A physics-based model for clear-water scour development around a pile foundation in clayey soils

Abstract

Significant advancements have been made in understanding local scour around pile foundations in non-cohesive soils; however, the scour phenomenon in clay soils remains relatively unexplored. Existing formulas for predicting scour development in clay soils around pile foundations often rely on empirical fittings to experimental data, rendering them limited by specific experiment conditions and prone to scale effects. To address this gap, this study proposes a physics-based model for clear-water scour development around a pile foundation in clay soils under both steady and unsteady flow conditions. By integrating a scaling expression for shear stress based on the phenomenological theory of turbulence (PTT) and incorporating a general sediment transport model, an ordinary differential equation (ODE) is derived to characterize the temporal variation in scour depth following the principle of sediment mass conservation. This ODE inherently considers all significant dimensional parameters influencing the scouring process, thereby effectively addressing potential scale-related issues. The predictions of the analytical solutions for the proposed ODE closely align with previously observed scour depth development curves around pile foundations in clay soils. Additionally, the model can be applied to scenarios with unsteady flow velocities, such as waterway floods and tidal currents.