LIMIT EQUILIBRIUM AS BASIS FOR DESIGN OF GEOSYNTHETIC-REINFORCED SLOPES

Limit equilibrium methods are evaluated with respect to their ability to predict failure of geosynthetic reinforced slope models tested in a geotechnical centrifuge. The variables considered in the centrifuge t esting program were the reinforcement spacing, reinforcement tensile s trength, and soil shear strength. Extensive testing was initially cond ucted to evaluate the strength properties under operational conditions of the backfill material, the model geotextile reinforcements, and th e several interfaces in the slope models. Parametric studies were perf ormed to evaluate the effect of the in-soil geotextile tensile strengt h, nonuniformity of unit weight in the centrifuge models, orientation of reinforcement forces, reinforcement overlapping layers, lateral fri ction of the models against centrifuge box, and selected method of slo pe stability analysis. All centrifuge slope models built using the sam e backfill soil yield a single Normalized Reinforcement Tension Summat ion. This normalized value can be interpreted as an earth pressure coe fficient that depends on the soil friction angle and on the slope incl ination, The evaluation also indicates that limit equilibrium should c onsider horizontal orientation of reinforcement forces, that significa nt contribution to stability is provided by the overlapping reinforcem ent layers, and that different rigorous limit equilibrium methodologie s provide equally good results. Very good agreement was obtained betwe en the g-levels at failure obtained experimentally and those predicted by limit equilibrium. Equally good agreement was obtained between exp erimental and predicted locations of the failure surfaces.