ABSTRACT
This chapter discusses the methods of excavation-hand, drill and blast, part-face road headers and full face tunnel boring machines. Over 260 km of tunnels have been excavated in the Sydney Region, since 1820, through rocks of the Wianamatta Group, Hawkesbury Sandstone and Narrabeen Formation. In Sydney, as in every major city in the world, continual population growth has and is making ever increasing demands on public utilities such as water supply, sewerage, drainage, electricity, gas, telecommunication and transport. Tunnelling methods are discussed under two distinct: the system used to develop the face; for example full face or part face and the method used to excavate the rock. The Important features of a dyke at tunnel level are degree of weathering and alteration, Width, Orientation, Joint spacing and degree of openess both in the dyke and in the surrounding country rock and Degree to which the country rock has been contact metamorphosed.
