Numerical and back analysis-based methodology for support design of cut slopes at the Turkish – Georgian Border (NE Turkey)


Sünnetci M. O. , Ersoy H. , Fırat Ersoy A.

Journal Of Mountain Science, vol.18, no.6, pp.1678-1695, 2021 (Journal Indexed in SCI Expanded)

  • Publication Type: Article / Article
  • Volume: 18 Issue: 6
  • Publication Date: 2021
  • Doi Number: 10.1007/s11629-020-6650-x
  • Title of Journal : Journal Of Mountain Science
  • Page Numbers: pp.1678-1695

Abstract

In this study, geophysical and geotechnical studies were carried out in NE Turkey to evaluate the stability and support design of cut slopes that will be excavated during the construction of a new border control complex. 13 vertical and 3 inclined boreholes were drilled, and 2D electrical resistivity tomography surveys were conducted along 8 profiles to investigate the horizontal and vertical continuity of the geological units. Strength characteristics of all units were determined by suggested laboratory tests. Limit equilibrium slope stability analyses were conducted on the geological model for static and pseudo-static conditions and factor of safety values as low as 0.227 were determined for the situation after excavation. Sensitivity analyses indicated that the slopes are sensitive to cohesion and unit weight, and semi-sensitive to frictional angle. This result indicates that the most important factor controlling the slope stability in this region is precipitation. In the study, back analysis was conducted for the determination of required support force to achieve a factor of safety of 1.3. A feasible support system consisting of bored piles and rock anchors was designed based on back analysis results for each cut slope. LE analyses were repeated after the implementation of the designed support systems and the lowest factor of safety value increased to 1.35. The utility and safety of the designed support systems, and also stress distributions in the supports were investigated using finite element slope stability analyses and SRF values higher than 1.3 were determined which means support systems will function as intended and no support failure will occur. Lastly, quick reference charts were created for alluvium and residual soil materials to easily determine the safe slope angle in the future in case no support measures will be applied.