###### Abstract  
The performance of soil nailed walls is evaluated based on lateral displacements, especially in high walls. In this study, the displacement behavior of nailed walls, which are frequently preferred in retaining wall systems in hard claye soils, was examined by taking into account the corner effect. The nailed wall model was created using Plaxis 2D v.23, and the performance of the model was verified with the results of inclinometer measurements taken on-site. To assess the influence of excavation pit dimensions on the corner effect, 25 three-dimensional and 25 plane-strain slice models were created using Plaxis 3D v.23, and the effect of excavation pit dimensions on the plane-strain ratio (PSR) was determined. Then, analysis studies were carried out by creating 336 3D and 336 plane-strain slice models with variable parameters, such as slope angle (\(\beta\)), wall angle (\(\alpha\)), nail length (L/H), excavation depth (H), and distance from the corner (xH). Its effects on PSR were determined. The interactions of the parameters with each other and PSR estimation were evaluated using machine learning (ML) methods: artificial neural networks (ANN), classical and regression tree (CART), support vector regression (SVR), extreme gradient boosting (XGBoost). The proposed ML prediction methods and PSR results were compared with performance metrics and reliable results were obtained. corner effect; finite element analysis; lateral displacement; machine learning; PSR; soil nailed wall +
Footnote †: journal: Applied sciences  
Numerical-based models have been widely used in research on soil nailed walls, particularly over the last three decades. Finite element (FE) software stands out as one of the widely used and reliable tools in this domain [19]. It provides results that are consistent with those of field measurements, laboratory experiments, limit equilibrium methods, and various numerical techniques [20; 21; 22; 23]. For example, in one of these studies, the construction stages and soil pressure during the application process of soil nails were comparatively examined under laboratory conditions and using Plaxis v.23 software, and compatible results were obtained. [24]. Similarly, in another study focusing on the mechanical behavior of soil nailed walls, consistent results were achieved through both experimental and numerical investigations [25]. In the research conducted on soil nailed walls, the strength reduction method (SRM), which is a deterministic approach, was examined comparatively with the finite element method (FEM), and compatible results were obtained [26]. The excavation environment is a three-dimensional environment by nature. Excavation corners have effects on displacements and stresses. Researchers have conducted studies on different sharing systems to investigate these effects. The expression plane-strain ratio (PSR) is used in excavation pits to describe the change in displacements according to the distance from the corner (corner effect). It is defined as the ratio between the maximum displacements obtained from the three-dimensional analysis and two-dimensional analysis of a section at a certain distance of from the corner [27]. There have been corner effect studies on different retaining wall systems. The PSR value was estimated by comparing the three-dimensional effect with 3D finite element analysis in a deep excavation supported by a diaphragm wall [28]. Another study investigated the corner effect in deep excavation work using soil nails, depending on whether the excavation pit is square, concave, or convex [29]. In a different study, an optimum design was made for a soil nailed wall-pile-anchor cable support system in deep excavation, taking into account the corner effect [30]. Empirical and theoretical models remain inadequate for accurately predicting displacements in soil nailed walls. While database performance is strong, the ability to generalize to unseen data still needs further improvement.