Page 203 - Numerical Analysis and Modelling in Geomechanics

184 ANNAMARIA CIVIDINI AND GIANCARLO GIODA

Figure 6.7 Comparison between the vertical displacements measured in the field and
those obtained by the elastic back analysis.
assumed for the peak failure envelope. Then the angle of dilatancy decreases
with increasing plastic deformation and it vanishes when the residual failure
condition is reached.
Details of the finite element implementation of this simple strain softening
constitutive model have been presented in [23].
This constitutive model was first applied to the analysis of the original
construction procedure of the railroad tunnel, using the same mesh and steps
already described for the elastic back analysis. The elastic moduli were those