1. Rheological properties of marine sediments from the port of KoperJasna Smolar, Matej Maček, Ana Petkovšek, 2016, original scientific article Abstract: 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.
Keywords: marine sediments, Bingham model, yield stress, plastic viscosity, coaxial cylinder rheometer, plug flow, Bay of Koper
Published: 18.06.2018; Views: 438; Downloads: 40
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2. Influence of mould suction on the volume - change behaviour of compacted soils during inundationMatej Maček, Bojan Majes, Ana Petkovšek, 2011, original scientific article Abstract: After construction, compacted clayey soils in different earth structures equilibrate their water content and suction with the local environment. In wet climatic conditions the compaction on the dry side of the Proctor curve, which enables a high layer stiffness during construction, may result in permanent deformation and softening during the lifetime of the structure. This paper presents the results of the tests, performed on a relatively large number of compacted test specimens, where the conventional index parameters, used to identify compacted soils, were supplemented with a suction–water-content curve and measurements of “mould” suction. Correlations were established between the optimum water content and the suction–water-content curve for representative samples, and the influence of the mould suction on the vertical deformation of the compacted samples during inundation in oedometers was studied.
Keywords: oedometer tests, suction, swelling, collapse
Published: 13.06.2018; Views: 393; Downloads: 66
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3. A laboratory characterization of soils and clay-bearing rocks using the Enslin-Neff water-adsorption testAna Petkovšek, Matej Maček, Bojan Majes, 2009, original scientific article Abstract: The application of the Enslin-Neff water-adsorption test for the determination of soil-index properties has been investigated on commercially available reference minerals and on real soils. The Enslin-Neff test is a simple and reliable laboratory method, which can provide important information about the behavior of soils, clay-bearing rocks and aggregate fines that are in contact with water. Although the test has been frequently used for bentonite testing, practically no results have been published about the physical meaning of the Enslin-Neff water-adsorption values for real soils. The results of this study indicate that the Enslin-Neff water-adsorption test can be used to obtain accurate values of some soil-index properties, such as the liquid limit, the plasticity index, the methylene-blue value, and the soil-water characteristic curve.
Keywords: water adsorption, soil water characteristic curve, methylene blue value, soil suction
Published: 06.06.2018; Views: 679; Downloads: 64
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