20.500.12556/RUL-188238 Vpliv dodatka biopolimerov na geomehanske lastnosti morske gline magistrsko delo Effect of biopolymer addition on geomechanical properties of marine clay V magistrski nalogi je bil preiskan vpliv biopolimerov na geomehanske lastnosti mulja, ki nastaja pri poglabljanju in vzdrževanju plovnih poti v Luki Koper. Mulj ima visoko naravno vlago in vsebuje raztopljene soli, kar omejuje možnosti njegove uporabe. Preiskan je bil vpliv dodatka 1 m% guar gumija, semenske sluzi rožičevca, ksantan gumija, hitozana in kalcijevega alginata. Biopolimeri so bili v naravno vlažen mulj vmešani v obliki prahu. Nedrenirana strižna trdnost je bila s krilno sondo spremljana v prvih 72 urah po pripravi mešanic. Med sušenjem preizkušancev na zraku sta bila z zaporednim fotografiranjem in binarno analizo slik spremljana razvoj razpok in površinsko krčenje, ki sta bila ovrednotena z deležem površine razpok oziroma krčenja (DPR). Retencijske lastnosti mulja so bile določene z meritvami matrične sukcije z napravo HYPROP in totalne sukcije z napravo WP4-T. Določena je bila tudi meja krčenja mulja brez dodatkov in mulja z dodatkom kalcijevega alginata. Dodatek vseh obravnavanih biopolimerov je povečal začetno nedrenirano strižno trdnost mulja. Pri dodatku guar gumija je bila izmerjena največja vrednost 6,23 kPa, vendar je bil njegov učinek kratkotrajen, medtem ko je pri dodatku hitozana ostala nedrenirana strižna trdnost v opazovanem obdobju približno konstantna. Kalcijev alginat ni vplival na mejo krčenja mulja in je bil edini izmed obravnavanih dodatkov, pri katerem so na površini preizkušanca nastale razpoke. Drugi štirje biopolimeri so preprečili nastanek razpok, preizkušancem pa se je na račun odmika od kalupa in nastanka reže med kalupom in robom preizkušanca zmanjšala površina. Pri mulju brez dodatkov ter mešanicah z dodatkom ksantan gumija in kalcijevega alginata se je začetek krčenja pojavil približno pri vlagi, ki ustreza poljski kapaciteti, prehod v počasnejše krčenje pa približno pri vlagi, ki ustreza točki venenja. Dodatek biopolimerov ni imel jasno izraženega vpliva na retencijske krivulje mulja. Zaradi prisotnosti soli je bil pri interpretaciji meritev totalne sukcije upoštevan ocenjeni prispevek osmotske sukcije, preverjena pa sta bila tudi vpliva mase raztopljenih soli in temperature sušenja na določeno vlago. Dosežene nedrenirane strižne trdnosti so bile kljub izboljšanju prenizke za uporabo mulja pri zemeljskih delih brez dodatnega tretiranja. Rezultati kažejo, da je bil vpliv biopolimerov izrazitejši pri spreminjanju načina krčenja in omejevanju nastanka razpok kot pri izboljšanju trdnosti in retencijskih lastnosti mulja. This master’s thesis investigated the effects of biopolymers on the geomechanical properties of dredged sediment generated during the dredging and maintenance of navigation channels at the Port of Koper. The sediment has a high natural water content and contains dissolved salts, which limit its potential applications. The effects of adding 1 wt.% guar gum, locust bean gum, xanthan gum, chitosan and calcium alginate were investigated. The biopolymers were mixed into the sediment at its natural water content in powder form. Undrained shear strength was monitored using a laboratory vane apparatus during the first 72 h after mixture preparation. During air-drying of the specimens, crack development and surface shrinkage were monitored by sequential photography and binary image analysis and quantified using the crack area and surface shrinkage ratio (DPR). The water-retention properties of the sediment were determined by measuring matric suction with a HYPROP device and total suction with a WP4-T device. The shrinkage limits of the untreated sediment and the sediment treated with calcium alginate were also determined. The addition of all the investigated biopolymers increased the initial undrained shear strength of the sediment. The highest value, 6.23 kPa, was measured for the sediment treated with guar gum; however, its effect was short-lived. By contrast, the undrained shear strength of the chitosan-treated sediment remained approximately constant throughout the observation period. Calcium alginate did not affect the shrinkage limit of the sediment and was the only investigated additive for which cracks developed on the specimen surface. The other four biopolymers prevented crack formation; however, the surface area of the specimens decreased because they separated from the mould, creating a gap between the mould and the specimen edge. In the untreated sediment and the mixtures containing xanthan gum or calcium alginate, shrinkage began at a water content approximately corresponding to field capacity, whereas the transition to slower shrinkage occurred at a water content approximately corresponding to the wilting point. The addition of biopolymers had no clearly discernible effect on the water-retention curves of the sediment. Owing to the presence of salts, the estimated contribution of osmotic suction was considered when interpreting the total suction measurements. The effects of the mass of dissolved salts and drying temperature on the determined water content were also examined. Despite the observed improvement, the undrained shear strengths achieved were too low for the sediment to be used in earthworks without further treatment. The results indicate that the effects of the biopolymers were more pronounced in modifying shrinkage behaviour and limiting crack formation than in improving the strength and water-retention properties of the sediment. magistrska dela biopolimeri morska glina sukcija razpoke nedrenirana strižna trdnost meja krčenja master thesis biopolymers marine clay suction cracks undrained shear strength shrinkage limit true false false [M. Rakita] Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-09-19 08:46:21 2026-09-19 08:46:26 2026-09-21 13:05:51 0000-00-00 00:00:00 2026 0 Ljubljana 2026 Ljubljana 1 spletni vir (1 datotek PDF (IX, 71 str.)) 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 624.131:577.11(043.2) 182690 291830275 23141.pdf 23141.pdf 1 737C06C8950FC7EAF3CE6CAF6A0A5376 33b9938a6832d83147e59a71f6d3cf71e38bed78082f900ce58d185165b0f2d7 c7cc8269-b3f5-11f1-8bc5-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=248267 Fakulteta za gradbeništvo in geodezijo 0 0 0