Dynamic centrifuge tests on seismic responses of air-dried deposit slopes
SUN Zhiliang,KONG Lingwei,GUO Aiguo
(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)
Abstract:In order to study the seismic behaviour of deposit slopes which distribute widely in south-west of China,a generalized model of deposit slopes was designed for the dynamic centrifuge tests with the geometric scale of 1∶50. In this paper,the influence of the amplitude of input earthquake excitations on the dynamic response of a air-dried deposit slope was studied in the 4-stage centrifuge tests and the effect of earthquake acceleration amplification,the deformation mode and the failure pattern of the slope model were analysed. The test results indicated that the horizontal amplification coefficients of peak ground acceleration(PGA) reached the maximum values at the crest,reflecting the amplification effect of altitude. The Fourier spectrum characteristics of input seismic wave were certainly changed along the height. The predominant frequencies corresponding to the Fourier spectrum peak at each measuring point on slope surface decreased with the increasing of PGA. Considering the influence of vertical acceleration amplification,the angle between the direction of the resultant amplification coefficient and the horizontal direction decreased with the increase of the slope elevation,which reveals the phenomena of wave field splitting and waveform conversion. In addition,both the horizontal and vertical amplification coefficients of PGA decreased first then increased considerably as the input acceleration amplitude increased. The failure of deposit slope in the dynamic centrifuge testing was observed to start when the input acceleration increased to 0.216 g. The residual displacements at the crest were obvious and the failure surface appeared to be fairly shallow.
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