A Moisture Reduction Factor for Pullout Resistance of Geotextile Reinforcement in Marginal Soils

Reinforced soil slopes and embankments in highways typically contain significant amounts of fines. Such (marginal) soils typically exhibit significant levels of matric suction during construction that decreases as a result of wetting during the service life of these structures. This will reduce the soil-reinforcement interface shear strength with potentially destabilizing consequences. Current design guidelines for reinforced soil structures do not address the influence of soil moisture content on the pullout resistance of reinforcement in marginal soils. In this study, a moisture reduction factor (MRF) is introduced to account for the reduction of reinforcement pullout resistance when the soil moisture content increases compared to its construction value. The variation of the MRF with the soil moisture content was determined using a series of pullout tests on a marginal soil and woven geotextile reinforcement. The preliminary data indicate that the pullout capacity of geotextile reinforcement in marginal soils can be measurably reduced as a result of an increase in the soil moisture content. Consequently, it is suggested that the influence of soil moisture content should be included in the future revisions of design guidelines for reinforced soil slopes and embankments that could contain significant amounts of fines.