The Influence of Porosity on Dynamic Properties of the Snail Soil from the Ljubljana Marsh

This article focuses on physical characteristics of snail soil from Ljubljana marsh and their influence on geomechanical characteristics. Mineral and chemical composition, visual appearance, specific surface and grain property of the snail soil were determined. The geomechanical characteristics were investigated for their dependence on the physical characteristics. These relationships are expressed as functions of the porosity. The performed cyclic triaxial tests show the dynamic characteristics of the snail soil. The damping ratio increases exponentially with strain, after some cycles it reach its maximum value, and after that it decreases to the asymptotic value. The reason for such behaviour is the large deformation. There is obviously no influence of the porosity on the damping ratio. The shear modulus is described in relation to shear strain. The increasing of the pore pressure is independent of the porosity until it reaches some value of the pore-pressure ratio (>0.7). Similarly, the increasing of the shear strain becomes dependent on the void ratio until it reaches some particular value of the shear strain (>3%). The deformation and pore-pressure ratio lines for the different porosities are determined from the relationship between the shear stress and the effective stress.