The analysis is a companion example of “3D Analysis of a Composite Support System for a Horseshoe Shaped Tunnel” where the exact same tunnel has been analyzed. The tunnel is excavated using the conventional method with full-face excavation and a 1 m advancement step. The temporary support system consists of a 20 cm shotcrete lining along with a series of cable bolts.

The aim of this exercise is to construct and run a 2D FE model corresponding to the same excavation process:

• Firstly, full excavation of the unreinforced rock mass will be considered the results of which will be used to evaluate the maximum plastic radius along with the 3D-equivalent deconfinement level as required in the so-called the convergence-confinement method.
• In the second part, the convergence-confinement method will be applied using the equivalent deconfinement level obtained in the first part. Once the desired level of deconfinement is obtained the structural elements will be activated. This will enable the calculation of structural forces in shotcrete lining and within the rock bolts along with the final tunnel convergence values. All calculated results will be ultimately compared with those obtained in 3D.