Effect of ice content on the interaction between rock–ice avalanche and rigid barrier: Physical and numerical modelling

Abstract

Rock–ice avalanches that occur in cold alpine regions often cause widespread devastation because of their high mobility and massive destructive potential. The protection structure designs are often empirical because of the current poor understanding of the impact mechanisms between rock–ice avalanches and rigid barriers. In this study, a series of small-scale flume tests were conducted to investigate the effect of ice content on the flow behavior and the impact dynamics on a rigid barrier. The experimental results were used to calibrate numerical simulations using the discrete element method. Results reveal that the normalized peak impact force and runup height increase with increasing ice content, while the bottom shear stress decreases. Additionally, particle segregation occurs in both the vertical and flow directions during the flow process—ice particles tend to segregate upward and forward and the overall degree of segregation peaks when the ice content is 40%. Both proportions of contact number and impact force on the rigid barrier contributed by the ice are larger than the initial ice content. This study helps reveal the influence of ice as a special component on the mobility and impact mechanisms of rock–ice avalanches and should improve rock–ice avalanche hazard assessments.