A Scale analysis of axisymmetric granular column collapses over a range of elevated gravitational accelerations

Granular flows can be found both in nature, as landslides, debris flows and rockfalls, and across a range of industries, such as food and pharmaceutical processing. In this research, we focus on the environmental setting, where the granular flow is typically complicated by the presence of water and a huge range of particle sizes present. These two factors greatly alter the scaling of these flows when creating laboratory prototypes.

One of the most simplistic and well researched laboratory scale representations of these phenomena is the collapse of an axisymmetric granular column. We will use this starting point to explore the effects of moisture, saturation and particle sizes ranging by orders of magnitude of 10^6. In order to physically represent the effects of fluid within a real debris flow at laboratory scale, we must artificially increase acceleration due to gravity, so that the g-dependent rates stay in balance despite physically much smaller flows.

It is planned to develop an axisymmetric granular column collapse experiment that will be able to be mounted to the geotechnical centrifuge located in the L2 building on University Park in order to conduct tests over a range of elevated gravitational accelerations.
The chief outcomes of the project are as follows:
To develop a comprehensive database of axisymmetric granular column collapse experiments, varying parameters; gravitational acceleration; saturation level; particle size and grading; sample aspect ratio.
To analyse pore pressure and image data from these experiments and compare with published dry column collapse data, and data from real debris flows.
Establish which dynamic processes determining flow outcomes are governed by which particle size ranges.
To implement these findings within simple analytical models and scalable numerical models.