Assessment of the factors affecting slope stability in the southern part of the Sofia Kettle

A specific sample area was selected, where an assessment model was made for the stability of a slope subjected to anthropogenic impacts. A hillside slope zone from the foot of the Vitosha and Lozen mountains in the southern periphery of the Sofia Kettle was chosen as an exemplary area for a part of the hazards arising in the Trans-Balkan valleys. The anthropogenic impact on their slope stability was studied on three particular slopes. The study area is about 1.25 km2 and has a maximum distance of up to 3.80 km between the slopes. Landslide processes resulting from anthropogenic impact often occur on the territory of the Sofia Valley. The rise of construction, the development of hard-to-reach terrains with steep slopes, their undercutting, the seismic impact and the low values of the strength-deformation parameters of the geological varieties building up the respective terrains contribute to their occurrence. The deforestation, the loads with heavy embankments, the hydration and the inhomogeneity of the layers of the earth base have a strong destabilizing effect. The paper presents the results of field and laboratory tests and analyses of slope stability by the method of Fellenius. The severity of the impact of the various destabilizing factors was assessed.