<p>This paper assesses the coupled effects of particle shape and water saturation on the mechanical performance of granular materials subjected to impact loading. Dynamic compression experiments at high strain rate (750&#xa0;s⁻¹–950&#xa0;s⁻¹) are performed on dry and wet glass particles with a porosity of 0.48 and different initial aggregate shape via the split Hopkinson bar device. Particle size and shape parameters are quantitatively characterized using high-resolution micro-CT imaging with a 6&#xa0;μm spatial resolution. Multi-scale experimental evidence demonstrates that particle shape has a more dominant influence on the mechanical behaviours of granular media than the saturation condition. Specifically, the fragmentation and subsequent particle arrangement are notably shape dependent, with rounded particles tending to produce more angular fragments and irregular particles generating more spherical fragments. Additionally, while particle saturation primarily affects the extent of breakage rather than altering the fundamental mechanisms of breakage, it significantly enhances the degree of fragmentation by reducing inter-particle friction and modifying stress distributions. The study further reveals that the particle breakage index, which quantifies the extent of fragmentation, shows a stronger correlation with its characteristic particle size under impact conditions. Particle melting has been observed in both dry and saturated conditions. The coevolving trends of particle size and shape reveal two mechanisms driving changes in particle shape: fracturing-activated and melting-activated processes. These findings highlight the complex interplay between particle shape and moisture content in governing granular material behaviours, emphasizing the need for detailed understanding of these factors to accurately predict and optimize material performance in various engineering applications.</p>