## 4 Results
### Performance Analysis for Gabion Wall
#### 4.2.1 Outside Stability Failure  
External stability failures in reinforced earth structures. Base slip control. Eccentric limit and eccentricity control. Assessment of the foundation bearing capacity. Settlement estimate. It can be checked as above. The gabion wall structure, which is planned to be built in order to control rockfalls within the scope of this study, is not expected to carry lateral loads. Since there is no lateral load, base slip control, eccentric limit control, and eccentricity control are not possible. In such structures, external stability failures are generally seen in the form of foundation settlement and bearing capacity failure. There are two types of failure caused by bearing capacity. The first is general shear (slip) failure, and the second is local shear (slip) failure. Local slip occurs when soft or loose soil units are present in the reinforced earth wall foundation. Bearing capacity calculations must be made to take into account both the strength limit state and the service limit state calculation. External stability analyses include the determination of the surcharge loads of the reinforcement earth system and the determination of settlements that may occur in the subgrade under its own weight. Many empirical approaches have been developed to estimate the bearing capacity of discontinuous rock masses. In these methods, the RQD (Rock-Quality Designation) value (which is one of the parameters that best reflects the discontinuity properties), the uniaxial compressive strength value of the rock material, and the rock mass constants obtained from the Hoek-Brown failure criterion are used. The approach developed by [PERSON] [37] is the most preferred in practical applications and is therefore still valid today. However, there are some limitations to this method. The method should be used in rock masses where the discontinuity spacing is greater than 0.3 m and the span is less than 10 mm (it can be up to 15 mm if the discontinuity is filled) while the foundation width is greater than 0.3 m.  
\[\mathrm{qa}=\sigma_{\mathrm{ci}}\times\mathrm{N_{j}} \tag{1}\]  
Figure 15: Three-dimensional rockfall analyses in case of designing a gabion wall. \[\text{N}_{\text{j}}=\text{Ks}=\frac{3+(\text{S}/\text{B})}{10\sqrt{1+300(\delta/ \text{B})}} \tag{2}\]  
qa: Allowable bearing capacity (MPa)  
\(\sigma\)ci: Uniaxial compressive strength of rock material  
Nj: The empirical coefficient depending on the discontinuity spacing  
6: Discontinuity span  
S: Discontinuity spacing  
B: Foundation width  
Note: The following Table 3 is frequently used in practice when calculating Nj. Ref. [38] suggested using the RQD values of the rock mass in the bearing capacity calculations. However, in these approaches, it is assumed that the bearing capacity value of the rock mass does not exceed the uniaxial compressive strength value of the rock mass. While calculating the bearing capacity, the average RQD value of the depth from the foundation base to the foundation width (B) is taken. Ref. [38] proposed equations using the uniaxial compressive strength (\(\sigma\)ci) values of the rock material together with the RQD value to estimate the bearing capacity of rock masses. Since it is simple and practical, this method is the most preferred method in practice. By using the determined reduction coefficient (DF), the allowable bearing capacity of the rock mass is calculated with the help of the following formula:  
\[\text{qa}=\sigma_{\text{c}}-(\sigma_{\text{c}}\times\text{Df}) \tag{3}\]  
qa: Allowable bearing capacity (MPa)  
\(\sigma\)ci: Uniaxial compressive strength of rock material (MPa)  
Df: Reduction coefficient (%)  
In Table 4, the input parameters used and the bearing capacity values calculated according to the equations proposed by different researchers are given. In this case, it is seen that the bearing capacity values of the tuffs forming the foundation's soil vary between 1.6-2.0 MPa. The floor area of each cell belonging to the gabion walls is 2 m\({}^{2}\).