Regional slope stability and slope failure mechanics under strong seismic events in the upper reaches of Yellow River cascade reservoir dams via the SEM–FDEM–SPH coupling approach

Early warning and hazardous point monitoring for large-scale slopes under strong ground motions are pivotal tools for safeguarding assets and stakeholders. In addition, the local-scale failure mechanisms and processes for earthquake-induced landslides can provide detailed information for decision making and planning. Providing regional seismic wave fields is critical for assessing regional slope stability and local-scale earthquake-induced landslides. Currently, most stable assessments and mechanism analyses of landslides use specified pseudo-accelerations or a small number of earthquake records because earthquake records are often very limited. Notably, these approaches cannot fully consider the spatial differences in seismology characteristics at various locations. In other words, there is always a generation gap between earthquake action and slope response and stability assessment. To reduce this gap, a hybrid simulation framework is created via the spectral element method (SEM), Bishop method, finite-discrete element method (FDEM), and smoothed-particle hydrodynamics (SPH) for large- and local-scale slopes in the upper reaches of Yellow River cascade reservoir dams. The SEM and Bishop methods enable straightforward estimation of seismic stability for regional slope systems subjected to earthquakes across 19 different scenarios by considering the sources, propagation paths, regional topographies, and geological conditions of the existing uncertainties. The weak coupling strategy of the time domain reduction method is implemented to achieve local-scale failure processes of earthquake-induced landslides via SEM–FDEM–SPH. The results indicate that the multiscale framework can realize regional earthquake landslide stability assessment and the chain disaster simulation of local unstable slopes. For projects involving regional-scale slope seismic stability assessment and local-scale mechanistic analysis, a physics-based mechanism framework for simulation studies and risk prediction is recommended.