1. Analysis of a dilatometer test in over-consolidated sediments, basin of the Duero river, SpainFélix Escolano Sánchez, Manuel Bueno Aguado, 2015, original scientific article Abstract: A dilatometer test is a useful method for in-situ geotechnical surveys. It can be compared with the results obtained using a mathematical model. The mathematical model of concentric rings shown in this article is governed by the constitutive equation of the “Hardening Soil Model”. A large number of tests made on the Dueñas Geological Facies, with a consistency ranging from firm clays to soft rocks, are compared to the model results. In this way, the “Hardening Soil Model” parameters are adjusted to the Dueñas Facies materials.
Keywords: Dueñas, geotechnical parameters, hardening soil model, soft rocks and clays deformation
Published in DKUM: 14.06.2018; Views: 1303; Downloads: 95
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2. Determination of the fabric alteration of marine claysSuchit Gumaste, 2014, original scientific article Abstract: This paper presents details of investigations that were conducted to determine the fabric (i.e., the arrangement of soil grains and pores) of undisturbed marine clay samples that were retrieved from 5 m to 65 m below the seabed. Impedance Spectroscopy (IS), which is a non-destructive and non-invasive technique, was employed to determine the electrical conductivities of the marine clay samples in their longitudinal and transverse planes of sedimentation. These results were employed to define the extent of the fabric anisotropy in terms of an anisotropy coefficient, Ae, as a function of depth. In addition, Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) were employed to study the fabric and pore-size distribution of these samples, respectively. Based on these investigations it has been observed that Ae increases with sampling depth, which is indicative of the alteration from flocculated fabric, at shallower depths, to the dispersed fabric, at deeper depths. The study highlights the importance and usefulness of the anisotropy coefficient, Ae, for determining the alteration in the fabric of marine clays, due to self-weight consolidation.
Keywords: marine clays, anisotropy, laboratory tests
Published in DKUM: 14.06.2018; Views: 1006; Downloads: 184
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3. A coupled thermo-hydro-mechanical model of expansive clays subjected to heating and hydratationNadia Laredj, Hanifi Missoum, Karim Bendani, Mustapha Maliki, 2011, original scientific article Abstract: The focus of this work is to provide a numerical formulation for coupled thermo-hydro-mechanical processes in unsaturated expansive clays, especially in compacted bentonite, with a multiphase fluid flow. The model is characterized by the presence of a deformable solid matrix filled with two fluid phases (liquid water and air). In the proposed model, both pore-water and air transfers are assumed to be governed by the generalized Darcy’s law. Fully coupled, nonlinear partial differential equations are established and then solved by using a Galerkin weighted residual approach in the space domain and an implicit integrating scheme in the time domain. The model has been validated against an experimental test from the literature, which involves bentonite under laboratory conditions. The calculated relative errors between the experimental and numerical results are 3% for the temperature and 7% for the stresses. Consequently, the developed numerical model predicts satisfactory results, when compared to the experimental test measures. The model is applicable to two-dimensional problems with various initial and boundary conditions; non linear soil parameters can be easily included in this model.
Keywords: thermo-hydro-mechanical process, unsaturated bentonite, finite element, numerical modelling, expansive clays
Published in DKUM: 13.06.2018; Views: 1162; Downloads: 60
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4. Undrained shear strength of saturated cohesive soils depending on consolidation pressure and mineralogical propertiesBojana Dolinar, 2004, original scientific article Abstract: The relationship between the water content and the undrained shear strength of finely grained soils can be described with a nonlinear function in which the type of soils is determined by two parameters. These parameters depend primarily on the size of clay minerals, their quantity in soil composition and the interlayer water quantity in expanding clay minerals. This article asserts that there exists also the exactly defined relationship also between the water content and consolidation pressure. In the function describing this relationship, the type of soil is determined by two parameters. They can be expressed depending on the same mineralogical properties of soils as the values of parameters in the function showing the relationship between the water content and the undrained shear strength. These findings allow us to express the ratio between undrained shear strength and consolidation pressure depending on mineralogical properties of soils.
Keywords: soil mechanics, properties of soils, clays, specific surface, undrained shear strenght, compressibility
Published in DKUM: 15.05.2018; Views: 1506; Downloads: 110
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5. Undrained shear strength in dependence on the quantity of free water and firmly adsorbed water in fully saturated claysBojana Dolinar, Ludvik Trauner, 2003, original scientific article Abstract: The article describes the dependence between the undrained shear strength of fully saturated cohesive soils, the quantity of intergrain water and mineralogical properties of soils on the basis of theoretical analysis and practical tests on monomineral clay samples, it was determined that the total quantity of intergrain water is composed of free pore water and the firmly adsorbed water on the external surface of clay grains. The undrained shear strength of saturated soils is precisely dependent on the quantity of free water. The amount of free water and likewise the thickness of the water film around the clay grains are the same for different soils at the same undrained shear strength. The total quantity of firmly adsorbed water and the total quantity of integration water depends on the specific surface of soils.
Keywords: soil mechanics, properties of soils, clays, water
Published in DKUM: 01.06.2012; Views: 2071; Downloads: 32
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6. Impact of soil composition on fall cone test results : technical noteBojana Dolinar, Ludvik Trauner, 2005, original scientific article Abstract: The cone penetrometer method is being increasingly used for the determination of the liquid limit of cohesive soils. The same method can be used to determine the plastic limit according to the known relationship between soil moisture content and depth of cone penetration. This relationship is non-linear, yet becomes linear on a log-log scale resulting in a simple methodof determination of liquid limit and plastic limit values. This technical note determines the soil properties that define these index parameters. Experimentally obtained results suggest that the index parameters primarily depend on the type, size, and quantity of the clay minerals in soil.Soil index parameters such as the liquid limit and plastic limit can be determined from knowledge of the mineralogical properties of the soil because this dependence appears well defined.
Keywords: soil mechanics, soil tests, clays, cohesive soils, soil properties, Attenberg limits, cone penetration tests
Published in DKUM: 01.06.2012; Views: 2315; Downloads: 63
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7. Relationship between the undrained shear strength, water content, and mineralogical properties of fine-grained soilsLudvik Trauner, Bojana Dolinar, Miha Mišič, 2005, original scientific article Abstract: The relationship between the undrained shear strength of fine-grained soils and the water content can be described with a nonlinear function in which the type of soil is determined by two parameters. It is well known that these parameters depend mainly on the mineral compositions of soilsč these relationships, however, have not yet been investigated. The findings describedin this paper define those mineralogical properties of soils which determine the values of both parameters. Experimentally obtained results suggest that the parameters primarily depend on the size of the clay minerals,their quantity in soil composition, and the interlayer water quantityin the expanding clay minerals. As this dependence is well defined, the parameters, and thus the undrained shear strength at different water content, can be defined from knowledge of these mineralogical soil properties.
Keywords: soil mechanics, clays, fine-grained soils, shear strength, water content, mineralogy
Published in DKUM: 01.06.2012; Views: 2786; Downloads: 118
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8. The impact of mineral composition on compressibility of saturated soilsBojana Dolinar, 2006, original scientific article Abstract: This article analyses the impact of soils` mineral composition on their compressibility. Physical and chemical properties of minerals which influence the quantity of intergrain water in soils and, consequently, the compressibility of soils are established by considering the previous theoretical findings. Test results obtained on artificially prepared samples are used to determine the analytical relationship between the water content and stress state, depending on the mineralogical properties of the soils. A practical applicability of the established interdependence is verified on fiverandomly selected samples of natural soils. The selected approach to the analysis of the influence of soils composition on the water content at different stress states allows for the first time to establish generally validcriteria for determining such relationship.
Keywords: soil mechanics, clays, specific surface, compressibility, mineral composition
Published in DKUM: 30.05.2012; Views: 1864; Downloads: 149
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