Assessment of cut slope stability in western Black Sea Region (Turkey)

Özköse, Merve
Cut slopes are intensely prone to weathering in the cause of excavation effects. Weathering effects can reduce strength of rocks and results in instabilities in the long run. By the reasons of rocks containing joints, fractures, faults, bedding planes and pore spaces, they are likely to be weathered because of wetting-drying cycles, climate changes, and chemical action of solutions absorbed. This study is mainly concerned with the slope stability analysis for sixteen permanent cut slopes that are composed of limestone, sandstone, marl and mudstone, having heights between 8 and 60 m, along the highways within the borders of Karabük, Zonguldak and Düzce province at Western Black Sea Region in Turkey. Stability analyses were conducted by considering weathering effects with the help of field works, laboratory tests and computer softwares. The purpose is to reveal instability possibilities occurring throughout the determined slopes, chances that the road cuts may move downslope, and the most vulnerable slopes. Within the scope of this thesis, literature researches, field studies, laboratory works, and stability analyses were conducted. Field studies were performed in order to investigate the rock types that were encountered at the studied road cuts. Field observations about weathering degree and excavation types of the road-cuts have been done to examine their effects on stability, geometry and geological characteristics of the studied cut slopes. Scan line surveys were carried out with the aim of obtaining discontinuity-related data of the road-cuts. As an in-situ test, Schmidt hammer rebound test was carried out in the field to assess the strength of the rock units. Laboratory tests as unit weight, point load and uniaxial compression strength (UCS) tests have been performed on the rock specimens that were taken during field works for determining strength parameters and investigating the differences in weathering degrees of the rocks with the tests of methylene blue and slake durability. Slope stability analyses of the road-cuts were performed in accordance with strength parameters values of the rocks as weathered and relatively fresh types. The analyses were performed by modeling surface of the cut slopes as weathered rock with the determined depths and modeling rest of the slope material as relatively fresh. In addition to the slope stability analyses, rockfall analyses were performed in order to investigate the rockfall risks of the studied cut slopes. Taking into account of the studies performed, instability risks were assessed and prevention about drainage channels were recommended as a remedial measure due to surficial failures of the cut slopes.


Weathering and Excavation Effects on the Stability of Various Cut Slopes in Flysch-Like Deposits
Ersöz, Timur; Topal, Tamer (2018-12-01)
Cut slopes are very sensitive to weathering because of disturbed rock mass and topographical condition by excavation. During and right after an excavation process of a cut slope, weathering and erosion may act on this newly exposed rock material and mass. These acting on the rock may degrade and change its engineering properties and the stability of the cut slope in its engineering lifetime. In this study, weathering and excavation effects on stability of sixteen cut slopes in flysch-like deposits at North ...
Effect of disturbed zone depth on slope stability analysis: a case study from Western Black Sea Region (Turkey)
Ersöz, Timur; Topal, Tamer (2019-10-07)
Rocks in road cuts are affected by weathering, excavation and tectonic activities. The weak rocks especially disturbed by tectonic activities lose their strength over the years due to excavation and weathering. One of the most important parts to consider here is the damage caused by the type of excavation to the rock mass. In addition, weathering reduces the rock strength towards inside of the slope through discontinuities. In this study, the effects of weathering and excavation on rock strength parameters ...
Assessment of rock slope stability with the effects of weathering and excavation by comparing deterministic methods and slope stability probability classification (SSPC)
Ersöz, Timur; Topal, Tamer (2018-07-01)
Cut slopes are prone to fail due to the disturbance on original geometry and strength. In addition, because of these disturbances and stress relief, natural apertures which increase the weathering effects widen in engineering time. Owing to these reasons, slope stability assessment has a prominent role on these road cuts. Generally, slope stabilities are assessed by deterministic approaches with a significant engineering judgment. Because of this reason the reputation of probabilistic approaches is increasi...
Probabilistic Slope Stability Analyses: Effects of the Coefficient of Variation and the Cross-Correlation of Shear Strength Parameters
Oğuz, Emir Ahmet; Yalçın, Yağızer ; Huvaj Sarıhan, Nejan (2017-03-15)
The assessment of the safety level of natural slopes, road cuts, embankments and levees require consideration of uncertainties and variability in material properties. In this study, for a number of slope geometries, including a real-life landslide case, probability of failure (PF) and the most critical failure surface are investigated with and without cross-correlation of shear strength properties. Slopes having different traditionally-defined factor of safety (FS) levels are studied. The uncertainty of soi...
Stability Charts for the Collapse of Residual Soil in Karst
DRUMM, Eric C.; Akturk, Oezguer; Akgün, Haluk; Tutluoğlu, Levend (American Society of Civil Engineers (ASCE), 2009-07-01)
Collapse of the residual soil over bedrock cavities often occurs during construction in karst terrain, particularly when the thickness of the residuum is reduced during excavation. Even if an estimate of the strength of the residual soil is known, uncertainty with respect to the size/geometry of the subterranean voids makes a detailed analysis difficult, and straightforward methods to check the stability are needed. In this study, numerical analyses were performed to develop a stability chart expressed in t...
Citation Formats
M. Özköse, “Assessment of cut slope stability in western Black Sea Region (Turkey),” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Geological Engineering., Middle East Technical University, 2019.