GIS-based determination of potential instabilities and source rock areas on the Torul-Kürtün (Gümüşhane) motorway, rockfall, and protection structure analyses

The Torul-Kürtün-Tirebolu motorway, one of the alternative routes for access between the Eastern Anatolia Region and the Black Sea Region, has an important traffic potential in this respect. However, rockfall events that occur frequently in almost every season especially in the part of the route between Torul and Kürtün may occasionally cause loss of life and property and lead to disruption in transportation in a much more common way. Departing from this point, the parts of the motorway that pose a greater threat in terms of slope instability and rockfall potential were selected as the study area. Instability maps produced by the kinematic analysis results showed that the probability of toppling type failure in the study area was quite higher, while the general results were as follows: the probability of toppling type failure was found in 204 different locations and approximately 97,900 m2 of area. Taking account of geographic information system (GIS)–based final instability maps, profile lines were determined for potential rockfalls in the instability-intense source rock areas. The profile lines which were determined were analyzed two-dimensionally in the RocFall 7.0 computer program. The rockfall analyses revealed that the rolling rock blocks in the section SP7 shall remain on the surface of the slope, while the rock blocks in other sections shall reach the road route. The application of barrier types determined by barrier sensitivity analysis on profile lines will minimize or completely prevent potential hazards.