This offshore vibro piling method was chosen in line with the soil conditions. The water depth in this area is 23-27 meters, and the conditions are unsuitable for impact hammering: first, a 25m soil layer, followed by hard layers that require drilling. The ICE 170NF-tandem was selected to drive the 2940mm diameter, 51-58m long casings (with a weight of around 80 tonnes) right up to the hard layer, after which a drill emptied rock and soil from the piles. Steel piles were then inserted in the sockets and secured in place with concrete. The outer casing was then cut off at seabed level, and the jacket foundation was positioned and installed on the foundation.
The casings have a wall thickness of 20mm, with a double ring welded to the top of the pile to provide a better clamping surface for the four clamps. The ICE 170NF performed reliably, driving the piles without incident to the required depth, thereby contributing to the overall efficiency of the installation. The ICE 170NF was added to the CRMBC rental fleet in 2019 and previously worked on a bridge project in Shantou. CRMBC likes the flexibility of tandem set up, as the single or tandem option helps the rental company achieve higher overall equipment utilization rates. The 170NF set was customized to meet the most common diameter sizes, as well as to ensure no part of the vibro set exceeds standard road transport dimensions. This has the additional benefit of a compact hammer design that reduces the amount of deck space required.