A method of dredging construction

Abstract

The present application relates to nuclear power drainage system construction technical field, specifically to a kind of dredging construction method, comprising the following steps: S1, the meteorological condition of construction area is determined, using dredging equipment to test area is carried out test dredging, deviation information caused by meteorological condition to test dredging is obtained according to the result of test dredging;S2, under corresponding meteorological condition, using dredging equipment carries out dredging operation in construction area, and using deviation information corrects dredging operation;Dredging equipment includes cutter suction dredger and / or dredger, cutter suction dredger and / or dredger is used to carry out dredging operation in the area outside n meter range from drainage riser;Dredging equipment further includes submersible sand pump, submersible sand pump is used to carry out dredging operation in the area within n meter range from drainage riser.The present application can overcome the technical problem that existing technology uses cutter suction dredger or dredger to carry out dredging operation, when cleaning nuclear power drainage system, easy to collide with drainage riser, resulting in leakage of drainage tunnel even scrap.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant drainage system construction technology, and in particular to a dredging construction method. Background Technology

[0002] Nuclear power plant drainage systems generally consist of drainage tunnels and drainage risers. The drainage tunnels are located in the strata below the seabed. The lower end of the drainage riser connects to the drainage tunnel, and the upper end extends upwards until it emerges from the seabed to discharge the cooling water that flows into the drainage tunnel into the ocean. After the jacking construction of the drainage riser is completed, it is also necessary to dredge and excavate the seabed around the drainage riser, backfill with gravel, and install drainage cylinders to prevent ships from anchoring and damaging the riser, thereby reducing the risk of damage to the drainage system.

[0003] To efficiently carry out dredging operations, existing dredging methods mainly employ cutter suction dredgers or dredgers. However, these two types of dredging equipment are designed for large-scale dredging scenarios such as channel expansion and lock construction, making it difficult to accurately clean the silt around drainage risers. In addition, environmental factors such as ocean currents and wind forces can easily cause collisions with drainage risers during dredging operations. This can result in damage to the ends of the drainage risers, or even damage to their sealing, leading to leakage or even the abandonment of the entire drainage tunnel. Therefore, there is an urgent need to develop a dredging method that can ensure dredging efficiency while avoiding damage to drainage risers and drainage tunnels. Summary of the Invention

[0004] The purpose of this invention is to overcome the technical problem that existing technologies using cutter suction dredgers or dredgers for dredging operations are prone to collisions with drainage risers when cleaning nuclear power plant drainage systems, leading to leakage or even the abandonment of drainage tunnels, and to provide a dredging construction method.

[0005] In a first aspect, the present invention provides a dredging construction method, comprising the following steps: S1. Determine the meteorological conditions of the construction area, and conduct trial dredging of the test area using dredging equipment under the meteorological conditions. The test area should be located far away from the drainage riser. Obtain information on the deviation caused by the meteorological conditions to the trial dredging based on the results of the trial dredging. S2. Under corresponding meteorological conditions, use dredging equipment to carry out dredging operations in the construction area, and use deviation information to correct the dredging operations; the dredging equipment includes cutter suction dredgers and / or dredgers, and dredging operations are carried out using cutter suction dredgers and / or dredgers in areas within n meters of the drainage riser; the dredging equipment also includes submersible sand pumps, and dredging operations are carried out using submersible sand pumps in areas within n meters of the drainage riser, where n is a positive number.

[0006] Preferably, in S2, the construction area is divided into several construction blocks, with overlapping areas between adjacent construction blocks; construction is carried out on each construction block separately.

[0007] Preferably, the deviation information in S1 includes the amount of siltation in the construction area; in S2, the construction blocks with smaller amounts of siltation are dredged first, and then the construction blocks with larger amounts of siltation are dredged.

[0008] Preferably, during the dredging operation in S2, the bottom surface of each construction block is excavated to a depth of m meters below the predetermined elevation, where m matches the amount of silt returned in S1.

[0009] Preferably, the deviation information in S1 includes the drift amount of the dredging position during the trial dredging, and in S2, the dredging position of the dredging equipment is adjusted according to the drift amount.

[0010] Preferably, when using a dredger in S2, a positioning device is installed on the boom of the dredger. During dredging operations, the boom angle remains unchanged, and the position information of the bucket is inferred from the position information of the positioning device and the amount of drift.

[0011] Preferably, in S2, the dredging equipment is parked on the side of the drainage riser away from the direction of the tide.

[0012] Preferably, the dredging operation in S2 is carried out from the direction away from the drainage riser towards the direction closer to the drainage riser.

[0013] Preferably, the dredging operation in S2 is carried out from the side of the construction area closest to the direction of the tide towards the side furthest from the direction of the tide.

[0014] Preferably, in S2, as the depth of the submersible sand pump decreases, the air supply of the submersible sand pump is reduced.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a dredging construction method. Before formally commencing dredging operations, a trial dredging is conducted in a test area under specified weather conditions to collect deviation information caused by the corresponding weather conditions. Subsequently, formal dredging operations are carried out, and the deviation information is used to correct the dredging operations, thereby reducing or even eliminating the deviation caused by the corresponding weather conditions. Furthermore, this invention uses different dredging equipment in areas near and far from the drainage riser. It can efficiently and quickly remove silt in areas far from the drainage riser using cutter suction dredgers and / or dredgers, while submersible sand pumps can remove silt near the drainage riser with more precise and gentle movements. This ensures both the efficiency and speed of the dredging operation, while also guaranteeing the safety of the drainage riser and reducing the risk of leakage or even decommissioning of the nuclear power plant drainage system due to dredging operations. Attached Figure Description

[0016] Figure 1This is a schematic diagram of the plan layout of the construction area for a dredging construction method in Example 1; Figure 2 yes Figure 1 A partially enlarged plan view of the construction area; Figure 3 yes Figure 2 A schematic diagram of the elevation section of the construction area. Figure 4 This is a schematic diagram of the construction steps of a dredging construction method in Example 1. Figure 1 ; Figure 5 This is a schematic diagram of the construction steps of a dredging construction method in Example 1. Figure 2 ; icon: 100 - Land; 200 - Ocean; 210 - Seabed; 300-Drainage Tunnel; 400 - Drainage riser; 410 - Grouting reinforcement zone; 420 - Drainage cylinder; 500 - Construction area; 510 - Crushed stone; 610-Dredge; 611-Dumping bucket; 620-Barge; 621-Crane; 622-Submersible sand pump; 623-Suction pipe. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0019] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0020] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0021] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0022] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0023] Example 1 like Figures 1 to 5 As shown, a dredging construction method includes the following steps: S1. Determine the meteorological conditions of the construction area 500, including but not limited to wind conditions, tide conditions, wave conditions, rainfall conditions, and temperature conditions; under the corresponding meteorological conditions, use dredging equipment to conduct trial dredging of the test area. The test area should be set far away from the drainage riser 400 to avoid damage to the drainage riser 400 during the trial dredging; obtain the deviation information caused by the meteorological conditions to the trial dredging based on the results of the trial dredging.

[0024] S2. Under meteorological conditions matching S1, use dredging equipment to carry out dredging operations in the construction area 500, and use deviation information to correct the dredging operations, such as changing the dredging location or dredging depth.

[0025] The dredging equipment includes a cutter suction dredger and / or a dredger 610, which is used to carry out dredging operations in an area within n meters of the outer wall of the drainage riser 400; the dredging equipment also includes a submersible sand pump 622 (also known as a submersible sand pump, pneumatic mud pump, or pneumatic mud pump), which is used to carry out dredging operations in an area within n meters of the outer wall of the drainage riser 400, where n is a positive number.

[0026] It is important to note that Figure 3 , Figure 4 and Figure 5 Different profile lines were used for different areas, simply to facilitate the differentiation of different areas such as construction area 500, seabed 210, drainage tunnel 300, drainage riser 400, and grouting reinforcement, and not to restrict the materials of each area to be different.

[0027] Before commencing formal dredging operations, this embodiment conducts trial dredging under specified weather conditions in a test area to collect deviation information caused by these weather conditions. Formal dredging operations are then carried out, and the deviation information is used to correct the dredging work, reducing or even eliminating deviations caused by the weather conditions. Furthermore, this embodiment uses different dredging equipment in areas near and far from the drainage riser 400, enabling efficient and rapid cleaning of areas far from the drainage riser 400 using a cutter suction dredger and / or a dredger 610. The silt can be removed by a submersible dredging pump 622 with a more precise and gentle motion. Since the size and weight of the submersible dredging pump 622 are much smaller than those of the cutter suction dredger and the dredger 610, even if the submersible dredging pump 622 scrapes or collides with the drainage riser 400, there will be no serious consequences. It can be seen that this embodiment can not only ensure the construction efficiency and speed of the dredging operation, but also reduce the risk of collision between the vessel and the drainage riser 400, ensure the safety of the drainage riser 400, and reduce the risk of leakage or even scrapping of the nuclear power plant drainage system due to the dredging operation.

[0028] In an optional implementation, the meteorological conditions of the construction area 500 can be obtained through long-term observation and recording.

[0029] In optional implementations, all dredging equipment can be existing products. The mud and sand generated by the dredging equipment during the dredging operation can be directly dumped to the predetermined dumping site through a floating pipeline at sea, or transported to the predetermined dumping site one ship at a time by transport ships.

[0030] In an optional implementation, n=3, meaning that submersible sand pumps 622 are used for dredging within 3 meters of the side wall of the drainage riser 400, while cutter suction dredgers and / or dredgers 610 are used for dredging beyond 3 meters of the side wall of the drainage riser 400. This value minimizes the proportion of dredging work done by submersible sand pumps 622, thus ensuring the efficiency of the dredging operation, while also providing sufficient safety space between the drainage riser 400 and the cutter suction dredger, or between the drainage riser 400 and the dredger 610, thereby reducing the risk of damage to the drainage riser 400 during the dredging operation.

[0031] It is important to note that, such as Figure 3 As shown, n is taken as 3 with the outer wall of the drainage riser 400 as the distance reference. However, in actual construction, other structures can also be used as the distance reference, such as the axis of the drainage riser 400 or the absolute coordinates on the seabed 210, as long as sufficient safety space can be left between the drainage riser 400 and the cutter suction dredger, or between the drainage riser 400 and the dredger 610.

[0032] In an optional implementation, in S2, the construction area 500 is divided into several construction blocks, with overlapping areas between adjacent construction blocks; construction is carried out on each construction block separately, which not only helps to improve the construction efficiency and speed of dredging operations, but also makes it easier for the construction party to arrange the dredging operations in a more orderly manner; while the overlapping areas can prevent missed excavation between adjacent construction blocks.

[0033] In an optional implementation, the width of the overlapping area between two adjacent construction blocks is greater than or equal to one meter and less than or equal to two meters. This can effectively prevent missed excavation under complex sea conditions and avoid excessive repetitive work in dredging operations.

[0034] In an optional implementation, the deviation information in S1 includes the amount of siltation in the construction area 500 (the elevation change caused by the redeposition of mud and sand back to the bottom of the siltation location after the trial dredging is excavated to the specified elevation); in S2, the dredging operation is carried out first on the construction blocks with smaller siltation amounts, and then the dredging operation is carried out on the construction blocks with larger siltation amounts.

[0035] Due to environmental factors such as tides and earthquakes, some mud and sand will redeposit back to the bottom of the construction area 500 after a period of time, requiring additional dredging operations. Furthermore, different construction sections have different environmental characteristics and different siltation rates. If the dredging operation is carried out on the construction sections with faster siltation first, these sections can make full use of the construction time of other sections to achieve sufficient siltation, thus increasing the workload of additional dredging operations.

[0036] Therefore, this implementation method selects to collect the amount of siltation in S1, and according to the amount of siltation, adopts the dredging sequence of first dredging the construction blocks with smaller amounts of siltation, and then dredging the construction blocks with larger amounts of siltation. This makes the completion time of the construction blocks with larger amounts of siltation as close as possible to the completion time of the entire dredging operation, thereby compressing the siltation time of these construction blocks, reducing their siltation amount, and correspondingly reducing the workload of additional dredging operations.

[0037] In optional implementations, the amount of siltation can be a simple value of siltation thickness or a functional relationship, such as the relationship between siltation thickness and time, or the relationship between siltation thickness and time and tides, as long as it can be used to assist in determining the construction sequence and dredging depth of the construction blocks in S2.

[0038] In an optional implementation, during the dredging operation in S2, the bottom surface of each construction block is excavated to a predetermined elevation of m meters, where m matches the amount of siltation backfilled in S1. For example, if the predetermined elevation of the bottom surface of a construction block is -10 meters, and the amount of siltation backfilled for the corresponding construction block is measured to be 2 meters in S1, then in S2, the corresponding construction block can be directly excavated to -12 meters. After siltation backfilling occurs, the ground elevation of the corresponding construction block will return to -10 meters, thereby reducing or eliminating the need for subsequent additional dredging operations.

[0039] In an optional implementation, the deviation information in S1 includes the drift amount of the dredging position during the trial dredging (the deviation between the actual dredging position and the predetermined dredging position); in S2, the dredging position of the dredging equipment is adjusted according to the drift amount. For example, when using the dredger 610, if the drift amount measured in S1 is 3m northward, the dredger 610 can be moored 3m south of the predetermined dredging position, or the position of the bucket 611 can be adjusted so that the bucket 611 is placed into the ocean 200 from 3m south of the predetermined dredging position.

[0040] In an optional implementation, the drift amount can be a simple drift distance value (e.g., Figure 4 The dimension e in S2 can also be a complex functional relationship, such as the relationship between the angle of the bucket 611 of the dredger 610 deviating from the vertical axis under corresponding weather conditions and the tide, or the relationship between the angle of the sling of the crane 621 deviating from the vertical axis under corresponding weather conditions and the tide. As long as it can be used to assist in calculating the actual dredging position of the dredging equipment in S2.

[0041] In an optional implementation, when using the dredger 610 in S2, a positioning device is installed on the boom of the dredger 610. The positioning device can be an existing product, including but not limited to a GPS positioning device or a GNSS positioning device. During dredging operations, the position information of the bucket 611 is deduced from the position information and drift amount of the positioning device. For example, if the boom of the dredger 610 is set to the north, the angle between the boom and the horizontal plane is α, the length of the boom is L, the positioning device is installed at the midpoint of the boom, and the drift amount is 3 meters to the north, then the bucket 611 is located at L*cosα*0.5+3 meters north of the positioning device.

[0042] This embodiment can help workers accurately determine the position of the bucket 611 in the ocean, thereby accurately determining the excavation position of the bucket 611 and reducing the risk of the bucket 611 colliding with the drainage riser 400.

[0043] In alternative embodiments, the submersible dredging pump 622 can be moved underwater in various ways to pump out silt from various locations in the drainage riser 400; for example, a diver can hold the submersible dredging pump 622 and move it underwater, or an underwater propulsion system (such as a propeller or jet device) can be installed on the submersible dredging pump 622 to enable the submersible dredging pump 622 to move autonomously.

[0044] In an optional embodiment, in S2, the submersible sand pump 622 is connected to a crane 621 on a vessel (including but not limited to a self-propelled vessel or barge 620). The crane 621 is used to operate the relative position of the submersible sand pump 622 and the drainage riser 400 (e.g., the depth of the submersible sand pump 622, the distance between the submersible sand pump 622 and the drainage riser 400). Compared to directly moving the vessel, this embodiment can more precisely control the position of the submersible sand pump 622, thereby reducing the risk of collision between the submersible sand pump 622 and the drainage riser 400.

[0045] In optional implementations, such as Figure 5 As shown, the vessel can be a barge 620, and the crane 621 can be a self-moving crawler crane or truck crane. This allows the position of the submersible sand pump 622 to be operated by luffing and rotating, and the position of the submersible sand pump 622 to be adjusted by the movement of the crane 621 on the barge 620. This not only helps to improve the construction efficiency and speed of dredging operations, but also helps to further reduce the risk of collision between the submersible sand pump 622 and the drainage riser 400.

[0046] In optional implementations, such as Figure 4 and Figure 5 As shown, in S2, the dredging equipment is positioned on the side of the drainage riser 400 away from the direction of the tide, allowing the dredging position of the equipment to drift away from the drainage riser 400 under the influence of the tide, thereby reducing the risk of collision between the dredging equipment and the drainage riser 400.

[0047] In an optional implementation, the dredging operation in S2 is carried out from the direction away from the drainage riser 400 towards the direction closer to the drainage riser 400. This allows the vibration generated by the dredging operation to cause the soil to collapse away from the drainage pipe, thereby improving the construction efficiency and speed of the dredging operation. At the same time, it also allows the dredging equipment to gradually approach the drainage riser 400 from a distance, reducing the risk of collision between the dredging equipment and the drainage riser 400.

[0048] In an optional implementation, the dredging operation in S2 is carried out from the side of the construction area 500 closest to the direction of the tide towards the side furthest from the direction of the tide. This not only prevents the mud and sand disturbed by the dredging operation from being carried by the tide to the excavated area, but also allows the tide to help flush the mud and sand in the construction area 500, thereby improving the construction efficiency and speed of the dredging operation.

[0049] In an optional implementation, in S2, as the depth of the submersible sand pump 622 decreases, the air supply of the submersible sand pump 622 is reduced to maintain a moderate mud concentration, thereby maintaining the mud suction efficiency of the submersible sand pump 622.

[0050] The following section uses a nuclear power plant drainage system as an example to illustrate the construction steps of this dredging method; for example... Figures 1 to 2 As shown, the nuclear power plant drainage system includes two drainage tunnels 300. The northern section of each drainage tunnel 300 is connected to the siphon well of the nuclear power plant. Several drainage risers 400 and drainage cylinders 420 are installed at the southern end of each drainage tunnel 300. A grouting reinforcement zone 410 is also provided around the drainage risers 400. Figure 3 The diagram shows the elevation section of the drainage riser 400 after the dredging operation has been completed, the gravel 510 has been backfilled, and the drainage cylinder 420 has been installed. It can be seen that a trench-shaped structure needs to be excavated downward at the seabed 210 near the drainage riser 400 to backfill the gravel 510. Therefore, the area where the trench-shaped structure used for backfilling the gravel 510 is located is the construction area 500 waiting for the dredging operation.

[0051] The dredging operation can then be carried out according to the following specific steps: SA. Determine the local meteorological conditions. Since waves have the greatest impact on construction accuracy, this embodiment mainly uses waves as an example for explanation. After on-site investigation and collection of meteorological records from previous years, it is known that the construction area 500 will alternately experience tides flowing from land 100 to ocean 200 and from ocean 200 to land 100. The two tide directions are respectively recorded as the first meteorological condition and the second meteorological condition. Correspondingly, at least two test areas are set up at a location far away from the drainage riser 400.

[0052] SB, under the first meteorological conditions, conduct a trial dredging in one of the test areas. After the trial dredging, scan the test area to obtain the deviation between the predetermined dredging position and the actual dredging position, and obtain the first drift amount caused by the first meteorological conditions to the dredging position. In the same way, obtain the first drift amount caused by the second meteorological conditions to the dredging position.

[0053] SC. Use dredger 610 to dredge the area 3 meters away from drainage riser 400. A GNSS positioning device should be installed on the boom of dredger 610, and the boom angle should be kept constant during the dredging operation to accurately determine the specific position of bucket 611, ensuring that the distance between bucket 611 and drainage riser 400 is always greater than or equal to 3 meters. When the construction area 500 is under the first weather condition, moor dredger 610 on the side of drainage riser 400 away from land 100, and use the first drift amount to correct the dredging position of dredger 610. When the construction area 500 is under the second weather condition, moor dredger 610 on the side of drainage riser 400 closer to land 100, and use the second drift amount to correct the dredging position of dredger 610.

[0054] When using the dredger 610 for dredging operations, the construction area 500 can be divided into multiple layers along the horizontal and vertical directions, with each layer including several construction blocks. Dredging operations are carried out separately for each construction block. The dredging quality is checked at any time using a differential global positioning system and a digital depth sounder to ensure acceptance on the first attempt. The dredger 610 moves with the tide while dredging, utilizing the tide to wash and disturb the silt, thereby increasing the dredging effect. When dredging, the dredger 610 also excavates from the direction away from the drainage riser 400 towards the direction closer to the drainage riser 400, using the collapse caused by vibration during excavation to speed up the excavation. Furthermore, during excavation, the silt is dredged evenly layer by layer throughout the entire construction area 500 to avoid forming ridges, which would make it difficult to clear shallow areas later in the construction process.

[0055] SD uses a submersible dredging pump 622 to dredge an area within 4003 meters of the drainage riser. The submersible dredging pump 622 is connected to a negative pressure system (e.g., an air lifter) on a barge 620 via a suction pipe 623 to lift the sludge onto the barge 620 for subsequent transfer or direct spraying. The submersible dredging pump 622 is also connected to a crane 621 on the barge 620 via a sling to allow precise operation of the submersible dredging pump 622 by adjusting the amplitude, rotation, and movement of the crane 621. When the construction area 500 is under the first weather condition, the barge 620 is moored on the side of the drainage riser 400 away from the land 100, and the dredging position of the submersible dredging pump 622 is corrected using a first drift amount. When the construction area 500 is under the second weather condition, the barge 620 is moored on the side of the drainage riser 400 closer to the land 100, and the dredging position of the submersible dredging pump 622 is corrected using a second drift amount.

[0056] When using a submersible sand pump 622 for dredging operations, the lower end of the submersible sand pump 622 is placed on the mud surface of the area to be dredged by a crane 621. When compressed air is input into the submersible sand pump 622, the water and air inside the submersible sand pump 622 immediately mix and rise along the suction pipe 623, thereby generating a negative pressure in the suction pipe 623, which attracts the mud and water below the submersible sand pump 622 into the suction pipe 623. The mixture of mud, water and air rises along the suction pipe 623 onto the barge 620, achieving the purpose of dredging.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dredging construction method, characterized in that, The steps include the following: S1. Determine the meteorological conditions of the construction area (500), including wind conditions, tide conditions, wave conditions, rainfall conditions and temperature conditions; use dredging equipment to conduct trial dredging of the test area under the meteorological conditions, the test area being located far away from the drainage riser (400); obtain the deviation information caused by the meteorological conditions to the trial dredging based on the results of the trial dredging; S2. Under the meteorological conditions, the dredging equipment is used to carry out dredging operations in the construction area (500), and deviation information is used to correct the dredging operations; the dredging equipment includes a cutter suction dredger and / or a dredger (610), which is used to carry out dredging operations in an area n meters away from the drainage riser (400); the dredging equipment also includes a submersible sand pump (622), which is used to carry out dredging operations in an area n meters away from the drainage riser (400), where n=3; in: In S2, the construction area (500) is divided into several construction blocks, with overlapping areas between adjacent construction blocks; construction is carried out on each construction block respectively; The deviation information in S1 includes the amount of siltation in the construction area (500); in S2, the construction blocks with smaller siltation are cleaned first, and then the construction blocks with larger siltation are cleaned. When carrying out dredging operations in S2, the bottom surface of each construction block will be excavated to m meters below the predetermined elevation, and m will match the amount of silt return in S1. The deviation information in S1 includes the drift amount of the dredging position during the trial dredging, and in S2, the dredging position of the dredging equipment is adjusted according to the drift amount. When using the dredger (610) in S2, a positioning device is installed on the boom of the dredger (610). During the dredging operation, the boom angle remains unchanged, and the position information of the bucket (611) is reversed by the position information and drift amount of the positioning device. The dredging equipment described in S2 is parked on the side of the drainage riser (400) away from the direction of the tide. The dredging operation in S2 is carried out from the direction away from the drainage riser (400) towards the direction closer to the drainage riser (400); The dredging operation in S2 starts from the side of the construction area (500) closest to the direction of the tide and moves away from the direction of the tide. In S2, as the depth of the submersible sand pump (622) decreases, the air supply of the submersible sand pump (622) is reduced.

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