Cutter force measurement on tunnel boring machines – Implementation at Koralm tunnel

• Disk cutting forces were measured successfully at Koralm tunnel in Austria.
• Peak forces are in the same order of magnitude at all positions and a multiple of average forces.
• Average forces decrease significantly from the center to the gauge area of the cutterhead.
• Forces correlate with geological features such as orientation of schistosity.

Loading of a disk cutter on tunnel boring machines (TBM) is usually estimated from global machine thrust. In order to be able to measure cutting forces of an individual disk cutter, a new measurement method was developed and published in a previous paper (Entacher et al., 2012). This study presents the implementation process of the measurement method at the first TBM of the Austrian Koralm tunnel. Results show that peak forces are a multiple of average forces and that the distribution of forces across the tunnel face can be very irregular. The occurring forces are in very good agreement with geological features of the tunnel face such as highly fractured zones and orientation of schistosity.