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Abstract Toppling is an important failure mode of rock slopes，which is dominantly controlled by the discontinuities existing in the slopes. Adopting the concept of the transfer coefficient，an analytical approach of toppling failure of rock slopes due to earthquakes is developed based on the corresponding geomechanical model，and influence of seismic actions on the toppling stability of rock slopes is analyzed. The variables of every rock block potential to toppling，used for stability analysis of a rock slope，are expressed by the geomechanical parameters of the slope and the serial number of the blocks，and hence have uniform expressions. Consequently，the method is easily implemented using a Microsoft Excel spreadsheet. An idealized example is analyzed adopting the Excel procedure. The results show that the failure mode of a rock slope，such as sliding or toppling，depends on the relationship between the seismic influence coefficient and its critical value which is determined by the direction of the seismic force，the dip angle and the friction angle of the slightly dipping discontinuities. The rock slope is potential to topple if the seismic influence coefficient is less than the critical value，or it will slide. It is also indicated that the toppling stability of rock slopes increases slightly with the angle of the seismic force with respect to the horizontal plane rising but descends markedly with the seismic coefficient increasing.
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Received: 31 December 2009
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