This paper summarises a cost optimisation procedure by minimising the
total drill metres and the overbreak that occurs in tunnel excavation in
medium strength rock (uniaxial compressive strength <80 mpa). the cost>
optimisation approach discussed here is an alternative interpretation of
the concept of rock fragmentation through seismic waves (Grand, 1980).
The proposed practice is an alternative approach to smooth blasting
techniques employed in tunnel excavation, since this approach reduces
overbreak and speeds up the excavation. This approach was successfully
employed in derivation, energy, and grouting tunnel excavations of
Bekme Dam Project. The on-site experience and the points that should be taken into account
in practice are given in the conclusions. The proposed practice was
employed in strong rock conditions (calcareous limestone) at Diyarbakir
irrigation tunnels in Turkey with a very limited success.