Suction caissons for cross-flow tidal power system

This paper describes a geotechnical site investigation and feasibility study of suction caisson foundations for fixed seabed tidal substructures in soft clay as part of the first US commercial-scale, grid-connected, tidal power installation located in Cobscook Bay, Maine. Feasibility was analysed through two-dimensional plane strain numerical modelling of the maximum capacity of a pair of rigidly connected suction caissons experiencing combined horizontal, vertical and moment loading when aligned with the direction of the current. Maximum load capacity for a single caisson diameter with varying skirt depths was investigated to determine effects of aspect ratio, uplift resistance of the windward leg and influence of shallow bedrock. Analyses in this paper indicate that suction caissons with relatively shallow skirts are a viable option to resist vertical and horizontal loading of the tidal power unit at the Cobscook Bay sites.