SRK undertook a remote review of pit slope performance and performed design updates for three gold mines in the Middle East.
Due to the COVID-19 pandemic, a planned site visit to gather geotechnical data was cancelled. Instead, the client’s on-site team collected data from the iSite laser scanners which were then processed and analysed using Maptek’s PointStudio program. These data assisted with a review of slope performance of the current pits and a slope stability assessment and subsequent update of slope design.
SRK generated heat maps displaying the variation in bench face angle and berm width across multiple sections of each pit. The data were then processed to produce histograms of inter-ramp angle variability, as well as bench face angle and berm width, enabling visual interpretations of the condition of each pit and compliance with the approved slope design. The outputs were not only informative for the mine production team, but were also used to inform design recommendation changes in later slope stability assessments.
To assess slope stability, SRK selected thousands of exposed discontinuity surfaces from the high-resolution laser scans to generate data on discontinuity orientation, area, length and spacing. The use of laser scans enabled data to be generated from all benches of each pit, which is often not possible with on-site pit wall mapping. The datasets were then used in slope stability analysis using S-Block, a probabilistic program that calculates the berm widths required to retain a given percentage of expected failure volumes from slope benches. The slope performance was calibrated, including observed bench failure modes, using SBlock. This enabled determination of slope inter-ramp angles required to retain a minimum average of 80% of expected failed material in each bench. New geotechnical domains were subsequently created with updated slope design angles based on structural variability, enabling slope angles to be optimised for several domains across the three mines.
