# Numerical Study of Geotextile-Reinforced Flexible Pavement Overlying Low-Strength Subgrade
## 1 Introduction  
A large percentage of global road network infrastructure comprises low-volume roads (LVRs), accounting for over 80% [1]. Most of the LVRs serve rural areas, such as farming areas, national forests, and remote mountainous areas, and, in some low-income countries, they serve part of the urban population [2]. They include both paved and unpaved roads. The paved roads are built as granular pavements with bituminous surfacing. Unpaved roads are usually composed of granular bases placed on the prepared subgrade. Compared to higher volume roads, LVRs differ in design, road users, and the nature of the operation. The design may lack certain characteristics, such as super elevation in the case of curves, cross slopes meant for drainage, and adequate maintenance. Road users include heavy vehicles, pedestrians, passenger vehicles, cyclists, farm machinery, and more. In terms of operation, LVRs may lack posted speed limits and rely on the statutory limit. Most LVRs experience higher deterioration and, consequently, do not last for the entirety of their designed lifespan. According to [PERSON] et al. [3] and [PERSON] et al. [4], the significant challenges facing LVRs include: increased traffic loads, variation in climatic conditions, and absence or untimely maintenance. Geosynthetics have emerged among sustainable and cost-effective construction materials [5]. Some of the most widely used forms of geosynthetics in terms of flexible pavement are geotextiles, geogrids, geocomposites, geocells, geonets, geofoams, and geobags [6; 7; 8]. They perform one or more of the following functions: separation, sealing lateral drainage, filtration, and reinforcement [9; 10]. Separation involves placing geosynthetic materialbetween two pavement layers with different particle size distribution in order to prevent mixing and maintain their integrity. In pavement overlays, geosynthetics minimize crack propagation by sealing the asphalt layer [11; 12]. The ability of geosynthetic material to allow liquid to flow across the plane while restricting the movement of fine particles enables it to perform a filtration function [13]. Reinforcement is aided by developing tensile forces in geosynthetic material, which helps improve the stability of the geosynthetic-soil composite system. The effectiveness of reinforcement by geosynthetic materials is influenced by factors such as the engineering and geometric properties of the geosynthetics and subgrade stiffness [14; 15]. Reinforcement increases the area in which the wheel load is distributed, resulting in a decrease in vertical stress and subgrade deformation [16]. Geotextiles are polymeric textile materials that are permeable and exist as flexible sheets. Based on the manufacturing process, they are categorized as woven, non-woven, knitted, or stitch-bonded [17]. Many researchers have studied geosynthetics as reinforcement materials in pavement using three approaches: full-scale field studies, laboratory experiments, and numerical modeling. The Finite Element Method is a reliable technique that can simulate tire-pavement interaction and predict pavement responses [18]. For instance, [PERSON] et al. [19] investigated the effectiveness of using glass fiber grids to reinforce the asphalt layer in the flexible pavement through experiments and the FEM. It was concluded that glass fiber grids improved pavement performance and provided resistance against crack propagation. In a parametric analysis based on 2-D Finite Element modeling by [PERSON] et al. [20], which aimed to determine the impact of reinforcing the subgrade using a geogrid in pavement design, it was noted that the number of load cycles increased due to reinforcement, indicating increased pavement life. The application of geogrids in road pavements on karst geohazards zones was analyzed using numerical simulation by [PERSON] et al. [21]. It was concluded that embedding the geogrid between the bedrock and the subgrade mitigated the failure effectively. A study conducted by [PERSON] et al.