Influence of discontinuities on the stability of cut slopes in weathered meta-sedimentary rocks

Abstract

The meta-sedimentary rocks along Pos Selim Highway in Perak State, Malaysia showed a gradational weathering profile based on differences particularly in textures, hardness, lateral changes in colour and consistency of material extension. Both large and small scale discontinuities observed in the investigated rocks reduce the physical and mechanical properties of the rocks, and provide slip surfaces for failures. Rock and soil samples were tested using established standards to determine their characteristics and responses under a wide variety of disturbances. Kinematic analyses were also carried out to determine the modes and likely modes of failures.Petrographic analyses revealed associated micro-structures, and the implications of these micro-structures showed shearing components along planes of weakness. From the determined index properties of the tested soil samples, the weathered quartz mica schist is not suitable for structural support. Further study involving unconsolidated undrained direct shear box tests carried out under total stress, revealed a non-uniform response of the rocks to shearing disturbance along discontinuity planes, and the rate and depth of deformation. The shear strength components of the investigated rocks were thereby prescribed in terms of cohesion and friction angle. From the kinematic analyses across this extended cut slope, there are possibilities of wedge and planar failures.

Issues, reality and role of geologists on hill site development in Malaysia – Case study from a luxurious housing project in Taiping, Perak

“…Persilangan antara ketakselanjaran ini menghasilkan blok-blok batuan yang longgar dan pelbagai saiz (beberapa cm hingga 1.0 m). Kehadiran satah ketakselanjaran relikta pada jasad batuan terluluhawa boleh menyebabkan kegagalan berlaku (Nkpadobi et al, 2015;Tajul Anuar Jamaluddin, 2007;Tajul Anuar Jamaluddin & Mohd Fauzi Deraman, 2000). Permukaan satah ketakselanjaran biasanya beralun hingga kasar, mempunyai bukaan yang ketat hingga sempit dan biasanya tanpa bahan pengisi.…”

Influence of weathering-induced iron precipitation on properties of sandstone in a tropical environment

“…The importance of the condition of discontinuities in rock masses and how these determine, for example, shear strength along discontinuities, permeability, and stability of foundations, slopes and tunnels, are extensively discussed in the literature (e.g. Patton 1966;Barton 1973;Palmstrøm 1975;BS 5930:1981BS 5930: 1981Hoek & Bray 1981;Goodman 1989;Barton & Stephansson 1990;Laubscher 1990;Hack 1998;BS 5930:1999BS 5930: 1999Vincente Silvestre et al 2002;ISO 14689-1:2003ISO 14689-1: 2003Blue Book 2007;Hencher & Knipe 2007;Lee & Hencher 2009;Price et al 2009;Alejano & Carranza-Torres 2011;Tating et al 2014;Hencher 2015;Nkpadobi et al 2015;Gratchev & Kim 2016).…”