Effects of viscous behavior of geosynthetic reinforcement and foundation soils on the performance of reinforced embankments

The combined effects of viscoelastic behavior of geosynthetic reinforcement and viscoplastic nature of rate-sensitive foundation soils on the performance of reinforced embankments are investigated. The variation of viscoelastic properties is examined using geosynthetic products that are made of polyester, polypropylene and polyethylene. The foundation soils consist of two soft clay deposits with different strain-rate sensitivities. Embankment construction is numerically simulated to identify the magnitude of creep deformation of the reinforcement and the foundation soil under both limit state and working stress conditions and the consequent effects on the stability of the embankment. It is shown that the creep of geosynthetic reinforcement and foundation soil can decrease the short-term stability of embankments and that the mobilized reinforcement stiffness and corresponding tensile force can be significantly lower than that measured from standard laboratory test. The isochronous stiffness can reasonably represent the mobilized reinforcement stiffness at the critical stage of the embankment. During post-construction periods, reinforcement strain can increase substantially and it has shown that the increase in reinforcement strain is largely due to the viscoplastic behavior of foundation soils. The mobilized reinforcement strain under working stress conditions with respect to reinforcement stiffness are also discussed.