## 4 Results and Discussion
### Effect of Exavation Pit Dimensions on PSR
As seen in Figure 12, depending on the distance from the corner, the plane-strain ratio (PSR) value was approximately 0.1 at the corner under back slope angle \(\beta=0^{\circ}\) conditions. However, this value increased to 0.50 at a distance of 0.5H from the corner and even reached values as high as 0.80 with increasing nail length. At 1H and beyond, the rate of increase in PSR decreased, and the values approached maximum levels earlier with the increases in nail length and wall angle. With the increase in \(\beta\), the PSR value at the corner also increased, and depending on the increase in nail length (L/H) and wall angle (\(\alpha\)), the PSR value in the corner increased up to 0.50. Figure 12: _Cont._  
At distances from the same corner, the plane-strain slice (PSR) value decreased as the back slope angle (\(\beta\)) increased, and reached maximum values again at farther distances as \(\beta\) increased. While the PSR value was approximately 0.1 at the corner under \(\beta=0^{\circ}\) conditions, it approached 1 as it moved away from the corner. It can be observed that the PSR value reached 0.90 at most when the \(\beta\) value was \(10^{\circ}\), 0.80 at \(20^{\circ}\), and 0.70 at \(34^{\circ}\). Increasing \(\beta\) led to a decrease in the PSR value, thereby increasing the corner effect. As the wall angle (\(\alpha\)) increased, the PSR value approached the maximum value at shorter distances from the corner under \(\beta=0^{\circ}\) conditions [56]. This situation becomes more evident as the nail length increases (Figure 12a). In the case of \(\beta=10^{\circ}\), increasing the \(\alpha\) angle brought the PSR curves, which changed with depth, closer to each other (Figure 12b). The fact that the PSR curves approached each other with depth was also observed under other \(\beta\) (\(20^{\circ},34^{\circ}\)) conditions (Figure 12c,d). The effect of increasing the \(\alpha\) angle on PSR gradually decreased with the increase of the \(\beta\) angle. Under \(\beta=0^{\circ}\) conditions, as the excavation depth increased, the PSR value decreased, thus increasing the corner effect. While increasing the excavation depth clearly showed the decrease in PSR in the case of \(\beta=0^{\circ}\), increasing the \(\beta\) angle caused this effect to decrease and the PSR curves became closer to one another. In a study conducted by Tabur in 2014, it was observed that the corner effect continued to affect areas farther away as the excavation depth increased in hard clay soils [57]. While the effect of nail length on PSR remained at lower values in the case of \(\beta=0^{\circ}\) and nail length L/H = 0.50, as the nail length increased, PSR progressed to higher values and approached 1. Additionally, with increasing nail length, higher PSR results were obtained at the same distance from the corner under the same \(\beta\) conditions, indicating a reduction in the corner effect. An increase in the \(\beta\) angle decreased the effect of nail length on PSR. As the stiffness increases  
Figure 12: PSR changes in nail walls under different slope angle (\(\beta\)), wall angle (\(\alpha\)), excavation depth (H), and nail length (L/H) conditions; (a) \(\beta=0^{\circ}\) (b) \(\beta=10^{\circ}\) (c) \(\beta=20^{\circ}\) (d) \(\beta=34^{\circ}\). in nailed walls, the corner effect decreases. Increasing the slope angle (\(\beta\)) and excavation depth (H) increases the corner effect because it causes a decrease in the stiffness of nailed walls. Increasing the nail length (L/H) and wall angle (\(\alpha\)) will increase the stiffness, thus increasing the PSR value and decreasing the corner effect [29; 58].