Calculation method of flow drag around a pile in soft soil considering Bingham fluid properties and analysis of single pile response

Abstract

The lateral displacement of deep soft soil caused by large-area heap loading is a common issue in engineering practice, which affects the stability of neighboring pile foundations. This study investigates the calculation of thrust force exerted by the flow of soft soil around piles and its impact on pile foundations. The surrounding soft soil is considered a Bingham fluid. An analytical formula for single pile flow drag during the internal slip of deep soft soil is derived based on fluid mechanics theory and the fluid characteristics of the Bingham fluid. The traditional cantilever pile approach is modified by assuming a rectangular distribution of flow drag along the pile body and using the matrix transfer method. The response of a single pile body under field heap loading conditions is then analyzed, and the results are compared with the calculation results of the traditional soil pressure method and field-measured data to validate the proposed calculation method for flow drag around a pile in soft soil. Finally, a parametric study is conducted to analyze the effects of the relative flow velocity and dynamic viscous coefficient of soft soil on flow drag.