Page 269 - 360.revista de Alta Velocidad - Nº 5

Calculation and rational dimensioning of railway infrastructure materials using numerical modelling

In relation to the seat layers, these are re-modelled with parallelepiped volumes assuming that
each of these behaves as a continuous medium. Further:

1. It has been assumed that all granular materials of the granular layers are homogeneous
and isotropic materials where the geomechanical properties are constant throughout
the volume and there is no change in the value of these.

2. In the case of ballast, by its rheology and interaction between particles, it would be
more advisable to use discrete elements for its numerical modelling, in this numerical
model it is modelled as a continuous medium by finite elements, paying close attention
to that, if a model is adopted sufficiently adequate, it will be able to reproduce a more
accurate tenso-deformational response than using simpler models (Ishikawa, et.al.,
2014).

3. The geometry of the cross section has been defined following the dimensions proposed
by ADIF (2006) in its different regulations for High-Speed lines, as shown in Fig. 2. In this
figure you can see how it would also be configured the section of eliminate the confining
ballast by refining the numerical model.

Fig. 2. Layer dimensions for the High-Speed cross section in Spain.

The mechanical and geomechanical properties of the different materials are listed in
Table 1. In this it can be seen how, for the sensitivity analysis, the value of the internal
friction angle has different values for two of the granular materials shown. In the case
of the Formation layer there will be a decrease in the resistance and, in the Subballast
the opposite. It has been assumed that all granular materials are in perfectly drained
conditions, so that the tensions obtained will be in terms of effective coincident with the
values of total stresses.

International Congress on High-speed Rail: Technologies and Long Term Impacts - Ciudad Real (Spain) - 25th anniversary Madrid-Sevilla corridor 267