## 3 Field Studies and Measurements  
### Rockfall Potential of the Study Area  
Investigation of rock slope stability is essential for designing many engineering processes such as open cast mines, highways, and natural slopes. Slope designs made using appropriate and correct methods not only increase the stability of the slope, but also provide the opportunity to work in a safe environment by reducing accidents. Failures in rock slopes are mostly due to discontinuities in the mass. Most rock slope problems depend on geometric relationships between discontinuities. Therefore, kinematic evaluation of discontinuities is an important issue in the field of rock engineering. Slope stability is generally evaluated with rock mass classification systems such as kinematic analysis, limit equilibrium analysis, numerical analysis, and Slope Mass Rating (SMR) [25; 26; 27]. In kinematic analysis, internal friction angle is used as data from slope geometry and shear strength parameters of discontinuities. These analyses can be used where failures in rock slopes are controlled by discontinuities [28; 29; 30]. Possible failure types (planar, wedge type, and tipping type failures) in rock slopes can be determined by kinematic analysis. If any danger of failure occurs as a result of the kinematic analysis, the possible danger is investigated with limit equilibrium analysis. Limit equilibrium analyses consider shear strength along the failure plane, pore water pressure, and external forces such as maximum horizontal ground acceleration. Rock mass classifications have been used successfully for years in tunnel and underground mining [31; 32]. Some rock mass classifications developed for underground excavations were applied to slopes in the following years [32] or rearranged [33; 34]. In this study, the studied slope was evaluated using the classification system suggested by [35]. While making the classification, the data obtained from field measurements and laboratory experiments were used (Table 1). This value shows that the rock slope in the study area is classified as \"medium risk slope (risk class III)\". When Table 1 is evaluated, it can be seen that it may be necessary to take easy protection (for example, bolts, meshes, removing unstable blocks, simple lightweight fences) in order to minimize the risks that may arise from rockfall events in the study site. However, it has been seen that as a result of the detailed field studies carried out in the study area, the dimensions of the moving blocks have reached 2 m, and these blocks have reached areas very close to the village by moving approximately 400-500 m from the source rock (Figure 3). Although it was desired to prevent rockfalls by digging trenches (width 2 m, depth 1 m) on the slope, these trenches were effective only for 50 cm blocks (Figure 4). For this reason, trenching on the slope is not an effective solution. Although enlargement of the ditches is considered, it is thought that these ditches will not be sufficient to stop the movement of the blocks reaching 2 m. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Risk Class**} & **Total Weighted Score 1–100** & **Risk** & **Indicative Protection Measures (the Choice is Site Specific)** \\ \hline I & \textless{}20 & Very Low & Not necessary. May be sparse spot interventions. \\ \hline II & 21–40 & Low & In limited extent \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification of slopes according to rockfall risk and the situation of the rock slope, which is the subject of this study, within this classification system. Gabion walls can be effectively used as a method due to their many advantages, especially if there is a suitable area. Gabion walls are generally designed to eliminate the risks that may arise from large blocks with low bounce height but very high energy. This situation is also present in the study area. In addition, the fact that there is a buffer (flat) zone between the place area and the base of the slope shows that structures such as gabions can be applied on the slope.