The effect of clay swelling on crack generation in red stratum soft rock during water-induced disintegration: a matrix-based discrete element simulation study

Red stratum soft rock, which is prevalent in the deep backfill regions of southwest China, exhibits water-induced disintegration characteristics that significantly impact the bearing capacity and deformation behaviours of the foundation. To further examine its damage evolution after encountering water, a numerical simulation study was conducted utilising the particle discrete element method, based on immersion testing. The water-induced disintegration of soft rock is characterised by the expansion of clay mineral particles and a reduction in breaking force and residual strength coefficient. The findings indicate that the disintegration of red stratum soft rock can be categorised into three stages: Surface Erosion, Crack Development, and Crack Penetration. Natural cracks enhances permeability, while any increase in clay mineral content heightens hydration sensitivity. These factors decrease the slaking durability index, exacerbating failure and potentially altering the disintegration mode. The excellent simulation outcomes in this case indicate that the discrete element method effectively simulates the disintegration process of red stratum soft rock. The work thus enhances understanding of disintegration mechanisms and paves the way for further elucidation of the complex behaviours of soft rock.