Physical, geochemical, and clay mineralogical properties of unstable soil slopes in the Cameron Highlands

Abstract

The physical, geochemical, and clay mineralogical properties are location dependent and influence landslide, yet this relationship is understudied in the Cameron Highlands. Therefore, this study demonstrates the effect of the selected physical–geochemical properties and clay mineralogy on landslide susceptibility (LS) in the Cameron Highlands, Malaysia. Seven soil samples were taken from non-landslide-affected slopes (NAS) and 13 from landslide-affected slopes (LAS), making a total of 20 samples that were analyzed. The degree of the LAS and NAS ranges from 42–80° and 30–70°, respectively. The NAS soils were characterized by lower sand, higher clay, higher organic matter content (OMC), and higher cation exchange capacity (CEC). Soils with high sand tend to have larger free pores and weak bonds, making them more vulnerable to landslides. The electrostatic charges on the clay’s surface bind the solution ions, increasing cohesion between soil particles. Also, high CEC in soils improves their stability through the binding effect resulting from the attraction between solution ions via the electrostatic surface charges of the clay in the soil. The clay mineralogy revealed the abundance of kaolinite and illite, indicating the last stage of weathering associated with the weathering of primary minerals forming the bedrock. In this study, it was demonstrated that high sand, low clay, low OMC, low CEC, and clay mineralogy of the soil were associated with slope failure in the study area.