Fourie, AB & Haines, A 2007, 'Obtaining Appropriate Design Parameters for Slopes in Weathered Saprolites', in Y Potvin (ed.), Slope Stability 2007: Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering
, Australian Centre for Geomechanics, Perth, pp. 105-116, https://doi.org/10.36487/ACG_repo/708_5
In many open pit operations, the near-surface profile exposes weathered material. If this weathered material
is shallow, or still relatively competent, it presents no major problems and conventional design approaches
remain relevant. However, in some cases the weathered profile may be very deep such that the material
cannot be considered as rock. A common approach in these circumstances is to use designs based on soil
mechanics principles. However, some recent failures of slopes in highly weathered, saprolitic profiles have
highlighted inadequacies in this approach. A case study is presented from a mine in Guinea, West Africa,
where the approach was to obtain very high quality block samples from the saprolitic zone for testing in the
laboratory to obtain truly undisturbed material properties and ultimately provide much improved design
parameters. The pit has now been in operation for over six years and the performance of the excavated
slopes in the saprolitic material validated the approach adopted.
Baligh, M.M. (1985) Strain path method. Journal of Geotechnical Engineering, ASCE 111, pp. 1108-1136.
Blight, G.E. (1997). Origin and formation of residual soils. Chapter 1 in: Mechanics of Residual Soils, Ed. G.E. Blight,
Fourie, A.B. (1996) Predicting rainfall-induced slope instability. Proceedings of the Institution of Civil Engineers,
Geotechnical Engineering 119, pp. 211-218.
Fourie, A.B. (1997) Classification and index tests, Chapter 5 in: Mechanics of Residual Soils, G.E. Blight (editor),
A.A. Balkema, 237 p.
Geological Society Engineering Working Party (1990) Report: Tropical Residual Soils. The Quarterly Journal of
Engineering Geology 23(1), pp. 1-101.
Gerscovich, D.M.S., Vargas, E.A. and de Campos, T.M.P. (2006) On the evaluation of unsaturated flow in a natural
slope in Rio de Janeiro, Brazil. Engineering Geology 88, pp. 23-40.
Lumb, P. (1975) Slope failure in Hong Kong. Quarterly Journal of Engineering Geology 8, pp. 31-65.
Troncone, A. (2005) Numerical analysis of a landslide in soils with strain-softening behaviour. Geotechnique 55(8),
Obtaining Appropriate Design Parameters for Slopes in Weathered Saprolites A.B. Fourie, A. Haines
116 Slope Stability 2007, Perth, Australia