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Measurement and interpretation of the small strain stifness of Boštanj silty sand
Gregor Vilhar, Vojkan Jovičić, 2009, original scientific article

Abstract: This paper presents measurements, and an interpretation of these measurements, based on the use of bender-element probes for Boštanj silty sand. The samples were prepared at different initial void ratios and isotropically compressed up to 5 MPa. The bender-element technique was used to determine the dynamic shear modulus ($G_0$) of the soils at very small strains. The multiple bender-element probes were shot at different excitation frequencies in order to increase the reliability of the measurements. The $G_0$ stiffness was determined by using three different techniques: a) the first-time arrival, b) the phase-change method and c) the cross-correlation method. The systematic differences observed between the $G_0$ values, calculated using the three techniques, are discussed. The variation of $G_0$ in the log$G_0$ - log$p'$ plane was evaluated for the Boštanj silty sand and compared with other sands.
Keywords: silty sand, triaxial testing, small strain stiffness, bender elements, time-domain and frequency-domain, measurements
Published in DKUM: 06.06.2018; Views: 1194; Downloads: 159
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The influence of porosity on geomechanical characteristics of snail soil in the Ljubljana Marsh
Bojan Žlender, Ludvik Trauner, 2006, original scientific article

Abstract: This article focusses on mineralogical and physical characteristics of snail soil and their influence on parameter values of geomechanical characteristics.Snail soil, which got its name from fossil remains, is a typical layer observed in the Ljubljana marsh. It is distincltly porous, saturated and in a liquid consistency state. Snail soil was investigated for mineralogical and physical characteristics in the Laboratory of Soil Mechanics, Faculty of Civil Engineering of the University in Maribor. Mineral and chemical composition, visual appearance, specific surface and grain property were determined. Physical characyteristics show that snail soil is saturated in nature, highly porous and almost liquid. Geomechanical characteristics were investigated for their interdependency on physical characteristics. A series of triaxial tests were performed on snail soil samples of different porosity, density and water content. Cylindrical samples of the height of 100 mm and the diameter of 50 mm were tested using three-axial testing apparatus. The results of the tests show that interdependency exists between geomechanical characteristics and porosity. These relationships can be expressed as functions of density, porosity or water content. It is evident from the results that changes of the coefficient of permeability, the coefficient of consolidation, and the coefficient of volume compressibility are nonlinear with respect to changes in porosity. Changes of mechanical parameters, such as Young`s modulus, Poisson`s ratio andfriction angle are indistinct and almost linear at lower changes of porosity.
Keywords: geomechanics, properties of soils, snail soil, triaxial testing, porosity, permeability, consolidation, Young`s modulus, Poisson`s ratio, shear angle
Published in DKUM: 17.05.2018; Views: 1623; Downloads: 87
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