Effect of disturbed zone depth on slope stability analysis: a case study from Western Black Sea Region (Turkey)

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 have been investigated by using twenty rock slopes located in Western Black Sea region of Turkey. Strength parameters and index rock properties were investigated in laboratory extensively. Detailed discontinuity analyses were done for all cut slopes by scan line surveys in the field. The intact rock and rock mass properties were determined for both weathered and relatively fresh zones at the cut slopes. The evaluations of disturbance depths were made according to strength differences and visual estimations of weathering degrees. According to these investigations the effects of weathering and excavation were found to be changing between 10 and 50 cm for the studied cut slopes within 5 years of lifetime. Throughout the study area the disturbance factor was assigned only to weathered zones to evaluate the stability of the slopes. Also the slope stability analyses were done by assigning the disturbance factor to different depths. It is found that the field observations are matching with the stability assessments considering the disturbed zone depths. Fresh and weathered rock mass properties were evaluated by Geological Strength Index (GSI) and the ratio between global rock mass and intact rock strength. It has been obtained that fresh and weathered rock mass properties are coherent with the Hoek Brown criterion on disturbance factor. Results indicate that the surfaces of the slopes reveal different degrees of disturbances and towards inside effects of weathering and excavation decrease. As a result, it is noted that the disturbance factor value should be used only for a certain depth and rest of the slope should be assigned as zero disturbance.


Assessment of cut slope stability in western Black Sea Region (Turkey)
Özköse, Merve; Topal, Tamer; Department of Geological Engineering (2019)
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 o...
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 thickness on rock slope stability
Ersöz, Timur; Topal, Tamer (2021-04-01)
Cut slope surfaces are affected by excavation activities and weathering agents. Disturbances on the surface can penetrate down to a certain depth. Slope stability analyses made on the cut slopes can reveal unsatisfactory results unless the disturbance depth is determined. Moreover, false designs ignoring the shear strength parameter differences of inner and surface sections of the slopes can affect the safety of the highways. Disturbance thickness due to blasting effect is already presented in the literatur...
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The effect of axial stresses on rock is known to affect porosity, permeability, and rock compressibility and will be important in some reservoir rock types that are buried deep and at high temperatures. The aim of this project is to determine reservoir rock properties under in situ stress conditions and to observe the effects of axial stresses on reservoir rocks. For this purpose, a uniaxial stress device, which is capable of applying axial stress to the core samples, was used. The core samples chosen were ...
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Citation Formats
T. Ersöz and T. Topal, “Effect of disturbed zone depth on slope stability analysis: a case study from Western Black Sea Region (Turkey),” presented at the 7th International Earth Science Colloquium on the Aegean Region (2019), İzmir, Türkiye, 2019, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/70715.