Characteristics of Slope Failures in Tropical Hill Slopes of South West India

The occurrence of rainfall induced slope failures in residual soil slopes is a common natural disaster encountered in many tropical regions. Furthermore factors such as hill slope, relative relief, attitude of joints, material properties of rocks, type of vegetation and landuse practices make a hill slope vulnerable to slope failures. Its ferocity depends upon the material properties and thickness of the loose unconsolidated overburden formed by the weathering process. The triggering factor for the slope failures is found to be continuous heavy rainfall for a couple of days. The paper examines the mechanism of slope failures in hill ranges of Kerala state which lies in the south west part of Indian peninsula. The failure surface is identified and located from the field and its interaction with material properties and hill slope is critically examined. Highly weathered rock samples were collected from the failed areas for the determination of material property such as friction angle. Geometrical method is used for understanding the role of joints in the slope instability.