Reinforcement Pullout Capacity in Mechanically Stabilized Earth Walls with Marginal-Quality Soils

Abstract

Pullout capacity of geotextile reinforcement is an important consideration in the analysis of internal stability of reinforced soil structures, especially those constructed with marginal soils. Precipitation, ground water infiltration, and seasonal variations of water content during the construction process or service life of the structure could result in significant reductions in the matric suction and lead to a reduction in the strength of the soil–geotextile interface. Consequently, the reinforced soil structure may experience unacceptable deformations or even failure during its construction or postconstruction periods. The loss of matric suction in the soil influences both the shear strength of the soil and the soil–reinforcement interface. However, the focus of this study was merely on the latter. Nine pullout tests and 18 interface shear tests were performed to measure the pullout resistance of a reinforcement geotextile in a marginal soil that was compacted at different gravimetric water contents (GWCs). The marginal soil was selected to meet the limiting requirements of the National Concrete Masonry Association guidelines for segmental retaining walls with respect to fines content, gradation, and plasticity. The range of GWC values investigated varied from the dry to the wet side of the optimum moisture content of the soil. The matric suction in the soil was measured to evaluate its influence on the soil–reinforcement interface shear strength. A moisture reduction factor is proposed to account for the reduction in the soil–geotextile interface strength as a result of the loss in matric suction.