Seismic displacement analysis of a reinforced soil model wall considering progressive development of reinforcement force

Progressive development of the reinforcement force in a geosynthetic-reinforced model soil retaining wall subjected to irregular ground accelerations was investigated in a pseudo-static-based analytical model. The progressive development of the reinforcement force was expressed as a function of maximum input ground accelerations in the proposed analytical model, which also incorporated a multi-wedge failure mechanism and Newmark's sliding-block theory. This analytical model eliminated a disadvantage inherent in the conventional pseudo-static approach, namely a possible overestimation of the seismic stability of the wall due to the assumption of full mobilization of the reinforcement force regardless of the intensity of ground excitation. It was also found that the value of the critical seismic coefficient $(khc)$ calculated using a peak internal friction angle (ϕ_p) and a fully mobilized reinforcement pull-out force can be used to simulate the ultimate state of the model wall when subjected to irregular ground excitations. A softened friction angle of ϕ = 0.9ϕ_p simulated the wall behavior well when the horizontal displacement of the wall (D_h) was greater than 5% of the wall height (H_t). This finding is consistent with that for a conventional gravity-type soil retaining wall previously reported. A non-uniform distribution of tensile force along the reinforcement, with a peak value at the intersection of the reinforcement and slip surface and a reduced value at the facing-backfill interface was obtained, using a reduction factor of R_r–f = 0.5, based on the calibration of seismic displacements of the tested wall. A reduction factor that accounted for the mobilization of the friction angle along the soil-reinforcement interface, R_r–s, was also calibrated, based on the displacement analysis. It was found that values of R_r–s between 0.7 and 0.8 could be used to represent the pull-out behavior of reinforcement subjected to seismic loading. The proposed method is based on a single set of experimental results and therefore the applicability of the proposed method needs to be verified using more physical tests and/or numerical analyses of various wall geometries and reinforcement configurations.