EVALUATION OF FORCE-EQUILIBRIUM AND DEFORMATION-BASED DESIGN APPROACHES FOR PREDICTING REINFORCEMENT LOADS WITHIN GEOSYNTHETIC- REINFORCED SOIL STRUCTURES

The appropriate estimation of reinforcement loads is crucial for evaluating the internal stabilities of geosynthetic-reinforced soil (GRS) structures. The prediction methods used for the reinforcement loads within the GRS structures in the current research and practice can be categorized into two approaches: The force-equilibrium approach (i.e., the earth pressure method and the limit equilibrium method) and the deformation-based approach (i.e., the K-stiffness method and the finite element method). To date, the accuracy of these methods has not yet been examined and evaluated. In this paper, each method is introduced and their advantages and disadvantages are discussed. Afterward, the reinforcement loads measured from a 3.6 m high full-scale GRS structure using careful construction and instrumentation were used to examine the prediction of reinforcement loads using the aforementioned methods. The comparison results indicated that the force-equilibrium approach, including the earth pressure method and the limit equilibrium method, overestimates reinforcement loads up to 2.57 times. The finite element method is in good agreement with the measured data under working stress conditions; however, numerical illness (i.e., the convergence problem) might occur earlier than the actual failure of the structure at large soil deformation (or strain) conditions. The K-stiffness method showed a clear underestimation in surcharging conditions. The reasons for the discrepancy between the predicted reinforcement loads and the measured data are discussed. The principal sources of the conservatism in the force-equilibrium approach to predict the reinforcement loads for the wall case used in this study are the inability to appropriately model the effect of facing, and the disregard for the strain compatibility between two dissimilar materials (i.e., soil and reinforcement) in the force-equilibrium approach. The results obtained from this study provide insightful information for the design of GRS structures.

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