Analysis of Load Transfer and Penetration Mechanisms of Rock Fall Sand Cushion using 2D Discrete Element Method

Abstract

Cushioning materials, such as sand cushion placed on rock sheds, are attracting attention as construction devices that can effectively disperse and reduce rock fall energy before rocks collide with rock fall protection works. To support performance-based designs for rock fall countermeasures, the present study estimated rock fall behaviors and impact forces using 2D discrete element method (2D-DEM). As one of the typical behaviors, propagated impact force can exceed impact force of falling mass. We conducted two numerical analysis focused on this phenomenon; monotonic penetration test controlling under constant penetration velocity, and removing falling mass during penetration process for any time. In addition, the effects based on some condition of sand cushion, weight of falling mass and its velocity are examined from the view point of impact force-penetration relationship of sand cushion.

Loading rate dependence of granular cushion under rockfall impact and proposal of an analytical model for impact force estimation

“…A previous study has shown that the maximum value and duration of the impact force waveform of a falling mass are significant factors for generating the maximum transmitted impact force [12]. In addition, the shape of the collision surface of the falling mass strongly affects the impact force waveform.…”