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Application of Cutter Suction Dredger in Channel Dredging

Application of Cutter Suction Dredger in Channel Dredging

1. Overview of channel dredging by cutter suction dredger

In recent years, with the continuous development of transportation, machinery and equipment related to water transportation have been popularized and widely used. Dredgers, as an indispensable equipment for digging and cleaning silt, and maintaining waterways, play a role in ensuring the capacity of waterways. Plays an important role. At present, dredgers are mainly divided into bucket chain dredgers (including grab and bucket), suction dredgers (including bucket wheel and cutter suction), trailing suction dredgers, etc. Among them, the cutter suction dredger has the characteristics of high efficiency and low cost, and is currently a type of ship that is widely used in dredging projects.

The scope of application of dredgers is extremely large, such as in the water conservancy related to the development of agricultural economy, flood arrest, drainage, alkali control, water diversion, power generation, dredging, and reduction of many rivers, lakes, irrigation canals and reservoirs all over the inland Groundwater and expansion of water storage capacity, especially river blockage, siltation, etc., require the use of dredgers for dredging treatment. In addition, hydraulic reclamation, shallow sea oilfield mining, coastal reclamation, artificial islands and pile construction, as well as construction projects such as dredging, slag removal, cofferdam removal, underwater sand and gravel collection, and construction of water conservancy hubs and hydropower stations, It also needs a dredger to complete.

Because the dredger has the characteristics of high efficiency, low unit price, and ability to complete underwater earth and rock excavation that manpower and other machinery are incapable of, it is applied to water conservancy and power engineering, and its advantages are increasingly obvious.

1.1 Construction principle of cutter suction dredger

The cutter suction dredger uses steel piles for positioning. A main positioning pile that falls on the center line of the trench is used as the center of rotation of the hull. According to the operating standards and requirements of the dredging area, the cutter is used for digging. A construction method in which the reamer cuts the soil layer of the excavated section layer by layer by horizontally swinging left and right in the groove width. The working characteristics of the cutter suction dredger are: it is a static operation, the cutter head is installed as a digging tool, and the soil is sucked after being cut. The cutter suction dredger can continuously complete dredging, transporting and unloading at one time, with high efficiency and low cost.

1.2 Construction technology of cutter suction dredger

Cutter suction vessel channel dredging generally adopts horizontal digging method to carry out dredging construction along the water. According to the scope of channel dredging, different construction methods such as layering, sectioning, and sectioning are adopted. First, use the main pile of the cutter suction dredger as the stepping pile, and the auxiliary pile of the cutter suction dredger as the positioning pile. The main pile shall be set on the center line of the trench (adopting split construction) and used as the horizontal Move the center of the swing, retract the horizontally moving anchor cables on both sides of the ship’s bow cutter frame, and the soil produced during dredging is transported to the designated dumping area through the mud pipe. The first is to tow the cutter suction dredger to the pre-designed position of the construction work area by the construction personnel, and determine the starting point of the trench through GPS positioning. After the trench is accepted, the plug of the mud drainage pipeline is completed, and then the cutter is determined. Position, and do a good job in the lowering of the reamer bridge. Strictly control the migration distance of dredger construction, generally within the range of 0.5 meters to 1.5 meters. Among them:

  • 1. Layered construction

    It is mainly for the dredging process that is selected when the mud layer in the trench is thick and cannot be dug to the pre-designed line at one time. When determining the layer thickness, pay attention to the safety of the ship’s machinery and the slope ratio, and scientifically demonstrate the construction plan. To meet on-site construction requirements.

  • 2. Split construction

    It is mainly carried out according to the channel dredging with a wider width of the trench design. The main reason is that it is difficult to dig a trench to the designed trench width. At this time, it is necessary to choose a split method. The selection of the slitting process is mainly determined according to the natural conditions of the channel. For the dredging of the silt-sand-sand river section, the sand density and viscosity are fully considered during the slitting to make appropriate widening or shrinking. The dredging of clay river sections is appropriately widened or reduced according to the degree of softness and hardness.

  • 3. Subsection construction

    When the channel is dredging, it is often encountered that the groove is bent or the groove is too long. In order to achieve the dredging goal, it is often necessary to design the segmentation, and design the radius of curvature in combination with factors such as the sailing maneuver angle of the cutter suction dredger.

1.3 Key links and control of channel dredging

Cutter-suction dredgers should focus on the safety of side anchor placement, mud pipeline layout, construction and navigation during channel dredging. Among them, when setting the side anchors, two side anchors should be thrown at a certain angle (usually 75°) on both sides of the bow and the center line when the cutter suction vessel is working. The anchor position should be a certain distance outside the side line of the trench. The anchor is usually moved once when the cutter suction vessel travels 25m. In order to improve the efficiency of side anchor setting, a winch boat is used to assist in setting and shifting. Using GPS positioning, it is strictly forbidden to throw side anchors into the operation channel, and warning signs shall be set on the anchors to ensure the safety of operations. The layout of the mud pipeline should be based on the flow rate and direction of the water in the work area, and the appropriate moving path should be selected according to factors such as the length of the pipeline. The pipeline is strictly prohibited from occupying the channel. Perform navigation and safety during the construction period, adopt downstream operations, work outside the channel along the red float line, arrange for safety personnel to observe the side anchors and floating pipes at any time, reduce the impact on the navigation of the channel, and ensure the anchor floating lights Intact, pay attention to the safety of passage at any time according to the passage of ships on the water.

2. Measures to improve the quality of dredging in the channel of cutter suction dredgers

The channel dredging project requires operators not only to be proficient in the construction technology of cutter suction dredgers, but also to comprehensively manage the quality of channel dredging, improve the quality of construction projects, and give full play to the comprehensive benefits of cutter suction dredgers in channel dredging.

2.1 Reasonably choose the excavation direction of the dredger

The determination of the dredging direction is an important guarantee for the smooth progress of the dredging project. According to the difference in water flow direction, dredging operations are divided into downstream construction and upstream construction. Safety and efficiency should be fully considered when choosing a specific operation direction. In addition, it is necessary to avoid the channel siltation factor as much as possible. Practice has shown that when the river flow velocity is less than 0.5m3/s, it is recommended to adopt the downstream construction method, and when the river flow velocity is greater than 0.5m3/s, it is recommended to adopt the countercurrent construction method.

2.2 Strictly control the depth of river dredging and excavation

In the process of specific construction operations, dredging operators must fully grasp the changes in river water conditions, do a good job in the setting of fixed and temporary water gauges, and set them in a reasonable location of the operation area, so that the dredging operators can identify and read in time to prevent A collision accident occurred during the construction of the vehicle. Do a good job in daily management, regularly check the water gauge, and make corresponding adjustments to the depth of the reaming knife according to changes in the river water level. The depth of river channel excavation should not only consider the actual designed excavation depth, but also consider the river back siltation according to the river flow rate and soil quality, so as to ensure the scientificity of the excavation depth when the river channel is dredged.

2.3 Set out the construction of the centerline and the sideline of the excavation

During river dredging, in order to ensure the accuracy of construction operations and meet the requirements of the expected design plan, control piles and directional piles are often set on the left and right banks of the construction section respectively, and the center of the control piles and directional piles and the river bed should be ensured during installation. Equidistant, check them in time after laying to ensure the accuracy of the two piles. According to the previously designed position and pile number, the cross-section is laid vertically along the centerline of the river excavation, and more than 3 fan-shaped cross-sections are set at the curve of the river, and the spacing is strictly controlled. In the process of setting out the river channel, cross-section signs, horizontal signs and vertical signs should be set up so as to facilitate the safe construction of the operators at night. Eye-catching signs such as light signs, buoys or benchmark poles can be used.

3. Conclusion

Cutter suction dredger has the characteristics of higher overall application efficiency, lower cost, simple operation and wide application in channel dredging operations. It is widely used in current channel dredging operations. Cutter-suction dredger has the characteristics of adapting to small and oscillating water flow. When the flow is very small (< 50m3/s), the cutter-suction dredger and ship pump can be used for combined operation. The high cost of dispatch has become one of the restrictive factors in the practical application of cutter suction dredgers. Before the dredging of small and medium-sized waterways, the land transfer and dispatch method should be done well in cross-regional operations.