Influence of forest stands and root morphologies on hillslope stability

Forest plantations can help to reinforce soil and improve hillslope's stability against shallow landslides. Based on 3D finite element method implemented in SIMULIA software, this paper develops a 3D numerical simulation model to assess impact of forest's stands structure and 3D root system morphologies on hillslope's stability. A preliminary analysis is performed to assess the impact of different stand parameters and root morphologies on the slope's safety factor as well as on the volume of soil mobilized by a landslide. Regarding tree's root morphology, we found that the overall slope's stability mainly depends on the depth of root's system and on additional cohesion provided by the roots. Hence, tap-like block morphology provides the best overall stability improvement. Furthermore, among the stand parameters, inter-tree distance in the slope direction has the greatest influence on the slope's safety factor. The rectangular pattern of stand distribution exhibits the lowest inter-tree distance in the slope direction and significantly improves slope's stability. Finally, the volume of soil mobilized during a landslide shows noticeable variations through root block morphologies. However, for a given root morphology, the stand distribution does not cause significant differences in the volume of soil mobilized during a landslide.