UNDRAINED SHEAR STRENGTH PARAMETERS OF SAPROCK FROM A WEATHERING PROFILE OVER PORPHYRITIC BIOTITE GRANITE AT KM 31 OF THE KUALA LUMPUR - KARAK HIGHWAY, PENINSULAR MALAYSIA
DOI:
https://doi.org/10.11113/mjce.v33.16400Keywords:
unconsolidated undrained triaxial tests; saprock; weathering profile over granite; apparent cohesion; friction angle.Abstract
Three broad zones can be differentiated at the weathering profile; an upper, 9.4 m thick, pedological soil (zone I), an intermediate, 31.7 m thick, saprock (zone II) and the bottom bedrock (zone III). The saprock (zone II) comprises gravelly silty sands that distinctly preserve the minerals, textures and structures of the original granite and can be separated into sub-zones II A, II B, II C, and II D, based on differences in preservation of relict structures and content of litho-relicts (core-boulders). To characterize the undrained strength of saprock, samples were collected from sub-zones II A, II B, II C and II D and their physical and soil index properties determined before unconsolidated undrained triaxial tests were carried out on remolded samples. Three to four individual samples from each sub-zone were compressed under confining pressures of 138 kPa, 207 kPa, 276 kPa and/or 345 kPa. Plots of pf = [(σ1 + σ3)/2] versus qf = [(σ1 - σ3)/2] were then used to calculate apparent cohesions of 41.9 kPa, 100.3 kPa, 76.1 kPa and 73.9 kPa, and friction angles of 32.2o, 28.1o, 26.6o and 27.8o, for the samples from sub-zones II A, II B, II C, and II D, respectively.
Regression analyses show apparent cohesions to decrease with increasing clay contents, and degrees of saturation; features indicating the influence of negative pore water (or suction) pressures. Regression analyses also show apparent friction angle to increase with increasing sand contents; a feature attributed to greater inter-locking and resistance to displacement of these particles. It is concluded that the undrained shear strength parameters of saprock are characterized by an average apparent cohesion of 54.6 kPa, and friction angle of 30.5o; the parameters influenced by the degree of saturation as well as clay and sand contents.
References
Bishop, A. W. and Henkel, D.J. 1957 The Measurement of Soil Properties in the Triaxial Test. Edward Arnold, London. 189
Dearman, W.R. 1974 Weathering classification in the characterization of rock for engineering purposes in British practice. Bulletin International Association of Engineering Geology, 9: 33-42.
Faisal Hj. Ali, Bujang B.K. Huat and Low, T.H. 2005 Infiltration characteristics of granitic residual soil of various weathered grades. American Journal Environmental Sciences, 1: 64-68.
GSL (Geological Society of London) 1990 Tropical residual soils. Geological Society Working Group Report, Quarterly Journal Engineering Geology, 23: 1-102.
Haile, N.S., Stauffer, P.H., Krishnan, D., Lim, T.P. and Ong, G.B. 1977 Palaeozoic redbeds and radiolarian cherts: reinterpretation of their relationships in the Bentong and Raub areas, West Pahang, Peninsular Malaysia. Bulletin Geological Society of Malaysia, 8: 45-60.
IAEG (International Association Engineering Geology) 1981 Rock and soil description for engineering geological mapping. Bulletin International Association of Engineering Geology, 24: 235-274.
Lambe, T.W. & Whitman, R.V. 1973 Soil Mechanics. Wiley Eastern Private Ltd., New Delhi. 553.
Ng, T.F. 1992 Petrography, structure and geotechnical studies of the Kuala Lumpur Granite, eastern part of Kuala Lumpur, Peninsular Malaysia. M.Phil. Thesis, Institute for Advanced Studies, University of Malaya. 527
Raj, J.K. 1983 A study of residual soils and their cut slope stability in selected areas of Peninsular Malaysia. Ph.D. Thesis, Faculty of Science, University of Malaya. 462
Raj, J.K. 1985 Characterisation of the weathering profile developed over a porphyritic biotite granite bedrock in Peninsular Malaysia. Bulletin International Association of Engineering Geology. 32: 121-128.
Raj, J.K. 2009 Geomorphology. Chapter 2 in Hutchison, C.S. and D.N.K. Tan (eds) Geology of Peninsular Malaysia, University of Malaya and Geological Scoiety of Malaysia, Kuala Lumpur, 5-29.
Raj, J.K. 2010 Soil moisture retention characteristics of earth materials in the weathering profile over a porphyritic biotite granite. American Journal of Geosciences, 1: 12-20.
Raj, J.K. (in press) Saturated hydraulic conductivity (Ks) of earth materials in the weathering profile over a porphyritic biotite granite in Malaysia. Bulletin, Geological Society of Malaysia.
Salih, A.G. 2012 Review on Granitic residual soils: Geotechnical Properties. Electronic Journal Geotechnical Engineering, Bundle T, 17: 2645-2658.
Salih, A. G. and Kassim, K. A. 2012 Effective shear strength parameters of remolded residual soil. Electronic Journal Geotechnical Engineering, Bundle C, 17: 243-253.
Tan, Y.C. and Gue, S.S. 2001 The determination of shear strength in residual soils for slope stability analysis. Proceedings Seminar Cerun Kebangsaan 2001, Cameron Highlands, 14-15 May 2001.
Thomas, M.F. 1974 Tropical Geomorphology - A study of Weathering and Landform Development in Warm Climates. Macmillan Press Ltd., 332
Ting, W.H. and Ooi, T.A. 1976 Behaviour of a Malaysian residual granite soil as a sand-silt-clay composite soil. Geotechnical Engineering, 7: 67-78.
Todo, H. and Pauzi, M.M. 1989 Geotechnical engineering properties of residual soils originated from granite in Malaysia and Singapore. Proceeding International Conference Tropical Terrains, Universiti Kebangsaan Malaysia, Bangi, 160-169.
Vaughan, P.R. 1988 Characterizing the mechanical properties of in situ residual soil. Keynote Paper, Proceedings Second International Conference Geomechanics in Tropical Soils, Singapore, 2: 469-487.
Wesley, L. 2009 Behaviour and geotechnical properties of residual soils and allophone clays. Obras y Proyectos, 6: 5-10
