Rockslide run-out prediction from distinct element analysis

Abstract

The Checkerboard Creek Rock Slope is located 1.5 km upstream of the Revelstoke Dam, which impounds the Columbia River in British Columbia, Canada. A detailed investigation completed in 2004 indicated that 2 to 3 million m³ of a rock slope was moving toward the reservoir at rate of approximately 10 mm/year. There was concern that, if a portion of the slow-moving rockslide accelerated rapidly into the reservoir, the resultant wave could overtop the dam. Distinct element analyses were carried out using UDEC to assess potential rockslide run-out characteristics (time histories of rock volume, thickness and velocity). A Voronoi tessellation scheme was used to create a rock fabric that allowed the moving rock slope to disaggregate. The range of slide behaviours was investigated by varying the following four factors: (1) type and amount of damping used to simulate the coefficient of restitution and, thus, energy loss during run-out; (2) friction angle of contacts during movement; (3) reservoir effects; and (4) rock fragment sizes. The results from these analyses were used as input to a physical wave model study.

Keywords:

• DEM analyses
• rockslide
• run-out
• rock-fall
• Voronoi tessellation
• numerical analysis
• UDEC

Acknowledgements

We would like to recognise the Dam Safety Office at BC Hydro and their external advisory board consisting of Drs Evert Hoek and Winfrith Riemer. We would also like to thank Tom Stewart, John Psutka, Doug Baker and Kathy Groves of BC Hydro and all those involved in the different aspects of this project. The physical model studies were conducted by Northwest Hydraulic Consultants Inc., North Vancouver.