TUNNELLING TRIALS IN CHALK: ROCK CUTTING EXPERIMENTS

This report presents the results of the performance of arrangements of drag picks and disc cutters cutting through Lower Chalk during the tunnelling trials at Chinnor, Oxfordshire. Power changes produced by varying the cutter tool type and arrangement on the machinehead were recorded and plotted against cutter tool and machine variables. The depth of cut and cutting to relief were found to be the major influences on the efficiency of cutting with both types of cutters. The implications of the trials are that cutter arrangements should be adaptable to rock conditions and that the fitting of simple intrumentation to record the power used in cutting would enable the best operational depth of cut to be identified. /Author/