Performance of nonwoven geotextile-reinforced walls under wetting conditions: laboratory and field investigations

The first geosynthetic retaining wall in Brazil was constructed in 1984 as an instrumented 10 m high geotextile-reinforced soil wall with a poorly draining backfill. This structure has been showing excellent performance throughout its service life, even after long periods of rainfall. In the past, the excellent performance of the wall had been attributed to the influence of soil confinement on the geotextile strength properties as well as the comparatively high interface shear strength between the fine soil and the nonwoven geotextile. Now there is also evidence of the beneficial effect of the internal drainage capacity when using nonwoven geotextiles as reinforcements. In order to clarify the understanding of the performance of the pioneer history case wall (SP-123 wall) and the effect of nonwoven geotextiles as reinforcements of fine-grained soils, full-scale laboratory models of geotextile reinforced walls were tested under wetting conditions. Results from the instrumentation have shown no significant positive water pressures and relatively small displacements even after intense periods of precipitation. The consistency between field and laboratory investigations provides strong evidence in support of the use of nonwoven geotextiles to reinforce poorly draining soils.