The bottom wedge is fully stable.The wedge numbers 4 and 8 areassumed as potential failure due to low factor of safety (FS b 3). Therefore, to stabilize these wedge blocks, grouted rock bolts of 32 mm diameter with 4.4 m length and 100 mm thickness shotcrete were installed during the excavation (Figure 6b). The details of the wedge information with unsupported and supported conditions are given in Fig. 7 and Table 3. This analysis helps to control overbreak in tunnels by drilling and blasting methods (cf. Anbalagan et al., 2003 for half tunnels).