Comparative Study of the Excavation Damage and Rockburst of the Deeply Buried Jinping II Diversion Tunnels Using a TBM and the Drilling-Blasting Method

Figure 8

Typical rock burst failures during the excavation process of 1^#∼4^# diversion tunnels: (a) extrusion and slabbing on the left arch foot of 1^# diversion tunnels (section k14 + 318∼328), (b) slabbing caused by stress concentration on the right arch foot of 4^# diversion tunnels (section k13 + 255∼270), (c) folding and belling on the left sidewall of 1^# diversion tunnels (section k14 + 789∼800), and (d) structure planes controlled failure on the right arch of 2^# diversion tunnels (section k14 + 580).

(a)

(b)

(c)

(d)