Tunnel drainage device and method

Abstract

The invention discloses a tunnel drainage device and method, and belongs to the technical field of tunnel drainage, the tunnel drainage device comprises annular drainage pipes arranged between a waterproof layer and a primary support layer, a communicating drainage pipe is arranged between every two adjacent annular drainage pipes, and the two ends of each communicating drainage pipe communicate with the adjacent annular drainage pipes correspondingly; water permeable holes are evenly formed in the surfaces of the annular drainage pipes and the communicating drainage pipes, longitudinal drainage pipes are longitudinally laid along the lining bottom of the tunnel, the annular drainage pipes are communicated with the longitudinal drainage pipes, drainage side ditches are arranged at the bottom of the tunnel, drainage blind ditches are arranged below the drainage side ditches, transverse drainage pipes are further arranged, and the transverse drainage pipes are perpendicular to the axis of the tunnel. The transverse drainage pipes are used for guiding water of the longitudinal drainage pipes to the drainage blind ditches, and water guiding pipes are arranged between the drainage blind ditches and the drainage side ditches and used for guiding water of the drainage side ditches to the drainage blind ditches. The problem that the drainage capacity is insufficient when only an annular drainage pipe is adopted can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel drainage, and particularly relates to a tunnel drainage device and method. Background Art

[0002] Tunnel waterproofing and drainage is a core link in tunnel design, construction and operation, and its importance is reflected in the following aspects: The long-term accumulation of groundwater will generate huge hydrostatic pressure on the tunnel lining (especially the secondary lining), which may cause the lining to crack, deform or even collapse. Mudstone, shale, etc. are easily softened by water, reducing the self-stabilizing ability of the surrounding rock and increasing the risk of collapse. In water-rich strata, the groundwater that is not drained in time may damage the stress balance of the surrounding rock and induce water inrush and mud inrush disasters. The CO carried by seepage water 2 reacts with Ca(OH) in concrete 2 to generate CaCO 3 , reducing the alkalinity of the concrete and accelerating the corrosion of steel bars.

[0003] In the prior art, the seepage water between the primary support layer and the waterproof layer is guided and drained through the circumferential drain pipes provided. However, due to the overall arch shape of the tunnel, the seepage water flowing downward along the arch side cannot all enter the circumferential drain pipes. Therefore, the water diversion ability of the circumferential drain pipes is limited. In addition, the drainage capacity of the side drainage ditches arranged on the tunnel pavement is limited during rainy days. Once the rainwater cannot be drained in time, water accumulation will occur on the tunnel pavement. Therefore, in view of the above problems, tunnel drainage needs further improvement. Summary of the Invention

[0004] The purpose of the present invention is to provide a tunnel drainage device and method to solve the above problems existing in tunnel drainage in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical scheme: A tunnel drainage device includes a primary support layer arranged on the inner wall of the tunnel. A waterproof layer is provided inside the primary support layer. A circumferential drain pipe is arranged between the waterproof layer and the primary support layer. The circumferential drain pipes are arranged at intervals along the tunnel circumference. A connecting drain pipe is arranged between two adjacent circumferential drain pipes. The two ends of the connecting drain pipe are respectively connected to the adjacent circumferential drain pipes. The surfaces of the circumferential drain pipes and the connecting drain pipes are evenly provided with water permeable holes. A longitudinal drain pipe is longitudinally laid along the bottom of the tunnel lining. The circumferential drain pipe is connected to the longitudinal drain pipe. Drainage side ditches are arranged on both sides of the tunnel bottom. A drainage blind ditch is arranged below the drainage side ditch. A transverse drain pipe is also provided. The transverse drain pipe is perpendicular to the tunnel axis. The transverse drain pipe is used to lead the water in the longitudinal drain pipe to the drainage blind ditch. A water diversion pipe is arranged between the drainage blind ditch and the drainage side ditch. The water diversion pipe is used to lead the water in the drainage side ditch to the drainage blind ditch.

[0006] As a further description of the above technical solution: the waterproof layer is formed by splicing a plurality of unit waterproof parts, the unit waterproof parts are arched and the outer side surfaces form a spherical surface, the annular drainage pipe is located in a groove at the connection between the outer sides of the two unit waterproof parts, the connecting drainage pipe is arranged along the spherical surface of the outer side surface of the unit waterproof part, and the connecting drainage pipe forms an angle with the axis of the tunnel.

[0007] As a further description of the above technical solution: a water diversion assembly is arranged in the water diversion pipe, and the water diversion pipe is composed of an upper drain pipe and a lower drain pipe. The water diversion assembly includes a one-way valve for connecting the upper drain pipe and the lower drain pipe. A float is arranged in the lower drain pipe, and the float is slidably arranged along the axial direction of the lower drain pipe. A sleeve is arranged on the float, and a sleeve rod is slidably arranged in the sleeve. A limiting arc plate is arranged at one end of the sleeve rod away from the sleeve, and a limiting part is arranged on the rocker arm of the one-way valve. When the valve disc of the one-way valve is closed, the outer periphery of the limiting part corresponds to the inner side surface of the limiting arc plate.

[0008] As a further description of the above technical solution: the upper drain pipe is vertically arranged in the drainage ditch, and the length of the upper drain pipe is the same as the height of the drainage ditch; the lower drain pipe is vertically arranged in the drainage blind ditch, and the length of the lower drain pipe is the same as the height of the drainage blind ditch; the upper end of the upper drain pipe is sealed, and water inlets are evenly spaced on the upper circumference of the upper drain pipe; the lower end of the lower drain pipe is sealed, and drainage outlets are opened on the lower circumference of the lower drain pipe.

[0009] As a further description of the above technical solution: the annular drain pipe, the connecting drain pipe, the transverse drain pipe, and the longitudinal drain pipe all adopt double-wall corrugated pipes, and the inner wall of the double-wall corrugated pipe is sprayed with anti-crystallization material.

[0010] As a further description of the above technical solution: a filter net is provided on the upper part of the upper drainage pipe.

[0011] As a further description of the above technical solution: a sliding block is arranged on the float, and the sliding block slides in the drain outlet.

[0012] The drainage method using the above tunnel drainage device comprises the following steps: S1. Tunnel seepage water flows directly from the annular drainage pipe into the longitudinal drainage pipe or from the connecting drainage pipe into the annular drainage pipe and then into the longitudinal drainage pipe, and finally into the drainage blind ditch through the transverse drainage pipe; S2, the rainwater on the tunnel road surface is discharged into the drainage ditch. When the water level in the drainage ditch reaches the drainage outlet, the rainwater enters the drainage blind ditch through the water diversion pipe. When the rainwater in the drainage blind ditch is full and the water level reaches the valve disc position of the one-way valve in the water diversion pipe, the rainwater in the drainage ditch no longer enters the drainage blind ditch through the water diversion pipe, and S1 is carried out simultaneously; S3: After the water level of the drainage blind ditch drops to the set position, repeat S2 and S1 simultaneously.

[0013] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: (1) In this application, by setting the waterproof layer into multiple spherical arc-shaped unit waterproof parts and the circumferential drain pipe and the connecting drain pipe arranged on the outside thereof, the seepage water flows along the spherical surface, most of the seepage water flows into the groove and then directly flows into the circumferential drain pipe, and the other seepage water flows into the circumferential drain pipe through the connecting drain pipe, greatly improving the seepage drainage capacity and reducing the seepage water flowing into the bottom of the lining.

[0014] (2) By arranging a water diversion pipe between the drainage side ditch and the drainage blind ditch, the rainwater in the drainage side ditch can flow into the drainage blind ditch under rainy weather conditions, reducing the drainage pressure of the drainage side ditch.

[0015] (3) While helping the drainage side ditch to drain water, the drainage blind ditch reserves a time window for seepage water drainage. When the water level in the drainage blind ditch reaches the limit, the water level of the lower drain pipe connected thereto is lower than the water level line of the longitudinal drain pipe, and the seepage water accumulated in the transverse drain pipe and the longitudinal drain pipe can be effectively discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a three-dimensional structure schematic diagram of the present invention; Figure 2 is a sectional view of the present invention; Figure 3 is Figure 2 the enlarged view at A in Figure 4 is a three-dimensional structure schematic diagram of the pipeline connection state of the present invention; Figure 5 is a sectional view of the water diversion pipe of the present invention; Figure 6 is an exploded view of the water diversion pipe of the present invention; Figure 7 is a three-dimensional structure schematic diagram of the floating ball, sleeve, sleeve rod and limiting arc plate of the present invention; Figure 8 is a three-dimensional structure schematic diagram of the valve flap and rocker arm of the check valve of the present invention.

[0017] Legend: 1, primary support layer; 2, unit waterproof part; 3, groove; 4, circumferential drain pipe; 5, connecting drain pipe; 6, longitudinal drain pipe; 7, drainage side ditch; 8, drainage blind ditch; 9, transverse drain pipe; 10, upper drain pipe; 11, lower drain pipe; 12, water inlet; 13, drain outlet; 14, check valve; 15, floating ball; 16, sliding block; 17, sleeve; 18, sleeve rod; 19, limiting arc plate; 20, limiting part; 21, valve flap; 22, rocker arm. DETAILED DESCRIPTION OF THE INVENTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to Figure 1-8 , the present invention provides a technical solution for a tunnel drainage device: A tunnel drainage device includes a circumferential drain pipe 4 disposed between the primary support layer 1 and the waterproof layer on the inner wall of the tunnel. The primary support layer 1 is in close contact with the surface of the surrounding rock and is the first layer of support for the tunnel structure. It is constructed immediately after the tunnel excavation and is used to stabilize the surrounding rock and prevent collapse. In this example, the primary support layer 1 adopts the construction process of initial spraying of concrete, positioning by drilling in a plum blossom shape, installing anchor bolts, installing steel arch frames, hanging steel mesh, and re-spraying concrete.

[0020] The waterproof layer is formed by splicing multiple unit waterproof parts 2. Specifically, the unit waterproof part 2 is arched and its outer side forms a spherical surface. The circumferential drain pipe 4 is located in the groove 3 at the connection of the outer sides of two unit waterproof parts 2. A connecting drain pipe 5 is provided between adjacent circumferential drain pipes 4. The connecting drain pipe 5 is arranged along the spherical surface of the outer side of the unit waterproof part 2. The connecting drain pipe 5 forms an angle with the axis of the tunnel. Both ends of the connecting drain pipe 5 are connected to the corresponding circumferential drain pipe 4. The unit waterproof part 2 includes an outer non-woven fabric buffer layer and an EVA waterproof board. The non-woven fabric buffer layer is formed by splicing multiple prefabricated and formed arc-shaped spherical panels. The base of the arc-shaped spherical panel is a concrete board with a steel wire mesh and its surface is coated with non-woven fabric. The arc-shaped spherical panel is fixed by nail guns (with hot-melt gaskets), and the overlapping width at adjacent positions is not less than 5 cm. In this embodiment, the overlapping width is 5 cm. The EVA waterproof board is laid circumferentially from bottom to top, first at the arch feet and then at the arch crown, and the longitudinal overlapping direction is the same as the water flow direction. The connecting drain pipe 5 and the circumferential drain pipe 4 are arranged outside the non-woven fabric buffer layer, and the connecting drain pipe 5 and the circumferential drain pipe 4 are connected by a tee.

[0021] Inside the waterproof layer, a secondary lining layer is provided. In this embodiment, it is formed by cast-in-place concrete construction. The secondary lining layer is a permanent support structure that bears part of the surrounding rock pressure and improves the overall durability of the tunnel.

[0022] The circumferential drain pipes 4 are arranged at intervals along the tunnel circumference. In this embodiment, the spacing is 5 m. The circumferential drain pipes 4 and the connecting drain pipes 5 are evenly provided with water permeable holes on the side.

[0023] Longitudinal drain pipes 6 are longitudinally laid along the bottom of the tunnel lining. One longitudinal drain pipe 6 is arranged on each side of the tunnel. The two ends of the circumferential drain pipe 4 are respectively communicated with the corresponding longitudinal drain pipes 6. Drainage side ditches 7 are arranged on both sides of the bottom of the tunnel. A drainage blind ditch 8 is arranged below the drainage side ditch 7. Inspection wells are arranged on the drainage blind ditch 8 and are sealed at the inspection wells, so that the surface water of the tunnel cannot flow into the drainage blind ditch 8 through the inspection wells. A transverse drain pipe 9 is also provided. The transverse drain pipe 9 is perpendicular to the tunnel axis. The transverse drain pipe 9 is used to lead the water in the longitudinal drain pipe 6 to the drainage blind ditch 8. The transverse drain pipes 9 are arranged at intervals of 5 meters along the length direction of the longitudinal drain pipe 6. A water diversion pipe is arranged between the drainage blind ditch 8 and the drainage side ditch 7. The water diversion pipe is used to lead the water in the drainage side ditch 7 to the drainage blind ditch 8.

[0024] The circumferential drain pipe 4, the connecting drain pipe 5, the transverse drain pipe 9, and the longitudinal drain pipe 6 are all made of double-wall corrugated pipes. An anti-crystallization material is sprayed on the inner wall of the double-wall corrugated pipe. The anti-crystallization material in this embodiment is a siliphos scale inhibitor.

[0025] Both the drainage side ditch 7 and the drainage blind ditch 8 are formed by splicing precast concrete pipes. The splicing joints and the inner walls are waterproofed. The drainage blind ditch 8 and the drainage side ditch 7 are communicated through a connecting water pipe (not shown in the figure). A plurality of connecting water pipes are arranged at equal intervals along the length direction of the drainage side ditch 7. In this embodiment, the distance between adjacent connecting water pipes is 10 m. A water diversion pipe is inserted into each connecting water pipe. The water diversion pipe is detachably arranged in the connecting water pipe. A sealing gasket is arranged between the connecting water pipe and the water diversion pipe. The water diversion pipe is fixed in the connecting water pipe through the elastic action of the sealing gasket.

[0026] A water diversion assembly is arranged in the water diversion pipe. The water diversion pipe is composed of an upper drain pipe 10 and a lower drain pipe 11. The upper drain pipe 10 is vertically arranged in the drainage side ditch 7. The length of the upper drain pipe 10 is the same as the height of the drainage side ditch 7. The lower drain pipe 11 is vertically arranged in the drainage blind ditch 8. The length of the lower drain pipe 11 is the same as the height of the drainage blind ditch 8. The upper end of the upper drain pipe 10 is sealed. Water inlet openings 12 are equally spaced on the upper circumferential side of the upper drain pipe 10. A filter screen (not shown in the figure) is sleeved on the upper part of the upper drain pipe 10 to prevent the water inlet openings 12 from being blocked. The lower end of the lower drain pipe 11 is sealed. Drainage openings 13 are arranged on the lower circumferential side of the lower drain pipe 11.

[0027] The water diversion assembly includes a one-way valve 14 for connecting the upper drain pipe 10 and the lower drain pipe 11. A floating ball 15 is arranged in the lower drain pipe 11. The floating ball 15 is slidably arranged along the axial direction of the lower drain pipe 11. A sliding block 16 is arranged on the floating ball 15, and the sliding block 16 slides in the drain port 13. A sleeve 17 is arranged on the floating ball 15, and a sleeve rod 18 is slidably arranged in the sleeve 17. A limiting arc plate 19 is arranged at one end of the sleeve rod 18 away from the sleeve 17. A limiting portion 20 is arranged on the rocker arm 22 of the one-way valve 14. A torsion spring is arranged at the rotation axis of the rocker arm 22, and the valve flap 21 remains in a closed state when not under force. When the valve flap 21 of the one-way valve 14 is closed, the outer peripheral edge of the limiting portion 20 corresponds to the inner side surface of the limiting arc plate 19.

[0028] The drainage method and working principle of the above tunnel drainage device are as follows: For the seepage water in the primary support layer 1 and the waterproof layer, a large amount of seepage water flows along the outer side surface of the unit waterproof part 2 towards the groove 3 at its joint and flows into the circumferential drain pipe 4 through the water permeable holes of the circumferential drain pipe 4, while a small amount of seepage water flows downward along the outer side surface of the unit waterproof part 2 and flows into the connecting drain pipe 5 through the water permeable holes of the connecting drain pipe 5. The seepage water in the connecting drain pipe 5 then flows into the circumferential drain pipe 4. All the seepage water in the circumferential drain pipe 4 flows into the drainage blind ditch 8 through the longitudinal drain pipe 6 and the transverse drain pipe 9 and is drained away by the drainage blind ditch 8.

[0029] The above drainage process and method can efficiently drain the seepage water at the tunnel vault in case of rainy weather. For rainy weather, especially in case of heavy rain and extremely heavy rain, the drainage pressure of the drainage side ditch 7 increases. When the water level in the drainage side ditch 7 rises to the water inlet 12 of the upper drain pipe 10, the rainwater will enter the drainage blind ditch 8 through the upper drain pipe 10 and along the one-way valve 14. At this time, the one-way valve 14 and the rocker arm 22 rotate to open the valve flap 21, and a large amount of rainwater enters the drainage blind ditch 8. At this time, the floating ball 15 and the sleeve 17 float upward. Under the action of the water flow impact and the gravity of the limiting arc plate 19, the sleeve rod 18 and the limiting arc plate 19 remain stationary. As the water level in the drainage blind ditch 8 rises, the floating ball 15 rises until it can push the sleeve rod 18 and the limiting arc plate 19 to move upward until the limiting arc plate 19 contacts the valve flap 21. Subsequently, until the water fills the water diversion pipe and the drainage blind ditch 8, that is, the water level is not lower than the water inlet 12 of the upper drain pipe 10, the valve flap 21 is not impacted by the water flow, and the valve flap 21 returns to its initial state. At this time, under the buoyancy pushing action of the floating ball 15, the limiting arc plate 19 is adapted to the outer side of the limiting portion 20 on the rocker arm 22.

[0030] Subsequently, as the water level in the drainage blind ditch 8 drops, first, when the water level is higher than the floating ball 15, the floating ball 15 remains stationary. Subsequently, the floating ball 15 and the sleeve 17 drop together with the water level. During this process, the sleeve rod 18 and the limiting arc plate 19 remain stationary, mainly because the limiting part 20 is clamped with the limiting arc plate 19, and the water pressure cannot make it move until the floating ball 15 and the sleeve 17 drive the sleeve rod 18 and the limiting arc plate 19 to move. During this process, due to the gravity of the floating ball 15 and the limiting arc plate 19, the limiting arc plate 19 disengages from the clamping with the limiting part 20, and the water flow enters the lower drain pipe 11 from the upper drain pipe 10 again, and the drainage pressure of the side drainage ditch is relieved again through the water diversion pipe. And during the above process, within the gap from the highest state of the water level in the drainage blind ditch 8 to the state of water inlet through the water diversion pipe again, the horizontal drain pipe 9 can normally drain the seepage water in the vertical drain pipe 6 into the drainage blind ditch 8. During the process of the water level in the drainage blind ditch 8 rising and falling repeatedly, the drainage pressure of the drainage side ditch 7 is relieved, and at the same time, the normal drainage of the seepage water is not affected.

[0031] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art of this technology, within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, any equivalent replacement or change should be covered within the protection scope of the present invention.

Claims

1. A tunnel drainage device, characterized in that: The invention comprises an initial support layer (1) arranged on the inner wall of a tunnel, a waterproof layer is arranged inside the initial support layer (1), an annular drainage pipe (4) is arranged between the waterproof layer and the initial support layer (1), the annular drainage pipe (4) is arranged at intervals along the annular direction of the tunnel, a connecting drainage pipe (5) is arranged between two adjacent annular drainage pipes (4), both ends of the connecting drainage pipe (5) are respectively connected to the adjacent annular drainage pipes (4), water permeable holes are evenly opened on the surface of the annular drainage pipe (4) and the connecting drainage pipe (5), and longitudinal drainage pipes are laid along the longitudinal direction of the bottom of the tunnel lining. A longitudinal drainage pipe (6) is connected to the annular drainage pipe (4) and the longitudinal drainage pipe (6). Drainage side ditches (7) are arranged on both sides of the tunnel bottom. A drainage blind ditch (8) is arranged below the drainage side ditch (7). A transverse drainage pipe (9) is also arranged. The transverse drainage pipe (9) is perpendicular to the tunnel axis. The transverse drainage pipe (9) is used to guide water from the longitudinal drainage pipe (6) to the drainage blind ditch (8). A water diversion pipe is arranged between the drainage blind ditch (8) and the drainage side ditch (7). The water diversion pipe is used to guide water from the drainage side ditch (7) to the drainage blind ditch (8).

2. The tunnel drainage device according to claim 1, characterized in that: The waterproof layer is formed by splicing a plurality of unit waterproof parts (2), the unit waterproof parts (2) are arched and the outer side surfaces form a spherical surface, the annular drainage pipe (4) is located in a groove (3) at a connection point outside two unit waterproof parts (2), the connecting drainage pipe (5) is arranged along the spherical surface of the outer side surface of the unit waterproof part (2), and the connecting drainage pipe (5) forms an angle with the axis of the tunnel.

3. The tunnel drainage device according to claim 1, characterized in that: A water diversion assembly is arranged in the water diversion pipe. The water diversion pipe is composed of an upper drainage pipe (10) and a lower drainage pipe (11). The water diversion assembly comprises a one-way valve (14) for connecting the upper drainage pipe (10) and the lower drainage pipe (11). A floating ball (15) is arranged in the lower drainage pipe (11). The floating ball (15) is slidably arranged along the axial direction of the lower drainage pipe (11). A sleeve (17) is arranged on the floating ball (15). A sleeve rod (18) is slidably arranged in the sleeve (17). A limiting arc plate (19) is arranged at one end of the sleeve rod (18) away from the sleeve (17). A limiting portion (20) is arranged on the rocker arm (22) of the one-way valve (14). When the valve flap (21) of the one-way valve (14) is closed, the outer peripheral edge of the limiting portion (20) corresponds to the inner side surface of the limiting arc plate (19).

4. The tunnel drainage device according to claim 3, characterized in that: The upper drainage pipe (10) is vertically arranged in the drainage ditch (7), and the length of the upper drainage pipe (10) is the same as the height of the drainage ditch (7). The lower drainage pipe (11) is vertically arranged in the drainage blind ditch (8), and the length of the lower drainage pipe (11) is the same as the height of the drainage blind ditch (8). The upper end of the upper drainage pipe (10) is sealed, and water inlets (12) are evenly spaced on the upper circumference of the upper drainage pipe (10). The lower end of the lower drainage pipe (11) is sealed, and a drainage outlet (13) is opened on the lower circumference of the lower drainage pipe (11).

5. The tunnel drainage device according to claim 1, characterized in that: The annular drainage pipe (4), the connecting drainage pipe (5), the transverse drainage pipe (9), and the longitudinal drainage pipe (6) are all double-walled corrugated pipes, and anti-crystallization material is sprayed on the inner wall of the double-walled corrugated pipe.

6. The tunnel drainage device according to claim 4, characterized in that: The upper portion of the upper drainage pipe (10) is sleeved with a filter screen.

7. The tunnel drainage device according to claim 4, characterized in that: The floating ball (15) is provided with a sliding block (16), and the sliding block (16) slides in the drainage port (13).

8. A drainage method for a tunnel drainage device, characterized in that: The tunnel drainage device according to any one of claims 1 to 7 comprises the following steps: S1, tunnel seepage water flows directly from the annular drainage pipe (4) into the longitudinal drainage pipe (6) or flows from the connecting drainage pipe (5) into the annular drainage pipe (4) and then into the longitudinal drainage pipe (6), and finally flows into the drainage blind ditch (8) via the transverse drainage pipe (9); S2, rainwater on the tunnel road surface is discharged into the drainage ditch (7). After the water level in the drainage ditch (7) reaches the drainage outlet (13), the rainwater enters the drainage blind ditch (8) through the water diversion pipe. When the rainwater in the drainage blind ditch (8) is full and the water level reaches the position of the valve disc (21) of the one-way valve (14) in the water diversion pipe, the rainwater in the drainage ditch (7) no longer enters the drainage blind ditch (8) through the water diversion pipe, and S1 is performed simultaneously; S3: After the water level in the drainage blind ditch (8) drops to the set position, S2 and S1 are repeated simultaneously.

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