Understanding the behavior of a rock block after detachment is essential to effectively control rockfall hazards and implement protection measures. Rigid body rockfall models allow a more realistic interpretation of rockfall events by representing rock with a real size and geometrical form. This study presents the analysis of potential rockfalls that threaten the Sumela Monastery, Turkey, which is one of the important historical and touristic places. The structure of the Monastery is located in a rocky steep cliff, surrounded by a highly fractured surface of the cliff from top. The structure has been subjected to several damages due to rock detachments from the cliff surface in the last couple of years and is considerably threatened by potential rock blocks that can fall. Field studies and discontinuity surveys are performed to determine the potential rockfall source areas. The geomechanical properties of the rock materials are determined from laboratory tests. A LIDAR measurements as well as aerial photos are used to prepare slope profiles. According to previous rockfall evidences, back analyses are performed to identify the slope surface characteristics like restitution coefficients. For each profile, different rock size and shapes are simulated and corresponding runout distance, bounce height, kinetic energy and translational velocity are recorded. It is found that, since the structure is located in an almost vertical cliff with considerable height, in all cases, the detached blocks hit the structure with large peak kinetic energy values.
Rockfalls are spontaneous rapid phenomena with high-energy bearing features in hilly regions, which cause significant threats to the environment as well as human lives and property. A rockfall occurs when rock boulders detach from their original locations following four basic types of motions: free-falling, bouncing, rolling and sliding. Rockfall kinematics and dynamics mainly depend on the topography, block weight and geometry, mechanical properties of the slope forming material such as friction angle, roughness, restitution characteristics and rolling resistances (Azzoni et al. 1995, Dorren & Seijmonsbergen 2003). When a rock-fall event reveals a threat to people or structures, it is essential to describe the trajectory of the falling rock along a slope in order to design and implement protection measures or to prevent hazard by an appropriate land use planning. The accuracy in the estimation of the trajectories and motion of the potential falling rocks forms the basis of a safe design and verifies the protective measures.
