Mesoscopic fracturing mechanism in sandstone: Influence of confining pressure unloading rate
Year: 2025
Type: article
Abstract: The rock mass damage and failure induced by underground coal resource exploitation are strongly influenced by the confining pressure unloading (CPU) rate. However, the impact of CPU rate as a sole variable remains inadequately understood. This study utilizes discrete element numerical tests to explore the influence of CPU rate on the mesoscopic fracturing mechanism of sandstone. Homogeneous three-dimensional models with consistent mesoscopic parameters and constant axial pressure are subjected to varying CPU rates. By isolating the CPU rate as the sole variable, macroscopic failure patterns, mesoscopic damage evolution, and energy density distributions are investigated. The numerical results are validated against existing physical experimental results, confirming the rationality of the discrete element model parameters. The results show that lower CPU rates induce multistage, sudden, and progressive failure, characterized by stepwise increases in energy density, more abrupt fractures, and enhanced mobilization of local load-bearing capacity. The defined medium CPU rate results in distinct physical responses, attributed to particle rearrangement driven by unloading rate. Particle displacement is identified as a quantitative indicator of rock damage. The results underscore the importance of isolating the CPU rate effect to improve the understanding of rock fracturing mechanisms and associated physical properties.
Language: English
Topic: Rock Mechanics and Modeling
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,000
Awards: G7615560614, G83819099
OpenAlex ID: W4408420748