Analyses of the factors causing mass movements in the unvegetated highway slopes: A case study of Kastamonu - Karabuk highway

Abstract: Slope failure occurs when the downward movements of material due to gravity exceeds the shear strength. Therefore, factors that tend to increase the shear stresses or decrease the shear strength increase the chances of failure of a slope. Different processes can lead to reduction in the shear strengths of rock mass. Increased pore pressure, cracking, swelling, decomposition of clayey rock fills, creep under sustained loads, leaching, strain softening, weathering, cyclic loading and the lack of stabilizing vegetation are common factors that decrease the shear strength of slope masses. In contract to this the shear stress in highway slopes may increase due to additional loads at the top of the slope, increases in water pressure through cracks at the top of the slope, increases in soil weight due to increased water content, excavations at the bottom of the slope and seismic effects. In the scope of this project, the six freguently broken back-slopes were be modeled, measuring simulaneously with a total station and drone and the soils samples were collected from two depths. Heavy clay content and extreme slope gradients were found responsible in failures.