A Cavity Expansion Model for Normal Indentation in Jointed Rocks

ABSTRACT Cavity expansion models serve as a valuable analytical tool for investigating rock–tool interactions. However, the conventional assumption of intact rock conditions may limit their applicability to engineering practice, where jointed rock masses are prevalent. To address this gap, this study proposes a cavity‐expansion‐based model tailored for normal indentation in jointed rocks. The model explicitly incorporates distinct failure modes identified in numerical and experimental studies—namely, damage zone evolution and brittle fracture mechanisms. The mechanical behavior of jointed rock masses is captured through the Hoek–Brown failure criterion. The model validation shows good agreement between theoretical predictions and experimental data. A comprehensive parametric analysis further elucidates the key factors influencing rock fragmentation. Notably, jointed rock masses characterized by lower Geological Strength Index (GSI) values require lower initiation pressures to generate macroscopic fractures during indentation—a trend opposite to the strengthening effect of elevated confining pressure. The study establishes a quantitative relationship between rock strength properties (e.g., GSI, uniaxial compressive strength), cutting tool geometries, and confinement conditions, offering a novel framework for optimizing rock‐cutting tool interactions in jointed rock masses.