Selection methodology for roadheader and tunnel boring machine in different geological conditions: national perspective plan project (CPRI) – a success story

A national perspective plan project was completed recently which reports the development of a selection methodology for roadheader and tunnel boring machines, the two principal technologies in tunnelling. This involved comprehensive studies at five major tunnelling projects in India where roadheader or tunnel boring machines were deployed. The data on performance of the machines was collected along with the intact rock and rockmass properties. Samples were tested for various specialised laboratory properties. Secondary data was also used in one of the cases. Various models of field penetration index, static and dynamic rock boreability index, and penetration rate were developed for roadheader and tunnel boring machines involving laboratory and field data including dynamic properties. The models were used to define the selection methodology of the machines in various rock formations. In addition to the above, major national rock cutting testing facilities, namely, linear cutting, brittleness and tool wear properties of rock/cutting tools, was developed that can prove to be of great help in defining rock properties vis-a-vis the selection method for forthcoming projects. This paper summarizes the achievements of the research conducted and facilities developed.