Three-dimensional refined discrete element numerical modeling method and its application for reef limestone based on digital core technology

The increasing scale of reef engineering construction has heightened the importance of understanding reef limestone’s mechanical properties in load-bearing strata. High-precision CT scanning provided digital core data, enabling precise characterization of pore-matrix structures through multi-level filtering and adaptive threshold segmentation. To enhance spatial mapping accuracy and computational efficiency in high-resolution modeling, we developed a three-dimensional refined discrete element method incorporating BallTree algorithm and two-level Euclidean distance logical filtering. The model was validated through pore characteristic comparison and mechanical testing before conducting systematic uniaxial compression simulations. Analysis revealed that shallow weakly-cemented compact reef limestone exhibits vesicular and banded pores, demonstrating microscopic heterogeneity alongside macroscopic homogeneity. Under uniaxial loading, the limestone undergoes five distinct stages: pore compaction, linear elasticity, crack propagation, peak failure, and residual strength. Stress transmission occurs preferentially along the 45° direction, governing crack development. The failure process initiates with tensile cracking and evolves into a combined tensile-shear failure mode. Energy analysis indicates that elastic strain energy dominates storage, while sliding friction heat represents the primary dissipation mechanism during failure. This study integrates digital core with numerical simulation to elucidate the relationship between pore structure and failure evolution in reef limestone, offering new perspectives on deformation and failure mechanisms in porous rocks.