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Geosynthetic-Reinforced Embankments on Soft Soils: Numerical Analysis of the Strain Mobilization in the Reinforcement During Consolidation Process

Resumo

In this paper the behavior of geosynthetic-reinforced embankments constructed on soft cohesive foundations under undrained and partially drained conditions is examined by conducting a rigorous numerical analysis using the finite element method for a particular case study (a hypothetical road embankment). Special attention is given to the mobilized strains in the geosynthetic reinforcement at short and long-term working conditions considering the influence of the time-dependency of the system in terms of construction rate and excess pore pressure dissipation. The effects of reinforcement stiffness are also investigated. The obtained numerical results illustrated the significant influence of consolidation process on the embankment performance (particularly in terms of mobilized reinforcement strains). A simple normalization procedure was carried out for the case study as an attempt to develop an analytical approach capable to predict the maximum mobilized reinforcement strain after a certain degree of consolidation in the soft soil foundation.

Conclusão

This article studied the mobilization of reinforcement strains in geosynthetic-reinforced embankments constructed over soft soil foundation at working conditions. A comprehensive series of finite element analyses were conducted in order to simulate the embankment behavior for a hypothetical case. In this manner, the short and long-term response of the system was examined considering various factors such as the compatible allowable reinforcement strain, tensile stiffness of the reinforcement, construction rate and consolidation process of the foundation soil. The following conclusions can be drawn from the studies presented in this article:

- Under working conditions, consolidation process after the end of embankment construction induces additional strains in the reinforcement. This maximum observed increase in mobilized reinforcement strain was about 53 % for the case of Jmin.

- As expected, a slower construction rate provokes slightly higher mobilized reinforcement strains as a consequence of partial consolidation occurred during construction.

- The maximum mobilized reinforcement strain at the end of construction obtained from Hinchberger & Rowe (2003) methodology combined with limit equilibrium analysis showed consistency in comparison with the numerical result, which represents a preliminary validation of this approximated approach.

- A normalization chart was developed as an initial approximated methodology to study additional mobilization of strains in the reinforcement as a result of consolidation process (disregarding soil and reinforcement creep).

- The short and long-term performance of the embankment in terms of mobilized reinforcement strains can be improved by increasing the reinforcement stiffness. The short and long-term lateral displacements were also substantially reduced by the use of higher values of reinforcement tensile stiffness.