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GNSS monitoring of geologically demanding areas
Boštjan Kovačič, Boško Pribičević, Rok Kamnik, 2016, original scientific article

Abstract: Displacement research using the three-dimensional global navigation satellite system (GNSS) as part of geodetic monitoring is becoming the key investigation for establishing a cause-and-effect relationships model between external natural factors, on the one hand, and the criteria that describes the level of functionality and safety of the observed natural or artificial object, on the other, in cases of motion of an object in space and time. The main objective of the deformation analysis is to confirm the stabilities of the reference points of a geodetic network, which are used to determine the movements of the control points that are stabilized on the observed objects. The assumption about the stabilities of certain reference points must be based on reasonable grounds, underpinned by measurements and proven by numerical methods. This is one part of the results of the deformation analysis when determining the extent of the movements and deformations. To do this a transformation is used in which a comparison is made between the coordinates of the points for two separate epochs. On the basis of the estimated transformation parameters, possible movements can be concluded within the reference points, i.e., on whether the datum parameters have changed. After confirming the stability of the geodetic network the coordinate differences of identical points measured within the different time windows can be determined as displacements and/or deformations of an object. In this paper one viaduct was assessed through geology and tectonic activities and also a load test of the viaduct was performed. The viaduct is in a quite active region, but the load test showed that the bridge response to the load is as expected.
Keywords: geodesy, geotehnics, monitoring, GNSS measurements, geology, deformation analysis, geodetic network
Published: 18.06.2018; Views: 575; Downloads: 42
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Modeling of a geocell-reinforced pavement
Samo Peter Medved, Bojan Žlender, Stanislav Lenart, Primož Jelušič, 2016, original scientific article

Abstract: This article details how the serviceability of a flexural pavement structure is improved by incorporating the Cellular Confinement System (geocells). For this purpose, two different pavement structures, with and without embedded geocells, were manufactured in a laboratory and an accelerated traffic type of loading was applied. The vertical and horizontal cyclic loads were applied simultaneously to simulate the effect of principal stress rotation. A comparative study between the conventional flexible pavement and the geocell-reinforced flexible pavement is presented. Additionally, numerical models of the laboratory tests were built and the results were compared. The simulation of the experimental tests using the Traffic Load Simulator (TLS) are carried out using the FEM and advanced models that describe the permanent strain behavior of the unbound granular material. The development of permanent deformation within the pavement structure, with and without the geocells, is also presented through the numerical model, which was verified by the experimental results.
Keywords: flexible pavement, reinforcement, geocell, traffic load simulator, permanent deformation, numerical modeling
Published: 18.06.2018; Views: 418; Downloads: 46
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A new method for testing the anti-permeability strength of clay failure under a high water pressure
Fu-wei Jiang, Ming-tang Lei, Xiao-zhen Jiang, 2015, original scientific article

Abstract: It is difficult to judge the failure of clay seepage under a high water pressure.This paper presents a new method to assess clay failure based on the anti-permeability strength, which is the critical water pressure to destroy the clay. An experiment is designed to test the value that avoids the problem of the time-consuming, traditional method to test clay seepage deformation. The experimental system and the process of testing are introduced in this paper. With a self-designed experimental system and method, 18 groups of sample were tested. The results show that the clay thickness and the seepage paths influence the anti-permeability strength. It also indicates that water infiltrates into the clay under the condition that its pressure exceeds a minimum value (P0).
Keywords: clay failure, seepage deformation, anti-permeability strength, high water pressure
Published: 15.06.2018; Views: 535; Downloads: 29
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Analysis of a dilatometer test in over-consolidated sediments, basin of the Duero river, Spain
Félix 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: 14.06.2018; Views: 438; Downloads: 35
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A multiscale approach to deformation and fracture of heat-resistant steel under static and cyclic loading
P. O. Maruščak, Denys Baran, Vladimir Gliha, 2013, original scientific article

Abstract: Regularities of static and cyclic deformation, damage and fracture of heat-resistant steel 25Kh1M1F, based on the approaches of physical mesomechanics and 3D interferometry method, are presented in this paper. The applicability of these techniques for different hierarchy levels of deformation was studied. The investigation of scanning microscope photos was conducted for several dissipative structures, fragmentation of the material, localisation of macrodeformation and subsequent failure on macro- and mesolevel. It is shown that the used modern techniques of experimental analysis are very efficient in understanding deformation and damage evolution in materials.
Keywords: fracture, heat-resistant steel, cyclic loading, fatigue, plastic deformation
Published: 18.08.2017; Views: 539; Downloads: 260
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The different methods of displacement monitoring at loading tests of bridges or different structures
Boštjan Kovačič, Rok Kamnik, Andrii Bieliatynskyi, 2016, published scientific conference contribution

Abstract: By measuring the displacements and deformations at different structures we deal in the Faculty of Civil Engineering, transportation Engineering and Architecture in University of Maribor for about 20 years. At that time we measured over 600 structures. Most loading tests of bridges and Viaducts were made. The measurements of movements needed to be as precise and accurate as possible. To do that laboratory test of instruments were made to see which instrument gives us reliable results. Displacements can be determined by geodetic and physical methods, depends of the construction. The use of geodetic methods are still preferable. In the paper the measurements with the total station, the level and rotation level, photogrammetry and solutions on the field by physical methods with inductive transducers are presented. We need to measure displacements as quick as possible but efficiently because we can not repeat the measurements under the same conditions. Also the surveying on the bridge and in the lab with the comparison of methods is presented under the different hard terrain conditions - water beneath the construction, big height of the structure, unapproachability, large span structures.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published: 02.08.2017; Views: 632; Downloads: 242
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Deformation analysis of bridges in exceptional transport in Slovenia
Rok Kamnik, Boštjan Kovačič, Andrej Štrukelj, 2010, short scientific article

Abstract: In August 1999 an exceptional transportation of two steamers of 666 tonnes was performed from the Port of Koper to the Nuclear power plant in Krško. The transport covered a distance of about 200km and represented one of the largest exceptional transports in Slovenia ever. Finding the best route represented one of the major issues, because the steamers had to cross more than 50 problematic sections and bridges, most of which have not been designed for such heavy loads. It was necessary to load-test almost all bridges on the route to determine whether those bridges need any extra supports or not. Consequently, a logistic operator has an important and indispensable role and becomes a co-modeller of logistic service. A deformation analysis or a polynomial interpolation of vertical displacements could also be used. Therefore, a laboratory load test of a concrete plate was made. The concrete plate was loaded with hydraulic cylinder PZ 100 with extensiometer up to 21kN. Every increase of load by 3kN was measured with Nikon Ser 800 total station.
Keywords: deformation analysis, exceptional transport, bridges, Slovenia
Published: 01.06.2017; Views: 627; Downloads: 93
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Superplastic deformation of an X7093 Al alloy
Srdjan Tadić, Aleksandar Sedmak, Radica Prokić-Cvetković, Abdsalam Eramah, Rebeka Rudolf, 2014, original scientific article

Abstract: We have investigated the superplastic deformation mechanism of a powder-metallurgy, high-zinc X7093 Al alloy. The objective was to examine the rate-controlling mechanisms that govern its superplastic deformation. The investigations were carried out in the temperature range 490–524 °C and strain rates of 4.17 × 10–5 s–1 to 2.1 × 10–2 s–1. The maximum ductility was slightly more than 500 % at 524 °C and 4.2 × 10–4 s–1. The values of the stress exponent (n) and the activation energy (Q) indicated that the deformation is rate-controlled by the climb within the grain-boundary diffusion path. The existence of a temperature-dependent threshold stress was confirmed.
Keywords: superplasticity, Al alloys, deformation mechanisms
Published: 23.03.2017; Views: 557; Downloads: 56
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Vertical displacements measuring methods during bridge load tests
Boštjan Kovačič, Ante Marendić, Rok Kamnik, Mikhail Volkov, Vera Roy, 2016, published scientific conference contribution

Abstract: This article introduces the use of the GNSS method for the load testings of bridge structures. We know that there area lot of methods by which you can determine vertical displacement. However, as new bridge constructions are constructed over almost impossible and inaccessible gorges and valleys, the classic measurements method do not allow us to determine vertical displacement so reliably any more or they are very time-consuming. The GNSS method is well known but there are difficulties when determining the altitude component of this method, which is rather questionable. For this purpose, the methods were tested as practical examples in which some difficulties were encountered, so subsequently another test recording was performed of altitude changes using this method.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published: 29.08.2016; Views: 885; Downloads: 358
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Računalniško simuliranje postopka kovanja
Janez Stupan, Iztok Potrč, 2000, professional article

Abstract: V prispevku je obravnavano tridimenzionalno računalniško simuliranje procesa kovanja z računalniškim programom MSC/SuperForge. Kovanje je izrazit proces tridimenzionalne deformacije, med katerim se stalno spreminjajo robni pogoji. Začetna oblika je v večini primerov preprosta, končna oblika pa je lahko zelo zahtevna in se doseže s preoblikovanjem v več stopnjah. Rezultati simuliranja so: deformirana oblika, temperaturno polje, polje toka materiala, tlaka, dejanske napetosti, dejanskih plastičnih deformacij itn.
Keywords: forging, deformation, finite volume method, material flow
Published: 10.07.2015; Views: 719; Downloads: 33
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