Investigation and testing for Norwegian hard rock TBM performance prediction

At the Norwegian University of Science and Technology, laboratory testing for predicting the drillability of percussive drilling has a long tradition. Today, the tests are most commonly used for predicting hard rock TBM performance. In the NTNU method, index testing of relatively small rock samples are used for defining the Drilling Rate Index (DRI), the Bit Wear Index (BWI) and the Cutter Life Index (CLI). For tunneling performance prediction in general, field mapping is of great importance, and for TBM performance prediction in particular, fracture mapping is crucial. In this paper the basic principles of laboratory testing and field investigations for performance prediction are described.