Channel dredging method using grab dredgers

Abstract

Disclosed in the present invention is a channel dredging method using grab dredgers, the method comprising: designating a part of an area to be constructed as a navigation-closure area, and dividing the navigation-closure area into a plurality of dredging areas; for a first dredging area, dividing same into a plurality of dredging strips on the basis of the trenching width of a grab dredger, sequentially performing construction operations from the first dredging area, and when 30% of dredging operations in a first dredging strip has been completed, transferring a second grab dredger to a dredging start point of a second dredging strip on the basis of positioning information so as to perform construction, until dredging of the first dredging area is completed; repeating said process until dredging operations in all the dredging areas of the navigation-closure area are completed; and after the navigation-closure area is restored to normal navigation, designating another part of the area to be constructed as a new navigation-closure area, and repeating said steps until dredging operations in the whole area to be constructed are completed. By means of the present invention, the dredging period is shortened, the duration of navigation closure of a channel is reduced, and the dredging efficiency of the entire channel is improved.

Description

Grab bucket dredger channel dredging method Technical Field

[0001] This invention relates to the field of dredging engineering technology. More specifically, this invention relates to a method for dredging waterways using a grab dredger. Background Technology

[0002] Channel dredging refers to the operation of removing underwater sediment from waterways using dredgers or other tools. Channel dredging is a crucial measure for maintaining unobstructed navigation and ensuring the safety of ships. Traditional channel dredging methods often require the complete closure of the channel for dredging; however, such methods suffer from low efficiency, high costs, and the inability to adjust operations during normal times. Therefore, a new channel dredging method is needed to improve dredging efficiency, reduce costs, and minimize the impact on normal navigation. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0004] Another objective of this invention is to provide a method for dredging waterways using a grab dredger.

[0005] To achieve these objectives and other advantages of the present invention, the following technical solution is provided:

[0006] The method of dredging waterways using a grab dredger includes the following steps:

[0007] Step 1: Designate a portion of the area to be constructed as a navigation closure area, and divide the navigation closure area into a first dredging area, a second dredging area, and a third dredging area. There is an overlap between adjacent dredging areas, and the first dredging area, the second dredging area, and the third dredging area cover the entire area of ​​the navigation closure area.

[0008] Step Two: Divide the first dredging area into multiple dredging zones according to the dredging width of the grab dredger. The width of each dredging zone shall not exceed the maximum dredging width of the grab dredger. Then, the first grab dredger shall be transferred to the excavation point of the first dredging zone in the first dredging area according to the positioning information, and the first mud barge shall be mounted. Construction operations shall be carried out sequentially starting from the first dredging area. During construction operations, the first grab dredger shall throw its grab bucket into the excavation point of the first dredging zone, fill it with dredged soil, and then transfer the dredged soil to the first mud barge. After the first mud barge is full, the dredged soil shall be dumped to the designated dumping area and the dredger shall return. During construction operations, when the dredging work in the first dredging zone reaches 30%, the second grab dredger shall be used to excavate... The dredger moves to the excavation point of the second dredging zone in the first dredging area according to the positioning information. The second grab dredger throws its grab bucket into the excavation point of the second dredging zone, fills it with dredged soil, and then transfers the dredged soil to the first barge. When the first barge is full and throws the dredged soil to the designated dumping area, the second barge moves to the upper position of the first barge. After the first barge dumps the soil, it travels back to the original stopping position of the second barge. When the first dredging zone is dredged, the first grab dredger and the first barge are transferred to the third dredging zone. When the second dredging zone is dredged, the second grab dredger and the second barge are transferred to the fourth dredging zone until the first dredging area is dredged.

[0009] Step 3: Repeat Step 2 until dredging operations are completed in all dredging areas of the closed navigation zone;

[0010] Step 4: After restoring normal navigation in the closed area, designate the remaining part of the area to be constructed as a new closed area, and repeat steps 1, 2 and 3 until the dredging operation in the area to be constructed is completely completed.

[0011] Preferably, in the grab dredger channel dredging method, step two further includes the following steps:

[0012] Several angle sensors and several displacement sensors are installed on the dredging arm of the grab dredger. The angle sensors and the displacement sensors are used to acquire the real-time attitude and position information of the dredging arm, respectively.

[0013] Several opening degree sensors and several depth sensors are installed on the grab bucket, and the opening degree sensors and the depth sensors are used to obtain the opening degree and digging depth of the grab bucket, respectively.

[0014] A dredging depth control system is installed on the grab dredger. This system contains a table showing the correspondence between each dredging zone, dredging bar, and theoretical dredging depth. The system is communicatively connected to the angle sensor, displacement sensor, aperture sensor, and depth sensor. The system obtains the actual dredging depth of the grab dredger based on information received from these sensors and compares it with the corresponding theoretical dredging depth. If the difference is within a preset dredging depth threshold, the system continues to control the grab dredger to continue dredging in the current state. If the difference exceeds the preset threshold and is positive, the system moves the grab dredger upwards for its next dredging action. If the difference exceeds the preset threshold and is negative, the system moves the grab dredger downwards for its next dredging action.

[0015] Preferably, the method for dredging waterways using a grab bucket dredger further includes installing a flexible perforated plate around the grab bucket dredger. The flexible perforated plate is equipped with a water flow velocity sensor and a sediment concentration sensor, which are used to monitor data around the grab bucket dredger. The water flow velocity sensor and the sediment concentration sensor are each communicatively connected to the dredging depth control system.

[0016] Preferably, the method for dredging waterways using a grab dredger further includes installing a pressure sensor on the grab bucket to obtain the stress on the grab bucket and the weight of the dredged soil.

[0017] Preferably, in the grab bucket dredger channel dredging method, in step two, when the dredging thickness is greater than the maximum thickness of the grab bucket in one go, a layered construction method is adopted for excavation. The dredging depth of the first layer is set to 90% to 95% of the maximum thickness of the grab bucket in one go, and the dredging depth of the last layer is set to no more than 50% of the maximum thickness of the grab bucket in one go.

[0018] Preferably, in the grab dredger channel dredging method, the overlap width between adjacent dredging areas is not less than 20 meters, and the overlap width between adjacent dredging strips is not less than 5 meters.

[0019] Preferably, in the grab dredger channel dredging method, in step one, the closed navigation area is divided into a first dredging area, a second dredging area, and a third dredging area according to the direction from upstream to downstream.

[0020] The present invention has at least the following beneficial effects:

[0021] This invention designates a portion of the area to be dredged as a navigation closure zone. When the dredging operation of the first dredging zone reaches 30%, the second dredging zone also begins construction. Two grab dredgers operate simultaneously, employing segmented and zoned construction. The first and second barges take turns handling the dumping of dredged material. After restoring normal navigation in the closed area, the remaining portion of the area to be dredged is designated as a new navigation closure zone, and steps one, two, and three are repeated until the dredging operation in the area to be dredged is completely completed. In this way, this invention not only shortens the dredging period and reduces the impact on the navigation time of the construction team, but also avoids the problem of prolonged channel closures required for dredging construction, thus shortening the channel closure time and improving the overall dredging efficiency of the waterway.

[0022] Furthermore, this invention installs several angle sensors and several displacement sensors on the dredging arm of the grab dredger. The angle sensors and displacement sensors are used to acquire the real-time attitude and position information of the dredging arm, respectively. Several opening degree sensors and several depth sensors are also installed on the grab bucket. Combined with the use of a dredging depth control system, this significantly improves the dredging depth accuracy of the grab dredger, meeting the requirements of high-precision dredging operations. At the same time, it is lower in cost and easier to promote and apply. Moreover, this invention can monitor the operating environment in real time and automatically adjust the movement state of the grab dredger according to environmental changes, exhibiting strong adaptability and robustness.

[0023] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the construction elevation of a grab bucket dredger according to one embodiment of the present invention.

[0025] Figure 2 is a schematic diagram of the construction plan of a grab bucket dredger in one of the embodiments of the present invention.

[0026] Figure 3 is a flowchart of the construction process of a grab bucket dredger in one of the embodiments of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0028] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate orientations or positional relationships based on the shown orientations or positional relationships, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0030] A grab dredger is a type of mechanical dredger. During operation, the empty bucket is first deployed in the air, then a guide line is laid. The bucket, relying on its own weight, cuts into the excavated soil, strictly controlling the cutting depth. The operator then closes the bucket, raising it above the water surface. The boom is rotated to move the loaded bucket above the barge, opening it to release the dredged material. The boom is then rotated in the opposite direction to drop the empty bucket back into the excavation site. It loads dredged soil onto a self-propelled barge via the grab bucket, and the barge then dumps the dredged material to the designated dumping area.

[0031] As shown in Figures 1, 2, and 3, the present invention provides a method for dredging waterways using a grab dredger, comprising:

[0032] Step 1: Designate a portion of the area to be constructed as a navigation closure area, and divide the navigation closure area into a first dredging area, a second dredging area, and a third dredging area. There is an overlap between adjacent dredging areas, and the first dredging area, the second dredging area, and the third dredging area cover the entire area of ​​the navigation closure area.

[0033] Step Two: For the first dredging area, divide it into multiple dredging zones according to the dredging width of the grab dredger. The width of each dredging zone shall not exceed the maximum dredging width of the grab dredger. Then, the first grab dredger shall be transferred to the excavation point of the first dredging zone in the first dredging area according to the positioning information, and the first mud barge shall be mounted. Construction operations shall be carried out sequentially starting from the first dredging area. During construction operations, the first grab dredger shall throw its grab bucket into the excavation point of the first dredging zone, fill it with dredged soil, and then transfer the dredged soil to the first mud barge. After the first mud barge is full, the dredged soil shall be dumped to the designated dumping area and the dredger shall return. During construction operations, when the dredging operation of the first dredging zone reaches 30%, the second grab dredger shall be deployed according to... The location information is transferred to the excavation point of the second dredging zone in the first dredging area. The second grab dredger throws its grab bucket into the excavation point of the second dredging zone, fills it with dredged soil, and then transfers the dredged soil to the first barge. When the first barge is full and dumps the dredged soil to the designated dumping area, the second barge is turned to the upper position of the first barge. After dumping the soil, the first barge travels back to the original stopping position of the second barge (the upper position of the second barge). When the first dredging zone is dredged, the first grab dredger and the first barge are transferred to the third dredging zone. When the second dredging zone is dredged, the second grab dredger and the second barge are transferred to the fourth dredging zone until the first dredging area is dredged.

[0034] Step 3: Repeat Step 2 until dredging operations are completed in all dredging areas of the closed navigation zone;

[0035] Step 4: After restoring normal navigation in the closed area, designate the remaining part of the area to be dredged as a new closed area, and repeat steps 1, 2, and 3 until the dredging operation in the area to be dredged is completely completed. The later sections to be dredged should overlap appropriately with the earlier sections to avoid leaving shallow embankments.

[0036] This invention designates a portion of the area to be dredged as a navigation closure zone. When the dredging operation of the first dredging zone reaches 30%, the second dredging zone also begins construction. Two grab dredgers operate simultaneously, employing segmented and zoned construction. The first and second barges take turns handling the dumping of dredged material. After restoring normal navigation in the closed area, the remaining portion of the area to be dredged is designated as a new navigation closure zone, and steps one, two, and three are repeated until the dredging operation in the area to be dredged is completely completed. In this way, this invention not only shortens the dredging period and reduces the impact on the navigation time of the construction team, but also avoids the problem of prolonged channel closures required for dredging construction, thus shortening the channel closure time and improving the overall dredging efficiency of the waterway.

[0037] In the above scheme, as a preferred option, step two also includes the following steps:

[0038] Several angle sensors and several displacement sensors are installed on the dredging arm of the grab dredger. The angle sensors and the displacement sensors are used to acquire the real-time attitude and position information of the dredging arm, respectively.

[0039] Several opening degree sensors and several depth sensors are installed on the grab bucket, and the opening degree sensors and the depth sensors are used to obtain the opening degree and digging depth of the grab bucket, respectively.

[0040] A dredging depth control system is installed on the grab dredger. This system contains a table showing the correspondence between each dredging zone, dredging bar, and theoretical dredging depth. The system is communicatively connected to the angle sensor, displacement sensor, aperture sensor, and depth sensor. The system obtains the actual dredging depth of the grab dredger based on information received from these sensors and compares it with the corresponding theoretical dredging depth. If the difference is within a preset dredging depth threshold, the system continues to control the grab dredger to continue dredging in the current state. If the difference exceeds the preset threshold and is positive, the system moves the grab dredger upwards for its next dredging action. If the difference exceeds the preset threshold and is negative, the system moves the grab dredger downwards for its next dredging action. Preferably, the distance is the absolute value of the difference between the actual excavation depth and its corresponding theoretical excavation depth.

[0041] This invention significantly improves the dredging depth accuracy of grab dredgers through the above-described solution, meeting the requirements of high-precision dredging operations. Simultaneously, it is lower in cost and easier to promote and apply. Furthermore, this invention can monitor the operating environment in real time and automatically adjust the movement state of the grab dredger according to environmental changes, exhibiting strong adaptability and robustness.

[0042] In the above scheme, as a preferred embodiment, a flexible perforated plate is installed around the grab dredger. The flexible perforated plate is equipped with a water flow velocity sensor and a sediment concentration sensor, which are used to monitor the data around the grab dredger. The water flow velocity sensor and the sediment concentration sensor are each communicatively connected to the dredging depth control system.

[0043] In the above scheme, as a preferred embodiment, a pressure sensor is also installed on the grab bucket to obtain the stress condition of the grab bucket and the weight of the dredged soil.

[0044] In one embodiment of the present invention, preferably, in step two, when the dredging thickness is greater than the maximum thickness of the grab bucket in one dredging operation, a layered dredging method is adopted. The first layer is dredged to a depth of 90%–95% of the maximum thickness of the grab bucket in one dredging operation, and the last layer is dredged to a depth not exceeding 50% of the maximum thickness of the grab bucket in one dredging operation. The thickness of each layer should be determined based on the soil quality and the performance of the dredger. The upper layer should be thicker to ensure the efficiency of the dredger; the last layer should be thinner to ensure project quality. When the mud surface is above the water surface before dredging, or the water depth is less than the draft of the dredger, the excavation depth of the uppermost layer should meet the requirements of the dredger's draft and minimum dredging depth. When the mud layer is too thick, the upper layer should be dredged at high tide and the lower layer at low tide to reduce landslides.

[0045] In one embodiment of the present invention, preferably, the overlap width between adjacent dredging zones is not less than 20 meters, and the overlap width between adjacent dredging zones is not less than 5 meters. To avoid missed dredging, each dredging vessel group is assigned a specific construction section and excavation zone according to its shift schedule.

[0046] In one embodiment of the present invention, preferably, in step one, the navigation closure area is divided into a first dredging area, a second dredging area and a third dredging area in the direction from upstream to downstream.

[0047] To enable those skilled in the art to better understand the technical solution of the present invention, the following embodiments are provided for further illustration:

[0048] As shown in Figures 1, 2, and 3, a method for dredging waterways using a grab bucket dredger includes:

[0049] Step 1: Designate a portion of the area to be constructed as a navigation closure zone, and further divide the navigation closure zone into three dredging zones: a first dredging zone, a second dredging zone, and a third dredging zone. Adjacent dredging zones shall overlap, and the first, second, and third dredging zones shall cover the entire area of ​​the navigation closure zone. The overlap width between adjacent dredging zones shall be no less than 20 meters, and the overlap width between adjacent dredging sections shall be no less than 5 meters. The navigation closure zone shall be divided into the first, second, and third dredging zones according to the direction from upstream to downstream.

[0050] Step Two: For the first dredging area, divide it into multiple dredging zones according to the dredging width of the grab dredger. The width of each dredging zone shall not exceed the maximum dredging width of the grab dredger. Then, the first grab dredger is transferred to the excavation point of the first dredging zone in the first dredging area according to the positioning information, and the first mud barge is mounted. Construction operations are carried out sequentially starting from the first dredging area. During construction operations, the first grab dredger throws its grab bucket into the excavation point of the first dredging zone, fills it with dredged soil, and then transfers the dredged soil to the first mud barge. After the first mud barge is full, the dredged soil is dumped to the designated dumping area and the dredger returns. During construction operations, when the dredging operation of the first dredging zone reaches 30%, the second grab dredger is transferred to the excavation point of the second dredging zone in the first dredging area according to the positioning information. The second grab dredger throws its grab bucket into the excavation point of the second dredging zone. The process begins with digging a dredging point, filling it with dredged soil, and then transferring the dredged soil onto the first barge. Once the first barge is full, the dredged soil is dumped into the designated dumping area. The second barge is then moved to the upper position of the first barge. After dumping the soil, the first barge moves back to its original stopping position (the upper position of the second barge). Once the first dredging zone is dredged, the first grab dredger and the first barge are moved to the third dredging zone. Similarly, once the second dredging zone is dredged, the second grab dredger and the second barge are moved to the fourth dredging zone, continuing until the first dredging zone is dredged. After the anchor position is set, the dredger, based on GPS positioning, is transported to the excavation point by the construction vessel via anchor winch. The barge is then notified to be on the upper position. Using the computer-displayed graphics and based on the actual pre-dredging water depth, the dredger performs bucket discharge, gate entry, and other construction operations step by step, gradually advancing forward.

[0051] In step two, when the dredging thickness is greater than the maximum thickness of the grab bucket in one go, a layered construction method is adopted for excavation. The excavation depth of the first layer is set to 90% to 95% of the maximum thickness of the grab bucket in one go, and the excavation depth of the last layer is set to no more than 50% of the maximum thickness of the grab bucket in one go.

[0052] Step 3: Repeat Step 2 until dredging operations are completed in all dredging areas of the closed navigation zone;

[0053] Several angle sensors and several displacement sensors are installed on the dredging arm of the grab dredger. The angle sensors and the displacement sensors are used to acquire the real-time attitude and position information of the dredging arm, respectively.

[0054] Several opening degree sensors and several depth sensors are installed on the grab bucket, and the opening degree sensors and the depth sensors are used to obtain the opening degree and digging depth of the grab bucket, respectively.

[0055] A dredging depth control system is installed on the grab dredger. This system contains a table showing the correspondence between each dredging zone, dredging bar, and theoretical dredging depth. The system is communicatively connected to the angle sensor, displacement sensor, aperture sensor, and depth sensor. The system obtains the actual dredging depth of the grab dredger based on information received from these sensors and compares it with the corresponding theoretical dredging depth. If the difference is within a preset dredging depth threshold, the system continues to control the grab dredger to continue dredging in the current state. If the difference exceeds the preset threshold and is positive, the system moves the grab dredger upwards for its next dredging action. If the difference exceeds the preset threshold and is negative, the system moves the grab dredger downwards for its next dredging action. The distance is the absolute value of the difference between the actual excavation depth and its corresponding theoretical excavation depth.

[0056] The system also includes a flexible perforated plate installed around the grab dredger. The flexible perforated plate is equipped with a water flow velocity sensor and a sediment concentration sensor, which are used to monitor data around the grab dredger. The water flow velocity sensor and the sediment concentration sensor are each connected to the dredging depth control system.

[0057] It also includes installing a pressure sensor on the grab bucket to obtain the stress on the grab bucket and the weight of the dredged soil.

[0058] Step 4: After restoring normal navigation in the closed area, designate the remaining part of the area to be constructed as a new closed area, and repeat steps 1, 2 and 3 until the dredging operation in the area to be constructed is completely completed.

[0059] This invention employs a segmented, zoned, and layered construction method for grab bucket dredgers. When the trench width exceeds the dredger's maximum dredging width, the maximum width of each segment must not exceed the effective working radius of the grab bucket crane. When the trench length exceeds the length that the dredger can excavate with a single main or side anchor placement, segmented excavation is used. When the thickness of the dredged soil layer exceeds the maximum thickness of the grab bucket in a single placement, layered construction is employed. The thickness of each layer is determined by the thickness excavated by the grab bucket in a single placement, the bucket weight, the bucket width, and the soil quality. During construction, buckets are placed laterally, and barriers are advanced longitudinally. To ensure passage in one pass, a certain overlap is required between buckets and barriers to prevent missed excavations. When constructing the edge line, "bucket return" is required, i.e., dredging an additional 1-2 buckets to leave a certain depth for siltation. The number of buckets placed and the forward movement of each barrier are determined based on the channel depth, the dredging capability of the soil, and the bucket size. Fixed-depth construction is used in areas with thinner silt layers. When commencing work and deployment, the dredger is towed to the construction area and positioned using tugboats or other auxiliary vessels. Deployment then commences based on water flow and wind direction.

[0060] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0061] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method of channel dredging by a grab dredger, characterized in that, Includes the following steps: Step 1: Designate a portion of the area to be constructed as a navigation closure area, and divide the navigation closure area into a first dredging area, a second dredging area, and a third dredging area. There is an overlap between adjacent dredging areas, and the first dredging area, the second dredging area, and the third dredging area cover the entire area of ​​the navigation closure area. Step Two: Divide the first dredging area into multiple dredging zones according to the dredging width of the grab dredger. The width of each dredging zone shall not exceed the maximum dredging width of the grab dredger. Then, the first grab dredger shall be transferred to the excavation point of the first dredging zone in the first dredging area according to the positioning information, and the first mud barge shall be mounted. Construction operations shall be carried out sequentially starting from the first dredging area. During construction operations, the first grab dredger shall throw its grab bucket into the excavation point of the first dredging zone, fill it with dredged soil, and then transfer the dredged soil to the first mud barge. After the first mud barge is full, the dredged soil shall be dumped to the designated dumping area and the dredger shall return. During construction operations, when the dredging work in the first dredging zone reaches 30%, the second grab dredger shall be used to excavate... The dredger moves to the excavation point of the second dredging zone in the first dredging area according to the positioning information. The second grab dredger throws its grab bucket into the excavation point of the second dredging zone, fills it with dredged soil, and then transfers the dredged soil to the first barge. When the first barge is full and throws the dredged soil to the designated dumping area, the second barge moves to the upper position of the first barge. After the first barge dumps the soil, it travels back to the original stopping position of the second barge. When the first dredging zone is dredged, the first grab dredger and the first barge are transferred to the third dredging zone. When the second dredging zone is dredged, the second grab dredger and the second barge are transferred to the fourth dredging zone until the first dredging area is dredged. Step 3: Repeat Step 2 until dredging operations are completed in all dredging areas of the closed navigation zone; Step 4: After restoring normal navigation in the closed area, designate the remaining part of the area to be dredged as a new closed area, and repeat steps 1, 2 and 3 until the dredging operation in the area to be dredged is completely completed.

2. The grab dredger channel dredging method as claimed in claim 1, characterized in that, Step two also includes the following steps: Several angle sensors and several displacement sensors are installed on the dredging arm of the grab dredger. The angle sensors and the displacement sensors are used to acquire the real-time attitude and position information of the dredging arm, respectively. Several opening degree sensors and several depth sensors are installed on the grab bucket, and the opening degree sensors and the depth sensors are used to obtain the opening degree and digging depth of the grab bucket, respectively; The grab dredger is provided with a digging depth control system, and a corresponding table of each dredging area, digging strip and theoretical digging depth is arranged in the digging depth control system. The digging depth control system is respectively communicated with the angle sensor, the displacement sensor, the opening degree sensor and the depth sensor. The digging depth control system is used to obtain the actual digging depth of the grab according to the information received by the angle sensor, the displacement sensor, the opening degree sensor and the depth sensor, and compare the actual digging depth with the corresponding theoretical digging depth. If the difference between the actual digging depth and the corresponding theoretical digging depth is within the preset digging depth threshold, the digging depth control system continues to control the grab to continue digging according to the current state. If the difference between the actual digging depth and the corresponding theoretical digging depth exceeds the preset digging depth threshold and the difference is a positive number, the digging depth control system controls the next digging action of the grab to move upward by a distance. If the difference between the actual digging depth and the corresponding theoretical digging depth exceeds the preset digging depth threshold and the difference is a negative number, the digging depth control system controls the next digging action of the grab to move downward by a distance.

3. The grab dredger channel dredging method as claimed in claim 2, characterized in that, The flexible hollow plate is arranged around the grab dredger, and a water flow velocity sensor and a sediment concentration sensor are arranged on the flexible hollow plate to monitor the data around the grab dredger. The water flow velocity sensor and the sediment concentration sensor are respectively communicated with the digging depth control system.

4. The grab dredger channel dredging method as claimed in claim 2, characterized in that, The pressure sensor is arranged on the grab to obtain the stress condition of the grab and the weight of the dredged soil.

5. The grab dredger channel dredging method as claimed in claim 1, characterized in that, In step two, when the dredging thickness is greater than the maximum thickness of one-time bucket lowering of the grab, the method of layered construction is used for digging. The digging depth of the first layer is set to 90% to 95% of the maximum thickness of one-time bucket lowering of the grab, and the digging depth of the last layer is set to not greater than 50% of the maximum thickness of one-time bucket lowering of the grab.

6. The grab dredger channel dredging method as claimed in claim 1, characterized in that, The overlapping width between adjacent dredging areas is not less than 20 meters, and the overlapping width between adjacent dredging strips is not less than 5 meters.

7. The grab dredger channel dredging method as claimed in claim 1, characterized in that, In step one, the closed navigation area is divided into a first dredging area, a second dredging area and a third dredging area in the direction from upstream to downstream. In step one, the closed navigation area is divided into a first dredging area, a second dredging area and a third dredging area in the direction from upstream to downstream.

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