Song, Y-K, Oh, J-R & Jung, MS, Son, YJ 2013, 'Risk evaluation of slope considering mechanical and hydraulic characteristics of unsaturated soils', in PM Dight (ed.), Slope Stability 2013: Proceedings of the 2013 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering
, Australian Centre for Geomechanics, Perth, pp. 473-481, https://doi.org/10.36487/ACG_rep/1308_30_Song
Rainfall is an important triggering mechanism of slope failure which accompanies severe damage and loss of life and property. Slope failure is mainly triggered by a deepening of the wetting band accompanied by a decrease in matric suction induced by water infiltration. Early warning methods for slope failure in Korea only tend to use rainfall intensity and duration as the main variables, not considering mechanical and hydraulic characteristics of unsaturated soils. In this study, geotechnical properties of unsaturated weathered soil, including basic physical properties, soil-water characteristics curve, unsaturated permeability curve, and unsaturated shear strength, were investigated in test beds in which slope failures frequently occurred. Also presented is a procedure for the risk evaluation of slope failures, which integrates the Factor of Safety of the infinite slope of unsaturated soil, considering not only rainfall intensity and duration, but also the mechanical and hydraulic properties of unsaturated soils.
ASCE (1996) American Society of Civil Engineers. Hydrology Handbook (second edition), ASCE Manual and Reports on Engineering Practice No. 28, pp. 75–90.
Collins, B.D. and Znidarcic, D. (2004) Stability analyses of rainfall induced landslides, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 130, No. 4, pp. 362–372.
Fredlund, D.G. and Xing, A. (1994) Equation for The Soil-Water Characteristic Curve, Canadian Geotechnical Journal, Vol. 31, pp. 521–532.
Iverson, R.M. (2000) Landslide triggering by rain infiltration, Water Resource Research, Vol. 36, pp. 1897–1910.
Kim, Y.K. (2003) Permeability of unsaturated weathered soils by analysing triaxial permeability test results, Masters thesis, KAIST.
Lee, M.L., Gofar, N. and Rahardjo, H. (2009) A simple model for preliminary evaluation of rainfall-induced slope instability, Engineering Geology, Vol. 108(3–4), pp. 272–285.
Li, A.G., Tham, L.G., Yue, G.Q., Lee, C.F. and Law, K.T. (2005) Comparison of field and laboratory soil-water characteristic curves, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 131, No. 9, pp. 1176–1180.
Lu, N. and Likos, W.J. (2006), Suction stress characteristic curve for unsaturated soil, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 132, No. 2, pp. 131–142.
Mein, R.G. and Larson, C.L. (1973) Modeling infiltration during a steady rain, Water Resources Research, Vol. 9, No. 2, pp. 384−394.
NDMI (2012) National Disaster Management Institute. Developments of the GIS based steep slope collapse determination system (II), National Disaster Management Institute, Research Report, 140 p.
NDMS (2012) National Disaster Management System, Nation-wide Disaster Information Compilation and Database System operated by the National Emergency Management Agency (in Korean).
Rahardjo, H., Lim, T.T., Chang, M.F. and Fredlund, D.G. (1995) Shear-strength characteristics of a residual soil, Canadian Geotechnical Journal, Vol. 32, No. 1, pp. 160–177.
Shin, H., Kim, Y.T. and Park, D.K. (2013) Development of Rainfall Hazard Envelope for Unsaturated Infinite Slope, KSCE Journal of Civil Engineering, Korean Society of Civil Engineers, Vol. 17, No. 2, pp. 351–356.
van Genuchten, M. (1980) A closed-form equation of predicting the hydraulic conductivity of unsaturated soils, Soil Science Society American Journal, Vol. 44, pp. 892–898.