Abstract
Abstract. The fracturing and fragmentation of rock blocks are important phenomena that occur ubiquitously during the propagation of rock avalanches. Here, the movement of a rectangular rock block characterized by different joint sets along an upper sloped and lower horizontal plane is simulated using discrete element method (DEM) models. The pattern of the joint set allows the block to break along weak joint planes at the onset of fragmentation. With this design, the fracturing and fragmentation of the sliding rock block and their influences on the conversion and transmission of energy within the system are investigated. The results show that rock fragmentation can significantly alter the horizontal velocities and kinetic energies of fragments in the block system, accelerating the front sub-block while decelerating the rear sub-block. Such energy conversion and transmission between the front and rear sub-blocks are attributed to the accumulation and release of elastic strain energy caused by fragmentation. The energy transfer induced by fragmentation is more efficient than that induced by collision. Furthermore, positive relationships between the kinetic energy increase in the front sub-block induced by joint fracturing and the joint strength can be reliably fitted with linear functions, indicating that a rock mass with a higher joint strength experiences more-energetic fragmentation effects.
Highlights
Rock avalanches are characterized by extremely rapid, massive, flow-like motions of fragmented rock pieces originating from large rockslides or rockfalls that intensely experience disintegration and fragmentation during propagation (McSaveney and Davies, 2006; Hungr et al, 2014; Knapp and Krautblater, 2020)
We present the multiscale effects of rock fragmentation on rock mass movement, which should shed light on the dynamics of fragmenting rock masses, such as rock avalanches
The results show that rock fragmentation can greatly affect the energy variations in different parts of the rock mass
Summary
Rock avalanches are characterized by extremely rapid, massive, flow-like motions of fragmented rock pieces originating from large rockslides or rockfalls that intensely experience disintegration and fragmentation during propagation (McSaveney and Davies, 2006; Hungr et al, 2014; Knapp and Krautblater, 2020). Due to their extremely high mobility and destructiveness, these events, which are powerful enough to effectively shape mountainous landscapes (Lucas et al, 2014; Crosta et al, 2018; Francioni et al, 2019; von Wartburg et al, 2020), have caused severe casualties and economic losses in recent decades (Evans et al, 2007, 2009; Fan et al, 2017; Zhang et al, 2021; Shugar et al, 2021).
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