Continuous Formwork Cable Protection (1997)

FoundOcean completed a project in South Korean-waters to protect a 48-kilometre long, 500 MW power cable from being damaged by local farming practices.

Farmers cultivate edible seaweed in stretches of water between the 200 or so islands at the southern tip of South Korea. They drive 35-metre long steel poles into the trench bed, stringing the seaweed between them. The concern was that the poles would penetrate the cable, leading to loss of power and potential injuries to the farmers.b

The solution was to cover the 0.5 metre-deep trenched cable with a grout-filled formwork mattress to give it enough protection to withstand the impact of a 600 kg steel pole being plunged into the water.

A 2-metre wide by 0.25-metre high formwork that could be simultaneously laid and filled with grout was designed. The deployment vehicle, designed by LD TravOCean, crawled along the sea floor laying the formwork from a reel as FoundOcean used its Recirculating Jet Mixer to continuously mix and pump the grout mix into the mattress.

The grout consisted of ordinary Portland cement (OPC) and seawater, with steel fibres for additional reinforcement.