Summary of Modelling Safety Factors of Slope Stability in A Tar-Sand Quarry: A Case Study
Keywords:Dahomey Basin, Geotechnical Characterization, Open-Pit Mining, Tar Sand
This research studies the importance of slope stability during open-pit mining of tar sand within the Dahomey basin, Southwest Nigeria. It involved the geotechnical characterization of the layers of Laterites and Alluvium which it underlies. In addition, SLOPE/W software of the GeoStudio package was utilized for deducing and modeling the bench face angles which had higher safety factors, through the Morgenstern Price method of slices. It was discovered that the lateritic soil layer possessed higher values of unit weight, cohesion and internal frictional angle than those of the Alluvial Sand layer. Factors of safety were generated for bench face angles ranging from 10o to 90o at 1m, 4m and above 40m groundwater levels; over a 10m bench width and 6m bench height. However, for heavy equipment, a bench width of 20m and height of 6m were assumed. This resulted in factors of safety varying between 3.58 and 1.73 for bench face angles between 10o and 30o during higher precipitation (and water tables). Thus, this suggests that stable slopes predominate at bench face angles of 10o to 30o. This can be further enhanced when sufficient drainage systems are constructed.
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