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Back-Analysis of Earthquake-triggered Las Palmas Tailings Dam Failure and Runout Processes

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The modelling approach for a landslide-type failure and runout assessment for a dry or partially unsaturated (dry stack) tailings storage facility is still evolving, mainly constrained by the scarce case history information. The Las Palmas tailings dam failure on 27 February 2010, triggered by the Mw 8.8 Chilean (Maule) earthquake, is a relatively well-documented case for a dry stack site that had been closed for over ten years. The survey photographs showed that the upper unsaturated tailings fractured as a series of blocks and were transported by a thin layer of saturated tailings underneath. The tailings travelled for about 400 m and inundated an area of about 8 ha downstream. To develop the procedures of modelling the failure and runout processes of a mixture of saturated and unsaturated tailings, the Las Palmas TSF failure was interpreted with Iverson’s mixture theory and backanalysed with a friction-based Coulomb model. The modelling results could reasonably match the tailings runout extent presented in the investigation reports. The back-calculated friction angle indicated that the saturated tailings with relatively high pore pressure dominated the runout distance. However, further research is required to answer the question of how the friction angle could vary with the pore pressure dissipation during the runout and deposition processes.

Text

2023-12-08

Attribution-ShareAlike 4.0 International

http://hdl.handle.net/2429/86844

Unreviewed

http://creativecommons.org/licenses/by-sa/4.0/