Squeezing Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 106

4.5.3 Influence of Residual Strength
Figure 4.14 shows the principal normal stresses and the extent of the plastic zone at
300 days after excavation which are calculated for case 2. Compared with case 1 the
plastic zone increases considerably. The vertical tangential stress at the unsupported
tunnel contour due to stress redistributions and viscoplastic behavior amounts to only
0.7 MPa corresponding to the reduced residual strength assumed for case 2 (cf. Fig. 4.10
and Table 4.2).
Figure 4.14 Case 2, principal normal stresses and plastic zone at 300 days after excavation