Micro-polluted and low-flow-velocity river ecological restoration device

Abstract

The utility model relates to a micro-polluted low-flow-velocity river ecological restoration device which is characterized in that a plurality of layers of heavy adsorption ecological bags are arranged at the bottom of a river, and a first gabion assembly is arranged above the heavy adsorption ecological bags and used for filtering river water and removing pollution components in the river water at the same time; step stone is arranged on the upper surface of the first gabion assembly; a second gabion assembly is arranged behind the heavy adsorption ecological bag and the first gabion assembly; plants are arranged on the upper surface of the second gabion assembly and between every two adjacent stepping stones; and the total height of the heavy adsorption ecological bag and the first gabion assembly meets the condition that at least 1 / 3 of river water flows over the first gabion assembly. The device can reduce the content of pollution components in river water and increase the oxygen content at the same time, does not need additional oxygenation equipment, and reduces the energy consumption.

Description

Technical Field

[0001] The utility model belongs to the technical field of river ecological management, in particular to an ecological restoration device for a slightly polluted and low-flow-rate river. Background Art

[0002] Affected by human activities, many rivers are polluted to a certain extent, such as excessive components such as heavy metals, ammonia nitrogen, phosphorus, organic matter, and suspended particles. In order to improve the water quality of rivers and meet environmental protection requirements, it is necessary to carry out ecological restoration of rivers. At present, the conventional restoration method is to build a filter dam. For example, CN201922141732.3 discloses an in-situ ecological restoration permeable dam for river water ecological restoration, which has functions such as aeration, filtration, and ecological restoration. It can improve water quality well, but the oxygen content in the water is increased by aeration, and the energy consumption is high. CN202020634971.2 discloses a composite structure for river ecological restoration. By setting up a restoration mechanism, a gabion, a restoration plant, etc., it can effectively filter out suspended matter in the river water, and can remove pollutants such as ammonia nitrogen, but it does not have the function of increasing oxygen content. The height of the existing ecological restoration structure is usually higher than the river water level to ensure that the river water can all pass through the restoration structure, but it does not have the function of natural oxygenation. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a device for ecological restoration of rivers with slight pollution and low flow rate, which is suitable for ecological restoration of rivers with flow rate between 0.1m / s and 0.3m / s, can reduce the content of pollutants in river water while increasing the oxygen content, does not require additional oxygen enrichment equipment, and reduces energy consumption.

[0004] In order to solve the above problems, the technical solution adopted by the utility model is: a slightly polluted, low-flow river ecological restoration device, including a multi-layer heavy-weight adsorption ecological bag arranged at the bottom of the river, a first gabion assembly is arranged above the heavy-weight adsorption ecological bag, and a plurality of mutually parallel stepping stones are arranged on the upper surface of the first gabion assembly, and there is a distance between adjacent stepping stones; a stepped second gabion assembly is arranged behind the heavy-weight adsorption ecological bag and the first gabion assembly, and the height of the second gabion assembly gradually decreases along the direction of water flow; a vegetation bearing frame is arranged on the upper surface of the second gabion assembly and between two adjacent stepping stones, and plants are planted on the vegetation bearing frame, and the total height of the heavy-weight adsorption ecological bag and the first gabion assembly is lower than the river water level.

[0005] Furthermore, inclined slopes are provided on both sides of the riverbed, tracks are provided on the slopes, third gabion assemblies are provided on the left and right sides of the heavy-weight adsorption eco-bag and the first gabion assembly, the bottom of the third gabion assembly is slidably matched with the track, and a driving mechanism for pulling the third gabion assembly to slide along the track is provided on the slopes; the upper surface of the third gabion assembly is at the same height as the upper surface of the first gabion assembly.

[0006] Furthermore, a V-shaped sand retaining wall is arranged in front of the heavy-weight adsorption eco-bag and the first gabion assembly, a plurality of water holes are arranged in the middle and upper parts of the sand retaining wall, and sand pits are arranged on both sides in front of the heavy-weight adsorption eco-bag.

[0007] Furthermore, the height of the sand retaining wall is higher than the water level during floods, and a downwardly extending slot is provided on the upper surface of the sand retaining wall, in which a sealing plate is provided; vertical water-blocking plates are provided on the left and right sides of the heavy-weight adsorption eco-bag and the first gabion assembly; a water-passing support plate is provided above the third gabion assembly, one end of the water-passing support plate is hinged to the upper end of the water-blocking plate, and the other end is overlapped on the slope; fences are provided at the front and rear ends of the stepping stone, a wire rope reeling and winding device is provided on the fence, and guide pulleys are provided on the tops of both ends of the fence, the wire rope reeling and winding device is connected to the wire rope, and the wire rope is connected to the water-passing support plate after passing through the guide pulley.

[0008] Furthermore, the water holes are provided in multiple rows, and the multiple rows of water holes are arranged in sequence from top to bottom, and the spacing between two adjacent rows of water holes is greater than or equal to the diameter of the water holes. The sealing plate is provided with multiple rows of through holes, and the sealing plate is connected to a lifting mechanism that drives the sealing plate to move from the water passing position to the blocking position. When the sealing plate is in the water passing position, each through hole is connected to a water hole, and when the sealing plate is in the blocking position, each row of through holes is located between two adjacent rows of water holes.

[0009] The beneficial effects of the utility model are as follows: the utility model arranges adsorption fillers, such as activated carbon, in the heavy-weight adsorption eco-bag, which can absorb nitrogen, phosphorus, antibiotics and other pollutants in the river water. The first gabion assembly and the second gabion assembly are filled with crushed stones, which can play a filtering role and reduce the content of suspended matter in the river water. In addition, the surface of the crushed stones can be used for the growth of microorganisms, and the microorganisms can decompose pollutants such as ammonia nitrogen in the sewage. By arranging vegetation above the first gabion assembly and the second gabion assembly, the vegetation can also absorb nutrients in the river water and further purify the water quality. In the utility model, the total height of the heavy-weight adsorption eco-bag and the first gabion assembly is relatively low, so that part of the river water flows over the top of the first gabion assembly. This part of the river water is blocked by the stepping stones and becomes turbulent, increasing the area in contact with the air, and then flows downward on the surface of the stepped second gabion assembly, achieving waterfall oxygenation, increasing the oxygen content in the water, and preventing eutrophication of the water body. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a top view schematic diagram of the utility model;

[0011] Figure 2 yes Figure 1 Schematic cross-sectional view of AA in the figure;

[0012] Figure 3 yes Figure 1 A schematic cross-sectional view of the middle BB;

[0013] Figure 4 yes Figure 2 Schematic diagram of flooding in China;

[0014] Figure 5 It is a cross-sectional schematic diagram of the sand retaining wall in a normal state;

[0015] Figure 6 It is a cross-sectional diagram of a sand retaining wall during a flood;

[0016] Figure numerals: 1—river bottom; 2—heavy-duty adsorption eco-bag; 3—first gabion group; 4—stepping stone; 5—second gabion assembly; 6—vegetation bearing frame; 7—plant; 8—track; 9—third gabion assembly; 10—slope; 11—driving mechanism; 12—water-passing support plate; 13—sand retaining wall; 14—sand pit; 15—sealing plate; 16—water-blocking plate; 17—fence; 18—wire rope reeling and unwinding equipment; 19—guide pulley; 20—wire rope; 21—through hole; 22—water-passing hole; 23—lifting mechanism. DETAILED DESCRIPTION

[0017] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0018] The utility model is a device for ecological restoration of micro-polluted and low-flow rivers. Figures 1 to 6 As shown, it includes a multi-layer heavy-weight adsorption ecological bag 2 arranged on the riverbed 1, a first gabion assembly 3 is arranged above the heavy-weight adsorption ecological bag 2, and a plurality of mutually parallel stepping stones 4 are arranged on the upper surface of the first gabion assembly 3, and there is a spacing between two adjacent stepping stones 4; a stepped second gabion assembly 5 is arranged behind the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3, and the height of the second gabion assembly 5 gradually decreases along the direction of the water flow; a vegetation bearing frame 6 is arranged on the upper surface of the second gabion assembly 5 and between two adjacent stepping stones 4, and plants 7 are planted on the vegetation bearing frame 6. The total height of the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3 is lower than the river water level, and the river water level here refers to the water level of the river under normal circumstances, not the flood water level. Specifically, the total height of the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3 satisfies: at least 1 / 3 of the river water flows over the top of the first gabion assembly 3.

[0019] The heavy-duty adsorption eco-bag 2 is a flexible packaging bag filled with an adsorption filler. The specific composition of the adsorption filler is determined according to the pollutant components in the river water. Multiple fillers can be mixed and used. For example, when the heavy metal content in the river water exceeds the standard, the adsorption filler contains a material that can adsorb heavy metals. The adsorption filler is preferably activated carbon, which can absorb nitrogen, phosphorus, antibiotics and other pollutants in the river water.

[0020] The first gabion assembly 3 and the second gabion assembly 5 include a plurality of gabions, each of which is filled with gravel. The gravel has a filtering effect and can reduce the content of suspended matter in the river water. In addition, the surface of the gravel can provide space for microorganisms to reproduce and grow, thereby decomposing pollutants such as ammonia nitrogen.

[0021] The stepping stone 4 is made of long strips of stone. After the stepping stone 4 is set, it serves as a pedestrian walkway, so that the device has the function of connecting the two sides of the river, which can be used for residents to walk and sightsee. The utility model is used for ecological restoration of low-flow rivers. The river flow rate is between 0.1m / s and 0.3m / s. Due to the low flow rate, the impact force on the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the stepping stone 4 is small. Therefore, the second gabion assembly 5 and the heavy-weight adsorption ecological bag 2 can be directly placed on the riverbed 1, the first gabion assembly 3 is naturally placed on the heavy-weight adsorption ecological bag 2, and the stepping stone 4 is naturally placed on the surface of the first gabion assembly 3, which can reduce the construction difficulty. Of course, reinforcement piles can be set around the second gabion assembly 5, the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3 to reinforce the second gabion assembly 5, the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3 to ensure the position stability of the second gabion assembly 5, the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3.

[0022] In the utility model, the total height of the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3 is relatively low, the first gabion assembly 3 is completely submerged in the river water, at least 1 / 3 of the river water flows over the first gabion assembly 3, becomes turbulent after being blocked by the stepping stones 4, and passes through the gaps between the stepping stones 4, and then flows along the second gabion assembly 5. Since the second gabion assembly 5 is in a stepped shape, it falls and rolls during the flow process, and is fully in contact with the air, thereby increasing the oxygen content. The rest of the river water passes through the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3 for filtration.

[0023] The vegetation bearing frame 6 is used to plant plants 7. The roots of the plants 7 can extend into the water and enter the first gabion assembly 3 and the second gabion assembly 5, and can absorb nutrients in the water to purify the river water. The plants 7 can be aquatic cannas, umbrella bamboos, etc.

[0024] When a flood occurs, it is necessary to discharge the flood water quickly to prevent the occurrence of a flood disaster. In order to meet the requirements of flood prevention and discharge, the utility model has inclined slopes 10 on both sides of the riverbed 1, and tracks 8 on the slopes 10. The heavy-weight adsorption ecological bag 2 and the left and right sides of the first gabion assembly 3 are provided with a third gabion assembly 9. The bottom of the third gabion assembly 9 is slidably matched with the track 8, and a driving mechanism 11 is provided on the slope 10 for pulling the third gabion assembly 9 to slide along the track 8; the upper surface of the third gabion assembly 9 is at the same height as the upper surface of the first gabion assembly 3.

[0025] The third gabion assembly 9 also includes a plurality of gabions, but all the gabions are integrated into a whole through a frame, and the bottom of the frame is slidably matched with the track 8. Under normal circumstances, the third gabion assembly 9 plays a filtering role. When a flood occurs, the driving mechanism 11 is used to pull the third gabion assembly 9 upward, thereby forming a flood discharge channel on the left and right sides of the heavy adsorption eco-bag 2 and the first gabion assembly 3, and the flood can flow downstream through the flood discharge channel to avoid excessive water level. After the flood, the third gabion assembly 9 can be reset downward. The driving mechanism 11 can be a conventional device such as a winch.

[0026] In the utility model, the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the second gabion assembly 5 are fixed, and the third gabion assembly 9 is movable. The size of the river channel space occupied by the fixed and movable gabions is reasonably allocated according to the local flood water volume. If the flood water volume is large, the proportion of the river channel space occupied by the third gabion assembly 9 is large. If the flood water volume is small, the proportion of the river channel space occupied by the third gabion assembly 9 is small.

[0027] In the present invention, the front and rear directions are based on the flow direction of the river, that is, the river flows from the front to the rear. When the human body faces forward, the left side of the human body is the left side of the present invention, and the right side of the human body is the right side of the present invention.

[0028] The river water carries sediment, and some of the sediment will accumulate in front of the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3, affecting the river water entering the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3. In addition, after the sediment enters the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3, the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3 will be quickly blocked. In order to prevent the sediment from quickly blocking the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3, the utility model is provided with a V-shaped sand retaining wall 13 in front of the heavy-weight adsorption eco-bag 2 and the first gabion assembly 3, and a plurality of water holes 22 are provided in the middle and upper parts of the sand retaining wall 13, and sand pits 14 are provided on both sides in front of the heavy-weight adsorption eco-bag 2.

[0029] The sand retaining wall 13 is vertically arranged, and the middle part protrudes forward, so that the sand retaining wall 13 is V-shaped. The weight of the silt is relatively large, and it is usually located at the bottom of the river water. When the silt reaches the sand retaining wall 13 with the river water, it is blocked by the sand retaining wall 13. Since the sand retaining wall 13 is V-shaped, when the river water in the lower layer reaches the sand retaining wall 13, it will flow to the left and right along the front side wall of the sand retaining wall 13, thereby driving the silt to flow to the left and right, and finally reach the sand pit 14. The river water in the middle and upper layers flows to the rear of the sand retaining wall 13 through the water holes 22, and then part of the river water passes through the heavy adsorption ecological bag 2 and the first gabion assembly 3, and part of it flows from the top of the first gabion assembly 3. When constructing the sand pit 14, first excavate the riverbed 1 to form a foundation pit, and then pour concrete in the foundation pit to form a sand pit 14 with smooth bottom and side walls and stable. When the sand pit 14 is filled with silt, the silt in the sand pit 14 can be cleaned to prevent the silt from accumulating in front of the heavy adsorption eco-bag 2 and the first gabion assembly 3, and to prevent the silt from entering the heavy adsorption eco-bag 2 and the first gabion assembly 3 and causing blockage.

[0030] When a flood occurs, the amount of sediment carried in the flood increases dramatically. If the flood directly enters the heavy adsorption eco-bag 2, the first gabion assembly 3 and the second gabion assembly 5, the heavy adsorption eco-bag 2, the first gabion assembly 3 and the second gabion assembly 5 will be quickly blocked. In addition, the flood may also destroy the plants 7.

[0031] In order to prevent the adverse effects of floods on plants 7, heavy-weight adsorption ecological bags 2, the first gabion assembly 3 and the second gabion assembly 5, in the utility model, the height of the sand retaining wall 13 is higher than the water level during the flood, and the water level during the flood is determined according to the historical flood level. The upper surface of the sand retaining wall 13 is provided with a slot extending downward, and a blocking plate 15 is provided in the slot. In normal times, the blocking plate 15 can be taken out to ensure that the river water can penetrate the sand retaining wall 13 through the water hole 22. When a flood occurs, when the water hole 22 needs to be blocked, the blocking plate 15 is inserted into the slot. At this time, the river water cannot penetrate the sand retaining wall 13, and can only pass through the left and right sides of the sand retaining wall 13, and will not reach the front side of the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3. Vertical water-blocking plates 16 are provided on the left and right sides of the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3. The water-blocking plates 16 play a role of water isolation to prevent floods from entering the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3 from the left and right sides of the heavy-weight adsorption ecological bag 2 and the first gabion assembly 3. A water-passing support plate 12 is arranged above the third gabion assembly 9, one end of the water-passing support plate 12 is hinged to the upper end of the water-blocking plate 16, and the other end is overlapped on the slope 10. The water-passing support plate 12 cooperates with the stepping stone 4 to form a pedestrian walkway connecting the two sides of the river, which can be used for pedestrians to pass through to reach the other side at ordinary times. Fences 17 are arranged at the front and rear ends of the stepping stone 4, and the fence 17 can play a protective role to prevent pedestrians or objects from falling into the river. A wire rope reeling and unwinding device 18 is arranged on the fence 17, and the wire rope reeling and unwinding device 18 can be a winch, etc., and guide pulleys 19 are arranged on the tops of the two ends of the fence 17, and the wire rope reeling and unwinding device 18 is connected to a wire rope 20, and the wire rope 20 is connected to the water-passing support plate 12 after passing through the guide pulley 19. When a flood occurs, the wire rope reeling and unreeling device 18 drives the wire rope 20 to reel, and the wire rope 20 pulls the water-passing support plate 12 to rotate upward to a vertical position. At this time, the end of the fence 17 is pressed against the water-passing support plate 12, which can keep the water-passing support plate 12 stable. At this time, the total height of the water-passing support plate 12 and the water-blocking plate 16 is higher than the flood level, preventing the flood from overflowing from the top of the water-blocking plate 16 to the top of the first gabion assembly 3 and the second gabion assembly 5.

[0032] In the utility model, when a flood occurs, the water holes 22 of the sand retaining wall 13 are closed, and the sand retaining wall 13, the water-blocking plate 16 and the water-passing support plate 12 surround the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the second gabion assembly 5, which can prevent the flood from reaching the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the second gabion assembly 5, and prevent the mud, sand and impurities in the flood from entering the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the second gabion assembly 5 to cause blockage, and prevent the flood from destroying the plants 7. In addition, since the heavy-weight adsorption ecological bag 2, the first gabion assembly 3 and the second gabion assembly 5 and other components do not bear the direct impact of the flood, the construction requirements are relatively low and the construction difficulty is lower.

[0033] With current meteorological technology, floods can usually be predicted relatively accurately. Therefore, when a flood is predicted, the wire rope reeling device 18 can be started in advance to pull the water-passing support plate 12 to rotate to a vertical state, and then the third gabion assembly 9 is pulled upward to a suitable position by the driving mechanism 11 to form a flood discharge channel, and finally the water-passing hole 22 on the sand retaining wall 13 is closed by the blocking plate 15. After the flood, the water-passing hole 22 is opened, the third gabion assembly 9 is reset downward, and then the water-passing support plate 12 is rotated to a horizontal position.

[0034] The blocking plate 15 can be a plate without holes. When blocking, the blocking plate 15 needs to be inserted into the sand retaining wall 13 as a whole. After the flood, the blocking plate 15 needs to be taken out as a whole. The moving distance of the blocking plate 15 is large, and the operation is difficult. In order to reduce the difficulty of operation, in the utility model, the water holes 22 are arranged in multiple rows, the water holes 22 are circular holes, and the multiple rows of water holes 22 are arranged in sequence from top to bottom, the spacing between two adjacent rows of water holes 22 is greater than or equal to the diameter of the water holes 22, the blocking plate 15 is provided with multiple rows of through holes 21, and the blocking plate 15 is connected to a lifting mechanism 23 that drives the blocking plate 15 to move from the water-passing position to the blocking position. When the blocking plate 15 is in the water-passing position, each through hole 21 is connected to a water hole 22, and when the blocking plate 15 is in the blocking position, each row of through holes 21 is located between two adjacent rows of water holes 22, at which time the through holes 21 and the water holes 22 are staggered, and the blocking plate 15 closes the water holes 22. The lifting mechanism 23 can be an existing device such as a winch.

[0035] In summary, the utility model can carry out ecological restoration of rivers and prevent floods from damaging ecological restoration devices, thereby ensuring that the ecological restoration devices can operate effectively for a long time and reducing subsequent maintenance costs.

[0036] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A device for ecological restoration of slightly polluted and low-flow rivers, characterized in that: The invention comprises a multi-layer heavy-weight adsorption ecological bag (2) arranged on the riverbed (1); a first gabion assembly (3) is arranged above the heavy-weight adsorption ecological bag (2); a plurality of mutually parallel stepping stones (4) are arranged on the upper surface of the first gabion assembly (3); and a spacing is provided between two adjacent stepping stones (4); a stepped second gabion assembly (5) is arranged behind the heavy-weight adsorption ecological bag (2) and the first gabion assembly (3); and the height of the second gabion assembly (5) gradually decreases along the direction of water flow; a vegetation bearing frame (6) is arranged on the upper surface of the second gabion assembly (5) and between two adjacent stepping stones (4); plants (7) are planted on the vegetation bearing frame (6); and the total height of the heavy-weight adsorption ecological bag (2) and the first gabion assembly (3) is lower than the river water level.

2. The device for ecological restoration of a slightly polluted and low-flow river according to claim 1, characterized in that: Inclined slopes (10) are arranged on both sides of the riverbed (1), and tracks (8) are arranged on the slopes (10). A third gabion assembly (9) is arranged on the left and right sides of the heavy-weight adsorption ecological bag (2) and the first gabion assembly (3), and the bottom of the third gabion assembly (9) is slidably matched with the track (8), and a driving mechanism (11) for pulling the third gabion assembly (9) to slide along the track (8) is arranged on the slope (10); the upper surface of the third gabion assembly (9) is at the same height as the upper surface of the first gabion assembly (3).

3. The device for ecological restoration of a slightly polluted and low-flow river according to claim 2, characterized in that: A V-shaped sand retaining wall (13) is arranged in front of the heavy-weight adsorption ecological bag (2) and the first gabion assembly (3), a plurality of water holes (22) are arranged in the middle and upper parts of the sand retaining wall (13), and sand pits (14) are arranged on both sides in front of the heavy-weight adsorption ecological bag (2).

4. The device for ecological restoration of a slightly polluted and low-flow river according to claim 3, characterized in that: The height of the sand retaining wall (13) is higher than the water level during floods. The upper surface of the sand retaining wall (13) is provided with a slot extending downward, and a blocking plate (15) is provided in the slot; vertical water-blocking plates (16) are provided on the left and right sides of the heavy-weight adsorption ecological bag (2) and the first gabion assembly (3); a water-passing support plate (12) is provided above the third gabion assembly (9), one end of the water-passing support plate (12) is hinged to the upper end of the water-blocking plate (16), and the other end is overlapped on the slope (10); fences (17) are provided at the front and rear ends of the stepping stone (4), and a wire rope reeling and unreeling device (18) is provided on the fence (17), and guide pulleys (19) are provided at the tops of the two ends of the fence (17), and the wire rope reeling and unreeling device (18) is connected to a wire rope (20), and the wire rope (20) is connected to the water-passing support plate (12) after passing through the guide pulley (19).

5. The device for ecological restoration of a slightly polluted and low-flow river according to claim 4, characterized in that: The water holes (22) are arranged in multiple rows, and the multiple rows of water holes (22) are arranged in sequence from top to bottom, and the spacing between two adjacent rows of water holes (22) is greater than or equal to the diameter of the water holes (22); the blocking plate (15) is provided with multiple rows of through holes (21), and the blocking plate (15) is connected to a lifting mechanism (23) for driving the blocking plate (15) to move from a water-passing position to a blocking position; when the blocking plate (15) is in the water-passing position, each through hole (21) is connected to a water hole (22); when the blocking plate (15) is in the blocking position, each row of through holes (21) is located between two adjacent rows of water holes (22).

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