Squeezing Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 112

Figure 4.20 Case 5, principal normal stresses and plastic zone, supporting pressure of p r = 0.6 MPa at
30 days after excavation
Figure 4.21 shows the viscoplastic displacements at the tunnel's contour that are calcu-
lated for cases 3 and 5. In case 5 the viscoplastic displacements are considerably larger
than for case 4 (cf. Figs. 4.19 and 4.21). However, the radial displacements taking place
after closing the supporting ring in case 5 only amount to approx. 1 cm and thus can be
carried by a 30 cm thick shotcrete membrane without damages.