Seismic Reliability Assessment Framework for Unsaturated Soil Slope under Near-Fault Pulse-Like Ground Motion

The seismic reliability of soil slopes in geohazard-prone regions, particularly under near-fault earthquake conditions, poses a significant challenge. This challenge is exacerbated by the scarcity of pulse-like ground-motion records for such scenarios and the limited consideration of unsaturated soil behavior. In response to these issues, we propose a comprehensive seismic reliability assessment (SRA) framework tailored to unsaturated soil slopes subjected to stochastic pulse-like ground motions (PLGMs). This framework integrates three critical components: a novel PLGM simulation method, a sophisticated nonlinear hydro-mechanical coupling analysis for unsaturated soil, and an advanced reliability assessment methodology. Compared to previous works, the proposed framework has advantages of connecting the seismic reliability and target spectrum in anti-seismic codes and evaluating the seismic stability of unsaturated soil from the perspective of the physical mechanisms. An unsaturated clay slope is illustrated to demonstrate the feasibility and effectiveness of the proposed SRA framework. The results of analysis demonstrate that the framework is highly capable of assessing seismic reliability under stochastic PLGMs. Notably, the seismic slope displacement subjected to PLGMs is significantly greater than that subjected to ordinary ground motions. Additionally, even when the acceleration spectra of input ground motions are controlled, the randomness of ground motions plays a dominant role in influencing seismic responses, outweighing the spatial variability of soil properties.