Numerical and experimental analysis of contact pressure in rock-disc cutter interaction using displacement discontinuity method and digital image correlation

Accurately predicting contact pressure distribution in rock-disc cutter interaction is crucial for optimizing tunnel boring machine (TBM) performance. This study presents a numerical and experimental investigation of contact pressure using the Higher-Order Displacement Discontinuity Method (HODDM) and Digital Image Correlation (DIC). The numerical model was developed to analyze stress and strain distributions under varying cutter force conditions, and its results were validated through controlled experimental testing using a linear cutting simulator. The numerical analysis reveals that pressure distribution follows a downward parabolic trend, with peak values concentrated in the central contact zone. This trend was also confirmed from experimental DIC measurements. The study further investigates the influence of the rotational-to-normal force ratio (F_r/F_n) on stress concentration, showing that increasing this ratio amplifies peak pressure and alters crack propagation patterns. Additionally, the proposed FWxM criterion quantifies pressure distribution zones, demonstrating that higher F_r/F_n ratios lead to a broader pressure spread beneath the cutter, potentially improving rock fragmentation efficiency. These findings enhance the understanding of rock fracturing mechanisms and provide a validated approach for predicting cutter forces, aiding in TBM cutter design optimization. The results indicate that accurate pressure distribution modeling can contribute to reducing cutter wear and enhancing excavation efficiency in hard rock tunneling.