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Approach

This research experimentally investigates how rainfall infiltration and earthquake shaking interact to trigger liquefaction and permanent ground deformation in slopes composed of granular soils. While liquefaction is traditionally studied under fully saturated conditions, many natural and engineered slopes experience seismic loading while partially saturated or following rainfall events. This study addresses that gap through a controlled, laboratory-based experimental program.

The research uses geotechnical centrifuge testing with in-flight shaking, combined with a rainfall simulation system, to reproduce realistic stress conditions and multi-hazard loading sequences at prototype scale. Slopes are subjected to different rainfall histories followed by earthquake motions, allowing direct observation of how changes in saturation and pore pressure prior to shaking influence liquefaction triggering, deformation patterns, and failure mechanisms.

Key Results

The experiments demonstrate that rainfall history plays a critical role in liquefaction behavior and seismic performance of slopes. Slopes subjected to rainfall prior to shaking exhibit earlier onset of liquefaction, higher excess pore pressure ratios, and significantly larger permanent deformations compared to otherwise identical slopes without prior infiltration. Even moderate rainfall events are shown to substantially reduce liquefaction resistance and increase vulnerability to lateral spreading and surface cracking.

These experimental observations provide a physical basis for improving how liquefaction and deformation are assessed under combined hydrologic and seismic loading, highlighting limitations of evaluations based on seismic loading alone.

Data and Impact

This research produces a unique, high-quality centrifuge dataset capturing liquefaction behavior under realistic combined rainfall–earthquake loading conditions. The dataset includes synchronized measurements of pore pressure, acceleration, displacement, and observed deformation patterns, and is archived for reuse by the broader research community. These experimental results support future centrifuge studies, model evaluation efforts, and infrastructure resilience research within CIEST and related experimental programs.