Effect of cutter sizes on the mechanical behaviour of cutting and predicting rock strength parameters

Cutter size is a key factor influencing rock failure modes, energy consumption, and cutting efficiency in tunnel excavation, mining, and related engineering applications. To investigate the effect of cutter sizes on cutting failure mechanisms of rock, this study establishes a mechanical and energy model describing the interaction between the cutter and rock. The real-time inversion model is proposed for predicting rock strength parameters. The digital cutting experiments were conducted on four types of rock using three cutter sizes of 10, 12, 14 mm. The dynamic influence mode and correlation of tool size on torque, thrust and specific cutting energy are emphatically explored. The results indicate that the cutting energy ratio measured by the 10 mm cutter is found to change the most with depth, with significant stress concentration. The 14 mm cutter had the lowest specific energy and produced the most stable variation curves for cohesion and internal friction angle over drilling time, with an average error less than 10% compared with the triaxial compression tests results. The coefficient of variation indicates that the predicted internal friction angle shows mostly highly stable, while cohesion shows general stability. The research will provide a theoretical basis for improving cutting efficiency and optimising real-time prediction of rock mechanical parameters.