The effects of clay on landslides: A case study

Abstract Landslides are triggered by geological structures, morphology, climate of the region, geotechnical properties of surface rock, engineering excavation for various purposes and waste water parameters. Weathering is a very important factor in landslide occurrences because it decreases the resistance of rock mass. Clay, a weathering product of rock mass, contributes to landslide occurrence because of their chemical and physical properties. It is believed that the intense rainfall in the East Black Sea region not only contributes to the weathering of the rock mass, but also increases the water content in the clays that leads to reduction in the stability of natural slopes. In this study, the clays forming as a result of completely weathering dacitic rock in Kanlica (Giresun) and surroundings were investigated in association with landslides and determined mitigation measures for landslide in Kanlica Village. The type of clays was determined as illite using Differential Thermal Analysis (DTA). From laboratory tests the geotechnical properties of clays were ascertained to be LL = 47.2%, PI = 19.6%, γs = 25.89 kN/m3, γd = 19.91 kN/m3, n = 44.7%, ϖ = 25.89%, c′ = 21.58 kN/m2, ϕ′ = 31°. As a result, both stress increase and strength decrease happen due to the increase of water content, thus a landslide occurred and causes extensive damage to property in the vicinity.