Measurements of induced vibrations due to steel pipe pile driving in Al-Fao soil: Effect of partial end closure

Abstract

The experimental study investigated the impact of partially closing the end of a tubular steel pile with a diameter of 1.22 m on the induced driving vibrations. Long piles, spanning 50 m, were driven into Al-Fao soil using hammers from Daewoo Company – the PTC-110HD vibro-hammer for the initial 24 m of penetration and the IHC S-280 hydro-hammer for the remaining depth. This study established comparisons between open-end pipe (OEP) and partially closed pipe (PCP) piles concerning various parameters. These parameters included the number of blows, driving energy delivered by the hydro-hammer along the depth, and the peak soil particle velocity (PPV). Data collection was carried out using pile dynamic integral sensors for pile driving analysis, strain gauges placed along the lengths of the piles, and geophones positioned at varying distances from the pile. The results of the study unveiled a substantial effect of partial closure on the vibration response. Specifically, vibrations in the vicinity of the pile were amplified by a factor of 3–4 at depths ranging from 1 to 22 m where the vibro-hammer was employed, and by a factor of 2.5 to over 3 for the remaining depth where the hydro-hammer was utilized. Furthermore, it was observed that the rate of vibration attenuation was higher for the OEP when compared to the PCP. The vibrations are attenuated along the distance from the source where the PPV is decreased to approximately average (3.5% for OEP) and (2.3% for PCP) at a distance of around two times the penetration depth (50 m) for all embedded depths. Varied properties like stiffness, density, and damping in different soils can influence the propagation of vibrations differently. Nonetheless, as the distance from the vibration source increases, the impact of soil properties may diminish, and the vibrations tend to homogenize. Consequently, the statistical analyses yielded empirical equations that can be used for estimating vibrations in scenarios involving similar pile and hammer characteristics within comparable site conditions.