266 Rock reinforcement and rock support
Figure 16.1 Workers awaiting the breakthrough of the south seaward running tunnel
TBM into the UK undersea shotcreted crossover cavern in the Channel Tunnel (from
Wilson, 1991).
Figure 16.2 Use of precast lining segments in the UK north landward running tunnel of
the Channel Tunnel showing spoil wagons running on temporary tracks (from Wilson,
1991).
tion, to ensure that the rock excavation retains its mechanical integrity.
Thus, the need to reinforce and support the rock mass surrounding an
excavation and the method by which this can be achieved successfully de-
pend on two key factors: the purpose of the excavation; and the concept