2013 Session: 595

• New Approach to Design of Closely Spaced Geosynthetic-Reinforced Soil for Load-Bearing Applications
  Abstract: The United States Federal Highway Administration (FHWA) recently published design and construction guid-ance for geosynthetic reinforced soil (GRS), specifically for its use to construct an Integrated Bridge System (IBS). The design methodology presented for GRS differs considerably from that typically used for mechanical-ly stabilized earth utilizing geosynthetics (GMSE). The principle design changes involve modifications to both external and internal stability. External stability is largely unchanged except for eliminating overturning as a failure mode. The changes involving internal stability are more significant and include the determination of ver-tical capacity, deformations, and required reinforcement strength. Additionally, pullout and connection strength are not considered for internal stability in the new design method. These changes are warranted by the require-ment for closely spaced reinforcement layers in the GRS (less than or equal to 0.3 m) which results in a unique composite material with different behavior from that of larger spaced, traditional GMSE systems. This paper outlines and assesses the major differences in design between GRS and conventional GMSE.
  Authors: Nicks, Jennifer E.; Adams, Michael T.; Wu, Jonathan T. H.
  Authors: Nicks, Jennifer E.; Adams, Michael T.; Wu, Jonathan T. H.
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Geotechnology
  Session: 595
  Paper Number: 13-3879
• Influence of Gravimetric Water Content on Geotextile Reinforcement Pullout Resistance in MSE Walls with Marginal-Quality Soils
  Abstract: Pullout capacity of geotextile reinforcement is an important consideration in the internal stability analysis of reinforced soil structures, especially those constructed with marginal soils. Precipitation, ground water infiltration and seasonal variations of moisture content during the construction process or service life of the structure could result in significant reductions in the matric suction, leading to a reduction in the soil-geotextile interface strength. Consequently, the reinforced soil structure may experience unacceptable deformations or even failure during its construction or post-construction periods. It should be noted that 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 is merely on the latter.In this study, a series of pullout and interface shear tests were carried out to measure the pullout resistance of a reinforcement geotextile in a marginal soil which was compacted at different gravimetric water contents (GWC). The marginal soil was selected to meet the limiting requirements of the National Concrete Masonry Association (NCMA) guidelines for segmental retaining walls with respect to the fines content, gradation and plasticity. The range of GWC values investigated varied from dry to wet side of the soil Optimum Moisture Content (OMC). The matric suction in the soil was measured in order to evaluate its influence on the soil-reinforcement interface shear strength. A Moisture Reduction Factor (MRF) is proposed to account for the reduction in the soil-geotextile interface strength as a result of the loss in matric suction.
  Authors: Hatami, Kianoosh; Granados, Jaime E.; Esmaili, Danial; Miller, Gerald Andrew
  Authors: Hatami, Kianoosh; Granados, Jaime E.; Esmaili, Danial; Miller, Gerald Andrew
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Geotechnology
  Session: 595
  Paper Number: 13-3836
  Practice-Ready: Yes
• Influence of Gravimetric Water Content on Geotextile Reinforcement Pullout Resistance in MSE Walls with Marginal-Quality Soils
  Authors: Hatami, Kianoosh
  Authors: Hatami, Kianoosh
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Bridges and Other Structures; Geotechnology
  Session: 595
  Paper Number: 13-3836