Physico-mechanical and mineralogical investigations of red bed slopes (Cluj-Napoca, Romania)

• Published in: Bulletin of engineering geology and the environment 2022-02, Vol.81 (2), Article 78
• Main Authors: Marat, Andreea Rebeca, Tămaş, Tudor, Samşudean, Cristian, Gheorghiu, Robert
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Nature Conservation; Original Paper
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-021-02542-6

The southern slope of the Cetățuia-Hoia Hill, located in the urban setting of Cluj-Napoca (Romania), consists of clayey deposits interbedded with sands and sandstones. The slope deposits belong to the Moigrad Formation and are representative of “red bed” continental deposits found across the world. Although documented as a landslide-prone area, the hillslope receives increased attention due to urban development and real estate pressure. The slope was affected by an old, deep-seated landslide; mudflows; and anthropogenic interventions. The stability of the old landslide is close to equilibrium (1.35) and its reactivation may be triggered by rainwater infiltration. The Moigrad Formation deposits are mostly active, expansive, and display medium to high plasticity. Their shearing resistance is described by effective friction angles of 6.7–33.7° and effective cohesive strengths of 7–122 kPa. With regard to mineralogy, the deposits are made up of quartz, feldspar, calcite, dolomite, and phyllosilicates (micas, chlorite, kaolinite, and minerals belonging to the smectite group), while their clay-sized fraction (