Deformation characteristics of lacustrine carbonate silt in the Julian Alps

The deformation characteristics, shear moduli and damping ratios of reconstituted lacustrine carbonate silt samples were investigated in different kinds of laboratory tests. Material from a landslide that occurred in a seismically very active area in Slovenia was used in the tests. The initial values of this material's deformation characteristics and the extent to which these values change due to increasing shear strain depend on a number of factors, such as the degree of saturation, the initial void ratio, over-consolidation, and the effective stresses. The use of a volumetric threshold strain has proved to be the best way of describing the shear modulus reduction curve irrespective of any other factors, and it fits well with the data obtained in the experiments. The critical state and consolidation lines for the investigated material are presented in the paper as deformational characteristics at critical strain levels. The material's liquefaction potential was studied for certain in situ conditions.