Deformation behaviour of railway embankment ... - Liikennevirasto

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addition, when both the complexity of the model and the number of parameters
increase, the physical meaning of a single parameter is more difficult to conceive. It
may also happen that the model describes very accurately the behaviour of the material
in the loading condition of a certain laboratory test, but the applicability of the model to
other loading conditions cannot always be guaranteed. Finally, it is not usually known
how the changes in the quality and physical state of the material affect the model
parameters. Instead, the changes must be investigated separately for all different
conditions.
Non-linear elastic models for resilient deformation are described in detail in Chapter 5.
3.3 Models of particulate mechanics
The counterpart of the continuum mechanics based modelling of the mechanical
behaviour of granular materials is the so-called particulate mechanics modelling, where
interactions between the distinct particles are explicitly investigated. The basic idea of
the approach is that, when the number of particles is sufficiently large, the behaviour of
the group of particles can be extended to describe the macroscopic behaviour of the
actual material.
The approaches for modelling the mechanical behaviour of the granular materials
starting from the particle level can be divided into two groups, namely, numerical
simulation models and analytical models (Kolisoja 1997).
A natural way to implement a model describing the behaviour of materials composed of
discrete particles is to use computer simulation. In the simulation model the material is
modelled by means of a particulate system where the location and the surfaces of each
particle are mathematically defined. Moreover, each contact point between the particles
is individually modelled along with the forces at the contact point. A mechanical model
of a contact point can be, for example, as illustrated in Figure 3.3:1.