Published: 2025-08-08 10:31:22
The technical specifications for the laying of underwater cables are mainly based on the 'Standards for Construction and Acceptance of Cable Lines in Electrical Installation Projects' GB50168-2018 and other related standards, as detailed below:
Cable joint requirements: Underwater cables should not have joints. When the entire cable exceeds manufacturing capabilities, flexible joints can be used for connection.
Route selection for laying: Cables should be laid in water areas where the riverbed is stable, the flow is relatively slow, the banks are not easily eroded, and the bottom is free of reefs, shipwrecks, and other obstacles. They should not be laid near docks, ferry terminals, and hydraulic structures, nor in dredging areas, planned port construction zones, and trawler activity areas. When no alternative routes are available, reliable protective measures should be taken.
Cable spacing requirements: Within the main channel, cable spacing should not be less than twice the maximum water level depth; the diverted shore spacing may be appropriately reduced. In non-navigable rivers with flow velocity not exceeding 1m/s, the spacing between single-core cables in the same circuit must not be less than 0.5m, and the spacing between cables in different circuits must not be less than 5m. In addition to the above situations, factors such as flow rate, cable burial depth, and burial control deviation should be considered.
Selection of laying method: The laying method, vessel selection, and construction organization design should be determined based on factors such as cable laying length, outer diameter, weight, water depth, flow velocity, and riverbed topography.
Requirements for laying vessels: The volume of the cabin, deck area, and ship stability should meet cable length, weight, bending radius, winding radius, torsion release height, and the requirements for the work site. The arrangement of equipment for laying (buried) equipment, communication, navigation and positioning, and vessel power should meet the needs of cable construction.
Selection of the starting point for laying: The starting point of underwater cable laying should preferably be on the side where landing operations are relatively difficult.
Laying timing requirements: Underwater cables should be laid during light tide or resting currents, or dry seasons, with clear visibility and wind force below level five.
Torsion release and resistance control: When laying the ship's torsion release frame, maintain an appropriate torsion release height. When cables pass through cable storage silos, torsion release racks, and other facilities, measures should be taken to reduce cable resistance. During cable laying, monitor the cable tension or water entry angle to meet product technical documentation requirements.
Positioning and measurement requirements: When laying underwater cables, guide markers should be set on both sides of the land according to design requirements. During laying, positioning and measurement should be conducted simultaneously, and route deviations should be corrected in a timely manner, and the laying length should be verified.
Terminal landing requirements: When the underwater cable ends land, all remaining cables should be held above the water surface, and appropriate tension should be maintained when the excess cable enters the water. When underwater cables are led onshore, anchoring devices should be installed. Onshore sections should be protected by measures such as pipe threading, trench boxes, and trenches. The lower end of the protection range should be placed below 1m of the minimum water level, and the upper end should be above the highest flood level.
Cable laying requirements: Underwater cables must not float in the water. In waterways and other areas where external damage needs to be prevented, cables should be buried on the seabed and securely covered for protection. The burial depth should not be less than 0.5 meters in shallow water and not less than 2 meters in deep water. When cable lines cross small rivers or streams, conduit laying can be used.
Set warning signs: Warning signs should be set on both sides of the underwater cable according to navigation mark specifications.