Effect of General Scour on the Axial Capacity of Piles Driven in Mixed Soil Layers Considering Pile Installation

Abstract

Bridge scour causes the removal of soil surrounding bridge foundations. The direct consequence of scour is a reduction in the foundation’s axial capacity. This study employs finite element modeling in ABAQUS software to simulate general scour affecting a pile in layered soil profiles. The aim is to quantify axial capacity reduction per each layer of soil at different depths, considering the entire installation process, including stages such as cavity expansion, pile placement, initial penetration, consolidation, scour, and pile load testing. In the first part, five cases similar to the Louisiana soil profile were simulated, with three scenarios included: no scour, initial-absence condition (similar to static methods), and long-term scour after excess pore pressure dissipation. Four scour depths (5, 10, 15, and 20 ft) were considered, and the scouring effect was quantified in total capacity, side friction, end-bearing, and per-layer capacity. In the second part, each soil type was simulated along the whole profile to obtain scour factors to be used in the design. The results of the five cases revealed considerable differences between the initial-absence condition and long-term scour, with reductions in total capacity reaching around 20% at a scour depth of 20 ft in some cases. This reduction is primarily owing to a decrease in side friction. The results of the second part show the scour factors that should be considered for pile design in each specific soil type at each depth/effective stress.