Soil reinforcement loads in geosynthetic walls at working stress conditions

Knowing the load in geosynthetic reinforcement layers in full-scale walls is an important step to improving internal stability design methods. Interpretation of empirical reinforcement load data enables analytical models to be properly calibrated. High-quality empirical data also provides a baseline against which new design methods can be validated. In this paper, loads in soil reinforcement layers from 16 full-scale geosynthetic wall case histories were estimated from strain measurements and converted to load through the stiffness of the reinforcement material. The paper summarizes these estimated peak loads, describes general trends in the data, and compares these reinforcement loads to predictions using current design practice applied to the wall case histories. It was found that reinforcement loads derived from strain measurements are, in general, much lower than would be predicted based on current limit equilibrium design methods that use classical earth pressure theory. The low reinforcement strains and loads measured to date in geosynthetic walls point to the desirability of using peak soil shear strength rather than constant volume shear strength for design. This approach will help to reduce design conservatism and will be consistent with the philosophy of preventing failure of a major component of the reinforced soil system, the soil. Once the soil has failed, for all practical purposes, the wall has failed as well.