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Evaluation of Green`s function for vertical point-load excitation applied to the surface of a semi-infinite elastic medium
Andrej Štrukelj, Tomaž Pliberšek, Andrej Umek, 2006, izvirni znanstveni članek

Opis: 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.
Ključne besede: civil engineering, soil mechanics, Green`s function, layered half-space, vertical point load
Objavljeno: 31.05.2012; Ogledov: 1493; Prenosov: 8
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The impact of mineral composition on compressibility of saturated soils
Bojana Dolinar, 2006, izvirni znanstveni članek

Opis: 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.
Ključne besede: soil mechanics, clays, specific surface, compressibility, mineral composition
Objavljeno: 30.05.2012; Ogledov: 950; Prenosov: 63
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Analysis of cracked slender-beams on Winkler's foundation using a simplified computational model
Matjaž Skrinar, Boris Lutar, 2011, izvirni znanstveni članek

Opis: This paper discusses the coupling of Winkler's soil model with a simplified computational model that is widely used for the calculation of transverse displacements in transversely cracked slender beams. The bending problem of a cracked beam embedded in Winkler's soil is addressed by means of an analytical approach. The solving of the corresponding differential equation solutions is studied in order to obtain exact analytical expressions for the transverse displacements of the simplified computational model. After the solutions for the displacements of the beam are obtained, the inner bending moment and the shear force distributions within the beam can be calculated, either by using known, established relationships from the Euler-Bernoulli beam theory or by implementing two mechanical equilibrium conditions. Numerical examples covering several load situations are briefly presented in order to support the discussed approach. The results obtained with the presented approach are then further compared with the values from huge 2D finite-element models, where a detailed description of the crack was achieved using the discrete approach. It is evident that any drastic difference in the computational effort is not reflected in the significant differences in the results between the models.
Ključne besede: beams with transverse cracks, simplified computational model, elastic foundation, Winkler's soil, transverse displacements, bending moment, shear forces
Objavljeno: 01.06.2012; Ogledov: 1144; Prenosov: 23
.pdf Celotno besedilo (356,02 KB)
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Relationship between the undrained shear strength, water content, and mineralogical properties of fine-grained soils
Ludvik Trauner, Bojana Dolinar, Miha Mišič, 2005, izvirni znanstveni članek

Opis: 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.
Ključne besede: soil mechanics, clays, fine-grained soils, shear strength, water content, mineralogy
Objavljeno: 01.06.2012; Ogledov: 1784; Prenosov: 74
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Upper-bound solutions of three-dimensional passive earth pressures
Stanislav Škrabl, Borut Macuh, 2005, izvirni znanstveni članek

Opis: This paper presents a novel approach to the determination of passive soil pressures: using the upper-bound method within the framework of limit analysistheory. It is based on a three-dimensional, kinematically admissible, rotational, hyperbolical failure mechanism. The failure mechanism is composed of the central and two lateral bodies, which are connected by a common velocity field. This approach is similar to two-dimensional stability analyses, where the log spiral potential failure surface is considered. The front surface of the central body interacts with the retaining wallč the uppersurface can be loaded by surcharge loadingč and the log spiral segment defines the curved failure surface of the central part. The cross sections of the lateral bodies are in agreement with the cross section of the central body. On the outer side, they are laterally bounded by a curved and kinematically admissible hyperbolic surface, which is defined by enveloping the hyperbolical half cones and part of the case surface of the leading half cone. The results give values for the passive soil pressure coefficients that are for most cases lower than the values determined by the upper-bound method of limit analysis for a translational failure mechanism, as published in the literature.
Ključne besede: geomechanics, soil-structure interaction, limit analysis, earth pressures, passive pressure, failure surface
Objavljeno: 01.06.2012; Ogledov: 1117; Prenosov: 72
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Impact of soil composition on fall cone test results : technical note
Bojana Dolinar, Ludvik Trauner, 2005, izvirni znanstveni članek

Opis: 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.
Ključne besede: soil mechanics, soil tests, clays, cohesive soils, soil properties, Attenberg limits, cone penetration tests
Objavljeno: 01.06.2012; Ogledov: 1309; Prenosov: 26
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Porosity sensor by using quartz crystals and two excitation signals
Vojko Matko, 2003, objavljeni znanstveni prispevek na konferenci

Opis: In response to a need for a more accurate porosity measuring method for small solid samples (app. 1 g in mass) the porosity measurement sensor using a sensitive capacitive-dependent crystal was developed. This paper presents the new sensor and the probe sensitivity, frequency dependence on the volume. In addition, the new idea of excitation of the entire sensor with stochastic test signals is described, and the porosity measuring method is provided. The latter includes the influence of test signals on the weighting function uncertainty. The experimental results of the porosity determination in volcanic rock samples are presented. The uncertainty of porosity measurements is less than 0.1% in the temperature range 10 - 30°C.
Ključne besede: electrical measurements, porosity, soil, capacitive dependent crystals, sensor, glass test tube, direct digital method
Objavljeno: 01.06.2012; Ogledov: 1263; Prenosov: 74
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Undrained shear strength in dependence on the quantity of free water and firmly adsorbed water in fully saturated clays
Bojana Dolinar, Ludvik Trauner, 2003, izvirni znanstveni članek

Opis: 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.
Ključne besede: soil mechanics, properties of soils, clays, water
Objavljeno: 01.06.2012; Ogledov: 1329; Prenosov: 25
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Soil-nail wall stability analysis using ANFIS
Primož Jelušič, Bojan Žlender, 2013, izvirni znanstveni članek

Opis: The safety-factor optimization for a soil-nail wall is presented. The optimization is performed using the non-linear programming (NLP) approach. For this purpose, the NLP optimization model OPTINC was developed. The safety factor and the optimal inclination of the soil nails from the horizontal direction depend on the design of the soil-nail wall. Based on these results the ANFIS-INC model was developed for the prediction of the optimal inclination of the soil nail for any design of soil-nail wall. Additionally, an ANFIS-SF model was developed to predict the safety factor for different inclinations of the wall, the slope angle of the terrain, the length of the nails, and the hole diameter. It was found that the inclination of the soil nail should be adjusted to the inclination of wall, the length of nail, the slope angle of the terrain and the hole diameter. With increasing inclination of the wall, the length of the soil nail and the hole diameter, the safety factor is increasing. On the other hand, the safety factor is decreasing with the increasing slope angle of the terrain. The use of nonlinear programming and an Adaptive Network based Fuzzy Inference System allows a comprehensive analysis of the geotechnical problems.
Ključne besede: soil-nail, wall stability, optimization, NLP, ANFIS
Objavljeno: 10.07.2015; Ogledov: 818; Prenosov: 36
.pdf Celotno besedilo (284,95 KB)
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