Tool wear analysis of pressurized face TBM drives in the glacial geology of the Pacific Northwest

For underground construction projects in the United States and Canada it is standard procedure to use a Geotechnical Baseline Report (GBR) to contractually define subsoil conditions. The GBR sets baselines based on which tunneling contractors develop bids and plan the works. Baseline values for soil abrasiveness are a focus especially where drives with pressurized-face Tunnel Boring Machines (TBM) beneath the groundwater table and in unstable face conditions require changing the cutterhead tools under hyperbaric conditions or in pre-constructed safe havens.
Several laboratory procedures exist that can be used for providing soil abrasiveness baselines in the context of the GBR. However, none of them cover all the soil characteristics that are relevant in causing tool wear. Also, other factors need to be considered for wear rate prediction. Analyzing the performance of previous TBM drives is a proven way to gain insight into the wear system behavior. This paper presents correlation analyses of geotechnical conditions, TBM operational data, and tool wear measurements from several TBM drives in the metropolitan areas of Seattle and Vancouver, B.C. These drives with earth pressure balance and slurry TBMs include various tool types and were conducted in glacial and interglacial deposits that are considered highly abrasive.