Mechanical characteristics study of bimrocks with different cementation types from a microstructural perspective

In the evolving field of geotechnical engineering, the study of bimrocks (block-in-matrix rocks) presents unique challenges and opportunities. Based on laboratory uniaxial compression tests (UCTs) and their corresponding numerical simulations, this study delves into the intricate mechanics of bimrocks to enhance the understanding of these complex materials. Firstly, this study innovatively proposes a “masking” modeling method, which allows for the creation of numerical models of bimrocks with realistic shapes and breakable blocks based on the discrete element method (DEM). Furthermore, two indicators are introduced to characterize the type of cementation, demonstrating their strong correlation with the Volumetric Block Proportion (VBP) and block sizes. The experimental results indicate that the peak strength of bimrocks in UCTs shows a negative linear correlation with the number of block-matrix contacts, and this relationship is independent of the block size. Moreover, when the number of block-matrix contacts exceeds a certain threshold, the strain corresponding to the initial fracture significantly decreases. For similar bimrocks in field, these results have significant implications for predicting their mechanical strength and understanding the micromechanical deformation and failure mechanisms.