ABSTRACT
In the last years, the availability of sound constitutive models and numerical codes has strongly improved confidence in geotechnical design, as they allow the engineers to take into account in their analyses complex geometries and construction patterns. However, the contribution of the new powerful tools is even more important if they are used at a research stage to take an insight into the relative influence that the adopted geometry and mechanical parameters have on the case to be studied. Such a task, which is the final goal of every parametric study, can help to sort out the essential features of the engineering problems, therefore helping the designer even if simpler approaches have to be adopted.
In this paper, the case of an ideal shallow tunnel excavated in neapolitan pozzolana is considered. Different combinations of mechanical characteristics, depths and unlined lengths behind the front are assumed, and a 2D analysis is carried out by means of Plaxis 7.0. The plain strain analysis behind the tunnel front is made possible by the adoption of a simple 2D model of the threedimensional interaction problem.
Considerations on the influence of tunnelling procedures on ground movements and inflections both along the tunnel axis and in the transverse plane are then drawn on the bases of the obtained simulation results.
