1. Upper-bound solutions of three-dimensional passive earth pressuresStanislav 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: 891; Prenosov: 9 Celotno besedilo (0,00 KB) |
2. Green's function for an elastic layer loaded harmonically on its surfaceTomaž Pliberšek, Andrej Štrukelj, Andrej Umek, 2005, izvirni znanstveni članek Opis: The Green's function in surface displacement plays an important role in soil structure interaction. In evaluating the Green's function, several difficulties occur because it is formulated in the infinite integral form. This paper outlines a method of analyzing the steady-state dynamic response of an elastic layer subjected to general point load excitation. It is assumed that the load is applied at the surface. The application Hankel integral transform, to the governing differential equations and boundary conditions yields the response displacements at the surface in integral representation. It will be shown that these semi-infinite integrals can be reduced to the integral with the finite range of integration, which can be efficiently taken numerically. The numerical results are presented, which show the efficiency of the developed procedure. Ključne besede: civil engineering, geomechanics, soil-structure interaction, layered halfspace, Green's function, elastodynamics Objavljeno: 15.05.2018; Ogledov: 70; Prenosov: 0 Celotno besedilo (375,59 KB) |
3. Interactional approach of cantilever pile walls analysisStanislav Škrabl, 2006, izvirni znanstveni članek Opis: This paper proposes a new method for the geomechanical analysis and design of cantilever retaining structures. It is based on the limit equilibrium method, but it uses some additional conditions for interaction between the retaining structure and the ground, when referring to the distribution of the mobilized earth pressures on the structure. The greatest benefit of the proposed method is shown in the analysis of structures of layered ground (heterogeneous above the dredge level and homogeneous below it), embedded in frictional and cohesive materials, and in the possibility of considering the influence of surcharge loadings on the active or passive side of the retaining structure. When analyzing such cases in practice, the proposed method gives results which are in better agreement with the results of FEM based elasto-plastic interaction analyses than with the results of currently used methods. At the same time, its results are in accordance with those published for homogeneaus cohesionless ground. Since in practice almost all retaining structures are erected in layered ground (heterogeneaus above the dredge level and homogeneous below it), the proposed method is very convenient and applicable for the analyses and design of cantilever structures under arbitrary geomechanical conditions. Ključne besede: geomechanics, soil-structure interaction, retaining walls, embedment, cantilevers, earth pressure, pressure distribution, friction soil - wall, limit analysis, shear forces Objavljeno: 17.05.2018; Ogledov: 23; Prenosov: 2 Celotno besedilo (411,22 KB) |
4. The limit values and the distribution of three-dimensional passive earth pressuresStanislav Škrabl, 2008, izvirni znanstveni članek Opis: This paper presents a novel approach to the determination of the critical distribution and limit values of three-dimensional passive soil pressures acting on flexible walls following the upper-bound method within the framework of the limit-analysis theory. The method of limit analysis with a set of three-dimensional kinematically admissible hyperbolic translational failure mechanisms is used to determine the critical distribution of the passive pressures along the retaining structurećs height. The intensity of thepassive pressures is gradually determined with the mentioned translational failure mechanisms in the top-down direction. Thus, the critical distribution,the trust point and the resultant of the passive pressures that can be activated at the limit state for the chosen kinematic model are obtained. The results of the analyses show that the total sum of passive pressures, considering the critical distribution, is lower than the comparable values published in the literature. Furthermore, the trust point of the passive pressure resultant is independent of the friction between the retaining structures and the soil. Ključne besede: limit analysis, earth pressure, passive pressure, failure surface, soil-structure interaction Objavljeno: 05.06.2018; Ogledov: 9; Prenosov: 0 Celotno besedilo (331,84 KB) |
5. A comparison of linear and nonlinear seismic tunnel-ground interaction analysesElefterija Zlatanović, Marina Trajković-Milenković, Dragan Lukić, Stanko Brčić, Vlatko Šešov, 2016, izvirni znanstveni članek Opis: In order to study the effects of a seismically induced tunnel–ground interaction, two-dimensional numerical analyses are performed using the sofware ANSYS. The study employs a coupled beam–spring model subjected to earthquake loading that is simulated under pure shear conditions and determined by a free-field ground-response analysis using the code EERA. The properties of the soil material are considered as both linear and nonlinear. The results obtained by linear dynamic analyses are compared with state-of-practice analytical elastic solutions. A comparison of the results of both linear and nonlinear analyses is also performed, and significant differences, as well as important factors influencing the tunnel–ground interaction for both cases, are evaluated. Ključne besede: circular tunnel, linear/nonlinear soil behaviour, beam–spring model, plane-strain conditions, simplified dynamic FE analysis, soil–structure interaction Objavljeno: 18.06.2018; Ogledov: 8; Prenosov: 0 Celotno besedilo (1,57 MB) |
6. Evaluation of dynamic soil pressures acting on rigid culvertsDeniz Ulgen, Mehmet Yener Özkan, 2016, izvirni znanstveni članek Opis: The seismic safety of underground structures (culvert, subway, natural-gas and water-sewage systems) plays a major role in sustainable public safety and urban development. Very few experimental data are currently available and there is no generally accepted procedure to estimate the dynamic pressures acting on these underground structures. This study aims to enhance the state of the prevalent information necessary to understand the dynamic behaviour of box culverts and the stresses acting under dynamic excitations through experimental analyses. For this purpose, a series of shaking-table tests were conducted on box-type culverts buried in dry sand. To simulate the free-field boundary conditions, a laminar box was designed and manufactured for use with a 1-g shake table. Two culvert models having different rigidities were tested under various harmonic motions in order to examine the effect of the flexibility ratio on dynamic lateral soil pressures. Based on the test results, a simplified dynamic pressure distribution acting on the sidewalls of the culvert model was suggested. Then, a dynamic lateral coefficient was defined for the proposed peak pressure value in the distribution. The values of this coefficient were obtained as a function of the shear strain by considering the relative stiffness between the soil and the underground structure. Ključne besede: box culvert, dynamic earth pressure, shaking table, dynamic soil-structure interaction, laminar box, dynamic lateral coefficient Objavljeno: 18.06.2018; Ogledov: 9; Prenosov: 0 Celotno besedilo (584,65 KB) |