Sürdürülebilir Kalkınma Amaçları
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- MakaleAçık Erişim2023Investigation of changes in geomechanical properties of sandstones under different saturation and anisotropy conditions: Example from Gümüşhane (NE Türkiye); [Farklı doygunluk ve anizotropi koşullarında kumtaşlarının jeomekanik özelliklerindeki değişimlerin incelenmesi: Gümüşhane örneği (KD Türkiye)]
Gültekin, Zarife; Dağ, Serhat
gIn this study the changes in various geomechanical properties were studied for sandstones cropped out at the Mescitli region of the Gümüşhane city under different saturation and anisotropy conditions. For this purpose, 225 specimens were prepared considering the lamination planes of those were chosen to have orientation of 0, 30, 45, 60 and 90° relative to loading direction. Index properties of the sandstones such as dry unit weight (dryg), saturated unit weight (sat), water absorption by weight (Aw) and water absorption by volume (Av) were assigned. In accordance with the objective of study P wave velocity, uniaxial compressive strength and indirect tensile strength values were determined based on different saturation and anisotropy conditions. It was noted as a result of the observations carried out that specimens parallel to lamination have higher wave velocities in general when compared with specimens that are perpendicular to lamination planes. While uniaxial compressive strength values for sandstones are high for specimens which are parallel and perpendicular to lamination, the lowest strength value was observed in specimens with an anisotropy angle of 30°. In addition, it was also observed that the strength values decrease at a significant level with increasing saturation conditions. Strength anisotropy ratio (RUCS) for sandstones varies between 1.28–1.49 based on different saturation conditions. Similarly, while indirect tensile strength values were higher in specimens that were parallel and perpendicular to lamination, they were lower for other anisotropy orientations. Indirect tensile strength values also decreased with increasing degree of saturation.
- MakaleYalnız künye2020Comparison of sandstone and mudstone with different methods for assessing toxic element contamination in the Early–Middle Jurassic sediments of Gümüşhane (NE Turkey)
Saydam Eker, Çiğdem; Arı, Uğur Volkan
To investigate the vertical changes of toxic elements in Jurassic sediments, sampling was performed in four sites. Samples were collected from sandstones and mudstones/marls and analyzed for some toxic elements (Cu, Pb, Zn, As, Ni and V). Results exhibited that the sediment grain size played a significant role in controlling the concentrations of the toxic elements in the sediments. The mean toxic element contents of mudstones/marls were higher than those of sandstones (except Cu). The contamination level of toxic elements was detected by enrichment factor (EF), geo-accumulation index (Igeo), potential ecological risk index (Eir), pollution index (Pi) and united pollution index (PIn). The low EF, Igeo, Eir, Pi and PIn for Cu, Pb, Zn, Ni, V in the sandstones and Cu, Zn, Ni in the mudstones/marls exhibited an absence of clear these elements pollution. The high EF, Eir, Pi and PIn for As (9.7, 73, 7 and 29, respectively, as mean values) in the sandstones and for As (49.3, 222, 22 and 75, respectively, as mean values) Pb (8.8, 24, 5 and 19, respectively, as mean values), V (8.3, 15, 7 and 39, respectively, as mean values) in the mudstones/marls indicated significant contamination. Additionally, according to the potential ecological risk (RI) values, the sandstones had low potential ecological risk for the toxic elements (RI < 150) and the mudstones/marls had moderate potential ecological risk (150 ≤ RI ≤ 300). The potential ecological risk As, Pb, V (especially As) were higher in urban areas than in agricultural activities. Therefore, the source of As, Pb, V could be gasoline combustion, burning coal and vehicle exhausts. The contents of these elements generally increased from bottom to top of the measured stratigraphic sections, which indicated transported by atmospheric conditions.