Required reinforcement stiffness for vertical geosynthetic-reinforced-soil walls at strength limit state

In the design of geosynthetic-reinforced-soil (GRS) retaining walls for strength limit state, it is usually assumed that the soil strength is fully mobilised, but generally design guidelines do not have the specification on the required long-term reinforcement stiffness that may mobilise the design soil strength under the design load. In this study, a validated analytical method for reinforcement loads of vertical GRS walls was employed to investigate the required reinforcement stiffness at the strength limit state. The analysis was based on the compatible soil-reinforcement deformation at the potential failure surface. The study found that design of the strength limit state of GRS retaining walls should adequately take into account reinforcement stiffness, without which the targeted state cannot be obtained. The mobilised lateral soil strain and the required local reinforcement stiffness J/S_v to mobilise the lateral soil strain are both larger under higher vertical soil stress. The required local reinforcement stiffness increases with an increase in the soil stiffness, a decrease in the soil dilatancy and a decrease in the peak friction angle. A series of design tables was provided, which could be used to select proper geosynthetic reinforcements for vertical GRS walls at the strength limit state.