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ENERGIX-Stort program energi

Seabed ConePressuremeter for in-situ testing of soil and rocks for strength and stiffness parameter for offshore windfarm foundation

Alternative title: ConePressuremeter for geoteknisk undersøkelse av havbunn med tanke på styrke og stivhet for offshore vindkraft fundamenter.

Awarded: NOK 6.0 mill.

Project Manager:

Project Number:

327618

Project Period:

2021 - 2024

Funding received from:

Partner countries:

The offshore renewable industry, where structures the height of the Eiffel Tower are founded on the seabed and are subjected to continual wave and rotor forces, has created a demand for more precise methods to better determine the geotechnical engineering properties of the seabed. Additional types of data (compared with oil and gas structures) are needed for the design and installation of wind turbine foundations. Pressuremeter testing is an existing method frequently used onshore (especially in France) for determining soil stiffness under small strain conditions. Several attempts have been made to use these instruments in a subsea environment, with varying degrees of success, but no specific offshore solutions exist.

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Geotechnical investigations are essential for almost every advanced civil engineering project at a cost on the order of 0.1% to 0.5% of total offshore project capital cost. If an investigation is done properly it will prevent massive cost and schedule overruns. Developers are therefore willing to pay for the most accurate data. The primary objective of an investigation is to obtain information on the physical properties of the ground (soils) and layering beneath an area where foundations for structures will be constructed or installed. The higher the quality of the data obtained the more economic and safer foundations can be designed, in turn this ensures long term stability and optimum performance. In addition, for offshore structures, particularly wind turbines, an investigation is, in nearly all cases, required to obtain insurance and government licences. The offshore renewable industry, where structures the height of the Eiffel Tower are founded on the seabed and are subjected to continual wave and rotor forces, has created a demand for more precise methods to better determine the geotechnical engineering properties of the seabed. Additional types of data (compared with oil and gas structures) are needed for the design and installation of wind turbine foundations. Pressuremeter testing is an existing method frequently used onshore (especially in France) for determining soil stiffness under small strain conditions. Several attempts have been made to use these instruments in a subsea environment, with varying degrees of success, but no specific offshore solutions exist. Excess Engineering, and partners,intends to develop and build a “ConePressuremeter” tool (joint CPT and pressuremeter) capable of accurately obtaining all seabed geotechnical engineering data that is needed for the design of foundations of offshore structures, particularly wind turbine foundations.

Funding scheme:

ENERGIX-Stort program energi