The main geotechnical challenge offshore is handling the large cyclical loads from waves and wind platforms and foundations are exposed to.

NGI makes significant contributions to the development of new concepts for offshore structures, which are installed at increasing water depths and in places with unfavourable ground conditions.

NGI's state-of-the-art expertise

• the strength and deformation characteristics of sediments under cyclic loading
• optimal foundation engineering solutions
• the combination of geological, geophysical and geotechnical knowledge, which is used for example to assess geohazards

Services related to offshore foundation engineering

Since the start of Norwegian oil and gas activities, NGI has built up comprehensive expertise in offshore geotechnics. Instrumented monitoring has provided valuable information and verification of how offshore platforms and installations behave during day-to-day operations.

Steel platforms/Jackets have traditionally been founded on piles driven to great depths, and gravity base platforms of concrete (GBSes) are founded on skirts (foundation walls) that penetrate far down into the seafloor. Experience from GBSs is used today in the foundation engineering for large LNG terminals that are placed off the coast, and for the foundation engineering for offshore windmills.

The installation of circular skirts using negative pore pressure (suction) led to the development of bucket foundations as an alternative to piles, and later to suction anchors used to secure  floating platforms (FPSOs).

Research and development
The challenges and NGI's research in offshore foundation engineering are currently concerned with:

• software development - for example calculation of the holding capacity of skirt foundations/suction anchors, soil structure interaction (SSI)
• model testing and behaviour of pipelines and flexible pipes in soft clay
• decommisioning of offshore installations
• geotechnical aspects of offshore windmill parks
• new challenges at greater sea depths with softer sediments
• risk assessment in connection with geohazards