Short-Term Strain and Deformation Behavior of Geosynthetic Walls at Working Stress Conditions

The paper reviews geosynthetic reinforcement strain measurement techniques that have been reported in a database of well-documented case studies and more recent full-scale laboratory test walls. Interpretation of strain measurements, accuracy of readings, and advantages and disadvantages of different techniques are discussed. In general, properly calibrated strain gauges have proven useful to estimate reinforcement strains at low strain levels (0.02 to 2%). Extensometers are shown to be accurate at strains greater than 2% and to have marginal reliability at strains between 0.5 and 2%. A strategy to improve confidence with interpretation of strain readings is to use strain gauges and extensometers in the field and to adjust strain gauge calibration factors based on in situ measurements from both devices. Corrected reinforcement strains can be used together with appropriately selected reinforcement stiffness values to estimate reinforcement loads. Estimated loads can then be compared to predicted values using current and proposed design methods for the internal stability of geosynthetic-reinforced soil walls.