Investigation of seismic displacements in bedding rock slopes by an extended Newmark sliding block model

Earthquake-induced plane failure is typically generated on bedding rock slopes. This failure mode has been widely observed in the past earthquakes in Western China (e.g., Wenchuan earthquake). Among them, the multi-slip plane failure may occur with the presence of multiple bedding planes or internal discontinuities within the slopes. This study developed an extended Newmark sliding block model to investigate the multi-slip seismic displacements of the bedding rock slopes. The unified formulation is presented for seismic sliding analysis of bedding rock slopes with arbitrary numbers and inclinations of bedding planes. Both horizontal and vertical earthquake ground motions and the possible amplifications that may result from site and topographic effects are considered. The developed model is validated by the results from shaking table test. The multi-slip mechanism and the effects of dip angle of bedding planes and vertical ground motion are investigated. The results show that (1) the multi-slip failure evolution is different to that identified from the traditional method, indicating the significant interactions among the seismic sliding behavior associated with bedding planes. (2) The influence of the vertical component of ground motion on the multi-sliding displacement is within a range of 20%. (3) The dip angle of sliding planes has a large effect on the sliding displacement, even if the yield coefficient remains the same. Finally, the proposed method is used to evaluate the seismic displacement and performance of the Liujiawan landslide that was triggered in Wenchuan earthquake.