How to model sea floor and soil contact for slender system lines

This is valid for slender system only

1. Models in SIMA

  • The seafloor/soil models can be split into three groups

    1. Seafloor contact : Structures laying on the sea floor

    2. Soil contact : Structures penetration the soil

    3. Alternative methods covers both group a and b.

See user manual: Contact Formulation

seafloor soil groups

2. Sea floor contact (a)

  • The seafloor contact formulation includes

    • contact normal to the seafloor modelled by springs

    • in-plane contact modelled by a combination of springs and frictional forces.
seafloor contact

  • Sea floor contact specification

    • Specify the relation between the sea floor contact and the line ID and line segments
seafloor contact spec

3. Riser soil (a)

  • The contact model includes in addition to the sea floor contact

    • nonlinear stiffness as the pipe is pressed into the seafloor and a separate unloading curve as the pipe is lifted

    • suction forces are activated as the pipe is lifted off the seafloor

Ref. Voie, P. E., Skeie, G. and Bergan-Haavik, J. (2014): Importance Rating of Riser-Soil Interaction Effects,OMAE2014

riser soil

4. Geotechnical spring specification (b)

  • Used to specify geotechnical springs in the global X-Y plane suitable for modelling cyclic geotechnical data with degradation

geotech

5. Geotechnical soil model (b)

The input to the geotechnical soil model consists of
geotech sand

  • The Geotechnical specification
geotech spec

  • The Geotechnical line Specification

    • Links the geotechnical input to a line ID
geotech line spec

6. PISA Soil Model (b)

  • Soils for use with the soil layer profile definition, intended for modelling of embedded piles

The input to the PISA Soil Model consists of

  • Soil components. The options are

    • Pisa Clay

    • Pisa Sand

    • Dunkirk sand
pisa soils

  • Pisa Soil layer profile

    • The soil layer profile is a vertical slice of soil layers with specified thickness

    • The soil characteristics are specified in Soil (Soil components)
pisa soil layer

7. Alternative methods to model sea floor and soil contact (c)

  1. Option I:

    1. Global springs

    2. see user doc
global spring

  1. Option II:

    1. User defined elements ..
userdefined