Optimal ground motion intensity measures for probabilistic assessment of seismic slope displacements.

摘要

The estimation of seismically-induced permanent, displacements in earth slopes can benefit from the recent developments in performance-based engineering and probabilistic approaches,from ongoing research in modelling a slope's dynamic response, and from the availability of an abundance of new ground motion recordings. These elements have been incorporated in the development of an empirical relationship for seismic slope displacement that can be used in both a deterministic analysis and a probabilistic evaluation of the seismic displacement, hazard.; The probability of "zero" displacement occurring and the amount of the seismic displacement, once "nonzero" displacement occurs are estimated as functions of the slope's yield coefficient,its initial elastic fundamental period; earthquake magnitude, and the spectral acceleration at the degraded period of 1.5 times the fundamental period of the sliding mass. The latter was shown to be the optimal scalar intensity measure, because it minimizes the dispersion in its correlation with seismic displacement.; The seismic slope displacement model was developed from regression on simulated displacement data based on an equivalent-linear generalized single degree of freedom stick-slip model. This analytical model was selected after showing its favorable agreement with observed displacements in physical model tests. The proposed model is then calibrated against observations from sixteen well-documented case histories of landfill and earth darn performance. The model estimates seismic displacement due to sliding along a, failure surface and distributed deviatoric shear and uses a yield coefficient reduced by 10% from the value calculated pseudostatically based on the material's shear strength to account, for the phenomena of progressive formation of the failure surface and distributed deviatoric shear.; A period-independent intensity measure is more useful for correlation to seismic displacements when an evaluation involves many potential landslides across vast areas. No one period-independent intensity measure was as efficient across all slope periods as spectral acceleration. However, arias intensity and response spectrum intensity were identified as the optimal intensity measures for stiff and flexible slopes, respectively. Due to its promise for this and other applications, an empirical relationship was developed for arias intensity, which was first based on a sound seismological model. The proposed relationship suggests that arias intensity was overpredicted magnitude earthquakes (M > 7) and underpredicted for smaller magnitude (M 6) by former relationships.