In classifying the rock slope, it is important to determine the characteristic controlling instability. The difficulties remain in deciding when too many variables in such a complex material. The objective of this paper is to identify parameters that control instability in the rock slope, which has been based on the extensive parametric study of rock slopes. Modelling was carried out using the Universal Discrete Element Code (UDEC), and the slopes are modelled in terms of the percent of strain. Then, the analytical results from UDEC were analysed using a statistical method called Analysis of Variance (ANOVA). This allowed a robust method of identifying the controlling factors governing rock slope stability.
From this study, it was found that discontinuity orientation was the most important parameter. This followed by water, slope angle, Volumetric Joint Count (Jv), Joint Roughness Coefficient (JRC), block shape and Joint Compressive Strength (JCS). The explanation is lies in the low stress levels in slope applications, as the blocks are free to move. The movement is along the inclined discontinuity surface, and the JCS is least significant since that the overriding of asperities is more common than shearing of the asperities. However, it should be noted that for JCS, even though it is the least significant factor, the parameter is still significant as indicated by ANOVA analysis.