Seabed Interaction |
 
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Seabed Interaction |
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Flexcom has a range of options for modelling seabed interaction. Both rigid and elastic seabed models are provided. Rigid Seabeds may be flat, sloping, or have an arbitrary 2D piecewise linear bathymetry. Elastic Seabed geometries may be flat, sloping, or have arbitrary bathymetry specified in 2D or 3D.
Elastic seabed stiffness may be defined using a linear (constant) stiffness or characterised in terms of non-linear force-embedment curves.
Seabeds of either type may be smooth or have longitudinal and/or transverse friction included. For structures running through and below the mudline, soil-structure interaction may also be modelled by the specification of P-y curves.
The various program options for modelling seabed interaction are discussed in the following sections:
•Rigid Seabed Profile describes the various options for defining a rigid seabed bathymetry.
•Elastic Seabed Profile describes additional options available for defining an elastic seabed bathymetry.
•Seabed Contact Modelling describes both the elastic and rigid contact modelling algorithms.
•Seabed Friction describes the Coulomb friction model implemented in Flexcom, and examines the effect of characteristic (mobilisation) length.
•Seabed Modelling in Frequency Domain Analysis discusses how seabed contact is modelled in frequency domain analyses.
•Seabed Modelling in Modal Analysis discusses how seabed contact is modelled in modal analyses.
•Soil Modelling describes the soil-structure interaction modelling facility, for structures running through and below the mudline.
Note that, when determining the effect of hydrodynamic loading, Flexcom calculates water particle velocities and accelerations on the basis of the user-specified (constant) water depth, irrespective of whether an arbitrary profile surface is present in the model or not. In other words, the presence of an arbitrary surface is not considered to affect the hydrodynamic loading on a structure.
•*SEABED PROFILE is used to specify the seabed profile/bathymetry.
•*SEABED PROPERTIES is used to specify properties such as seabed type (i.e. rigid or elastic) and friction parameters.
•*SEABED STIFFNESS is used to define nonlinear seabed contact stiffness.
•*P-Y is used to define P-y curves for modelling soil structure interaction.
Note also that the old *ELASTIC SURFACE, *RIGID SURFACE and *EMBEDMENT keywords have effectively been superseded by the new seabed definition keywords which facilitate the modelling of arbitrary seabed profiles.