Finite Element Method (FEM) - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 272

Figure 10.46 Vertical displacements of the rock mass along vertical sections and the vault (Wittke 1990)
Figure 10.47 Stress resultants in the shotcrete (Wittke 1990)
This leads to a high normal thrust in the shotcrete membrane, resulting in punching
of the support's foot into the rock mass. In addition, the load resulting from the over-
burden can increase the bending moment at the tunnel's roof to such an extent that a
flexural failure of the membrane occurs in this area. Depending on the in-situ stress
state and the parameters of the rock mass a combination of these two failure modes is
also possible (Fig. 10.48, right).