Cross-Scale Analysis of Basalt Rock-Mass Deformation and Energy Evolution Based on In Situ Bearing Plate Tests and DEM Simulation

Reliable characterization of rock-mass deformability is essential for rock-supported infrastructure. This study combined six in situ rigid bearing plate tests with two-dimensional discrete element method (DEM) simulations implemented in Particle Flow Code (PFC2D) to investigate basalt deformation and energy evolution at the Gushui Hydropower Station. Five nested loading–unloading cycles reached 10.203 MPa. Mean deformation/elastic moduli were 15.402/22.236 GPa for weakly weathered basalt and 18.082/30.205 GPa for slightly weathered basalt; excluding fault-controlled E2-2 increased the weakly weathered means to 21.197/29.486 GPa. Three inverse-calibrated models reproduced the field paths with displacement root-mean-square errors of 0.090, 0.058, and 0.184 mm. Additional seed, particle-size, and domain-size calculations showed that contact strain energy was comparatively stable, whereas peak displacement, slip energy, and crack counts were realization- or boundary-dependent. The simulations therefore provide plausible, unit-thickness mechanism interpretations rather than unique three-dimensional reconstructions. Field stiffness and apparent dissipation are controlled jointly by matrix condition and local discontinuity geometry.