Triggering Mechanisms and Stabilization of a Massive Pit Slope Failure

Abstract

The 2013 Bingham Canyon slope failure was probably the largest non-volcanic landslide in NorthAmerican history. Because it took place in an active mine with substantial monitoring systemsalready in place, its geological setting and progress to failure are better understood than mostlandslides. The simple mechanics of the landslide make it relatively easy to analyze usingsoftware.This paper presents the results of two-dimensional slope stability analysis on the BinghamCanyon landslide. Even with a highly simplified model, the results generally agreed with eventsat the mine. The instabilities were predicted accurately, down to the two separate slope failures.After analyzing the failure as it occurred, the model was used to estimate properties of the slideand assess stabilization techniques. Back-calculated material properties agreed fairly well withmeasured material properties, although only one sample had been available to test.Stabilization techniques tested included dewatering, reinforcement, and adjusting the slopegeometry. Dewatering was effective, but not sufficient to stabilize the slope, and for a landslideof this size reinforcement was impractical. Removing material from the top of the landslide wasjudged viable for short-term stabilization, and while expensive regrading the slope angle was theonly method likely to be effective in the long term. Of the potential triggers studied, a change inpore water pressure was the most probable, although since the landslide was preceded by along period of slow motion it did not necessarily have a single trigger.