1. On-water pipeline assembly and laying method: The on-water pipeline of the dredging vessel uses a structure of alternating self-floating steel pipes and rubber hoses. The steel pipe specifications are 6 meters × Φ800mm, and the rubber hose specifications are 1.5 meters × Φ800mm. The total length of the on-water pipeline is 600 meters. One end is connected to the mud discharge pipe of the construction vessel, and the other end is fitted with an air release valve and connected to the underwater pipe. The pipeline is anchored every 150 meters, and all connections use flanged joints.
2. Underwater pipeline layout: To avoid affecting navigation during construction, a suitable length of underwater mud discharge pipeline needs to be laid. One end of the underwater pipe is connected to the on-water pipe, and the other end is connected to the land-based pipe. The underwater pipe assembly involves splicing assembled units and lowering them into the water. The entry end is supported by pontoons and its position is controlled by an anchor boat. With the cooperation of a land-based crane and the anchor boat, the pipeline is gradually extended to the required length. To ensure that the flanged joints are sealed and do not leak mud, pneumatic wrenches are used during connection, and the flange connection bolts are reinforced.
3. Underwater pipe sinking and floating: The sinking and floating of the underwater pipe are operated based on the principle of buoyancy by changing the weight of the pipeline through water injection and discharge. During sinking, the assembled pipeline is towed to the designated location by an anchor boat, and both ends are fixed with anchors (the land end can be directly connected to the land-based pipe opening). Then, water is injected using a water pump to sink it to the mud surface. During floating, both ends are disconnected from the on-water and land-based pipes, and the pipe openings are sealed with blind plates. Compressed air is injected into the land end using an air compressor, and a water discharge regulating valve (made of cast iron, cast steel, stainless steel, etc.) is left at the water end. As the water is discharged from the pipe, the pipeline gradually floats due to buoyancy.
