Evaluation of protective measures against rockfall hazard with 3D analysis (Mardin Castle, Türkiye)

Abstract Rockfall is one of the most abundant slope instabilities, which affects the engineering structures and planning of residential areas. There are several reasons and parameters which control the rockfall mechanism which should be evaluated in a wide perspective. A crowded part of Mardin city is located close to the ancient castle which is still in use for touristic purposes. Recent rockfall cases have caused severe damage to the structures around. Limestones and dolomitic limestones of Early Eocene aged Gercüş Formation and Early Oligocene aged Midyat Group are the main geological units in close proximity. The study area is formed by a steep slope with one kilometer length. Numerous fallen blocks spread around flat sections and possible blocks prone to rockfall have been detected by field studies and high-resolution images obtained from unmanned aerial vehicle (UAV) monitoring. The area has been divided into five sections to perform discontinuity characterization, also taking the slope geometry into account. Exact locations of the fallen blocks and the blocks on the slope have been determined using the UAV images. Digital slope, slope direction and geological maps have been prepared using point cloud data. This study aims to evaluate the rockfall hazard for the whole area based on imagery, numerical modelling and 3D rockfall analysis for considering protection measures. Combining the field work, imagery and mechanical properties of the limestones, 3D rockfall analysis have been performed and reinforced embankments have been offered with the evaluation of their performance.