ABSTRACT
Tunnelling operations, apart from fixing the alignment and lining (which are the preliminary and final aspects of construction of a tunnel) comprise the under mentioned intermediate operations:
(a) Excavation, picking or blasting, the first being applicable to soft soils, the second for medium soils and very soft rocks and the last applicable to medium and hard rocks.
(b) Fixing temporary supports, as necessary.
(c) Removal of blasted/excavated material (mucking).
(d) Dressing, fixing permanent supports, followed by
(e) Final operation of lining, wherever necessary.
