Shaking table tests and stability analysis of steep nailed slopes

Abstract

Shaking table tests were performed on five model slopes to examine the effects of the angle and length of the nails and the frequency of excitation on the seismic resistance and failure mechanism of the slopes. Seismic excitation was also applied to slopes at various angles. Experimental results showed that nails markedly improved the seismic resistance of all model steep slopes. Additionally, nailed slopes exhibit characteristics of ductility under strong excitation. The angle of the nails influences the deformation of the slope but only slightly affects seismic resistance. An increase in the length of the nails increased the seismic resistance of the slope and reduced the displacement of the facing only when subjected to strong excitation. The slope at an angle of 90° to the horizontal has a markedly lower seismic resistance than that at 80°. The rocking of the model slope was strong for the slope with inclined nails and the slope at 90° to the horizontal. The failure surface of the soil mass is approximately a bilinear surface; the pullout of nails from the lower rows of nails caused total slope failure. The seismic resistance of a nailed slope is categorized viz. response of the models by three stages: stable, seismic resistance, and incipient collapse phases. Critical seismic acceleration coefficients of all models are evaluated and compared with values predicted by a developed pseudo-static, limit-equilibrium-based slope stability approach, which postulates a two-wedge failure mechanism.Key words: shaking table test, steep nailed slope, seismic resistance, pseudo-static approach.