Laboratorijske meritve reologije naravnega drobirskega materiala : magistrsko delo št.: 156/II. GR

Jurček, Timotej (author), Maček, Matej (mentor), Mikoš, Matjaž (co-mentor)

Drobirski tokovi spadajo med izjemno hitre pobočne masne premike, ki se navadno prožijo v hribovitih in gorskih območjih. Veljajo za izredno kompleksen naravni pojav, katerega je težko napovedati. Za razliko od drugih vrst zemeljskih plazov, drobirski tokovi lahko prepotujejo velike razdalje. Zaradi velikih hitrostih gibanja evakuacija ob njihovi sprožitvi praktično ni mogoča. Gibanje drobirskih tokov razložimo z dinamiko nenewtonskih tekočin. Za njihovo modeliranje se uporablja različne matematične modele, za katere je nujno poznati reološke lastnosti drobirske mešanice. Pri določevanju reoloških lastnosti drobirskega materiala se najpogosteje uporablja Binghamov reološki model, ki ima dva reološka parametra % strižno napetost na meji tečenja in plastično viskoznost. Po naravni katastrofi v Logu pod Mangartom leta 2000, ko se je 15. novembra tega leta sprožil plaz Stože in je 17. novembra Log zasul drobirski tok, se je v Sloveniji začelo resneje in bolj sistematično raziskovalno ukvarjati s pojavom drobirskega toka. V ospredje se je postavilo vprašanje, kakšne lastnosti mora imeti plazovina zemeljskih gmot, da se ob določenih pogojih spremeni v drobirski tok. Z magistrsko nalogo smo želeli ugotoviti zanesljivost in natančnost določevanja reoloških parametrov drobirskega materiala s pomočjo laboratorijskih reometrov ter raziskati možnost določevanja reoloških lastnosti drobirskega materiala s standardiziranimi laboratorijskimi testi, ki se v gradbeništvu uporabljajo za določevanje obdelovalnosti in pretočnosti betonov, malt ter zalivnih mas. Reološke lastnosti smo določevali na vzorcih drobirskega materiala, ki so se v preteklosti že sprožili kot drobirski tok oz. bi se potencialno lahko sprožili kot drobirski tok. Na izbranih mešanicah drobirskega materiala znane zrnavosti in vlažnosti smo reološke lastnosti merili z dvema koaksialnima valjastima reometroma % Brookfield DV3T HB in ConTec Viscometer 5. Reološke parametre smo skušali določiti tudi posredno preko meritev s standardnimi testi oz. napravami % lijaki, V-lijak in pravokotni kanal. Reološke lastnosti smo določevali tudi različno vlažnim vzorcem kamene moke. Natančnost in zanesljivost samih postopkov meritev smo preverili s pomočjo vode in glicerina, ki se uvrščata med newtonske tekočine in imata dobro znane reološke lastnosti. Rezultate vseh meritev smo sistematično prikazali v diagramih in jih med seboj tudi primerjali.

• Language: Slovenian
• Keywords: gradbeništvo, magistrska dela, GR, drobirski tok, reologija, laboratorijske preiskave, drobirski material, viskoznost, strižna napetost na meji tečenja
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [T. Jurček]
• Year: 2020
• Number of pages: XII, 76 str.
• PID: 20.500.12556/RUL-119485
• UDC: 556.5:624.1(497.4)(043.3)
• COBISS.SI-ID: 37028867
• Publication date in RUL: 09.09.2020

Secondary language

• Language: English
• Title: Laboratory analysis of natural debris material rheology : master thesis no.: 156/II. GR

Abstract

Debris flow is very fast mass moving mass of debris material, which frequently occur in hilly and mountain regions worldwide. The triggering mechanism of debris flow is very complex and difficult to predict. Debris flows can move vast distance as opposed to landslides. When debris flow occur the evacuation is not possible due to high velocity of moving masses. Behavior of debris flow can be described as non-Newtonian fluid. For describing debris flow behavior by different mathematical models is necessary to know rheological properties of debris mixture. The Bingham rheological model is most commonly used model for describing rheological parameters of debris material. Bingham model has two parameters % yield stress and plastic viscosity. The interest for debris flow hazard after catastrophic debris-flow event in the village of Log pod Mangartom in November 2000 in Slovenia has increased. The main question that arises was what kind of properties must soil have in order to be transformed into a debris flow under certain condition. In this master thesis we wanted to determine the reliability and accuracy of determining the rheological parameters of debris material using laboratory rheometers and explore the possibility of determining the rheological properties of debris material with standardized laboratory tests used in construction to determine workability and flowability of concrete, mortar and grout. We determined rheological properties on samples of debris material, which in the past have already been triggered as debris flows or could potentially be triggered as a debris flow. The rheological parameters were measured on different debris mixtures of known grain size and water content with two coaxial cylinder rheometers % Brookfield DV3T HB and ConTec Viscometer 5. We also tried to determine the rheological parameters indirectly through measurements with standard tests or devices % funnels, Vfunnel and canal. The rheological properties were also determined for different wet specimens of limestone flour. The accuracy and reliability of the measurements were checked with the help of water and glycerin, which are Newtonian fluids and have well known rheological properties. The results of all measurements were systematically presented in diagrams and compared with each other.

• Keywords: civil engineering, master thesis, debris flow, rheology, laboratory test, debris material, viscosity, yield stress