Mobilized Response of Piles Subjected to Downdrag: Fid-Bau Portal

Mobilized Response of Piles Subjected to Downdrag

Ashour, Mohamed / Abbas, Aser

This paper presents a model that allows the evaluation of the mobilized response of piles subjected to downdrag and drag forces. The presented technique couples the soil and pile settlement profiles with the pile-mobilized skin friction and end-bearing resistance in an interactive model to determine the downdrag (pile settlement), load distribution along the pile length, and location of the neutral plane or transition zone. The load transfer (t–z and q–z) models employed in the current technique are constructed based on soil and pile properties, soil–pile interaction, and a constitutive soil model. The proposed model detects the variation of the neutral plane location with the increase of pile-head load up to the pile’s geotechnical limit. Additionally, the technique deals with superlong piles under downdrag forces and determines the mobilization of negative (downward) and positive (upward) skin friction with an increase of soil settlement and the effect of the pile’s end-bearing stiffness on developing drag forces. The proposed procedure is described in a detailed flowchart and validated through comparisons with long-term full-scale field tests conducted on piles subjected to negative skin friction.