Theoretical modelling of a suction caisson foundation using hyperplasticity theory Lam Nguyen-Sy and Guy Houlsby

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Theoretical modelling of a suction caisson
foundation using hyperplasticity theoryLam
Nguyen-Sy and Guy Houlsby
MOTIVATION the purpose is to define a complete
theoretical model which describes the behaviour
of a caisson foundation under general loading.
The model, which is called ISIS, can be
incorporated into the numerical analysis of a
structure such as a wind-turbine
The model is expressed in terms of force
resultants on the foundation (and the
corresponding displacements) rather than in terms
of details of stress and strain within the soil
HYPERPLASTICITY is used as the framework for the
model. In this approach the response is defined
by specifying two scalar functions, for instance
the Gibbs free energy and the yield function. The
model uses continuous hyperplasticity which
allows many yield surfaces to be specified.
Monopod caisson foundation
Tripod or tetrapod caisson foundation
EXAMPLE ANALYSES show comparisons between
laboratory tests and the ISIS model
The Gibbs free energy defines various aspects of
behaviour
The analysis can deal with special features such
as suction-installed caissons
Elasticity
Plastic strains
Strain hardening
Cyclic response with changing stiffness and
hysteresis can be modelled
The other important expression is the yield
function
Vertical movements during cyclic moment loading
are predicted
The model is implemented in numerical
calculations using a rate-dependent formulation
in the time domain
This research has been supported by the DTI,
EPSRC, Vietnamese Government, SLP, Fugro, Garrad
Hassan, GE Energy, Shell and Vestas
See also www-civil.eng.ox.ac.uk