Computation of Slope Movements Initiated by Rain–Induced Shear Bands in Small–Scale Tests and In Situ

Computati onal investi gati ons of the complex fl ow and deformati on processes of natural slopes within a conti nuum-mechanical approach become more and more important due to an increasing number of slope movements and slope failure situati ons caused by heavy rainfall events. Numerical simulati ons of hillslopes can support the detecti on of various coupled failure mechanisms by simply changing the initi al and boundary conditi ons of the considered initi al-boundary-value problem. This procedure can contribute to a deeper and bett er understanding of various complex slope failure processes. In this study, the slope system, generally understood as an unsaturated soil, was considered as a triphasic material consisti ng of a soil skeleton, such as sand, a pore liquid, such as water, and a pore gas, such as air. The model was embedded in the well-founded theory of porous media, while numerical soluti ons were realized by use of the fi nite-element solver PANDAS. Proceeding from cohesionless sand as the basic soil under study, the material parameters governing the soil behavior were taken from triaxial experiments on dry sand specimens performed under homogeneous loading conditi ons, whereas the parameters governing the hydraulic behavior were determined by experiments on saturated soil specimens under nondeforming conditi ons. Furthermore, numerical investi gati ons of slope failure scenarios under diff erent loading conditi ons were compared with each other to fi nd out how the pore water infl uences the failure behavior. The computati ons reveal a strong coupling between the soil deformati on and the hydraulic behavior during failure processes. Finally, the fl ow and deformati on behavior of the natural Heumoes slope in Ebnit situated near Dornbirn in the eastern part of the Voralberg Alps (Austria) was studied qualitati vely. Unfortunately, this slope is sti ll in moti on.