A numerical assessment of the influence of compaction on the seismic performance of Geosynthetic-Reinforced Earth retaining walls

Over the past three decades, field observations have demonstrated the resilience of Geosynthetic-Reinforced Earth (GRE) retaining walls to severe earthquakes. Seismic damage to GRE walls generally manifests as permanent deformations due to the transient activation of plastic mechanisms within the soil-reinforcement system, demonstrating their overall ductile behaviour. However, a limited understanding of the reinforcement-soil interactions under static and dynamic conditions and the lack of specific guidelines in many building codes for the seismic design of GRE walls have hindered their widespread adoption. In particular, the design parameters for both the backfill and the mechanical properties of the reinforcement are usually selected according to an overly conservative approach which neglects the effects of high compaction energy. As a result, a GRE wall in a well compacted granular soil is often designed with a soil shear strength that is much lower than the strength available. This paper discusses the effects of compaction on the initial stress and strain distribution in the reinforcement and their impact on the seismic performance of GRE walls. To this end, iterative pseudo-static and dynamic time-domain numerical analyses were carried out to assess how compaction affects both the plastic mechanisms and the seismic performance of reinforced soil walls.