Assessment of Rockfall Hazard on Steep Slopes: Ermenek (Karaman, Turkey)

Authors : Hidayet Taga, Kıvanç Zorlu

Pages : 161-178

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Publication Date : 2017-08-01

Article Type : Research

Abstract :Ermenek is a extraordinary settlement area due to its topographical features in Karaman (Turkey). The city is located in the northern side of the steep cliffs, which are formed of jointed limestone that abruptly increases from 1250 m to 1850 m. Moreover, these cliffs, having a slope dip of nearly 90°, are the main rockfall source areas due to their lithological characteristics, climatic effects and the engineering properties of rock units. Up to now, depending on the rockfall event, nearly 500 residences have been severely damaged, and the loss of life has occurred in Ermenek. The rockfall phenomenon is initiated by discontinuities, lithological changes, weathering and the freeze-thaw process in the study area. In this study, extensive fieldwork including the determination of locations and dimensions of hanging, detached and fallen blocks; a detailed discontinuity survey; and the description of geological, morphological and topographical characteristics was performed. Additionally, rockfall hazard has been evaluated by two-dimensional rockfall analysis involving 10 profiles. While these profiles were determined, the locations where the most of the fallen blocks are observed are selected in the field study. During the rockfall analysis, run-out distance, bounce height, kinetic energy and the velocities of various sizes of blocks for each profile were determined through the use of RocFall v4.0 software. The results obtained from the rockfall analysis were used to map the areas of possible rockfall hazard zones, and rockfall source areas were interpreted. According to the rockfall analysis, field study and laboratory testing, protective and preventive recommendations can be suggested for the areas threatened by rockfall. However, the most widely known remedial measures in literature, such as trenches, retaining walls (barriers), wire mesh, cable/stretching nets and rock bolting, etc., are not sufficient in the study area due to its topographical, atmospheric and lithological features. For these reasons, hanging blocks in the reachable locations can be removed, the total evacuation of the danger zone may applied, and then taking safety measures in this area to make it safer for the residents.
Keywords : Ermenek, hazard, limestone, rockfall, zonation map