A 3D landslide analyses with constant mechanical parameters compared with the results of a probabilistic approach assuming selected heterogeneities at different spatial scales.

The aim of this paper is to compare the results of numerical analyses, related to an actual landslides (Roccamontepiano, Abruzzo, Italy), carried out assuming spatially constant mechanical parameters, with the correspondent results obtained including some selected heterogeneities at different scales. By laboratory tests, the values range of some important parameters of the soil materials, characterizing the selected situ and related to the assumed constitutive models, have been measured and evaluated. Then, FLAC-3D numerical analysis, assuming the averaged values of the parameters in each physical points of the geological system, has been elaborated. Parameters variability has been included in a second calculation, by the means of a method already proposed in literature, degrading the averaged numerical values in some way proportional to the standard deviations of the experimental measures obtained in laboratory. In all the previous calculations, however, spatial heterogeneities have been excluded. A large scale parameters variation, in particular with the depth, has been assumed. Then, a further analysis has been discussed considering the values of the parameters distributed randomly through the spatial grid, to take into consideration local variabilities and small scales. Finally the previous results have been compared with which has been obtained applying a probabilistic procedure, already proposed and discussed by the Authors in previous papers, carried out making several runs of the same numerical models, varying each time, in an automatic way, only the numerical realization of the parameters values whose ensemble was assumed belonging to a selected statistic. The comparison highlighted, for this kind of analyses, not only the obvious importance to include large variabilities, but also the less obvious importance of local inhomogeneities, in this case, around a deterministic trend of the mechanical parameters.