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Povzetek: The frequent dredging of sediments from port areas often leads to the rapid accumulation of excess material, potentially resulting in landfill challenges. Dredged marine sediments typically exhibit high water content, a significant proportion of fine-grained soil, limited bearing capacity, substantial settlement tendencies, and low shear strength. Addressing these issues is imperative for construction projects on such soil types. Recent trends in soil stabilization have witnessed the rising popularity of sustainable bio-binders, particularly biopolymers, owing to their environmentally friendly attributes and extensive use in various geoenvironmental applications. This study investigates the utilization of four different types of biopolymers for the stabilization of marine dredged sediment sourced from the Port of Koper, Slovenia. The research investigates the influence of biopolymer incorporation on the geotechnical properties of biopolymer-treated sediment through Atterberg limits and cone falling tests. In addition, samples were analyzed by scanning electron microscopy (SEM) to elucidate the interaction between biopolymer and the sediment. The findings demonstrate a significant enhancement of undrained shear strength with the addition of biopolymers to the sediment. The formation of hydrogel within the soil pores not only increases the sediment consistency but also positively affects the soil's shear strength.
Ključne besede: marine sediment, biopolymer, stabilization, consistency, undrained shear strength
Objavljeno v DiRROS: 11.08.2025; Ogledov: 594; Prenosov: 341
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Povzetek: Seepage during the first filling of a reservoir is a critical aspect for earth dams and embankments safety, which requires precise monitoring. The thermometric method has demonstrated significant potential for detecting seepage anomalies through continuous temperature measurements using optical fiber distributed temperature sensing (DTS). However, most previous research has primarily focused on thermal monitoring when seepage flow reached a steady-state condition, which highlights the need for more research on seepage and heat transfer in transient state, particularly in unsaturated soils during the reservoir’s first filling. This paper addresses the transient seepage flow and heat transfer during the first filling of a laboratory sand model. Temperature variations within the sand were recorded using an optical fiber DTS, while seepage progression was tracked through digital imaging at regular intervals, followed by image processing. A coupled hydrothermal numerical model was also developed to simulate transient seepage flow and heat transfer within the unsaturated and variably saturated sand. In numerical modeling, heat dispersion and the thermal conductivity of sand were investigated through parameter calibration. Results indicate that thermal monitoring using optical fiber DTS is an effective method for estimating the development of the phreatic line during the first filling of the reservoir. Numerical simulations further revealed that seepage velocity plays a key role in the heat transfer process during transient seepage. Additionally, the results highlight that heat dispersion significantly influences heat transfer, particularly during transient seepage flow, whereas the effect of thermal conductivity is relatively minor as seepage progresses.
Ključne besede: seepage, phreatic line, temperature, heat dispersion, optical fiber DTS
Objavljeno v DiRROS: 09.05.2025; Ogledov: 674; Prenosov: 446
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Povzetek: In the past couple years, the region of South-East Europe is subjected to gust rainfall events activating many landslides which cause significant material and human losses. To revaluate the existing risk maps and set new standards some old case histories are revaluated. This paper presents two case histories of landslide instabilities subjected to excess climatic perturbations, gust rainfall, namely the «Stanjevci» cut-slope near the railway line in North-East of Slovenia; and the «Ramina» a natural landslide in urban area near the city of Veles in Central Macedonia. They are briefly described later to be analysed using coupled thermo-mechanical calculations. They are subjected to specific short and gusting rainfall considered as possible trigger. Hence, van Genuchten's hydraulic model is used in combination with elastoplastic material models. The results are summarized with critical comments regarding the mathematical formulation used to describe atmospheric-soil interaction and the influence of different aspects on the accuracy is discussed briefly.
Ključne besede: numerical, unsaturated soil, slope stability analysis, climate effect
Objavljeno v DiRROS: 04.03.2025; Ogledov: 747; Prenosov: 532
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Povzetek: Insufficient effective confining pressure within the ballast layer can lead to the permanent rotation of grains, causing increased wear and abrasion. Augmenting confinement may not only mitigate ballast degradation but also enhance the overall performance of the track. The increased confining pressure causes the increase of ballasted track stiffness and reduction of resilient and permanent deformation. This paper outlines developing a cost-effective ballast wall arrangement (BWA) to boost ballast layer confinement without disrupting maintenance procedures. It involves incorporating specific secondary raw material elements along the track shoulder, combined with a horizontal geosynthetic reinforcing layer at the base of the ballast layer. These shoulder elements not only impact the track's geometry but also facilitate a reduction in required ballast volume. The efficacy of the ballast confinement mechanism has undergone small-scale testing to prove the concept of reinforcement. Numerical modeling has been developed, which plays a crucial role in supporting the optimal design of this solution.
Ključne besede: ballast, railway track, geosynthetics, confining pressure, small-scale test
Objavljeno v DiRROS: 30.01.2025; Ogledov: 1753; Prenosov: 464
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Povzetek: Energy-efficient homes are constructed with a continuous and uniform thermal envelope and are commonly built on top of a thermal insulation (TI) layer that encloses the entire building. Lightweight aggregates such as foamed glass aggregate, expanded clay aggregate, and extruded polystyrene (XPS) insulation boards are commonly used as materials for the TI layer to prevent thermal bridging at the ground floor slab. However, the reinforced concrete slab foundation above the TI layer is susceptible to horizontal sliding during seismic loading. To improve the seismic behavior of buildings founded on TI layers, this study discussed the shear stiffness and damping characteristics of lightweight aggregates and three types of XPS boards through laboratory tests available in the literature. A 2-dimensional numerical analysis is performed, and the corresponding validation results of the simulations are presented. The effect of TI layers on the seismic performance of buildings constructed with TI layers made from these materials is assessed. A comparative analysis of various interface conditions of the TI materials under seismic loading is also conducted. Overall, this research aims to enhance the resilience and sustainability of energy-efficient homes by investigating the impact of TI layers on their seismic performance. The findings provide valuable insights for designing more robust structures that can withstand seismic events.
Ključne besede: energy-efficient buildings, thermal insulation, extruded polystyrene (XPS), finite element analysis, foamed glass aggregate, seismic response
Objavljeno v DiRROS: 21.01.2025; Ogledov: 885; Prenosov: 511
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