Numerical analysis of field geosynthetic-reinforced retaining walls with secondary reinforcement

Geosynthetic-reinforced retaining (GRR) walls typically have vertical reinforcement spacing of 0.6 m, and this relatively large spacing has been known to cause comparatively high connection forces. To reduce this connection force, short geosynthetic reinforcement layers (referred to as secondary reinforcement layers) are installed between blocks where there are no primary reinforcement layers. This paper presents two-dimensional numerical simulations that were developed to analyse an instrumented GRR wall with secondary reinforcement layers in the field. A finite differential software was employed to develop the numerical model. In addition to the Mohr-Coulomb model, the cap yield model based on the theory of hardening plasticity was used to represent the behaviour of backfill. Inclinometer casings, earth pressure cells and strain gauges were installed in the instrumented GRR walls to measure the facing deflections, lateral earth pressures, vertical earth pressures and geogrid strains. The measured results and numerical predictions were compared and discussed, and reasonable agreement between these results was found. Compared to the measured results, the numerical predictions slightly underestimated the maximum wall facing deflections and vertical earth pressures, and slightly overestimated lateral earth pressures and strains in primary and secondary reinforcement layers. For comparison, a numerical model without secondary reinforcement was developed as well. This comparison revealed that the GRR wall with secondary reinforcement resulted in smaller facing deflections and maximum strains in primary reinforcement layers. Overall, the numerical analysis indicated that secondary reinforcement could provide clear benefits in improving the performance of GRR walls.