Study of the uniaxial compressive strength of water-sensitive carbonaceous mudstones based on the single-particle crushing strength

Fundamental research on single-particle breaking and the uniaxial compressive strength (UCS) of carbonaceous mudstone aggregates at different water contents was carried out to investigate the relationship between the single-particle crushing strength and UCS. Based on elasticity theory and the superposition principle, a shape factor α was introduced to propose a mechanical model of crushing strength that considers the effect of particle shape, and a model was developed to predict the UCS of soil–rock aggregates (SRAs) from the single-particle crushing strength. The test conditions were set to a dry state and a water content of 6–10% according to the water content test results for carbonaceous mudstones with different dimensions. The experimental results reveal that the shape factor α of particles ranges from 0.44 to 1.0 when the crushing strength model is applied considering shape effects. As the water content increases, the crushing strength of the carbonaceous mudstone decreases linearly, the effect of the dimension is significant, and the crushing strength decreases by 7.4% in the dry state and by 41.02% at a water content of 10%. The UCS model considering the single-particle crushing strength accurately reflects the variation of the UCS with the volume block proportion (VBP) and provides a new approach for predicting the UCS.