ABSTRACT
In the current plane strain analyses three different tunnel geometric configurations are considered. In the first case a single tunnel analysis is carried out (ST case). In the second a twin tunnel analysis is carried out, where both tunnels are horizontally aligned (TH case). Finally in the third case twin tunnels are vertically and diagonally aligned (TVD case). A parametric study was performed for the above three cases varying the position of the tunnel axis (zo), pillar width (P), pillar depth (PD) as well as the position of the surface loaded area (W ). Figure 1 shows the parameters varied in this study. For the ST case (shown as a solid circle) zo varies. For the twin tunnel configuration (where the second tunnel is presented as a dotted circle) P and PD vary. In all cases the loaded area shifts from W 1 to W 6. Throughout this parametric study the dimensions of the domain (x, y), tunnel diameter (D), magnitude (400 kN/m) and area (W ) of the applied load were constant. Surface load was applied directly to the surface of the finite elements hence modelling a flexible footing. No interface elements were used to model the existence of any type of foundations or treatment of the ground prior to its loading.
