At AGEC we’ve been involved in many back-analyses of landslides and slope failures (check out some useful papers in our downloads section). Invariably, there are many processes involved in a slope stability failure but it is common that a localised specific mechanism will be governing. It is for this reason that we, at AGEC, while fans of probabilistic oversight on slope stability for asset maintenance, always recommend a site walkover and geomorphological study of the asset by an experienced engineer.
The experienced eye will pick up on the localised factor that contributes to instability which may be missed in a probabilistic or deterministic analysis despite best efforts. Appropriately, the paper above goes on to state that designers should consider the stability of the slope as a whole system rather than examining the critical slip plane in isolation –this is to account, for example, for a rainfall-induced reduction in near-surface suctions giving rise to a preferential shallow slip.
In summary, we love the detailed mathematics and novel approach outlined in the paper which would have real applications in practice, particularly for extensive geotechnical asset management but we would always advocate putting experienced eyes on the asset.