Rock Excavation Tests for Mechanized Tunnelling – From TBM Perspective

TBM tunnelling is on great surge and many tunnelling projects today deploy or planning to deploy TBMs for speedy development. The sectors include of hydel, water, irrigation, sewer and metro projects in particular. Meeting varied geology and optimizing cutting performance need to go hand in hand. Considering the huge investment involved in deploying TBM and the associated risks, it is important that a TBM is selected and operated to its full capacity. Thus, suitability of TBM needs to be established on priority based on various geological and geophysical investigations coupled with laboratory tests. Most of the TBM performance prediction models, namely, NTH, CSM, RMi-NTH & QTBM, utilize various rock properties such as PPI, BWI, AVS, DRI, CLI, CAI, Specific Energy using linear cutting including petrography. This lecture discusses the specialized rock excavation tests that are carried out for enabling the selection of TBMs alongwith their use in performance prediction for a case. These facilities are available in only a few universities and institutes globally and in India at IIT(ISM) Dhanbad. Some of these facilities were recently designed, fabricated and are being used successfully for different projects. A few major facilities have received funding from CPRI, MoP under a joint R&D project of CSIR-CIMFR and IIT (ISM) paving way for indigenous testing.