Three-Dimensional Analysis of a Landslide Process on a Slope in Carpathian Flysch

The paper presents a 3D (spatial) analysis of deformation processes in the landslide slope Bystrzyca in Szymbark near Gorlice (Low Beskid – Carpathians; N 49°37′ 09″, E 21°05′ 49″) carried out by the computer code FLAC3D based on the finite difference method. The numerical analysis was performed to determine the influence of the orientation of layers and discontinuities and of hydrogeological conditions on slope deformations and the failure mechanism during sliding processes. The massif is modeled as an elasto-plastic medium obeying the Coulomb-Mohr criterion. Two variants of hydrogeological conditions are analyzed, namely the “dry slope” (without water) and the “wet slope” (entirely saturated). The influence of the orientation of discontinuities (modeled as “ubiquitous”) on the landslide mechanism is investigated as well. Few orientations of discontinuities with respect to the dip direction of the slope surface are considered, namely consequent, insequent, and subsequent (two variants in each case). The results show a clear impact of the pattern of discontinuities and hydrogeological conditions on the deformational behavior of the landslide and the shape of the slip surface. The 3D approach and results of the numerical simulation of the landslide movement prove the necessity of 3D modeling in some cases.