Volume 29, Issue 4 (July 2001)
Model Tests by Centrifuge of Soil Nail Reinforcements
Soil nailing is an in situ technique to reinforce slopes in the vadose zone where the soil is partially saturated. In this research, model tests of soil nailing on steep cuttings of an unsaturated silty clay were performed using a centrifuge. The results show that soil nailing can greatly increase the stability of cuttings. The length and density of soil nails have significant effects on the deformation behavior and failure mechanism of the soil-nailed structure. When the ratio between the maximum nail length and the excavation depth (L/H) was 0.32 or 0.34, the model slope was unstable with a prototype spacing less than 1.8 m. However, when the L/H ratio was 0.48 or 0.80, the model slope was substantially stable against global failure under the same spacing. External failure occurred in nailed structures with densely reinforced shorter nails; the prototype spacing was less than 1.29 m and the length ratios were 0.32 and 0.34. Internal failure occurred in nailed structures with sparsely reinforced longer nails: the prototype spacing was 3.6 m and the length ratio was 1.0. The failure surfaces of the nailed cuttings were deeper than that of the cutting without reinforcement.