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Lookup NU author(s): Professor Stefano Utili
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
This paper investigates the characteristics of dynamic rock fragmentation and its influence onthe postfailure fragment trajectory. A series of numerical simulations by discrete element method (DEM)were performed for a simple rock block and slope geometry, where a particle agglomerate of prismatic shapeis released along a sliding plane and subsequently collides onto a flat horizontal plane at a sharp kink point.The rock block is modeled as an assembly of bonded spherical particles with fragmentation arising from bondbreakages. Bond strength and stiffness were calibrated against available experimental data. We analyzedhow dynamic fragmentation occurs at impact, together with the generated fragment size distributions andconsequently their runout for different slope topographies. It emerges that after impact, the verticalmomentum of the granular system decreases sharply to nil, while the horizontal momentum increasessuddenly and then decreases. The sudden boost of horizontal momentum can effectively facilitate thetransport of fragments along the bottom floor. The rock fragmentation intensity is associated with the inputenergy and increases quickly with the slope angle. Gentle slopes normally lead to long spreading distanceand large fragments, while steep slopes lead to high momentum boosts and impact forces, with efficient rockfragmentation and fine deposits. The fragment size decreases, while the fracture stress and fragment numberboth increase with the impact loading strain rate, supporting the experimental observations. The fragmentsize distributions can be well fitted by the Weibull’s distribution function.
Author(s): Zhao T, Crosta GB, Utili S, De Blasio FV
Publication type: Article
Publication status: Published
Journal: Journal of Geophysical Research: Earth Surface
Online publication date: 06/03/2017
Acceptance date: 02/03/2017
Date deposited: 22/04/2017
ISSN (print): 2169-9003
ISSN (electronic): 2169-9011
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