Evaluation of TBM Cutter Wear in Naghadeh Water Conveyance Tunnel and Developing a New Prediction Model

Replacing worn disc cutters in a tunnel boring machine (TBM) operation is a time-consuming and expensive process. This article presents the study of disc cutter wear rate during the excavation of 36 km Naqadeh water conveyance tunnel with a diameter of 6.325 m. The construction of this tunnel in northwest Iran has been recently completed. The geological setting of the tunnel consists of variable lithology, including limestone, shale, granite, and granodiorite units. Field data were collected and analyzed from TBM tunneling of 9.5 km of the tunnel. The analysis was performed by incorporating the types of wear and comparing the accuracy of traditional cutter wear prediction models. The new model was developed using statistical analysis of the observed cutter wear in this project. The validity of the proposed model was evaluated using the excavation data for the following 2 km of the tunnel. The model developed in this study allows estimating wear rate and cutter life using common rock characterization parameters such as the Cerchar abrasivity index (CAI) and the uniaxial compressive strength (UCS).