The construction deployment refers to the preparatory work before dredging begins, including positioning, anchoring, erecting, and connecting drainage pipelines above and below water, as well as along the shore. There are various positioning methods. Currently, many applications domestically and internationally use GPS for positioning, with particular attention to nearshore channel positioning. This method is simple and efficient, with high accuracy, and is the direction for future development. During the positioning and anchoring process, the dredger is first towed to the starting guide mark, adjusting the ship's position to align a specific marker post with the construction center guide mark for the trenching (or cutting) operation, with the cutter positioned on the starting guide mark line. After the inertia of the tugboat's navigation dissipates, the positioning post below is set.
If the flow rate is high or the subsoil is hard, relying on a single pile to stabilize the ship's position is insufficient. First, drop the stern anchor and then release the stern line. When the cutter is on the starting guide rail, lower the positioning pile for alignment. When setting the anchor controls for left and right movements of the cutter, the lead angle of the anchor position should not exceed 25 degrees. To reduce the time for anchoring and moving the anchor, a few pairs of left and right anchors can be set at a certain distance along the direction of the dredging advance.
Based on the differences in positioning devices, construction methods for cutter suction dredgers have been categorized. Common methods include the symmetrical steel pile horizontal excavation method and the steel pile carriage horizontal excavation method. When a dredger is equipped with a three-line positioning device in areas with strong winds and waves, the three-line positioning horizontal excavation method should be used. In regions with high flow rates or strong winds and waves, cutter suction dredgers equipped with anchor cable horizontal excavation equipment should adopt the anchor cable horizontal excavation method.
During dredging, a simple forward method involves using two steel piles alternately inserted into the seabed as the rotation center of the hull. By deploying and retracting the anchors to the left and right, and swinging the cutter, the vessel is both dredged in a fan shape and propelled forward. This technique is known as the double-pile forward movement cross-dredging method.
The single pile forward horizontal excavation method involves using a steel pile as the main pile, rotating around the excavation center line continuously, with another steel pile serving as the auxiliary pile for forward replacement. As there is only one rotation center, the excavation paths of the cutters are parallel to each other. By maintaining the forward displacement of the steel pile, re-excavation and missed excavation can be avoided.
