water distribution branch line; a bypass pipe butterfly valve of the water distribution branch line is set on the bypass pipe of the water distribution branch line, and both the second water distribution branch line and the bypass pipe of the water distribution branch line are connected to a second water treatment plant.

[0011] A maintenance drainage pipe is connected between the upstream of the third section maintenance butterfly valve of the water conveyance tunnel and the downstream of the second water distribution branch line, a maintenance drainage pipe butterfly valve and a second maintenance drainage device are set on the maintenance drainage pipe, and the maintenance drainage pipe is connected to the second surface river or lake; the downstream of the third section maintenance butterfly valve of the water conveyance tunnel is connected to one end of a maintenance drainage bypass pipe, a maintenance drainage bypass pipe butterfly valve is set on the maintenance drainage bypass pipe, and the other end of the maintenance drainage bypass pipe is connected to the upstream of the second maintenance drainage device.

[0012] A first reservoir is set at the uppermost upstream of the water conveyance tunnel, a second reservoir is set at the lowermost downstream of the water conveyance tunnel, a first intake inspection gate is set in the first reservoir, and a second intake and inspection gate is set in the second reservoir.

[0013] A method for a sectional drainage and sectional maintenance system of a long-distance urban water conveyance tunnel project includes the following steps:

[0014] Step 1: Maintenance of the first section of the water conveyance tunnel:

[0015] When the first section of the water conveyance tunnel needs to be maintained, close the first intake inspection gate and the first section maintenance butterfly valve of the water conveyance tunnel, let the raw water in the first section of the water conveyance tunnel flow towards the maintenance drainage well by means of the slope, and then use the maintenance drainage device to pump the raw water in the tunnel along the maintenance drainage pipe to the first surface river or lake. After evacuation, the first section of the water conveyance tunnel can be maintained;

[0016] Open the maintenance gate of the second water intake, the maintenance butterfly valve of the third section of the water conveyance tunnel, the maintenance butterfly valve of the second water diversion branch line, the maintenance butterfly valve of the second section of the water conveyance tunnel, and the maintenance butterfly valve of the first water diversion branch line, and close the maintenance drain pipe butterfly valve, the maintenance drain bypass pipe butterfly valve, and the water diversion branch line bypass pipe butterfly valve. Water can be taken from the second reservoir and supplied to the first water plant and the second water plant through the first water diversion branch line and the second water diversion branch line respectively;

[0017] Step 2: Maintenance of the second section of the water conveyance tunnel:

[0018] When the second section of the water conveyance tunnel needs to be maintained, close the maintenance butterfly valve of the second section of the water conveyance tunnel, the maintenance butterfly valve of the second water diversion branch line, and the maintenance butterfly valve of the third section of the water conveyance tunnel, and open the maintenance drain pipe butterfly valve. Let the raw water in the second section of the water conveyance tunnel flow towards the maintenance drain well by means of the slope, and then use the second maintenance drainage equipment to pump the raw water in the second section of the water conveyance tunnel along the maintenance drain pipe to the second surface river or lake. After evacuation, the second section of the water conveyance tunnel can be maintained;

[0019] Close the maintenance drain bypass pipe butterfly valve, open the water diversion branch line bypass pipe butterfly valve and the maintenance gate of the second water intake. Water can be taken from the second reservoir and supplied to the second water plant through the water diversion branch line bypass pipe and the second water diversion branch line. At the same time, open the maintenance gate of the first water intake, the maintenance butterfly valve of the first section of the water conveyance tunnel, and the maintenance butterfly valve of the first water diversion branch line, and close the first maintenance drainage equipment. Water can be taken from the first reservoir and supplied to the first water plant through the first water diversion branch line;

[0020] Step 3: Maintenance of the third section of the water conveyance tunnel:

[0021] When the third section of the water conveyance tunnel needs to be maintained, close the maintenance gate of the second water intake, the maintenance butterfly valve of the third section of the water conveyance tunnel, and the water diversion branch line bypass pipe butterfly valve, and open the maintenance drain bypass pipe butterfly valve. Let the raw water in the third section of the water conveyance tunnel flow towards the maintenance drain well by means of the slope, and then use the second maintenance drainage equipment to pump the raw water in the third section of the water conveyance tunnel along the maintenance drain bypass pipe and the maintenance drain pipe to the second surface river or lake. After evacuation, the third section of the water conveyance tunnel can be maintained;

[0022] Close the maintenance drain pipe butterfly valve and the first maintenance drainage equipment, and open the maintenance gate of the first water intake, the maintenance butterfly valve of the first section of the water conveyance tunnel, the maintenance butterfly valve of the second section of the water conveyance tunnel, the maintenance butterfly valve of the first water diversion branch line, and the maintenance butterfly valve of the second water diversion branch line. Water can be taken from the first reservoir and supplied to the first water plant and the second water plant through the first water diversion branch line and the second water diversion branch line respectively.

[0023] Based on the existing check gates provided at both ends of the water conveyance tunnel, the present invention arranges check drainage equipment at the positions along the water conveyance tunnel where the drainage water volume can be absorbed, and installs check butterfly valves and / or bypass pipes upstream and downstream of the water diversion branch line that diverts water to the waterworks along the water conveyance tunnel, so as to achieve sectional drainage and sectional maintenance of the water conveyance tunnel.

[0024] Based on the existing water conveyance tunnel project that adopts one-section drainage and one-section maintenance for the entire length of the water conveyance tunnel, by setting check drainage equipment along the water conveyance tunnel and installing check butterfly valves or bypass pipes upstream and downstream of the water diversion branch line that diverts water to the waterworks along the water conveyance tunnel, the purpose of sectional drainage and sectional maintenance of the water conveyance tunnel is achieved.

[0025] The present invention sets a suitable longitudinal slope for the water conveyance tunnel, and takes the sectional drainage point as the lowest point within the section of the water conveyance tunnel, so as to facilitate check drainage.

[0026] The check drainage point of the present invention is selected at surface water bodies such as rivers and lakes that can absorb the check drainage volume, and the original water in the tunnel pumped and drained can be used as ecological water replenishment for the river and lake.

[0027] The present invention installs check butterfly valves or bypass pipes upstream and downstream of the water conveyance tunnel and the water diversion branch line to ensure that when any section of the water conveyance tunnel is under maintenance, normal water supply can be provided to the waterworks along the line through the non-maintained section of the water conveyance tunnel, so as to ensure the normal water use demand of the waterworks.

[0028] The present invention avoids problems such as large pumping and drainage volume of the original water, serious waste of the original water, and long maintenance time existing in the one-section drainage and one-section maintenance for the entire length of the water conveyance tunnel; significantly improves the water supply guarantee rate of the waterworks along the line; discharges the check drainage to the adjacent river section to realize ecological water replenishment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic plan view of one-section drainage and one-section maintenance for the entire length of the urban long-distance water conveyance tunnel project;

[0030] Figure 2 It is a schematic longitudinal sectional view of one-section drainage and one-section maintenance for the entire length of the urban long-distance water conveyance tunnel project;

[0031] Figure 3 It is a schematic plan view of sectional drainage and sectional maintenance for the urban long-distance water conveyance tunnel project;

[0032] Figure 4 It is a schematic longitudinal sectional view of sectional drainage and sectional maintenance for the urban long-distance water conveyance tunnel project.

[0033] In the figure: 1. First reservoir; 2. Maintenance gate of the first water intake; 3. Water conveyance tunnel; 4. Maintenance butterfly valve of the first water diversion branch line; 5. First water diversion branch line; 6. First water plant; 7. Maintenance butterfly valve of the second water diversion branch line; 8. Second water diversion branch line; 9. Second water plant; 10. Second water intake and maintenance gate; 11. Second reservoir; 12. Drainage and maintenance in sections along the whole length of the water conveyance tunnel; 13. Maintenance drainage well; 14. First maintenance drainage equipment; 15. Maintenance drainage pipe; 16. First surface river or lake; 17. Water distribution well; 18. Maintenance butterfly valve of the first section of the water conveyance tunnel; 19. Maintenance butterfly valve of the second section of the water conveyance tunnel; 20. Maintenance drainage and water distribution well; 21. Maintenance butterfly valve of the third section of the water conveyance tunnel; 22. Butterfly valve of the maintenance drainage pipe; 23. Butterfly valve of the maintenance drainage bypass pipe; 24. Butterfly valve of the bypass pipe of the water diversion branch line; 25. Second maintenance drainage equipment; 26. Bypass pipe of the water diversion branch line; 27. Maintenance drainage pipe; 28. Maintenance drainage bypass pipe; 29. Second surface river or lake; 30. First section of the water conveyance tunnel; 31. Second section of the water conveyance tunnel; 32. Third section of the water conveyance tunnel. Detailed implementation mode

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which is convenient for clearly understanding the present invention, but they do not constitute a limitation to the present invention.

[0035] Maintenance gate: Arranged at the gate section of the water intake, cutting off the water flow when maintenance is required at the water intake or the water conveyance line for maintenance work.

[0036] Butterfly valve: Equipment for cutting off the water flow.

[0037] Maintenance drainage well: Arranged on the water conveyance tunnel, with maintenance drainage equipment arranged inside. During maintenance, the original water in the tunnel can be uniformly pumped to the surface river or lake by the maintenance drainage equipment.

[0038] Water distribution well: Arranged on the water conveyance tunnel, where the water conveyance tunnel inside the well is connected to the water diversion branch line, guiding the water flow to the water plant, and at the same time can be used to arrange the maintenance butterfly valve and bypass pipe of the water conveyance tunnel.

[0039] Bypass pipe: A water filling pipe that bypasses the maintenance gate or butterfly valve and connects the reservoir to the main water conveyance line.

[0040] Refer to Figure 1 、 Figure 2 It can be known that the existing maintenance method for the existing water conveyance tunnel 3 is to close the maintenance gate of the first water intake 2, the maintenance gate of the second water intake 10, the maintenance butterfly valve of the first water diversion branch line 4 and the maintenance butterfly valve of the second water diversion branch line 7, pump and drain the original water in the tunnel to the first reservoir 1 (or the second reservoir 11), and drain and maintain in sections along the whole length of the water conveyance tunnel 3. The existing scheme has a large amount of original water pumping and drainage, serious waste of original water, long maintenance time, and the first water plant 6 and the second water plant 9 along the line cannot supply water normally.

[0041] Refer to Figure 3 、 Figure 4 As shown in: For a sectional drainage and sectional maintenance system of a long-distance water conveyance tunnel project in a city of the present invention, maintenance drainage equipment is arranged at positions along the water conveyance tunnel 3 where the drainage water volume can be absorbed, and maintenance butterfly valves and / or bypass pipes are provided upstream and downstream of the water diversion branch line that diverts water to the water plant along the water conveyance tunnel 3.

[0042] Specifically, at the first surface river or lake 16 and the second surface river or lake 29 along the water conveyance tunnel 3 where the drainage volume can be absorbed, a lower point of the tunnel is set, and the entire length of the water conveyance tunnel is divided into three sections: the first section 30 of the water conveyance tunnel, the second section 31 of the water conveyance tunnel, and the third section 32 of the water conveyance tunnel; a maintenance drainage well 13 is set in the first section 30 of the water conveyance tunnel, a first maintenance drainage device 14 is set in the maintenance drainage well 13, and the first maintenance drainage device 14 is connected to the first surface river or lake 16 through a maintenance drainage pipe 15; a water distribution well 17 is set between the first section 30 and the second section 31 of the water conveyance tunnel, and a maintenance butterfly valve 18 for the first section of the water conveyance tunnel and a maintenance butterfly valve 19 for the second section of the water conveyance tunnel are respectively set in the water distribution well 17; a maintenance drainage and water distribution well 20 is set between the second section 31 and the third section 32 of the water conveyance tunnel, and a maintenance butterfly valve 21 for the third section of the water conveyance tunnel is set on the water conveyance tunnel 3 in the maintenance drainage and water distribution well 20.

[0043] The water conveyance tunnel 3 in the water distribution well 17 is connected to the first water diversion branch line 5, a first water diversion branch line maintenance butterfly valve 4 is set on the first water diversion branch line 5, and the first water diversion branch line 5 is connected to the first water plant 6.

[0044] The water conveyance tunnel 3 in the maintenance drainage and water distribution well 20 is respectively connected to the second water diversion branch line 8 and a bypass pipe 26 for the water diversion branch line. A second water diversion branch line maintenance butterfly valve 7 is set on the second water diversion branch line 8; a bypass pipe butterfly valve 24 for the water diversion branch line is set on the bypass pipe 26 for the water diversion branch line, and both the second water diversion branch line 8 and the bypass pipe 26 for the water diversion branch line are connected to the second water plant 9.

[0045] A maintenance drainage pipe 27 is connected between the upstream of the maintenance butterfly valve 21 for the third section of the water conveyance tunnel and the downstream of the second water diversion branch line 8. A maintenance drainage pipe butterfly valve 22 and a second maintenance drainage device 25 are set on the maintenance drainage pipe 27, and the maintenance drainage pipe 27 is connected to the second surface river or lake 29; the downstream of the maintenance butterfly valve 21 for the third section of the water conveyance tunnel is connected to one end of a maintenance drainage bypass pipe 28. A maintenance drainage bypass pipe butterfly valve 23 is set on the maintenance drainage bypass pipe 28, and the other end of the maintenance drainage bypass pipe 28 is connected to the upstream of the second maintenance drainage device 25.

[0046] A first reservoir 1 is set at the uppermost reaches of the water conveyance tunnel 3, and a second reservoir 11 is set at the lowermost reaches of the water conveyance tunnel 3. A first intake maintenance gate 2 is provided in the first reservoir 1, and a second intake and maintenance gate 10 is provided in the second reservoir 11.

[0047] Refer to Figure 3 、 Figure 4 It can be seen that the working principle of the method for the sectional drainage and sectional maintenance system of a long-distance water conveyance tunnel project in a city of the present invention is as follows: At the first surface river or lake 16 and the second surface river or lake 29 along the water conveyance tunnel 3 where the drainage volume can be absorbed, a lower point of the tunnel is set, and the entire length of the water conveyance tunnel 3 is divided into three sections for maintenance. The operating conditions are as follows:

[0048] Maintenance of the first section 30 of the water conveyance tunnel:

[0049] When the first section 30 of the water conveyance tunnel needs to be maintained, close the first intake gate 2 and the maintenance butterfly valve 18 of the first section of the water conveyance tunnel, and let the raw water in the first section 30 of the water conveyance tunnel flow towards the maintenance drainage well 13 by means of the slope. Then, use the maintenance drainage equipment 14 to pump the raw water in the tunnel along the maintenance drainage pipe 15 to the first surface river or lake 16. After evacuation, the first section 30 of the water conveyance tunnel can be maintained.

[0050] At this time, open the second intake gate 10, the maintenance butterfly valve 21 of the third section of the water conveyance tunnel, the maintenance butterfly valve 7 of the second branch line, the maintenance butterfly valve 19 of the second section of the water conveyance tunnel, and the maintenance butterfly valve 4 of the first branch line, and close the maintenance drainage pipe butterfly valve 22, the maintenance drainage bypass pipe butterfly valve 23, and the branch line bypass pipe butterfly valve 24. Water can be taken from the second reservoir 11 and supplied to the first water plant 6 and the second water plant 9 through the first branch line 5 and the second branch line 8 respectively.

[0051] Maintenance of the second section 31 of the water conveyance tunnel:

[0052] When the second section 31 of the water conveyance tunnel needs to be maintained, close the maintenance butterfly valve 19 of the second section of the water conveyance tunnel, the maintenance butterfly valve 7 of the second branch line, and the maintenance butterfly valve 21 of the third section of the water conveyance tunnel, and open the maintenance drainage pipe butterfly valve 22. Let the raw water in the second section 31 of the water conveyance tunnel flow towards the maintenance drainage and water distribution well 20 by means of the slope. Then, use the second maintenance drainage equipment 25 to pump the raw water in the second section 31 of the water conveyance tunnel along the maintenance drainage pipe 27 to the second surface river or lake 29. After evacuation, the second section 31 of the water conveyance tunnel can be maintained.

[0053] At this time, close the maintenance drainage bypass pipe butterfly valve 23, open the branch line bypass pipe butterfly valve 24 and the second intake gate 10. Water can be taken from the second reservoir 11 and supplied to the second water plant 9 through the branch line bypass pipe 26 and the second branch line 8. At the same time, open the first intake gate 2, the maintenance butterfly valve 18 of the first section of the water conveyance tunnel, and the maintenance butterfly valve 4 of the first branch line, and close the first maintenance drainage equipment 14. Water can be taken from the first reservoir 1 and supplied to the first water plant 6 through the first branch line 5.

[0054] Maintenance of the Third Section 32 of the Water Conveyance Tunnel:

[0055] When maintenance of the third section 32 of the water conveyance tunnel is required, close the maintenance gate 10 of the second water intake, the maintenance butterfly valve 21 of the third section of the water conveyance tunnel, and the butterfly valve 24 of the bypass pipe of the water distribution branch line. Open the butterfly valve 23 of the maintenance drainage bypass pipe to allow the raw water inside the third section 32 of the water conveyance tunnel to flow towards the maintenance drainage sump well 20 by means of the slope. Then, use the second maintenance drainage equipment 25 to pump and discharge the raw water inside the third section 32 of the water conveyance tunnel along the maintenance drainage bypass pipe 28 and the maintenance drainage pipe 27 to the second surface river or lake 29. After it is emptied, the third section 32 of the water conveyance tunnel can be maintained.

[0056] At this time, close the maintenance drainage pipe butterfly valve 22 and the first maintenance drainage equipment 14. Open the maintenance gate 2 of the first water intake, the maintenance butterfly valve 18 of the first section of the water conveyance tunnel, the maintenance butterfly valve 19 of the second section of the water conveyance tunnel, the maintenance butterfly valve 4 of the first water distribution branch line, and the maintenance butterfly valve 7 of the second water distribution branch line. Water can be supplied from the first reservoir 1 to the first water plant 6 and the second water plant 9 respectively through the first water distribution branch line 5 and the second water distribution branch line 8.

[0057] The opening and closing conditions of the gates, butterfly valves, and maintenance drainage equipment under the three operating and maintenance conditions are shown in Table 1 below.

[0058] The above three operating and maintenance conditions can achieve sectional drainage and sectional maintenance of the long-distance urban water conveyance tunnel project. When there are more than two water supply plants along the line, sectional maintenance can be achieved by setting bypass pipes and maintenance drainage equipment at the water distribution points of the water plants.

[0059] Table 1 Opening and Closing Conditions of Gates, Butterfly Valves, and Maintenance Drainage Equipment under Three Operating Conditions

[0060]

[0061] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A sectional drainage and sectional maintenance system for a long-distance water conveyance tunnel project in a city, characterized in that: Maintenance drainage equipment is arranged at the parts along the water conveyance tunnel that can accommodate the drainage volume, and maintenance butterfly valves and / or bypass pipes are set upstream and downstream of the water diversion branch line that diverts water to the water plant along the water conveyance tunnel; At the first surface river or lake and the second surface river or lake where the drainage volume can be accommodated along the water conveyance tunnel, a lower point of the tunnel is set, and the entire length of the water conveyance tunnel is divided into three sections: the first section of the water conveyance tunnel, the second section of the water conveyance tunnel, and the third section of the water conveyance tunnel; a maintenance drainage well is set in the first section of the water conveyance tunnel, and a first maintenance drainage equipment is set in the maintenance drainage well. The first maintenance drainage equipment is connected to the first surface river or lake through a maintenance drainage pipe; a water distribution well is set between the first section of the water conveyance tunnel and the second section of the water conveyance tunnel, and a maintenance butterfly valve for the first section of the water conveyance tunnel and a maintenance butterfly valve for the second section of the water conveyance tunnel are respectively set in the water distribution well; a maintenance drainage and water distribution well is set between the second section of the water conveyance tunnel and the third section of the water conveyance tunnel, and a maintenance butterfly valve for the third section of the water conveyance tunnel is set on the water conveyance tunnel in the maintenance drainage and water distribution well; The water conveyance tunnel in the water distribution well is connected to the first water diversion branch line, a maintenance butterfly valve for the first water diversion branch line is set on the first water diversion branch line, and the first water diversion branch line is connected to the first water plant; The water conveyance tunnel in the maintenance drainage and water distribution well is respectively connected to the second water diversion branch line and a bypass pipe for the water diversion branch line, and a maintenance butterfly valve for the second water diversion branch line is set on the second water diversion branch line; a butterfly valve for the bypass pipe of the water diversion branch line is set on the bypass pipe of the water diversion branch line, and both the second water diversion branch line and the bypass pipe for the water diversion branch line are connected to the second water plant; A maintenance drainage pipe is connected between the upstream of the maintenance butterfly valve for the third section of the water conveyance tunnel and the downstream of the second water diversion branch line. A maintenance drainage pipe butterfly valve and a second maintenance drainage equipment are set on the maintenance drainage pipe, and the maintenance drainage pipe is connected to the second surface river or lake; the downstream of the maintenance butterfly valve for the third section of the water conveyance tunnel is connected to one end of a maintenance drainage bypass pipe, a butterfly valve for the maintenance drainage bypass pipe is set on the maintenance drainage bypass pipe, and the other end of the maintenance drainage bypass pipe is connected to the upstream of the second maintenance drainage equipment.

2. The sectional drainage and sectional maintenance system for a long-distance water conveyance tunnel project in a city according to claim 1, characterized in that: A first reservoir is set at the uppermost reaches of the water conveyance tunnel, and a second reservoir is set at the lowermost reaches of the water conveyance tunnel. A maintenance gate for the first water intake is set in the first reservoir, and a second water intake and a maintenance gate are set in the second reservoir.

3. The maintenance method of the sectional drainage and sectional maintenance system for a long-distance water conveyance tunnel project in a city according to claim 2, characterized in that: It includes the following steps: Step 1: Maintenance of the first section of the water conveyance tunnel: When the first section of the water conveyance tunnel needs to be maintained, close the maintenance gate for the first water intake and the maintenance butterfly valve for the first section of the water conveyance tunnel, and let the original water in the first section of the water conveyance tunnel flow towards the maintenance drainage well by means of the slope. Then, use the maintenance drainage equipment to pump the original water in the tunnel along the maintenance drainage pipe to the first surface river or lake. After evacuation, the first section of the water conveyance tunnel can be maintained; Open the maintenance gate of the second water intake, the maintenance butterfly valve of the third section of the water conveyance tunnel, the maintenance butterfly valve of the second water diversion branch line, the maintenance butterfly valve of the second section of the water conveyance tunnel, and the maintenance butterfly valve of the first water diversion branch line. Close the maintenance drain pipe butterfly valve, the maintenance drain bypass pipe butterfly valve, and the water diversion branch line bypass pipe butterfly valve. Water can be taken from the second reservoir and supplied to the first water plant and the second water plant through the first water diversion branch line and the second water diversion branch line respectively. Step 2: Maintenance of the second section of the water conveyance tunnel: When the second section of the water conveyance tunnel needs to be maintained, close the maintenance butterfly valve of the second section of the water conveyance tunnel, the maintenance butterfly valve of the second water diversion branch line, and the maintenance butterfly valve of the third section of the water conveyance tunnel. Open the maintenance drain pipe butterfly valve, allowing the raw water in the second section of the water conveyance tunnel to flow towards the maintenance drain sump by means of the slope. Then, use the second maintenance drainage equipment to pump the raw water in the second section of the water conveyance tunnel along the maintenance drain pipe to the second surface river or lake. After evacuation, the second section of the water conveyance tunnel can be maintained. Close the maintenance drain bypass pipe butterfly valve, open the water diversion branch line bypass pipe butterfly valve and the maintenance gate of the second water intake. Water can be taken from the second reservoir and supplied to the second water plant through the water diversion branch line bypass pipe and the second water diversion branch line. At the same time, open the maintenance gate of the first water intake, the maintenance butterfly valve of the first section of the water conveyance tunnel, and the maintenance butterfly valve of the first water diversion branch line. Close the first maintenance drainage equipment. Water can be taken from the first reservoir and supplied to the first water plant through the first water diversion branch line. Step 3: Maintenance of the third section of the water conveyance tunnel: When the third section of the water conveyance tunnel needs to be maintained, close the maintenance gate of the second water intake, the maintenance butterfly valve of the third section of the water conveyance tunnel, and the water diversion branch line bypass pipe butterfly valve. Open the maintenance drain bypass pipe butterfly valve, allowing the raw water in the third section of the water conveyance tunnel to flow towards the maintenance drain sump by means of the slope. Then, use the second maintenance drainage equipment to pump the raw water in the third section of the water conveyance tunnel along the maintenance drain bypass pipe and the maintenance drain pipe to the second surface river or lake. After evacuation, the third section of the water conveyance tunnel can be maintained. Close the maintenance drain pipe butterfly valve and the first maintenance drainage equipment. Open the maintenance gate of the first water intake, the maintenance butterfly valve of the first section of the water conveyance tunnel, the maintenance butterfly valve of the second section of the water conveyance tunnel, the maintenance butterfly valve of the first water diversion branch line, and the maintenance butterfly valve of the second water diversion branch line. Water can be taken from the first reservoir and supplied to the first water plant and the second water plant through the first water diversion branch line and the second water diversion branch line respectively.

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