Role of geotextile as rut arrester in unpaved roads: insights from finite element analyses

Unpaved roads built over weak marginalised soil subgrade layers are frequently susceptible to permanent damages, primarily due to rutting. This phenomenon of rutting is mostly due to the action of repetitive vehicular loading on the surface of aggregate layer, which eventually deteriorates the serviceability of unpaved road. This paper presents a detailed finite element-based study on unpaved road resting on generalised soil subgrade and subjected to repetitive loading. Outcomes from both two-dimensional (2D) and three-dimensional (3D) frameworks have been elucidated. For 2D loading condition, the development of rutting on the surface of aggregate layer is determined from the single line-section across the length of carriageway, while for 3D loading condition, multiple sections need to be drawn through the wheel imprint to assess the rutting. For unreinforced unpaved road, significant rutting has been observed under repetitive loading, often exceeding the serviceability limit. A geotextile reinforcement having high axial stiffness is found to be extremely beneficial in arresting such rutting, even in the tune of 60%–80% as compared to unreinforced unpaved road. Finally, a comparative study showcased the importance of resorting to 3D quasi-dynamic analysis, as the 2D analysis is shown to provide highly conservative rutting magnitudes.