UBC Theses and Dissertations

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UBC Theses and Dissertations

Development of an early warning time-of-failure analysis methodology for open pit mine slopes utilizing the spatial distribution of ground-based radar monitoring data Dick, Graham John

Abstract

Slope surface deformation monitoring in open pit mines is an essential component of day-to-day operations, playing a key role in assisting mine operators in maintaining safety and production schedules. The introduction of ground-based radar within the past decade to complement conventional geodetic monitoring programs provides near real-time deformation measurements over a broad coverage area; this allows geotechnical engineers to observe the distribution of pit wall movements and their progression over time. However, when a slope deformation alarm and/or accelerating deformation trend is observed in the radar measurements, common practice is to arbitrarily select a single or small cluster of pixels for analysis rather than following a systematic procedure that utilizes the full coverage. In addition, the absence of a methodical means of efficiently carrying out “Time-of-Failure” (TOF) analyses in real time can limit the effectiveness of the early warning, pressuring the geotechnical engineer to provide action response recommendations based on a partial and/or subjective assessment. This thesis presents a new systematic multi-pixel selection technique termed the “percent deformation method” where a benchmark pixel is methodically chosen within the deforming slope and multiple surrounding pixels are selected based on a percentage of the benchmark deformation. The percent deformation method was applied to eight slope failures captured by GroundProbe Slope Stability Radar (SSR) and detailed back-analyses conducted for each case using both the inverse-velocity and the SLO TOF analysis methods. The percent deformation multi-pixel selection technique was then incorporated into a newly proposed real-time TOF analysis procedure designed for use with ground-based radar measurements. The utilization of the percent deformation method in the proposed real-time TOF analysis methodology gives more reliable results than current practice by providing recommendations for pixel selections, data filtering, where and how to undertake TOF analyses, and presenting TOF results in real time. It is hoped that the addition of a more rigorous, methodical treatment of radar monitoring data when faced with a critical slope instability will reduce uncertainty and increase confidence in any trigger action response decisions, helping to ensure a safer work environment.

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