Channel dredging method for grab dredger

Abstract

The invention discloses a grab dredger channel dredging method which comprises the following steps: dividing a part of a to-be-constructed area into a navigation sealing area, and dividing the navigation sealing area into a plurality of dredging areas; and for the first dredging area, the first dredging area is divided into a plurality of dredging belts according to the grooving width of the grab dredger, construction operation is carried out in sequence from the first dredging area, and when the dredging operation of the first dredging belt reaches 30%, the second grab dredger is transferred to the excavation point of the second dredging belt for construction according to the positioning information. The first dredging area is dredged; repeating the steps until the dredging operation of all the dredging areas of the navigation sealing area is completed; and after the navigation sealing area is restored to normal navigation, other parts of the area to be constructed are classified as new navigation sealing areas, and the steps are repeated till the dredging operation of the area to be constructed is completely completed. The dredging construction period is shortened, the channel sealing time is shortened, and the dredging efficiency of the whole channel is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dredging engineering, and more specifically, to a method for dredging a waterway using a grab dredger. Background Art

[0002] Channel dredging refers to the operation of removing underwater silt from a channel using a dredger or other tools. Channel dredging is an important measure to maintain the smooth flow of channels and ensure the safety of ship navigation. Traditional channel dredging methods often require the channel to be completely closed for dredging. However, such dredging methods have problems such as low efficiency, high cost, and inability to adjust during normal operations. 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] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] Still another object of the present invention is to provide a channel dredging method using a grab bucket dredger.

[0005] In order to achieve these purposes and other advantages of the present invention, the following technical solutions are provided: The grab dredger channel dredging method comprises the following steps: Step 1: designate a part of the area to be constructed as a closed navigation area, and divide the closed navigation area into a first dredging area, a second dredging area, and a third dredging area, wherein there is an overlapping area between adjacent dredging areas and the first dredging area, the second dredging area, and the third dredging area cover all areas of the closed navigation area; Step 2: The first dredging area is divided into a plurality of dredging belts according to the digging width of the grab dredger, and the width of each dredging belt is not greater than the maximum digging width of the grab dredger. Then the first grab dredger is transferred to the excavation point of the first dredging belt in the first dredging area according to the positioning information, and the first mud barge is put on gear, and construction operations are carried out in sequence from the first dredging area. During the construction operation, the first grab dredger throws the grab into the excavation point of the first dredging belt, 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 spoil is thrown to the designated mud throwing area and the ship returns. During the construction operation, when the dredging operation of the first dredging belt reaches 30%, the second grab dredger is put on gear. The dredger is transferred to the excavation point of the second dredging belt of the first dredging area according to the positioning information, the second grab dredger throws the grab into the excavation point of the second dredging belt, fills it with dredged soil, and then transfers the dredged soil to the first mud barge. When the first mud barge is full and dumps the dredged soil to the designated mud dumping area, the second mud barge is transferred to the upper gear position of the first mud barge. After dumping the soil, the first mud barge drives to the original parking position of the second mud barge. When the first dredging belt is dredged, the first grab dredger and the first mud barge are transferred to the third dredging belt. When the second dredging belt is dredged, the second grab dredger and the second mud barge are transferred to the fourth dredging belt until the dredging of the first dredging area is completed; Step 3: Repeat step 2 until the dredging operation of all dredging areas in the closed navigation area is completed; Step 4: After the closed navigation area is restored to normal navigation, the rest of the area to be constructed will be designated as a new closed navigation area, and steps 1, 2 and 3 will be repeated until the dredging operation in the area to be constructed is completely completed.

[0006] Preferably, in the grab dredger channel dredging method, step 2 further includes the following steps: A plurality of angle sensors and a plurality of displacement sensors are installed on the dredging arm of the grab dredger, wherein the angle sensors and the displacement sensors are used to obtain real-time posture and position information of the dredging arm respectively; A plurality of opening sensors and a plurality of depth sensors are installed on the grab bucket, and the opening sensors and the depth sensors are used to obtain the opening degree and the digging depth of the grab bucket respectively; The grab dredger is provided with a depth control system, in which a corresponding table of each dredging area, digging strip and theoretical digging depth is provided. The depth control system is respectively connected to the angle sensor, the displacement sensor, the opening sensor and the depth sensor in communication. The depth control system is used to obtain the actual digging depth of the grab according to the information received from the angle sensor, the displacement sensor, the opening 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 a preset digging depth threshold, the 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 depth control system controls the next digging action of the grab to move relatively upward by a certain 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 depth control system controls the next digging action of the grab to move relatively downward by a certain distance.

[0007] Preferably, the grab dredger channel dredging method further includes installing a flexible hollow plate around the grab dredger, and the flexible hollow plate is provided with a water flow velocity sensor and a sediment concentration sensor, which are respectively used to monitor data around the grab dredger, and the water flow velocity sensor and the sediment concentration sensor are each respectively communicated with the depth control system.

[0008] Preferably, the grab dredger channel dredging method further includes installing a pressure sensor on the grab bucket to obtain the force condition of the grab bucket and the weight of the excavated dredged soil.

[0009] Preferably, in the channel dredging method of the grab dredger, in step 2, when the dredging thickness is greater than the maximum thickness of the grab bucket at one time, a layered construction method is adopted for excavation, wherein the excavation depth thickness of the first layer is set to 90% to 95% of the maximum thickness of the grab bucket at one time, and the excavation depth thickness of the last layer is set to no more than 50% of the maximum thickness of the grab bucket at one time.

[0010] Preferably, in the grab dredger channel dredging method, the overlapping width between adjacent dredging areas is not less than 20 meters, and the overlapping width between adjacent dredging belts is not less than 5 meters.

[0011] 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 in a direction from upstream to downstream.

[0012] The present invention has at least the following beneficial effects: The present invention designates a part of the area to be constructed as a navigation-closed area. When the dredging operation of the first dredging belt reaches 30%, the second dredging belt also starts construction, and two grab dredgers operate. At the same time, the grab dredgers adopt segmented and belted construction, and the first mud barge and the second mud barge take turns to undertake the mud throwing operation. After the navigation-closed area is restored to normal navigation, the other parts of the area to be constructed are designated as new navigation-closed areas, and steps one, two and three are repeated until the dredging operation of the area to be constructed is completely completed. In this way, the present invention can not only shorten the dredging period and reduce the impact of the construction team's channel passage time, but also avoid the problem of long-term channel closure required for dredging construction, shorten the channel closure time, and improve the dredging efficiency of the entire channel.

[0013] In addition, the present invention installs a plurality of angle sensors and a plurality of displacement sensors on the dredging arm of the grab dredger, and the angle sensors and the displacement sensors are used to obtain the real-time posture and position information of the dredging arm respectively; a plurality of opening sensors and a plurality of depth sensors are installed on the grab, and combined with the use of the depth control system, the depth accuracy of the grab dredger is significantly improved to meet the needs of high-precision dredging operations. At the same time, the cost is lower, and it is easy to promote and apply. Moreover, the present invention can monitor the working environment in real time, and automatically adjust the motion state of the grab dredger according to environmental changes, and has strong adaptability and robustness.

[0014] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic elevation diagram of a grab dredger construction in one of the schemes of the present invention.

[0016] Figure 2 This is a schematic diagram of the construction plan of a grab dredger in one of the schemes of the present invention.

[0017] Figure 3 The present invention is a construction flow chart of a grab dredger in one of the schemes of the present invention. DETAILED DESCRIPTION

[0018] The present invention is described in further detail below so that those skilled in the art can implement it according to the description.

[0019] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense. For example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The orientation or position relationship indicated by the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] Grab dredger is a mechanical dredger. During construction, the empty bucket is first opened in the air, and then the line is released. The bucket relies on its own weight to cut into the dredged soil, and the cutting depth is strictly controlled. The operator closes the bucket, lifts the bucket filled with dredged soil above the water surface, rotates the bucket arm to move the heavy bucket above the mud barge, opens the bucket to discharge the dredged soil, and then rotates the bucket arm in the opposite direction to throw the empty bucket into the excavation point. It loads the dredged soil onto the self-propelled mud barge through the grab bucket, and then the mud barge throws the dredged spoil to the designated mud dumping area.

[0022] like Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a channel dredging method using a grab dredger, comprising: Step 1: designate a part of the area to be constructed as a closed navigation area, and divide the closed navigation area into a first dredging area, a second dredging area, and a third dredging area, wherein there is an overlapping area between adjacent dredging areas and the first dredging area, the second dredging area, and the third dredging area cover all areas of the closed navigation area; Step 2: The first dredging area is divided into a plurality of dredging belts according to the digging width of the grab dredger, and the width of each dredging belt is not greater than the maximum digging width of the grab dredger. Then the first grab dredger is transferred to the excavation point of the first dredging belt in the first dredging area according to the positioning information, and the first mud barge is put on gear, and construction operations are carried out in sequence from the first dredging area. During the construction operation, the first grab dredger throws the grab into the excavation point of the first dredging belt, 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 waste soil is thrown to the designated mud dumping area and returns. During the construction operation, when the dredging operation of the first dredging belt reaches 30%, the second grab dredger is moved according to the positioning information. The positioning information is transferred to the excavation point of the second dredging belt in the first dredging area, the second grab dredger throws the grab into the excavation point of the second dredging belt, fills it with dredged soil, and then transfers the dredged soil to the first mud barge. When the first mud barge is full and dumps the dredged soil to the designated dumping area, the second mud barge is transferred to the upper gear position of the first mud barge. After dumping the soil, the first mud barge drives to the original parking position of the second mud barge (the upper gear position of the second mud barge). When the dredging of the first dredging belt is completed, the first grab dredger and the first mud barge are transferred to the third dredging belt. When the dredging of the second dredging belt is completed, the second grab dredger and the second mud barge are transferred to the fourth dredging belt until the dredging of the first dredging area is completed; Step 3: Repeat step 2 until the dredging operation of all dredging areas in the closed navigation area is completed; Step 4: After the closed navigation area is restored to normal navigation, the rest of the area to be constructed will be designated as a new closed navigation area, and steps 1, 2 and 3 will be repeated until the dredging operation in the area to be constructed is completely completed. The strip section constructed later should appropriately overlap with the strip section constructed earlier to avoid leaving shallow ridges.

[0023] The present invention designates a part of the area to be constructed as a navigation-closed area. When the dredging operation of the first dredging belt reaches 30%, the second dredging belt also starts construction, and two grab dredgers operate. At the same time, the grab dredgers adopt segmented and belted construction, and the first mud barge and the second mud barge take turns to undertake the mud throwing operation. After the navigation-closed area is restored to normal navigation, the other parts of the area to be constructed are designated as new navigation-closed areas, and steps one, two and three are repeated until the dredging operation of the area to be constructed is completely completed. In this way, the present invention can not only shorten the dredging period and reduce the impact of the construction team's channel passage time, but also avoid the problem of long-term channel closure required for dredging construction, shorten the channel closure time, and improve the dredging efficiency of the entire channel.

[0024] In the above scheme, as a preference, step 2 further includes the following steps: A plurality of angle sensors and a plurality of displacement sensors are installed on the dredging arm of the grab dredger, wherein the angle sensors and the displacement sensors are used to obtain real-time posture and position information of the dredging arm respectively; A plurality of opening sensors and a plurality of depth sensors are installed on the grab bucket, and the opening sensors and the depth sensors are used to obtain the opening degree and the digging depth of the grab bucket respectively; The grab dredger is provided with a depth control system, in which a corresponding table of each dredging area, digging strip and theoretical digging depth is provided. The depth control system is respectively connected to the angle sensor, the displacement sensor, the opening sensor and the depth sensor in communication. The depth control system is used to obtain the actual digging depth of the grab according to the information received from the angle sensor, the displacement sensor, the opening 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 a preset digging depth threshold, the 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 depth control system controls the next digging action of the grab to move relatively upward by a certain 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 depth control system controls the next digging action of the grab to move relatively downward by a certain distance. Preferably, the distance is the absolute value of the difference between the actual excavation depth and the corresponding theoretical excavation depth.

[0025] The present invention significantly improves the dredging accuracy of the grab dredger through the above scheme, and meets the requirements of high-precision dredging operations. At the same time, the cost is lower and it is easy to promote and apply. In addition, the present invention can monitor the working environment in real time and automatically adjust the motion state of the grab dredger according to environmental changes, and has strong adaptability and robustness.

[0026] In the above scheme, as a preference, it also includes installing a flexible hollow plate around the grab dredger, on which a water flow velocity sensor and a sediment concentration sensor are provided, which are respectively used to monitor the data around the grab dredger, and the water flow velocity sensor and the sediment concentration sensor are respectively communicated with the depth control system.

[0027] In the above scheme, as a preference, it further includes installing a pressure sensor on the grab bucket to obtain the force condition of the grab bucket and the weight of the excavated dredged soil.

[0028] In one of the schemes of the present invention, as a preferred embodiment, in step 2, when the dredging thickness is greater than the maximum thickness of the grab bucket at one time, a layered construction method is used for excavation, wherein the excavation depth thickness of the first layer is set to 90% to 95% of the maximum thickness of the grab bucket at one time, and the excavation depth thickness of the last layer is set to no more than 50% of the maximum thickness of the grab bucket at one time. The thickness of layered dredging should be determined according to the soil quality and the performance of the dredger. The upper layer of the layer should be thicker to ensure the efficiency of the dredger; the last layer should be thinner to ensure the quality of the project; when the mud surface before dredging is above the water surface, 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 draft and the minimum excavation depth. When the mud layer is too thick, the upper layer should be excavated at high tide and the lower layer should be excavated at low tide to reduce landslides.

[0029] In one of the solutions of the present invention, preferably, the overlapping width between adjacent dredging areas is not less than 20 meters, and the overlapping width between adjacent dredging belts is not less than 5 meters. To avoid missing dredging, each dredging ship group arranges the construction section and dredging belt of each shift according to the construction shift to prevent missing dredging.

[0030] In one of the solutions of the present invention, preferably, in step one, the closed navigation area is divided into a first dredging area, a second dredging area and a third dredging area in a direction from upstream to downstream.

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the following embodiments are provided for further explanation: like Figure 1 , Figure 2 and Figure 3 As shown, a channel dredging method using a grab dredger comprises: Step 1: designate a part of the area to be constructed as a closed navigation area, and divide the closed navigation area into the first dredging area, the second dredging area, and the third dredging area, wherein there is an overlapping area between adjacent dredging areas and the first dredging area, the second dredging area, and the third dredging area cover all areas of the closed navigation area; the overlapping width between adjacent dredging areas is not less than 20 meters, and the overlapping width between adjacent dredging belts is not less than 5 meters. The closed navigation area is divided into the first dredging area, the second dredging area, and the third dredging area from upstream to downstream.

[0032] Step 2: The first dredging area is divided into a plurality of dredging belts according to the digging width of the grab dredger, and the width of each dredging belt is not greater than the maximum digging width of the grab dredger. Then the first grab dredger is transferred to the excavation point of the first dredging belt in the first dredging area according to the positioning information, and the first mud barge is shifted up, and construction operations are carried out sequentially from the first dredging area. During the construction operation, the first grab dredger throws the grab bucket into the excavation point of the first dredging belt, 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 waste soil is thrown into the designated mud dumping area and the ship returns. During the construction operation, when the dredging operation of the first dredging belt reaches 30%, the second grab dredger is transferred to the excavation point of the second dredging belt in the first dredging area according to the positioning information, and the second grab dredger throws the grab bucket into the opening of the second dredging belt The first dredging belt is dredged at the digging point, filled with dredged soil, and then the dredged soil is transferred to the first mud barge. When the first mud barge is full and the dredged soil is dumped to the designated dumping area, the second mud barge is transferred to the upper gear position of the first mud barge. After the first mud barge dumps the soil, it drives to the original parking position of the second mud barge (the upper gear position of the second mud barge). When the first dredging belt is dredged, the first grab dredger and the first mud barge are transferred to the third dredging belt. When the second dredging belt is dredged, the second grab dredger and the second mud barge are transferred to the fourth dredging belt until the dredging of the first dredging area is completed. After the anchor position is set, the dredger is located according to the GPS, and the construction ship is transported to the excavation point by the anchor winch, and then the mud barge is notified to be up gear. Using the graphics displayed on the computer, the dredger performs construction operations such as bucket discharge and customs entry according to the actual water depth before dredging, and gradually moves forward.

[0033] In step 2, when the dredging thickness is greater than the maximum thickness of the grab bucket at one time, a layered construction method is adopted for excavation, wherein the excavation depth thickness of the first layer is set to 90%~95% of the maximum thickness of the grab bucket at one time, and the excavation depth thickness of the last layer is set to no more than 50% of the maximum thickness of the grab bucket at one time.

[0034] Step 3: Repeat step 2 until the dredging operation of all dredging areas in the closed navigation area is completed; A plurality of angle sensors and a plurality of displacement sensors are installed on the dredging arm of the grab dredger, wherein the angle sensors and the displacement sensors are used to obtain real-time posture and position information of the dredging arm respectively; A plurality of opening sensors and a plurality of depth sensors are installed on the grab bucket, and the opening sensors and the depth sensors are used to obtain the opening degree and the digging depth of the grab bucket respectively; The grab dredger is provided with a depth control system, in which a corresponding table of each dredging area, digging strip and theoretical digging depth is provided. The depth control system is respectively connected to the angle sensor, the displacement sensor, the opening sensor and the depth sensor in communication. The depth control system is used to obtain the actual digging depth of the grab according to the information received from the angle sensor, the displacement sensor, the opening 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 a preset digging depth threshold, the 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 depth control system controls the next digging action of the grab to move relatively upward by a certain 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 depth control system controls the next digging action of the grab to move relatively downward by a certain distance. The distance is the absolute value of the difference between the actual excavation depth and the corresponding theoretical excavation depth.

[0035] It also includes installing a flexible hollow plate around the grab dredger, on which a water flow velocity sensor and a sediment concentration sensor are provided, which are respectively used to monitor data around the grab dredger, and the water flow velocity sensor and the sediment concentration sensor are respectively connected to the depth control system for communication.

[0036] The method also includes installing a pressure sensor on the grab bucket to obtain the force condition of the grab bucket and the weight of the excavated dredged soil.

[0037] Step 4: After the closed navigation area is restored to normal navigation, the rest of the area to be constructed will be designated as a new closed navigation area, and steps 1, 2 and 3 will be repeated until the dredging operation in the area to be constructed is completely completed.

[0038] The grab dredger of the present invention is constructed in sections, strips and layers. When the trench width is greater than the maximum digging width of the dredger, the maximum width of the strips shall not exceed the effective working radius of the grab crane of the dredger. When the trench length exceeds the length that can be excavated by the dredger by dropping the main anchor or the side anchor at one time, the excavation is carried out in sections. When the thickness of the dredged soil layer in the dredging area exceeds the maximum thickness of the grab bucket at one time, the construction is carried out in layers, and the thickness of the layers is determined by the thickness of the grab bucket excavated at one time, the bucket weight, the width of the bucket, and the soil quality. During construction, the buckets are arranged horizontally and the gates are entered vertically. In order to ensure one-time passing, the buckets and gates need to overlap by a certain length to prevent leakage. When constructing the sideline, it is necessary to "return the bucket", that is, to dig 1-2 more buckets, leaving a certain depth for silting. According to the water depth of the waterway, the digging property of the dredged soil and the size of the bucket, the number of buckets arranged and the amount of forward movement at each gate are determined. Fixed-depth construction is adopted for areas with thinner mud layers. When the dredging work starts, the dredger is towed to the construction area by a tugboat or other auxiliary vessels to position the dredger, and the dredging work starts according to the water flow and wind direction.

[0039] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0040] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A grab dredger channel dredging method, characterized in that: The steps include: Step 1: designate a part of the area to be constructed as a closed navigation area, and divide the closed navigation area into a first dredging area, a second dredging area, and a third dredging area, wherein there is an overlapping area between adjacent dredging areas and the first dredging area, the second dredging area, and the third dredging area cover all areas of the closed navigation area; Step 2: The first dredging area is divided into a plurality of dredging belts according to the digging width of the grab dredger, and the width of each dredging belt is not greater than the maximum digging width of the grab dredger. Then the first grab dredger is transferred to the excavation point of the first dredging belt in the first dredging area according to the positioning information, and the first mud barge is put on gear, and construction operations are carried out in sequence from the first dredging area. During the construction operation, the first grab dredger throws the grab into the excavation point of the first dredging belt, 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 spoil is thrown to the designated mud throwing area and the ship returns. During the construction operation, when the dredging operation of the first dredging belt reaches 30%, the second grab dredger is put on gear. The dredger is transferred to the excavation point of the second dredging belt of the first dredging area according to the positioning information, the second grab dredger throws the grab into the excavation point of the second dredging belt, fills it with dredged soil, and then transfers the dredged soil to the first mud barge. When the first mud barge is full and dumps the dredged soil to the designated mud dumping area, the second mud barge is transferred to the upper gear position of the first mud barge. After dumping the soil, the first mud barge drives to the original parking position of the second mud barge. When the first dredging belt is dredged, the first grab dredger and the first mud barge are transferred to the third dredging belt. When the second dredging belt is dredged, the second grab dredger and the second mud barge are transferred to the fourth dredging belt until the dredging of the first dredging area is completed; Step 3: Repeat step 2 until the dredging operation of all dredging areas in the closed navigation area is completed; Step 4: After the closed navigation area is restored to normal navigation, the rest of the area to be constructed will be designated as a new closed navigation area, and steps 1, 2 and 3 will be repeated until the dredging operation in the area to be constructed is completely completed.

2. The grab dredger channel dredging method according to claim 1, characterized in that: Step 2 also includes the following steps: A plurality of angle sensors and a plurality of displacement sensors are installed on the dredging arm of the grab dredger, wherein the angle sensors and the displacement sensors are used to obtain real-time posture and position information of the dredging arm respectively; A plurality of opening sensors and a plurality of depth sensors are installed on the grab bucket, and the opening sensors and the depth sensors are used to obtain the opening degree and the digging depth of the grab bucket respectively; The grab dredger is provided with a depth control system, in which a corresponding table of each dredging area, digging strip and theoretical digging depth is provided. The depth control system is respectively connected to the angle sensor, the displacement sensor, the opening sensor and the depth sensor in communication. The depth control system is used to obtain the actual digging depth of the grab according to the information received from the angle sensor, the displacement sensor, the opening 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 a preset digging depth threshold, the 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 depth control system controls the next digging action of the grab to move relatively upward by a certain 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 depth control system controls the next digging action of the grab to move relatively downward by a certain distance.

3. The grab dredger channel dredging method according to claim 2, characterized in that: It also includes installing a flexible hollow plate around the grab dredger, on which a water flow velocity sensor and a sediment concentration sensor are provided, which are respectively used to monitor data around the grab dredger, and the water flow velocity sensor and the sediment concentration sensor are respectively connected to the depth control system for communication.

4. The grab dredger channel dredging method according to claim 2, characterized in that: The method also includes installing a pressure sensor on the grab bucket to obtain the force condition of the grab bucket and the weight of the excavated dredged soil.

5. The grab dredger channel dredging method according to claim 1, characterized in that: In step 2, when the dredging thickness is greater than the maximum thickness of the grab bucket at one time, a layered construction method is adopted for excavation, wherein the excavation depth thickness of the first layer is set to 90%~95% of the maximum thickness of the grab bucket at one time, and the excavation depth thickness of the last layer is set to no more than 50% of the maximum thickness of the grab bucket at one time.

6. The grab dredger channel dredging method according to claim 1, characterized in that: The overlapping width between adjacent dredging areas shall not be less than 20 meters, and the overlapping width between adjacent dredging belts shall not be less than 5 meters.

7. The grab dredger channel dredging method according to 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 a direction from upstream to downstream.

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