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ABSTRACT: This paper presents an evaluation of the performance of two instrumented sections of a geosynthetic-reinforced soil wall, 5.6 m high, constructed using a lateritic fine-grained soil. Two sections with identical layout of a nonwoven and a woven geotextile were monitored for comparison purposes. The unconfined tensile stiffness of the nonwoven geotextile was three times smaller than that of the woven geotextile. This allowed direct evaluation of the effect of soil confinement on geotextile stiffness. Instrumentation was used to measure face displacements, reinforcement displacement and strains, and soil matric suction. Rainfall occurred both during and after construction, which facilitated evaluation of the effect of soil wetting on the walls performance. Ultimate and serviceability limit state analyses were conducted to gain further insight into the performance of the two walls. The results show that the performance of the section reinforced with nonwoven geotextile was equivalent to the one reinforced with woven geotextile, even after the observed reduction in matric suction after rainfall. For both sections, the overall deformations occurred during construction. Negligible deformations were observed during service. Maximum face displacements were measured in the lowest instrumented layer for the nonwoven geotextile section whereas it was in the highest layer for the woven geotextile section. These behaviours of face displacement distributions can be the result of the significant differences in global stiffness of the sections. Design analyses and field performance show that soil confinement has a beneficial effect on the nonwoven geotextile stiffness. The significant contribution of the soil cohesion of the lateritic soil played an important role in the behaviour of the nonwoven geotextile-reinforced wall. [ABSTRACT FROM AUTHOR]

ABSTRACT: 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. [ABSTRACT FROM AUTHOR]