| Popis: |
Subaqueous, fine-grained, cohesive sediments are continuously fluidized by waves and other disturbances that cause their movement, which can be described with numerical models incorporating rheological parameters. The rheological behaviour depends on the soil (solid) type, the volume concentration, the salinity and the testing methods. In this study, rheological investigations of marine sediments from the Port of Koper were carried out by using two coaxial cylinder rheometers (DV3T HB, Brookfield and ConTec Viscometer 5). The influence of the specimen volume, the size of the gap and the type of measuring spindles were analysed and compared. The measured data were evaluated using the Bingham model. For each data set, the boundary between the sheared (“fluid”) and the un-sheared (“solid”) material was calculated and then the calculated boundary was used instead of the outer radius of the cylinder for the evaluation of the rheological parameters, where necessary. A good comparison of the results was found when using this approach. The results are also in agreement with the literature data. The ConTec Viscometer 5, primarily designed for mortars and concrete, was shown to be also suitable for the investigation of sediments. Sedimenti na morskem dnu so nenehno izpostavljeni valovanju in drugim motnjam, ki povzročajo njihovo premikanje. Premikanje lahko opišemo z numeričnimi modeli, ki vključujejo reološke parametre, odvisne od vrste zemljine (trdnine), volumske koncentracije, slanosti in preiskovalnih metod. Ta članek opisuje preiskave reoloških lastnosti morskega sedimenta iz Luke Koper. Raziskave so bile izvedene z uporabo dveh koaksialnih valjastih reometrov (DV3T HB, Brookfield in ConTec Viscometer 5). Analiziran je vpliv volumna vzorca, razdalje med notranjim in zunanjim valjem in vrste uporabljenih vreten. Meritve so analizirane z uporabo Bingham-ovega modela. Za vsako meritev je bila izvrednotena meja med materialom, ki teče in tistim, ki ne teče. Kjer je bilo potrebno, je bila za vrednotenje reoloških parametrov, namesto radija zunanjega cilindra uporabljena izračunana meja. Z uporabo te metode je bilo ugotovljeno dobro ujemanje rezultatov. Rezultati so primerljivi s podatki iz literature za podobne zemljine. ConTec Viscometer 5, ki je prvenstveno razvit za preiskave malt in betonov, je bil prepoznan, kot primeren tudi za preiskave sedimentov. |
