The additional cohesion exercised by vegetation roots (cr) provides an important contribution to the slope stability.This study proposes a methodology for estimating the cr term in a hillslope landslide analysis within a coupledecohydrological-stability model. The coupled model simulates the spatial distribution and temporal dynamics ofthe Factor of Safety (FS) as a function of soil moisture dynamics, by taking into account the hydrological effectsof vegetation through the root water uptaking.The additional mechanical root cohesion is estimated in a Fiber Bundle Model framework that allows for theevaluation of the root strength as a function of stress-strain relationships of populations of fibers. The use of sucha model requires the knowledge of the root architecture to evaluate the additional reinforcement from each rootdiameter class. The root architecture is reproduced by fitting a probability density function to the distribution ofthe number of roots with depth, within a branching topology scheme based on the Leonardo’s rule that gives anestimation of the root diameters. The methodology has been tested in a simple synthetic hillslope with differentconfigurations of vegetation types, i.e. tree and shrubs, and soil types, i.e. clay and loam. Parameters of thetopological model have been calibrated through observed depth profiles of root number, diameters and area of twospecies representative of the two considered vegetation types.Preliminary results demonstrated the high flexibility of the topological model here used, with consistent andpromising outcoms in terms of root cohesion, significantly lower than values obtained with the more popularWu/Waldron model. The simple case study highlighted the importance of both the root mechanical resistanceand the root interactions with the main eco-hydrological processes. The hydrological effect of roots can be moresignificant than the mechanical one, especially for tree species on clayey soils. The root cohesion effect becomesparticularly significant at low values of FS (i.e. 1, failure proximity), especially for tree species. Furtherimprovements of the work could take into account the weight of the plants, here neglected.
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2015|