The expert system Tunnex provides an interactive consultation on the excavation of tunnels through rock. As a first step it examines the interdependence between rock quality, unsupported span and stand time of the excavation (the “O-S-T” relationship) to determine the likely overall behavior of tunnels of different diameters, the time available for installation of supports, and the optimum choice of tunnel diameter, single or twin tunnels when such choice is available. Stand-time considerations also guide decisions on the deed or otherwise for a pilot heading or staged excavation. Tunnex guides the user in forecasting primary and secondary support requirements and in the choice between drill-and-blast versus full-face boring alternatives. It provides blast design and TBM design and performance data to match any given set of ground conditions. It predicts rates of advance and requirements for muck handling and disposal. The expert system places at the disposal of the designer a broad range of well-know and well-established empirical correlations based on RMR, Q and other systems of ground classification as well as introducing some newly established correlations such as TBM performance data based on statistics provided by the Robbins Company. An example compares Tunnex predictions with those obtained without the benefit of an expert system. The predictions are closely similar, yet the Tunnex predictions were obtained much more quickly at a reduced cost. Evidently, machine intelligence tends to be less versatile than the human kind but can be useful tool when properly applied
