Classification of cut slopes in weathered meta-sedimentary bedrocks

In order of abundance, the meta-sedimentary rocks along Pos Selim Highway in Perak state Malaysia comprise quartz mica schist, graphitic schist and quartzite layers. Field investigations revealed that these meta-sedimentary rocks have gradational weathering profile based on differences particularly in textures, hardness, lateral changes in colour, and consistency of material extension. The results from uniaxial compressive strength tests confirmed field observations whereby failure occurred mostly on outcrops having joints almost perpendicular to foliation. From the kinematic analyses, the investigated cut slopes are unstable with possibilities of wedge and planar failures. Application of rock mass classification schemes including Rock Quality Designation (RQD) and Rock Mass Rating (RMR) yielded almost similar poor to good quality ranges for each investigated rock mass. While Slope Mass Rating (SMR) classified the cut slopes from stable to unstable slopes, this study categorized them into one actively unstable, four marginally stable and five stable slopes.