Laboratorijski preskusi lastnosti mineralnih agregatov v fluvialni abraziji grobih sedimentov : doktorska disertacija

Kuzmanić, Tamara (author), Mikoš, Matjaž (mentor), Kryžanowski, Andrej (member of the commission for defense), Šmuc, Andrej (member of the commission for defense), Hübl, Johannes (member of the commission for defense)

Fluvial 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.

• Language: English
• Keywords: Built Environment, civil engineering, doctoral thesis, experimental abrasion, frost weathering, dynamic image analysis, particle morphology, power of abrasion, particle size distribution, coarse sediments
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [T. Kuzmanić]
• Year: 2024
• Number of pages: XXX, 176 str., 37 str. pril.
• PID: 20.500.12556/RUL-162539-335a5b36-a666-d739-c950-88b5ad5db9de
• UDC: 556.536:666.96.022.32-032(043)
• COBISS.SI-ID: 209047811
• Publication date in RUL: 25.09.2024

Secondary language

• Language: Slovenian
• Title: Laboratory tests of mineral aggregates’ properties in fluvial abrasion of coarse sediments : doctoral dissertation

Abstract

Rečna abrazija sodeluje pri oblikovanju rečnih okolij in okolja na splošno. Na zelo zapletene in dinamične rečne abrazijske procese vplivajo številni parametri, vključno z litologijo sedimentov (ki so podvrženi abraziji), pretočnimi pogoji in preperevanjem sedimentov. V okviru te doktorske naloge so bili raziskani različni parametri, ki vplivajo na obnašanje sedimentov pri abraziji, da bi bolje razumeli in opisali spremembe, ki so jim delci sedimenta izpostavljeni zaradi abrazije. Upoštevani so bili energijski pogoji eksperimentalne abrazije (količina vnesene energije oz. mehanskega dela in moč eksperimentalne abrazije), granulometrične lastnosti sedimentov in preperevanje (zmrzal). Abrazijski poskusi so bili izvedeni v več poskusnih napravah na naravnem rečnem sedimentu (sediment iz potoka Suhorica) in na lomljenih agregatih (dolomit iz kamnoloma). Poskusi so bili izvedeni s standardizirano opremo, ki se pogosto uporablja za testiranje materialov, s spremenjenimi postopki testiranja. Spremembe mase (in velikosti) in morfologije testiranih vzorcev sedimenta smo preučevali med ciklično abrazijo v različnih pogojih abrazije na napravah micro-Deval in Los Angeles. Morfološke spremembe delcev sedimenta s treh vidikov morfologije delcev so bile določene z analizo dinamične slike delcev med cikli abrazije. Vpliv preperevanja zmrzali na obrabno obnašanje smo raziskali z umetnim preperevanjem (v laboratorijski klimatski komori) zmrzali vzorcev pred njihovo abrazijo v napravi micro-Deval. Različni energijski pogoji abrazije so bili definirani z uvedbo izgube mase na gostoto moči – opisovanje količine masnih izgub na enoto mase pri dani moči abrazije, tako da bi primerjali različne nastavitve abrazijskih poskusov med seboj. Rezultati abrazijskih poskusov so pokazali, da je koeficient abrazije zelo odvisen od moči abrazije, zato ni samo značilen za litologijo, temveč tudi za moč. Obnašanje pri abraziji je opredeljeno tudi z granulometričnimi lastnostmi sedimenta, podvrženega abraziji, predvsem srednje velikosti, pa tudi koeficienta asimetrije sedimenta. Vpliv granulometričnih lastnosti se zmanjša po preperevanju zaradi zmrzali, ko preperevanje prevladujoče vpliva na določanje abrazijskega obnašanja. Poleg tega preperevanje zaradi zmrzali pri razmeroma blagih temperaturah na novo opredeli dinamiko abrazije in pospeši prvo, hitro fazo abrazije, a dolgoročno ne vpliva na skupno količino izgube mase ter lahko ostane neopaženo. Abrazijski poskus rečnega sedimenta je pokazal prednosti analize oblike med abrazijo. Tudi pri minimalni razliki v izgubah mase so razlike v spremembah parametrov oblike pokazale precejšnje razlike glede na lokacije vzorčenja. Večje spremembe v morfologiji delcev sedimenta kažejo na težnjo delcev, da ti med abrazijo postanejo bolj zaobljeni in bolj pravilni.

• Keywords: doktorske disertacije, gradbeništvo, grajeno okolje, eksperimentalna abrazija, zmrzalno preperevanje, analiza dinamičnih slik, morfologija zrn, moč abrazije, Los Angeles, micro-Deval, zrnavostna sestava, grobi sedimenti