Shaking table modelling on seismic response and failure mechanism of submerged silty clay slopes

Abstract

Abstract Earthquake-induced submarine landslides threaten marine infrastructure, yet their destabilization mechanisms remain poorly understood. This study utilizes a large-scale 1 g underwater shaking table test with intact marine silty clay to investigate the dynamic response of submarine slopes under multi-stage seismic loading. We systematically analyze the evolution of acceleration amplification, dynamic earth pressure, and excess pore water pressure (EPWP), highlighting the coupled effects of structural degradation and earthquake-induced hydrodynamic disturbances. Results show that the slope’s natural frequency decreases progressively with increasing seismic intensity, reflecting cumulative internal damage. While bedrock acceleration remains unamplified, the silty clay exhibits pronounced topographic amplification that diminishes at higher intensities due to plastic yielding. Notably, compressional waves in water significantly perturb the Peak Ground Acceleration (PGA) field at the slope surface. Furthermore, the continuous accumulation and slow dissipation of EPWP render submerged slopes highly susceptible to failure even under minor excitations. The downward localization of peak dynamic earth pressure marks the progressive formation of deep-seated sliding surfaces. This study emphasizes that the hydrodynamic pressure waves caused by earthquakes are a non-ignorable factor affecting slope instability and must be included in future marine geological hazard assessments.