Analysis of Wave-Driven Progressive Buildup of Excess Pore Water Pressure in Sands Supporting Marine Hydrokinetic Devices

Abstract

Abstract Instability of the seabed due to storm waves may cause damage to coastal/offshore structures. Saturated sand deposits in loose to medium dense condition contract under cyclic shearing causing the buildup of positive pore water pressure. For severe wave loadings, this could lead to a significant reduction of effective stress and soil liquefaction. In addition to detailed cyclic plasticity models for describing progressive generation of pore water pressure, a number of experimental models have been developed based on results of cyclic triaxial tests. Such tests mostly considered isotropic consolidation condition prior to cyclic shearing. However, the presence of static shear stress and hence anisotropy of geostatic stresses (e.g., under the foundation of structures) has been shown to alter the soil cyclic behavior significantly. Pan and Yang (2018) proposed a pore pressure buildup model for sands considering the effect of static shear stress ratio SSR on the residual response of the soil following anisotropic undrained cyclic triaxial tests. This study aims at modeling of wave-MHK-poro-elastoplastic seabed interaction with the focus on geomechanical investigation of pore pressure buildup in sands under various ranges of SSR.