Seismic stability of reinforced slopes: Failure mechanisms and displacements

Failure mechanisms of reinforced slopes with different seismic resistance capacities were examined, based on the results of tilting table tests previously reported by the authors. Three seismic resistance levels for slopes reinforced using various reinforcement materials and facing rigidities were identified, based on various ultimate tilting angles and modes of wall deformation. It was found that a high reinforcement interface friction angle (δ_r = 30°) is a prerequisite for attaining the highest level of seismic resistance with an ultimate tilting angle, θ_f ≥ 20° (or a critical seismic coefficient, k_hc ≥ 0.36). Reinforcement length and reinforcement stiffness play secondary roles, in the sense that these two factors are optional in attaining the highest level of seismic resistance. When a high tensile stiffness reinforcement was used, base sliding failure associated with maximum slope face deformation over the lower third of the slope occurred for slopes with a medium or a low seismic resistance level. Therefore, for a slope reinforced using a high tensile stiffness reinforcement, a maximum slope deformation in the lower third portion of the slope face may be used to identify a 'less robust' slope with a relatively low seismic resistance capacity. For slopes reinforced with a low tensile stiffness reinforcement, maximum deformation in the lower third of the facing is the dominant mode of deformation, regardless of the seismic resistance level. The bending rigidity of the facing may moderately influence the seismic resistance level when using a reinforcement sheet with a high interface friction angle (δ_r = 30°), but it has no influence on the seismic resistance level when using reinforcement sheets with relatively low surface friction angles of δ_r = 20° and 15°.