Paper contribution

Friction-Angle Sensitivity of Open-Pit Slope Stability and Field Performance

Cemalettin Okay Aksoy; Guzin Gulsev Uyar Aksoy; Ozan Savas; Burak Gurel; Bilal Akyuz; Yavuz Aydemir; Ali Burak Aktaş

Proceedings
EUROCK 2026
Pages
883-888
Submitted
28 January 2026
Accepted
15 June 2026
Published
12 August 2026

Summary

Abstract

This study investigates the sensitivity of slope stability to internal friction angle (φ) in open-pit mining by integrating limit equilibrium analysis with field observations. Two large-scale slopes were analyzed using friction-angle scenarios derived from geotechnical data. For Site 1, φ values of 24°, 28°, and 35° yielded a maximum factor of safety (FoS) of 1.324, while Site 2 with φ values of 25°, 26°, and 33° produced FoS up to 1.421. A normalized sensitivity framework was applied to evaluate the variation of FoS with respect to φ. Results confirm that FoS increases nonlinearly with φ; however, field evidence indicates that analytical stability may not represent actual slope behavior due to geological heterogeneity, structural discontinuities, and weathering effects. The study highlights that φ should not be treated as a fixed parameter but as an uncertainty-driven field-controlled variable. The proposed framework links analytical outputs with real slope performance, improving reliability in slope design.

Contributors

Authors

  1. Cemalettin Okay Aksoy Dokuz Eylul University, Turkiye ORCID 0000-0002-4328-4862
  2. Guzin Gulsev Uyar Aksoy Hacettepe University, Turkiye ORCID 0000-0002-9328-9899
  3. Ozan Savas GOA Mining Company, Turkiye
  4. Burak Gurel Tumad Mining Company
  5. Bilal Akyuz Tumad Mining Company
  6. Yavuz Aydemir Tumad Mining Company
  7. Ali Burak Aktaş Tumad Mining Company

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References

  1. Barton N, Bandis S (1990) Review of predictive capabilities of JRC-JCS model. Rock Mech Rock Eng.
  2. Bishop AW (1955) The use of the slip circle in the stability analysis of slopes. Geotechnique 5(1):7-17. https://doi.org/10.1680/geot.1955.5.1.7
  3. Duncan JM, Wright SG (2005) Soil strength and slope stability. Wiley.
  4. Griffiths DV, Lane PA (1999) Slope stability analysis by finite elements. Geotechnique 49(3):387-403. https://doi.org/10.1680/geot.1999.49.3.387
  5. Hoek E, Bray JW (1981) Rock slope engineering, 3rd edn. Institution of Mining and Metallurgy, London.
  6. Hoek E, Carranza-Torres C, Corkum B (2002) Hoek-Brown failure criterion – 2002 edition. Proceedings of NARMS-TAC Conference, Toronto, 267-273.
  7. Read J, Stacey P (2009) Guidelines for open pit slope design. CSIRO Publishing.
  8. Spencer E (1967) A method of analysis of the stability of embankments assuming parallel inter-slice forces. Geotechnique 17(1):11-26. https://doi.org/10.1680/geot.1967.17.1.11
  9. Stead D, Wolter A (2015) A critical review of rock slope failure mechanisms. Engineering Geology.