Laboratorijski preskusi lastnosti mineralnih agregatov v fluvialni abraziji grobih sedimentovKuzmanić, Tamara (Avtor) Mikoš, Matjaž (Mentor) Kryžanowski, Andrej (Član komisije za zagovor) Šmuc, Andrej (Član komisije za zagovor) Hübl, Johannes (Član komisije za zagovor) Built Environmentcivil engineeringdoctoral thesisexperimental abrasionfrost weatheringdynamic image analysisparticle morphologypower of abrasionparticle size distributioncoarse sedimentsFluvial abrasion participates in the shaping of fluvial environments and the Earth's landscape overall. Highly complex and dynamic fluvial abrasion processes are influenced by numerous parameters, including lithology of abraded sediments, flow conditions, and weathering of sediments. In the scope of this thesis, the different parameters influencing abrasion behaviour were investigated, in order to better understand and describe the changes abraded sediment particles undergo due to abrasion. The parameters considered were energetic conditions of experimental abrasion (amount of introduced energy, or mechanical work, and power of experimental abrasion), granulometric properties of abraded sediments, and weathering (frost weathering). Abrasion experiments were carried out in several experimental set-ups on natural fluvial sediment (sediment from the Suhorica stream) and on quarried aggregates (quarried dolomite). Experiments were carried using standardised equipment, widely used for material testing, with modified testing procedures. Changes in mass (and size) and morphology of tested samples were examined during cyclic abrasion in different conditions of abrasion in micro-Deval and Los Angeles machines. Morphology changes of sediment particles, in three aspects of particles’ morphology, were determined from dynamic image analysis of the particles between the abrasion cycles. The influence of frost weathering on abrasion behaviour was investigated by artificial frost weathering (in a laboratory climatic chamber) of the samples before their abrasion in a micro-Deval machine. Different energetic conditions of abrasion were defined by introduction of mass loss per power density – describing the amount of mass loss per unit mass at a given power of abrasion with the aim to be able to compare different abrasion settings between each other. The results of the abrasion experiments showed that the abrasion coefficient is greatly dependent on the power of abrasion, hence it is not only lithology-specific but also power-specific. The abrasion behaviour is also defined by the granulometric properties of abraded sediment, mainly the median size, but also the skewness of the abraded sediment. The influence of granulometric properties is buffered after frost weathering, and the weathering takes the dominant influence in defining abrasion behaviour. Furthermore, frost weathering at relatively mild temperatures redefines the dynamics of abrasion and accelerates the first, rapid phase of abrasion, but, in the long term, it does not influence the total amount of abraded material, and can go undetected. The abrasion experiment of fluvial sediment pointed out the benefits of the shape analysis during abrasion. Even with the minimal difference in abrasion rates, the differences in the changes of the shape parameters showed considerable differences with the sampling locations. The greater changes in morphology of sediment particles indicate particles’ tendency to become more rounded and more regular during abrasion.[T. Kuzmanić]20242024-09-25 07:45:06Doktorsko delo/naloga162539sl