Analytical approach to predicting pile self-weight penetration, considering penetration rate effects

Abstract

As offshore pile foundations increase in diameter and weight, the risk of uncontrolled and unsafe penetration events (pile run) also increases. Traditional approaches to evaluating this risk rely on static resistance to driving (SRD) formulations, equating the SRD to the effective weight of the pile. However, high penetration speeds during uncontrolled pile penetration can lead to a soil response much different to static conditions, particularly with regards to pore pressure dissipation around the pile. With this in mind, the paper proposes an analytical model for determining when uncontrolled penetration may occur and its extent. The model integrates novel SRD formulations with a penetration rate effect model, both of which are derived from cone penetration test (CPT) measurements. The model's predictions were then benchmarked against industry-standard methods using a database of self-weight penetration events in clays and sands of varying densities and strengths. The predicted self-weight penetrations compared well with field observations across the full range of soil conditions and gave a better performance compared to standard prediction methods. Furthermore, the results emphasise the critical role of soil volumetric behaviour during shearing and future research should clarify the influence of rapid penetration on the pile's shaft and base resistance.