Numerical Study on the Influence of Cavity Geometry on Rock Materials Under Uniaxial Compression

Roadway cross-sectional geometry dominates surrounding rock deformation and failure, yet most existing numerical studies adopt oversimplified ideal cavities rather than practical coal mine roadway profiles, lacking systematic comparisons of real engineering section shapes. This work aims to reveal how practical cavity geometries alter rock mechanical behaviors and fracture mechanisms under uniaxial compression. Twelve equal-area cavity models corresponding to four common underground coal mine roadway types (circular, arched, rectangular, trapezoidal) were constructed, and two-dimensional discrete element method (DEM) uniaxial compression simulations were performed. The results indicate that uniaxial compressive strength and elastic modulus continuously decrease as cavity shapes shift from smooth circular arcs to angular asymmetric profiles, with degradation aggravated by increasing sharp corners; cavity geometry exerts limited influence on Poisson’s ratio but enlarges surrounding rock radial displacement at sharp edges. Angular cavities trigger severe coupled tensile–compressive–shear stress concentration, advance microcrack nucleation and expansion, and generate broader X-type conjugate shear bands, significantly weakening rock bearing capacity. This study clarifies the mesoscopic stress evolution law of rock around roadways, offering theoretical support for roadway section optimization and surrounding rock disaster prevention in underground engineering.