Empirical cutting tool wear prognosis for hydroshield TBM in soft ground

The wear of cutting tools is a major issue in tunneling with Hydroshield TBM in soft ground, because it is a common reason for unplanned downtime. The replacement of cutting tools requires access to the excavation chamber, which is only possible with hyperbaric works or at fixed positions with prearranged grout blocks. In order to improve predictability of the maintenance stops, an empirical prognosis model for the required maintenance stops for changing of cutting tools and the amount of tools was developed. Based on the new Soil Abrasivity Index (SAI), the model helps to estimate distances between maintenance stops and the required amount of cutting tools to be changed. The authors validated the prognosis model based on the original reference projects. The validation lead to an adaption of the prognosis process and individual correction factors in the model itself. The article therefore describes the updated prognosis model.