Design Of High Strength Geotextiles For Basal Reinforcement Within Embankments

High Strength Geotextiles (HSG’s) are commonly used as basal reinforcement within embankments and structures founded upon weak ground. The polymeric composition of these products can bring high magnitudes of tensile strength to the system to prevent against slope instabilities and bearing type failures.

HSG’s are “passive” forms of reinforcement, whereby activation of its capacity occurs whence destabilising forces are applied, causing the reinforcement to undergo tensile strain. The polymeric materials in HSG’s undergo creep, i.e. deformation under sustained application of constant tensile loads. The combination of straindependent and time-dependent behaviours in HSG’s are a complex mix of material characteristics, which make them complicated to design with. The complexity of their behaviour has resulted in greatly varying design methods adopted in industry. The source of difference is often linked to how creep is addressed in the selection of HSG, and how its strain-dependent behaviour is accounted for. This paper discusses the design methodologies referred to in BS8006 (Code of Practice for Strengthened/Reinforced Soils and other Fills) – which follows a limit state design process to ascertain the design loads to be carried by HSG’s and methods on how to assess the design strength of proprietary products. The authors generally support the methodologies adopted in BS8006 with suggestions on limiting criteria and how these can be assessed.