Review of the stability analyses for slide-head toppling failure mechanisms: a different perspective

Slide-head toppling is a secondary toppling failure involving toppling of rock blocks at the top of a slope and sliding of blocks around the toe of the slope. The toppling or sliding is largely dependent on the width to height ratio of the blocks as well as the location of the center of gravity for the individual columnar blocks on the slope (either within or outside the block). Over the years, a number of methods have been proposed for analyzing slide-head toppling failure and these include analytical (limit equilibrium), numerical, physical modelling as well as the use of design charts. However, recent observations of the counter-tilting of the orientation of the failure plane of failure within the rockmass have affected the robustness of these methods of analyses for slide-head toppling failure. Another limitation of the preceding analysis methods is that they do not take into account other external loading conditions. Although a modified analytical approach has been proposed incorporating the counter-tilting of the orientation of the failure plane, it still needs to be validated for effective use. Therefore, among others, once the modified model has been validated, it needs to undergo further modifications to incorporate other external loading conditions such as surcharge loads from overlying material, dynamic loading (blast induced), water (rainfall and groundwater), as well as development of design charts for preliminary slope stability design of rock slopes in as far as slide-head toppling failure is concerned.