Authors: Kumar, NS; Ismail, MAM

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DOI https://doi.org/10.36487/ACG_repo/2025_46

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Kumar, NS & Ismail, MAM 2020, '3D limit equilibrium method for rock slope stability analysis using generalised anisotropic material model', in PM Dight (ed.), Proceedings of the 2020 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 715-730, https://doi.org/10.36487/ACG_repo/2025_46

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Abstract:
Rock anisotropy is a well-known phenomenon relating to the heterogeneity of rock mass. Nevertheless, its influence in geotechnical design, especially in rock engineering, is often ignored. Slope with certain modes of failure can be evaluated conventionally as well as numerically. For this study, the rock slope assessment was conducted numerically using 2D and 3D limit equilibrium method (LEM) utilising the Slide program by Rocscience. The fundamental roles of the discontinuities present in the study area were evaluated to study their influence on slope stability. Anisotropic material model was incorporated in the LEM analysis to investigate the presence of discontinuities. The measurement of discontinuity orientation in the rock slope by traditional scanline survey is time-consuming and challenging due to accessibility issues. Structure from Motion (SfM) photogrammetry using unmanned aerial vehicle (UAV) allows a quick and cost-effective way to do survey mapping for geotechnical assessment on rock slope compared to terrestrial laser scanner. Dense point cloud is exported to the CloudCompare tool for geological plane extraction. The stability of the rock slope was evaluated using the deterministic 3D and 2D LEM using the geometry of the 3D rock slope system. In this study, the anisotropic material model was utilised to examine the Factor of Safety (FoS) results. Generalised anisotropic material model was used for incorporating the generalised Hoek–Brown criterion (rock mass) and Barton–Bandis criterion (weak joint). The rock mass and shear strength parameter for numerical analysis were determined via destructive and non-destructive tests such as uniaxial compressive strength, Schmidt hardness and joint roughness coefficient estimation using Barton comb. Mean dip/dip direction obtained was used as an input for the value of the anisotropic plane where it causes a weakness in the strength of the rock slope. The results of FoS shows that rock slope without anisotropy model is stable and analysis using anisotropic material model predicts that the slope may fail. 3D slope stability analysis was able to identify the weakest spot easily rather than making an assumption based on the results of 2D slope stability assessment which might represent the whole rock slope. 3D rock slope stability assessment proves to be a very cost-effective method for remedial work whereas in 2D stability assessment, wrong cut-sections may provide inaccurate FoS. This study presents the approach of using anisotropic material model utilising basic rock testing and field observation data to analyse the rock slope stability.

Keywords: anisotropy, slope stability, limit equilibrium analysis, generalised Hoek–Brown, Barton–Bandis

References:
Agam, MW, Hashim, MHM, Murad, MI & Zabidi, H 2016, ‘Slope sensitivity analysis using Spencer’s method in comparison with general limit equilibrium method’, Procedia Chemistry, vol. 19, pp. 651–658,
Amadei, B 1996, ‘Importance of anisotropy when estimating and measuring in situ stresses in rock’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, vol. 33, issue 3, pp, 293–325.
Asadi, M 2016, ‘Optimized Mamdani fuzzy models for predicting the strength of intact rocks and anisotropic rock masses’, Journal of Rock Mechanics and Geotechnical Engineering, vol. 8, issue 2, pp. 218–224,
ASTM D4543 2001, Standard Practices for Preparing Rock Core Specimens and Determining Dimensional and Shape Tolerances, ASTM International,
ASTM D5873 1981, Determination of Rock Hardness by Rebound Hammer Method 1, ASTM International.
Bar, N & Weekes, G 2017, ‘Directional shear strength models in 2D and 3D limit equilibrium analyses to assess the stability of anisotropic rock slopes in the Pilbara Region of Western Australia’, Journal and News of the Australian Geomechanics Society, vol. 52, issue 4, pp. 91–104.
Barton, N & Choubey, V 1977, ‘The Shear Strength of Rock Joints in Theory and Practice’, Rock Mechanics Felsmechanik Mécanique Des Roches, vol. 10, pp. 1–54,
Bieniawski, ZT 1989, Engineering Rock Mass Classifications: A Complete Manual for Engineers and Geologists in Mining, Civil, and Petroleum Engineering, Wiley, Hoboken.
Cala, M 2007, ‘Convex and concave slope stability analyses with numerical methods’, Archives of Mining Sciences, vol. 52, issue 1,
pp, 75–89.
Cheng, YM, Lansivaara, T & Siu, J 2008, ‘Impact of Convergence on Slope Stability Analysis and Design’, Computers and Geotechnics, vol. 35, issue 1, pp, 105–113.
Cheng, YM, Liu, HT, Wei, WB & Au, SK 2005, ‘Location of Critical Three-Dimensional Non-Spherical Failure Surface by NURBS Functions and Ellipsoid with Applications to Highway Slopes’, Computers and Geotechnics, vol. 32, issue 6, pp. 387–399.
Deere, DU & Miller, RP 1966, Engineering classification and index properties for intact rock, technical report, Air Force Weapons Laboratory
Dewez, TJB, Girardeau-Montaut, D, Allanic, C & Rohmer, J 2016, ‘Facets : A Cloudcompare plugin to extract geological planes from unstructured 3D point clouds’, International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, pp. 799–804,
Francioni, M, Simone, M, Stead, D, Sciarra, N, Mataloni, G & Calamita, F 2019, ‘A new fast and low-cost photogrammetry method for the engineering characterization of rock slopes’, Remote Sensing, vol. 11, issue 11, pp. 1–24.
Francioni, M, Salvini, R, Stead, D & Coggan, J 2018, ‘Improvements in the integration of remote sensing and rock slope modelling’, Natural Hazards, vol. 90, issue 2, pp. 975–1004.
Gonzaga, GG, Leite, MH & Corthésy, R 2008, ‘Determination of anisotropic deformability parameters from a single standard rock specimen’, International Journal of Rock Mechanics and Mining Sciences, vol. 45, issue 8, pp, 1420–1438.
Hoek, E, Carranza, C & Corkum, B 2002, ‘Hoek–Brown failure criterion – 2002 edition’, Proceedings of the 5th North American Rock Mechanics Symposium and the 17th Tunnelling Association of Canada Conferenec, vol. 1, pp. 267–273.
Huang, CC & Tsai, CC 2000, ‘New Method for 3D and Asymmetrical Slope Stability Analysis’, Journal of Geotechnical and Geoenvironmental Engineering, vol. 126, issue 10, pp. 917–927.
Ismael, MA, Imam, HF & El-Shayeb, Y 2014, ‘A Simplified Approach to Directly Consider Intact Rock Anisotropy,in Hoek-Brown Failure Criterion’, Journal of Rock Mechanics and Geotechnical Engineering, vol. 6, issue 5, pp. 486–92,
Kassa, HM & Steinar, N 2016, ‘Numerical models on anisotropy of rocks’, Proceedings of the 17th Nordic Geotechnical Meeting, Icelandic Geotechnical Society, Reykjavik, pp. 587–596,
Kim, D 2016, Study on the accuracy of rock surface roughness data using close range photogrammetry, PhD Thesis, Griffith University, Brisbane.
Leong, EC & Rahardjo, H 2012, ‘Two and three-dimensional slope stability reanalyses of bukit batok slope’, Computers and Geotechnics, vol. 42, pp. 81–88.
Mohamad, AB, Zain, AM & Bazin, NEN 2014, ‘Cuckoo search algorithm for optimization problems - A literature review and its applications’, Applied Artificial Intelligence, vol. 28, no. 5, pp. 419–448,
Nian, TK, Huang, RQ, Wan, SS & Chen, GQ 2012, ‘Three-dimensional strength-reduction finite element analysis of slopes: geometric effects’, Canadian Geotechnical Journal, vol. 49, issue 5, pp. 574–588.
Nunes, ALLS 2002 ‘A new method for determination of transverse isotropic orientation and the associated elastic parameters for intact rock’, International Journal of Rock Mechanics and Mining Sciences, vol. 39, issue 2, pp. 257–273.
Özvan, A, Dinçer, I, Acar, A & Özvan, B. 2014, ‘The effects of discontinuity surface roughness on the shear strength of weathered granite joints’, Bulletin of Engineering Geology and the Environment,
Riquelme, AJ, Abellán, A, Tomás, R & Jaboyedoff, M 2014, ‘A new approach for semi-automatic rock mass joints recognition from 3D point clouds’, Computers and Geosciences, vol. 68, pp. 38–52,
Salvini, R, Mastrorocco, G, Seddaiu, M, Rossi, D & Vanneschi, C 2017, ‘The use of an unmanned aerial vehicle for fracture mapping within a marble Quarry (Carrara , Italy ): photogrammetry and discrete fracture network modelling’, Geomatics, Natural Hazards and Risk, vol. 8, issue 1, pp, 34–52,
Snow, DT 1969, ‘Anisotropic permeability of fractured media’, Water Resources Research, vol. 5, no. 6, pp, 1273–1289.
Westoby, MJ, Brasington, J, Glasser, NF, Hambrey, MH & Reynolds, JM 2012, ‘‘Structure-from-motion’ photogrammetry: a low-cost, effective tool for geoscience applications’, Geomorphology, vol. 179, pp, 300–314,
Wu, A 2012, Locating General Failure Surfaces in Slope Analysis via Cuckoo Search, Rocscience,




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