Improvement of disk cutters performance in the excavation of small tunnels

The problems arising in tunnel excavation into hard rocks with the use of mechanical tools consist chiefly in a slow advance rate accompanied by an intensive wear due to the toughness and abrasiveness of the rock. In order to allow the further extension of mechanical excavation beyond the limits of the presently available technology, the assistance of waterjet aiming at improving the performance of the equipment while reducing the wear rate of the tools has been recognised as one of the most interesting technical solutions. The paper illustrates the results obtained at the Waterjet Laboratory of the University of Cagliari on a medium-hard rock using a carrousel-type testing machine capable of reproducing the conditions of rock-tool interaction encountered in the industrial practice and discusses the prospects of the technological advances under development. The results are interpreted on the basis of a numerical model capable of describing the interactions involved.