*Tunnels DOI: http://dx.doi.org/10.5772/intechopen.109608*

many uncertainties in defining the rock. Most of the time, such approaches give results on a homogeneous medium, but in a complex situation, they should be evaluated with numerical analysis.

In addition to empirical methods, closed-form solutions are used in the determination of tunnel support systems. Closed-form solutions calculate the plastic behaviour of the rock mass and determine the deformations that occur according to the support pressures. The interaction of the ground and support systems is revealed by drawing the ground interaction curve and support interaction curves in the tunnel.

The assumptions made in the analysis are;

