1. Determination of passive earth pressure using three-dimensional failure mechanismHelena Vrecl-Kojc, Stanislav Škrabl, 2007, original scientific article Abstract: This paper presents a modified three-dimensional (3D) failure mechanism for determining the 3D passive earth pressure coefficient using the upper bound theorem within the framework of the limit analysis theory. The translational kinematically admissible failure mechanism generalized with a depth of h = 1.0 is considered in the analysis. The mechanism geometry presents a volume of rigid blocks composed of the central body and two lateral rigid bodies, which are connected by a common velocity field. The front surface of the central body interacts with the retaining wall, while the upper surface can be loaded by surcharge loading. The lateral body segments represent four- and three-sided polygons in the cross section of the central body; therefore, they define the polygonal failure surface of the central part. At the outer side, each segment of the lateral body is bounded by infinitesimally spaced rigid half-cones that describe the envelope of a family of half-cones. The numerical results of 3D passive earth pressure limit values are presented by non-dimensional coefficients of passive earth pressure influenced by the soil weight Kpg and a coefficient of passive earth pressure influenced by the surcharge Kpq. This research was intended to improve the lowest values obtained until now using the limit analysis theory. The results are presentedin a graphical form depending on the geometrical parameters and soil properties. A brief description of two world-recognized failure mechanisms based on the limit analysis approach, and the comparison of three failure mechanism results are also presented. Keywords: soil mechanics, passive earth pressure, upper bound theorem, optimization, three-dimensional failure mechanism Published in DKUM: 18.05.2018; Views: 999; Downloads: 55 Full text (504,97 KB) This document has many files! More... |
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3. Mean grain size as a function of spectral amplitude: a new regression law for marine sediment coresNelly Zanette, Darinka Battelino, 2017, original scientific article Abstract: Geophysics has been developed in order to supply indicative estimations in soil mechanics like the grain size distribution of finely grained soils as day, silt and fine sands. The paper describes the attempt to characterize porous and saturated marine sediments with a non destructive technique which is the acoustic wave, in order to determine the correlation with geotechnical measurements. The characterization of physical parameters of marine sediments was based on research methods which permit to describe the parameters defining different types of sediment and zones of sedimentation; to determine fundamental parameters that influence the propagation of the acoustic waves in saturated and porous means; to define quick and indicative methods for characterization of physical parameters of analysed means. The acoustic measurements were carried out at SACLANT-NATO of La Spezia (I), where the Vertical Multi Sensor Core Logger (V-MSCL) was used. The results of acoustic tests were compared to the grain size curves of the sediments and the propagation characteristics such as velocity, density, porosity and absorption of experimentally determined data. The analyses are based 011 various mathematical models presented in. literature, in order to predict and to describe physical mechanisms of the wave propagation using a simplification of the sediment structure. The target of the study was to determine a new mathematical law that linked the mean grain size to a directly measurable parameter such as the spectral amplitude, and to offer the possibility to obtain the first indicative value of the sediment mean grain size. The determined exponential law represents an innovative and quick approach to determine a physical characteristic of saturated and porous sediments such as the grain size in a non destructive way based on the spectral analysis of the wave propagation form. Keywords: soil mechanics, marine sediments, finely grained soil, acoustic waves, grain size curve Published in DKUM: 17.05.2018; Views: 945; Downloads: 79 Full text (437,86 KB) This document has many files! More... |
4. The assesment of pile shaft resistance based on axial strain measurements during the loading testAndrej Štrukelj, Stanislav Škrabl, Ksenija Štern, Janko Logar, 2005, original scientific article Abstract: Near Maribor, a new bridge over the Drava river is being under construction. Before the main works actually started, static and dynamic loading tests of piles were performed. The goal of the static loading test was to determine the bearing capacitiy of the test pile. It was also interesting to determine the share of the axial load distributed on the shaft and pile toe. In order to measure the distribution of the axial force along the pile, a specially made steel canal was built in the pile before concreting. Inside this canal the strain gauges were distributed evenly at the distance of one meter. The strains were measured for each loading phase in all measuring points. The distribution of the axial force was assessed from the obtained results and based on the distribution of the axial force the shaft resistance could be determined. The unexpectedly high bearing capacity of the pile shaft made the obtained results highly interesting. In this paper, measuring methods and measuring results are discussed. Behaviour of the pile and the soil during the loading test were also modelled by axial symmetric and three dimensional models. The calculated and measured results show a very good agreement. Keywords: civil engineering, bridges, soil mechanics, pile shaft resistance, loading test, strain measurements, elastoplastic soil modelling, finite element method Published in DKUM: 16.05.2018; Views: 1152; Downloads: 65 Full text (987,58 KB) This document has many files! More... |
5. 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: 1169; Downloads: 91 Full text (103,26 KB) This document has many files! More... |
6. 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: 1838; Downloads: 32 Link to full text |
7. 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: 2002; Downloads: 58 Link to full text |
8. 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: 2499; Downloads: 114 Link to full text |
9. Evaluation of Green`s function for vertical point-load excitation applied to the surface of a semi-infinite elastic mediumAndrej Štrukelj, Tomaž Pliberšek, Andrej Umek, 2006, original scientific article Abstract: The topic of this paper is to show that the integrals of infinite extent representing the surface displacements of a layered half-space loaded by a harmonic, vertical point load can be reduced to integrals with finite integration range. The displacements are first expressed through wave potentials and the Hankel integral transform in the radial coordinate is applied to the governing equations and boundary conditions, leading to the solutions in the transformed domain. After the application of the inverse Hankel transform it is shown that the inversion integrands are symmetric/antimetric in the transformation parameter and that this characteristic is preserved for any number of layers. Based on this fact the infinite inversion integrals are reduced to integrals with finite range by choosing the suitable representation of the Bessel function and use of the fundamental rules of contour integration, permitting simpler analytical or numerical evaluation. A numerical example is presented and the results are compared to those obtained by the CLASSI program. Keywords: civil engineering, soil mechanics, Green`s function, layered half-space, vertical point load Published in DKUM: 31.05.2012; Views: 2168; Downloads: 38 Link to full text |
10. 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: 1574; Downloads: 96 Link to full text |