The strength of gravel formations has long been studied by laboratory or insitu experiments. In this study, geological and topographical characteristics of gravel formations were
examined to correlate geological factors and their strength. The topographical features of slopes such as height and inclination that define the strength indices of gravel formations were measured from the data of digital elevation models. Then, the strengths of the study areas were distinguished. The relationship between the strength index and the measured geological factors including the grain size distribution,area concentration of gravels, matrix strength, and gravel strength was established. The geological factors affecting the strength index from greatest to least were gravel content (CG), matrix strength (qM), particle size (D30), and gravel strength (qG).
Key Words : Gravel formation, topography, strength.