Experimental and numerical study on rock breaking characteristics of TBM disc cutter under coupled static-dynamic loading

Abstract

Coupled static-dynamic loading is a promising technique for enhancing the rock-breaking efficiency of tunnel boring machines (TBMs) under hard rock conditions. This study investigates the effects of coupled static-dynamic loading on the rock-breaking characteristics of TBM disc cutters using scaled linear cutting tests and finite–discrete element method (FDEM) simulations. Scaled test results indicate that, compared to static loading, coupled static-dynamic loading reduces the cutting coefficient by up to 27 % and specific energy by up to 46 %. A validated FDEM model is developed to explore the influence of cutting penetration, speed, spacing, and impact force and frequency on cutting forces and rock fragmentation when using full-scale disc cutters. Numerical simulations reveal that specific energy decreases with increasing penetration, speed, and impact force up to an optimal threshold, beyond which efficiency declines. Too small a cutting spacing leads to excessive fragmentation, while overly large spacing results in incomplete breakage. High impact frequencies can induce repeated rock failure and reduce efficiency. These findings confirm the potential of coupled static-dynamic loading to substantially improve TBM rock breaking efficiency in hard rock environments and provides valuable guidance for the design and optimization of TBM cutters and operational parameters.