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This study evaluated the potential rockfall hazards in the Kayseri-Soğanlı settlement using the energy angle method and 3-dimensional probabilistic rockfall modeling. The high-resolution digital surface model (DSM) was obtained with the help of unmanned aerial vehicles (UAV) and high-resolution orthophoto. 3-dimensional probabilistic rockfall simulations were conducted on the DSM using the CONEFALL software, and rockfall zones were determined according to the energy line angle method. The dimensions of previously fallen rock blocks were determined using fieldwork and orthophoto generated by UAV. As a result of 3-dimensional probabilistic analyses, the maximum kinetic energy values of 15,000 kJ and bounce height of 15 m were determined during the movement of 3-meter rock blocks along the slope. When the energy line angle method was considered, it was found that the previously fallen blocks were mostly concentrated in the 40° energy line angle zone in the southern part of the slope. On the other hand, although the rolling lines obtained from probabilistic 3-dimensional rockfall analyses for 3 metre block size reach up to the maximum 30° energy line angle zone, these rolling lines end in the 40? energy line angle zone, especially in the southern part of the slope. Therefore, the empirical method, 3-dimensional probabilistic method, and the positions of measured blocks in the field show general consistency. [ABSTRACT FROM AUTHOR]

Rockfall ditches or areas can be constructed in order to protect against rockfalls in settlements that are in danger of rockfalls when the population density is not high. Nevertheless, in the design of such protection structures, essential site-specific engineering studies and analyzes are often not carried out appropriately. Therefore, rockfall ditches are occasionally not capable of preventing rockfalls. Within the scope of this study, the performance of a 2 m-deep and 1 km-long rockfall ditch excavated at the upper elevation of touristic Akköy (Ürgüp) settlement in 2012 in order to prevent the entrance of falling rocks to the residential area was evaluated on the basis of 3-dimensional rockfall analyses. According to the rockfall risk classification, the settlement is under moderate rockfall risk. The digital surface model used in 3-dimensional rockfall analyses was generated by point cloud data obtained from photogrammetric images taken by unmanned aerial vehicle. During field observations, it was determined that the dimension of the previously fallen ignimbrite blocks could reach up to 2 m. On the other hand, the high persistency of discontinuities in the source zone indicates that the dimensions of the potential rockfall blocks may be large. As a result of the 3-dimensional rockfall analyses carried out in RocPro3D software, it was defined that the falling blocks are generally caught by the ditch excavated between the source zone and the settlement, but in some sections of the ditch those blocks may continue to roll over the rockfall ditch. Eventually, Akköy settlement is still partially under the danger of rockfalls. If the rockfall ditch is not periodically cleaned in the course of time, the extent of danger will enlarge with the decrease in the capacity of the trench. [ABSTRACT FROM AUTHOR]

Rockfall ditches or catchment areas aim to collect falling blocks at the toe of a source zone by dissipating the energy of blocks in an excavated trench. The effectiveness of a rockfall ditch is simply expressed by its block catchment performance and can be evaluated by empirically using existing design charts as well as rockfall simulations. Although 2-dimensional (2-D) analysis has been executed to assess the catchment ditch effectiveness in engineering practice, 3-dimensional (3-D) rockfall models have not received enough attention so far. In this study, the effectiveness of a considerably long rockfall ditch to protect a settlement from falling rocks was assessed on the basis of 3-D rockfall analyses executed using high-resolution digital surface models. The rockfall ditch efficiency was found to be moderate to limited for various segments considering the percentage of blocks not trapped by the ditch. Moreover, the sensitivity of ditch efficiency to ditch depth was analyzed by automated image processing method as well. Additionally, a particular section of ditch alignment was fictitiously excavated or filled by synthetic Digital Surface Model (DSM) generation through image processing. 3-D rockfall modeling carried out using the DSMs with synthetically manipulated ditches points out that the effectiveness of a catchment ditch is highly depended upon ditch depth. Even a small volume of block accumulation inside the ditch definitely reduces the ditch performance resulting extended runout distances reaching to residential area. Finally, 3-D rockfall modeling is accepted to be an effective tool to rate the efficiency of existing rockfall ditches and synthetically generated ditches on DSMs (or DEMs) by means of automated image processing method may assist the control of current ditch dimension as well as new catchment ditch design. • 3-D rockfall analysis is an effective tool to evaluate ditch effectiveness. • Rockfall accumulation can radically reduce the efficiency of a ditch. • Automated image processing may be reasonable to evaluate ditch effectiveness. • Unmanned aerial vehicles may be advantageous while scanning irregular terrain. • The rockfall ditch efficiency is apparently sensitive to ditch depth. [ABSTRACT FROM AUTHOR]