# Analysis of the Working Performance of a Back-to-Back Geosynthetic-Reinforced Soil Wall
## 1 Introduction  
Geosynthetic-reinforced soil walls (GRSWs) have been widely used in various engineering fields such as roads and railways. A GRSW is a viable replacement for conventional concrete-retaining structures in infrastructure development and remedial treatments around the world [1; 2; 3; 4; 5; 6; 7]. To evaluate the stability and durability of GRSWs, researchers have conducted several experimental studies on the working performance of GRSWs under different conditions. The results suggest that the post-construction deformation of a well-designed wall (less than 13 m in height) will generally be less than 25 to 30 mm during the first year of service and less than 35 mm during the design life of the wall [8; 9]. However, this statement depends on several factors and cannot be generalized. In recent decades, various studies have analyzed the deformation and stress characteristics of GRSWs using different reinforcement lengths and vertical spacing, as well as different types of faces and found that the post-construction displacement of a reinforced soil wall is approximately 0.3-1% \(H\)[10; 11; 12]. However, these studies were based on a single GRSW and not a back-to-back geosynthetic-reinforced soil wall. Therefore, the actual post-construction performance of back-to-back geosynthetic-reinforced soil wall is still unclear.  
The concept of back-to-back geosynthetic-reinforced soil walls (BBGRSWs) has been addressed in design manuals [13] and has been divided into two types: (I) the width of the ramp or embankment allowing for the construction of two separate walls withsufficient spacing in between to allow each wall to act independently, and (II) an overlap in the reinforcement resulting in an interaction between the two walls. Many numerical studies have been conducted to analyze back-to-back mechanically stabilized earth walls (BBMSEWs) or BBGRSWs. The results indicate that the distance between the two back-to-back walls is the key to achieving the maximum tensile strength of the reinforcement in addition to the filling material properties that affect the distribution of tension in the reinforcement and lateral pressure of BBMSEWs [14; 15; 16; 17; 18; 19].  
In case II, suggested by [PERSON] et al. [13], the interaction mechanism between the two walls is still unclear. The width (\(W\)) of the BBGRSW could be smaller (i.e., \(W/H\) < 1.4), and, in that case, there was insufficient space for the minimum reinforcement length (i.e., 0.7 \(H\) on each side, 1.4 \(H\) in total) in the same layer.  
According to [PERSON] and [PERSON] [14], the distance between the reinforcement of each side is the key to the performance of the BBGRSW; this study focused on the lateral pressure behind the reinforcement and the tension in the reinforcement. Of the parameters affecting the performance of the BBGRSW, only the cohesion of the block facing and the wall width were analyzed. [PERSON] [20] also studied the performance of a BBMSEW under different reinforcement stiffnesses. [PERSON] [21] conducted a series of numerical modeling studies on the upper-bound bearing capacity of footing on BBMSEWs using the finite element limit analysis (FELA) method and suggested that a full-length top reinforcement layer is the most effective method to improve the bearing capacity of the structure. However, the working performance of BBGRSWs under different reinforcement lengths or arrangements has not been studied. To study the post-construction performance of a BBGRSW and optimize the design, we require a parametric study on the reinforcement length and layout. Therefore, a series of FEM analyses were conducted on the basis of the BBGRSW on-site. The findings provide a reference for the design and construction of GRSWs, which was the main purpose of this study.