Data from: The retard-boost effect of fragmentation in rock avalanches

This study presents a micro-mechanical numerical investigation into the
fundamental aspects of progressive fragmentation and its effects on rock
avalanche dynamics. The simulations involve breakable rock assemblies that
are released along an inclined plane and subsequently collide onto a
horizontal surface. A discrete-continuous numerical model is adopted to
effectively capture progressive particle breakage and complex
interparticle interactions. By incorporating variations in fracture
mechanics parameters, the model systematically evaluates the influence of
progressive grain fragmentation on rock avalanche dynamics. A multi-layer
analysis method and the interlayer transmitting coefficient is proposed to
analyze the temporal and spatial kinematics, stress distribution and the
ongoing particle size reduction process. The results indicate that grain
fragmentation significantly influences rock avalanche motion, identified
as the "retard-boost" effect in this study. At low fragmentation
degree, densely packed rock particles exhibit an interlayer transmitting
effect, with kinematic energy dissipation primarily resulting from grain
breakage. Conversely, full mobilization of rock fragmentation from the
base upwards enhances flow mobility by reducing basal friction through the
agitation of fragments. The findings indicate a competition between
positive feedback, which enhances rock avalanche mobility at high
fragmentation levels, and negative feedback, which results in energy
dissipation at low fragmentation levels, with the predominance of these
effects varying according to the degree of fragmentation.