1. Optimising energy piles: a multi-objective approach to cost and failure probabilityRok Varga, Primož Jelušič, Bojan Žlender, 2025, izvirni znanstveni članek Opis: This paper presents a comparative analysis of the influence of thermal loading on the design of optimally designed floating energy piles in soft consistency soils using a genetic algorithm. The nonlinear settlement of energy piles is also considered. The deterministic optimisation model (OPT-EP) includes a cost objective function constrained by design constraints and is later extended to include the probability of failure as a second objective function to perform multi-objective optimisation. This extension was undertaken because the Eurocode 7 approach only partially accounts for uncertainties in the soil, whereas the reliability-based design (RBD) approach fully exploits these uncertainties. Consequently, a multi-objective optimisation (cost vs. failure probability) was carried out in this study. The optimal designs obtained by the two different optimisation methodologies were further analysed and it was found that when the Eurocode 7 safety factor approach was used, the conditions related to thermal loading were not crucial for the design values. On the other hand, the multi-objective optimisation based on the RBD approach showed that the thermal loading affected the design, proving the usefulness of the multi-objective optimisation and the reliability-based design.
Ključne besede: energy pile, multi-objective optimisation, reliability-based design, genetic algorithm
Objavljeno v DKUM: 04.04.2025; Ogledov: 0; Prenosov: 9
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2. Use of Lignin, Waste Tire Rubber, and Waste Glass for Soil StabilizationSüleyman Gücek, Cahit Gürer, Bojan Žlender, Murat V. Taciroğlu, Burak E. Korkmaz, Kürşat Gürkan, Tamara Bračko, Borut Macuh, Rok Varga, Primož Jelušič, 2024, izvirni znanstveni članek Opis: The complex interactions between soil and additives such as lignin, glass powder, and rubber tires were investigated using principles of material and soil mechanics. Previous research has mainly focused on individual additives in clay soils. In contrast, this study investigates soil improvement with two different types of waste materials simultaneously. The improvement of soil properties by hybrid waste materials was evaluated using several laboratory tests, including the standard Proctor test, the unconfined compressive strength test, the California Bearing Ratio (CBR) test, and cyclic triaxial tests. The aim of this research is to identify key parameters for the design and construction of road pavements and to demonstrate that improving the subgrade with hybrid waste materials contributes significantly to the sustainability of road construction. The mechanical and physical properties were evaluated in detail to determine the optimal mixtures. The results show that the most effective mixture for the combination of waste glass powder and rubber tires contains 20% glass powder and 3% rubber tires, based on the dry weight of the soil. For the combination of waste glass powder and lignin, the optimum mixture consists of 15% glass powder and 15% lignin, based on the dry weight of the soil. These results provide valuable insights into the sustainable use of waste materials for soil stabilization in road construction projects.
Ključne besede: soil stabilization, waste glass, tire rubber waste, lignin, hybrid waste usage, mechanical
properties, pavement structure
Objavljeno v DKUM: 28.02.2025; Ogledov: 0; Prenosov: 6
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3. Razvoj metodologije za načrtovanje geotehničnih konstrukcij na podlagi verjetnosti porušitve in večnamenske optimizacijeRok Varga, 2024, doktorska disertacija Opis: Zemljine in kamnine na mestu, kjer so zgrajeni geotehnični objekti, predstavljajo inženirju negotov element, saj začetno napetostno stanje, predhodne obremenitve in razbremenitve ter prekonsolidacija zemljin niso znane. Prav tako se lastnosti zemljin spreminjajo v vertikalni in horizontalni smeri. Za upoštevanje raznih negotovosti pa se za načrtovanje konstrukcij uporabljajo verjetnostne analize. Za namene, da bi lahko upoštevali to negotovost, smo v doktorski disertaciji razvili celovit pristop za optimalno načrtovanje geotehničnih konstrukcij na podlagi verjetnosti porušitve in stroškov gradnje, z osredotočenostjo na večnamensko optimizacijo. Kadar načrtujemo konstrukcijo na podlagi verjetnosti porušitve, pravimo pristopu verjetnostna analiza ali angleško reliability based design (RBD). Naša razvita metodologija za optimizacijo uporablja genetski algoritem, ki je kodiran z realnimi števili.
V doktorski disertaciji smo analizirali številne metode, ki se uporabljajo pri načrtovanju geotehničnih konstrukcij na podlagi verjetnosti porušitve, pri čemer smo predstavili teoretična izhodišča in na primeru horizontalnega zdrsa točkovnega temelja pokazali njihovo kompleksnost.
Tako imenovana »razširjena RBD metoda« se je izkazala za inženirjem najbolj prijazno metodo, saj poda kakovostnejše informacije o zasnovi in o porušitvenih mehanizmih. V vseh treh aplikativnih primerih geotehničnih konstrukcij, to so težnostni podporni zid, geotermalni pilot in vpeta vitka oporna konstrukcija, smo pridobili detajlne podatke o kritičnih pogojih nosilnosti za porušitev, kar omogoča inženirjem, da preprečijo specifičen porušitveni mehanizem z dotično spremembo zasnove. V tem smislu smo postavili tudi glavno tezo doktorske disertacije, in sicer, da je možno razviti učinkovito metodologijo za načrtovanje geotehničnih konstrukcij na podlagi verjetnosti porušitve in z večnamensko optimizacijo.
Analize in primerjave z načrtovanjem geotehničnih konstrukcij v skladu z Evrokodom, ki upošteva delne količnike varnosti, pa so pokazale, da je razvita metodologija bolj občutljiva na vse spremenljivke in robne pogoje, kar omogoča celovitejšo obravnavo konstrukcij in privede do optimalnih zasnov danih konstrukcij.
Tako je bil z razvojem in preizkušanjem metodologije potrjen potencial le-te za praktično uporabo v inženirski praksi, kar bi lahko omogočalo dodatno analizo konstrukcij za večjo zanesljivost in bolj ekonomično gradnjo geotehničnih konstrukcij.
Ključne besede: Verjetnost porušitve, optimizacija, genetski algoritem, geotermalni piloti, geotehnične konstrukcije
Objavljeno v DKUM: 19.12.2024; Ogledov: 0; Prenosov: 44
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4. Cost effectiveness of chip seal and hot mix asphalt pavementsBojan Žlender, Cahit Gürer, Rok Varga, Primož Jelušič, 2024, izvirni znanstveni članek Opis: Chip seal pavements, consisting of one or more layers of asphalt binder and fine aggregate, can be mechanically characterized as a surface treatment that enhances evenness and trafficability. This paper examines the geotechnical aspects of chip seal applicability compared to traditional hot mix asphalt pavements. An analytical model was employed to design unpaved roads and determine the required thickness of unbound layers. Eight optimization models were developed for hot mix asphalt pavements and four for chip seal pavements, aimed at achieving optimal designs for various input parameters. These outcomes were used to conduct a multi-parametric analysis, incorporating an optimization loop for each combination of design variables. The results indicate that, under low traffic conditions, a chip seal pavement structure can be up to 40% less expensive than an optimal hot mix asphalt pavement structure, particularly when the subgrade has low bearing capacity and is exposed to unfavorable climatic conditions. However, at medium traffic loads, with good subgrade bearing capacity and favorable climate, the chip seal pavement structure incurs costs that are 25% higher than those of the hot asphalt pavement structure. In addition, chip seal pavements should always be designed with integrated geosynthetic reinforcement to minimize construction costs, and chip seal is not as sensitive to frost as hot mix asphalt.
Ključne besede: chip seal, hot mix asphalt, pavement design, cost optimization
Objavljeno v DKUM: 10.12.2024; Ogledov: 0; Prenosov: 13
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5. Optimization of embedded retaining walls under the effects of groundwater seepage using a reliability-based and partial factor design approachRok Varga, Bojan Žlender, Primož Jelušič, 2024, izvirni znanstveni članek Opis: In this paper, a comparative analysis of the effects of groundwater, seepage and hydraulic heave on the optimal design of embedded retaining walls is carried out. The optimization model for an optimal retaining wall (ORW) minimizes the total length of the retaining wall considering design constraints. The model is extended to include the probability of failure as an additional constraint. This overcomes the limitations of the partial safety factor approach, which does not fully account for uncertainties in the soil. In contrast, the reliability-based design (RBD) approach integrates these uncertainties and enables an assessment of the impact of seepage and hydraulic heave on the reliability of the structure. A real-coded genetic algorithm was used to determine optimal designs for both optimization methods. The results of the case study show that the addition of seepage (groundwater flow) to the hydrostatic conditions has a modest effect on the embedment depth. The design based on partial safety factors, which takes seepage into account, leads to a slight increase in the embedment depth of 0.94% compared to a retaining wall design that only takes the hydrostatic conditions of the groundwater into account. When designing on the basis of probability failure, the percentage increase in embedment depth due to seepage is between 2.19% and 6.41%, depending on the target probability of failure. Furthermore, the hydraulic heave failure mechanism did not increase the required embedment depth of the retaining wall, which means that the failure mechanism of rotation near the base was decisive for the design.
Ključne besede: embedded retaining wall, reliability-based design, partial safety factor design, optimization, genetic algorithm
Objavljeno v DKUM: 10.12.2024; Ogledov: 0; Prenosov: 14
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6. Sanacija zemeljskega plazu s kamnito zložbo v občini LučeDomen Ošep, 2024, diplomsko delo Opis: V diplomski nalogi je predstavljen postopek sanacije plazu s podporno kamnito zložbo. Plaz je nastal kot posledica avgustovskih poplav leta 2023 v občini Luče. Diplomska naloga opisuje vrste zemeljskih plazov in podrobno opiše vzrok za nastanek plazu v občini Luče ter mehanizem porušitve. Opisana je vsebina geološko geotehničnega poročila na podlagi katerega je bila izvedena geotehnična analiza kamnite zložbe. Geomehanske lastnosti temeljnih tal so bile določene na podlagi nekaterih terenskih in laboratorijih preiskav. Geotehnična analiza je bila izvedena skladno s standardi Evrokod. Podan je postopek izvedbe kamnite zložbe vključno z opisom osnovnih materialov in tehnologije gradnje. Podan je tudi popis del za izgradnjo kamnitega podpornega zidu. Diplomska naloga torej prikazuje ključne postopke za izvedbo sanacije plitvega zemeljskega plazu.
Ključne besede: plaz, sanacija, kamnita zložba, geotehnično poročilo, geotehnična analiza
Objavljeno v DKUM: 14.11.2024; Ogledov: 0; Prenosov: 87
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7. Analiza posedkov in napetosti geotermalnih pilotov : magistrsko deloMitja Madjar, 2023, magistrsko delo Opis: V magistrski nalogi obravnavamo določitev posedkov geotermalnih pilotov in osnih napetosti zaradi mehanske in termalne obremenitve. V teoretičnem delu smo opisali geotermalno energijo, vrste geotermalnih konstrukcij in navedli nekaj primerov iz prakse. V računskem delu pa smo izračunali vertikalno nosilnost pilota z metodo, ki jo je podal Berezantzev. Posedek zaradi mehanske obremenitve pa smo izračunali po metodi, ki jo je razvil Poulos. Izračunali smo tudi posedek pilota zaradi temperaturne obremenitve in analizirali vpliv spremembe temperature v različnih zemljinah in glede na dolžino pilota.
Analiza kaže na to, da je vpliv spremembe temperature na geotermalni pilot manjši v primerjavi z mehansko obremenitvijo na pilot, vendar ga ne smemo zanemariti, predvsem v drobnozrnatih zemljinah.
Ključne besede: geotermalna energija, geotermalne konstrukcije, geotermalni piloti, posedki
Objavljeno v DKUM: 20.09.2023; Ogledov: 439; Prenosov: 54
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8. Potential of using waste materials in flexible pavement structures identified by optimization design approachPrimož Jelušič, Süleyman Gücek, Bojan Žlender, Cahit Gürer, Rok Varga, Tamara Bračko, Murat V. Taciroğlu, Burak E. Korkmaz, Şule Yarcı, Borut Macuh, 2023, izvirni znanstveni članek Opis: This paper presents the design of geosynthetic reinforced flexible pavements and their modification by incorporating waste materials into bonded and unbonded layers of the pavement structure. The optimal design of flexible pavements was achieved by minimizing the construction cost of the pavement. The incorporation of waste materials into the pavement structure affects the material properties. Therefore, along with the traffic load, the effects of the material properties of the asphalt concrete, base layer, sub-base layer, and subgrade were analyzed in terms of pavement structure costs and CO2 emissions of materials used in pavement construction. In addition, a comparison was made between pavements with and without geosynthetic reinforcement in terms of design, optimum construction cost, and CO2 emissions. The use of geosynthetics is even more effective in pavement structures that contain waste materials in an unbound layer, both in terms of cost and CO2 emissions. The minimum value of the California Bearing Ratio of the subgrade was determined at which the use of geosynthetic reinforcement for pavement structure with and without the inclusion of waste materials is economically and sustainably justified. The use of geosynthetics could result in a 15% reduction in pavement structure cost and a 9% reduction in CO2 emissions due to the reduced thickness of unbound layers. In addition, reducing the CBR of the unbound layer from 100% to 30% due to the inclusion of waste materials implies a cost increase of up to 13%. While the present study is based on an empirical pavement design method in which pavement thickness is limited by the pavement thickness index, the same minimum thicknesses are obtained in the optimization process regardless of whether the objective function is the minimum construction cost or minimum CO2 emissions.
Ključne besede: pavement design, waste materials, optimization, minimum construction cost, CO2 emissions, geosynthetics, waste management
Objavljeno v DKUM: 18.09.2023; Ogledov: 644; Prenosov: 69
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9. Ogljični odtis optimalno načrtovane voziščne konstrukcije : magistrsko deloŠpela Kok, 2021, magistrsko delo Opis: Voziščna konstrukcija je osnova vsake cestne infrastrukture. Zagotavljati mora prometno prepustnost, prevoznost, trajnost in varnost vseh udeležencev v prometu.
Magistrsko delo obravnava teoretične osnove, življenjski cikel, ogljični odtis voziščne konstrukcije, vplive izgradnje na okolje ter optimizacijo dimenzioniranja voziščne konstrukcije glede na stroškovni vidik. Pri načrtovanju je treba poleg veljavnih zakonodaj in tehničnih specifikacij upoštevati ekonomski in okoljski vidik. Vedno pomembnejši je pristop življenjskega cikla, ki je v veliko pomoč pri načrtovanju tako cestne infrastrukture kot tudi samih voziščnih konstrukcij. Na podlagi takšnega pristopa lahko ocenimo uspešnost, ekonomsko stanje, tveganja ter izjemno pomembne vplive na okolje, ki jih povzročamo z gradnjo cestne infrastrukture. V praktičnem delu smo dimenzionirali voziščno konstrukcijo. Izvedena je bila stroškovna optimizacijo voziščne konstrukcije državne ceste. Za obravnavani cestni odsek je obravnavan tudi okoljski vidik oziroma ogljični odtis, ki ga voziščna konstrukcija odda v okolje v obdobju pridelave in vgradnje surovin.
Ključne besede: voziščna konstrukcija, tehnične specifikacije za ceste (TSC), ogljični odtis, življenjski cikel, vplivi na okolje, optimizacija
Objavljeno v DKUM: 19.11.2021; Ogledov: 970; Prenosov: 133
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10. Reševanje problematike voziščnih konstrukcij z nevezano nosilno plastjo s pomočjo tehnologije chip - seal : magistrsko deloRok Varga, 2020, magistrsko delo Opis: Magistrsko delo obravnava rešitev za voziščne konstrukcije, katerih nosilna plast je samo nevezana nosilna plast. V teoretičnem delu je opisana tehnologija gradnje, ki je zahtevana pri izvedbi cestišča s chip – seal obrabno plastjo. Prav tako so podane tehnične specifikacije in računski modeli za izgradnjo novih voziščnih konstrukcij, tako asfaltiranih kakor tudi vozišč z nevezano nosilno plastjo. V računskem delu so prikazane povezave med metodo končnih elementov in računskim modelom Giroud & Han, katere služijo poenostavitvi pri dimenzioniranju. Hkrati pa je opravljena tudi analiza, ki pokaže bistvene prednosti chip – seal voziščne konstrukcije napram asfaltirani.
Ključne besede: chip – seal, dimenzioniranje voziščnih konstrukcij, tehnična specifikacija, neasfaltirana voziščna konstrukcija, EverstressFE
Objavljeno v DKUM: 16.07.2020; Ogledov: 1245; Prenosov: 158
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