Squeezing Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 108

Figure 4.16 Case 3, principal normal stresses and plastic zone at 300 days after excavation
Figure 4.17 shows the viscoplastic displacements at the tunnel's contour that are calcu-
lated for cases 1 and 3. In case 3 the viscoplastic displacements are greater than 1 m at
the roof and the sidewalls of the tunnel and do not converge at 300 days after excava-
tion. Thus, a state of equilibrium cannot be achieved without a support.