Parametric Numerical Study of Seismic Slope Stability and Verification of the Newmark Method

Abstract

2D dynamic modelling of seismic slope stability is applied to a landslide-prone area in Central Asia, the Mailuu-Suu Valley, situated in the south of Kyrgyzstan. The calculations are made with models constructed from five long profiles located in the target area, presenting different geological, tectonic and morphological settings. These input data were extracted from a 3D structural geological model built with the GOCAD software. Geophysical and geomechanical parameters were defined on the basis of results obtained by multiple surveys performed in the area over the past 15 years. These include geophysical investigation, seismological experiments and ambient noise measurements. Dynamic modelling of slope stability is performed with the UDEC version 4.01 software that is able to compute deformation on the basis of discrete elements. Inside these elements pure elastic materials (similar to rigid blocks) were used. Various parameter variations were tested to assess their influence on the final outputs. The total parametric study involved more than 50 different models (about 400 computation hours). Preliminary results allow us to evaluate the influence of topography and geology on the amplification of Areas Intensity, which is a very important parameter needed for the computation of Newmark displacements using different GIS approaches [Jibson et al. (US Geol Surv Open file report 98–113,1998); Miles and Ho (Soil Dyn Earth Eng 18:305–323,1999), among others]. The final results of our studies should allow us to define the limitations of the simplified GIS-based Newmark displacement modelling; thus, the verified method would make landslide susceptibility and hazard mapping in seismically active regions more reliable.