Interpretation Considerations for Field Study of Axial Stresses/Forces in Driven H-Piles Due to Construction Activities for Fill Placement

Abstract

A field measurement was conducted on an H-pile driven into a multilayer soil profile to analyze the axial stresses/forces generated on the pile during bridge construction activities. Vibrating wire strain gauges and piezometers were utilized, and dynamic testing was conducted for this purpose. Measurements revealed that the pile's preinstallation and temperature changes after installation in cooler ground caused shifts in strain gauge readings. Furthermore, driving an adjacent pile into the vicinity equivalent to four pile diameters, caused a notable increase in pore water pressure, resulting in decreased stresses on the pile. Concreting on top of the pile induced compressive stress during the first day, followed by a considerable decrease and development of tension on the pile over the next two days. Considering the residual force due to pile installation, force distribution, neutral plane location, and maximum axial force along the shaft were different and higher than in the case where this force was ignored. This paper presents a robust methodology to evaluate forces/stresses in a pile subject to installation through to final loading, including drag force effects based on instrumentation measurements. This novel approach provides a better understanding of drag force impacts on actual load capacity under final production loading.