Investigation of basal friction effects on impact force from a granular sliding mass to a rigid obstruction

摘要

Understanding the behavior of rapid granular flow and quantifying the impact force from a granular sliding mass on a rigid obstruction provide useful information for risk assessment and engineering design against rapid flow-like landslides. Basal friction affects the governing mechanisms of rapid granular flow and consequently influences the impact force. This paper presents an experimental and analytical investigation on the effects of basal friction on flow front velocity and impact force from a granular sliding mass to a rigid obstruction. For the experimental investigation, the results of a series of 2-D flume tests with two different basal friction conditions at different inclination angles, sliding distances, and initial relative densities are presented and discussed. It is observed that increasing the basal friction angle induces more shearing within the sand mass and results in a more dominant spreading mechanism, a shallower flow profile, a lower flow front velocity, and a smaller dynamic impact force. For the analytical investigation, the static and dynamic force components are investigated individually and a method for calculating these forces is presented. In this approach, the static force is calculated using the limit equilibrium method and the dynamic force is calculated by considering the reflection of compression shock waves due to impact. This approach allows the material stiffness to be taken into account in the dynamic force calculation. Adding the static and dynamic force components, the instant value of the total impact force can be calculated and an excellent agreement is observed between the calculated and measured impact forces.