Macro-meso failure mechanism and meso-scale evolution law of aeolian sand under engineering low-velocity impact

Understanding the dynamic failure behavior of soil under impact loading is a fundamental issue at the intersection of geotechnical engineering and terramechanics, and is essential for evaluating soil mechanical properties. However, the macro- and meso-scale response mechanisms of aeolian sand—a typical loose and cohesionless granular material—under high-velocity impact remain poorly understood. In this study, a dynamic impact testing apparatus integrated with high-speed photography and layered tracer particle techniques was developed to investigate the response characteristics of aeolian sand under low-velocity impact. The system enabled non-contact, high-precision tracking of internal particle motion throughout the entire failure process. Based on the observed particle movement, a zoning model of soil failure was established, consisting of an active zone, a transition zone, and a passive zone, which allowed for accurate identification of the internal deformation field and particle trajectories. A dynamic increase factor (DIF) was then introduced to modify the Mohr-Coulomb strength parameters, leading to the formulation of a velocity-dependent prediction model for maximum failure depth. The model predictions agree with experimental results to within 25%, confirming its validity. This study reveals the multi-scale dynamic failure mechanism of aeolian sand under impact loading, providing a theoretical foundation for the analysis of rapid wheel-soil interaction and the stability assessment of soft ground.