Seismic stability of reinforced slopes: effects of reinforcement properties and facing rigidity

A series of tilting tests on reinforced model slopes backfilled with regularly packed 1.96 mm-diameter steel rods were performed to investigate the relative importance of facing rigidity, reinforcement length and reinforcement stiffness for the pseudo-static seismic stability of reinforced slopes. Aluminium full-height panel with a wide range of bending rigidities and reinforcing materials with significantly different tensile stiffnesses and interface friction angles were used in the tests to investigate their effect on the ultimate tilting angles (or pseudo-static-based critical seismic coefficient) of the reinforced model slopes. It was found that, of the factors investigated, the interface friction angle of the reinforcing materials plays an essential role in the pseudo-static seismic stability of the walls. When the interface friction angle of the reinforcement was too low, increasing the facing rigidity or tensile stiffness of the reinforcement resulted in a negligible effect on the ultimate tilting angle of the reinforced slopes. Increasing the ratio of reinforcement length to wall height (L_r/H_t) from 0.52 to 0.83 provided a substantial increase in θ_f, regardless of the interface friction angle (δ_r) and facing thickness (t_m) investigated in the study. This effect is a promising way of increasing the pseudo-static seismic stability of reinforced slopes. Increasing the tensile stiffness of the reinforcing material results in a small to moderate increase of θ_f (or k_hc) associated with the formation of a monolithic reinforced zone behind the facing. For the ranges of facing and reinforcement parameters investigated, facing rigidity plays a secondary role in the ultimate tilting angle of reinforced slopes, and is realised only when a sufficiently high interface angle of reinforcement or a relatively short reinforcement length (L_r = 0.52H_t) is used. The relative importance of the parameters was also examined from the viewpoint of lateral facing deformation. The deformation-based observations supported such findings in view of the critical tilting angles mentioned above.