Stability Analysis of an Over-tilted Slope in a Granite Quarry: The Role of Joint Spacing

This paper presents the case study of a stability analysis of an over-tilted (inverse) slope in an ornamental granite quarry. Based on traditional small quarrying practices and due to space constraints, the SW slope was carved following the occurrences of highly persistent joints that were dipping around 80° counter-slope. Experience dictates that this sort of slopes tends to be unstable, at least in case of average to low quality rock masses. In this way, a stability analysis was due to analyze slope stability. The good quality granite rock mass in the slope was characterized, joint data was recorded and laboratory testing was done to estimate the main significant parameters involved in the study and the geometry of the slope. A stability analysis of the slope was performed by means of the calculations of safety factors against toppling. These calculations have been done contemplating various possibilities regarding the occurrence of joints and its spacing, which was found to be the most relevant parameter controlling stability.