Geotechnical considerations on TBM tunneling in rock mass

The industry deals with underground excavation has always shown a major interest in the use of Tunnel Boring Machine (TBM) that is full-face tool to excavate rock, because of their demonstrated capabilities in attaining high rates of advance in tunnel construction. TBM tunneling may differ from other tunneling methods such as; drill and blast, due to the high level of machine-rock interaction. Accurate estimates of machine performance are a crucial part of any mechanical tunneling. It is almost impossible for owners or contractors to make realistic evaluations of time and cost required for completing a project, without estimating the machine advancement. Intact rock properties, including uniaxial compressive strength, Brazilian tensile strength and brittleness of rock, and also rock mass properties such as orientation of discontinuities, with machine specifications could be used for investigating TBM performance in rock mass. This paper presents the results of some case histories in TBM tunneling, field and laboratory data processing together with recent improvement for estimating TBM performance in rock mass.