VGeST - Virtual Geoscience Simulation Tools

Rock slide avalanche

This research was undertaken by Dr. Jiansheng Xiang at Imperial College under the direction of  Dr. J-P Latham.

The figure shows a 60m high rock slope with a wide valley and a massive rock block perched on a 45 degree slope.  The block is restrained only by basal fiction and with μ = 0.95  it begins to slide.

Strong rock sliding (top) Weak rock sliding (bottom)

Stress Cracks
Stress Cracks

Heterogeneous strains during sliding lead to fracture and fragmentation. The avalanche process is found to be very different for the two cases modelled where the tensile strength is set to 5MPa (strong rock) and 1MPa (weak rock). The stress fluctuations and cracking are shown side by side for each case. The comminution leads to a much wider size distribution for the stronger rock as large boulders remain on the valley floor.

Strong rock sliding (full valley), stress
Weak rock sliding (full valley), stress

The entire avalanche process with fragmenting boulders strewn across the valley floor, seen in the videos, lasts about 15 seconds in real time.

References

Xiang, J., Latham, J.P., Munjiza, A., Mindel., J. 2008. Applications of the combined finite-discrete element method. Proceedings, Beijing DEM’08. p223-231.

Munjiza, A., Andrews, K.R.F., White, J.K. 1999. Combined single and smeared crack model in combined finite-discrete element analysis. International Journal for Numerical Methods in Engineering, 44, 41-57.