Evaluating soil setup after open metallic pile driving

Abstract

After driving a pile, foundation soil is restructured and thus regains part of its resistance. This phenomenon is aptly named soil setup. This paper’s focus is to study said phenomenon on eight open metal piles driven in a soil composed of sand and marl, while basing our findings on data of dynamic PDA tests processed with CAPWAP software. Firstly, dynamic tests performed after driving phase and at subsequent re-driving phases show an increase in both the required number of blows for a 10-centimeter drive and in the static resistance to re-driving. The correlations of these resistances with the predictions of the models of Skov & Denver (1988) and Svinkin & Skov (2000) were not satisfactory (R2 of 0.77 and 0.75 respectively). Noting that the setup is mainly due to the increase in friction, a layer-by-layer analysis is carried out by treating the sand and the marl separately. Attained results fit well the Skov & Denver model and align with the experimental results of Murad (2014), but given the model’s limitations in terms of reference time determination, we develop a new function model potency considering immediate setup. The new model fits our attained results very well (R2 of 0.944 for sand and 0.980 for marl). The final static strength after setup is thus calculated as a function of time based on the power function model and conservative estimates. This approach encourages allowing time for the soil to gradually and naturally scar instead of rushing into immediate and costly measures such as patching.