EFFECT OF DOWNDRAG ON FLOATING AND END BEARING PILES

摘要

Negative skin friction is a long term, and nonlinear time dependent problem which cannot be investigated only through field measurements. Numerical analysis using finite element method provides a powerful tool that enables more detailed study of negative skin friction on piles in soft clay. In this paper, an axisymmetric finite element model was used to analyze the pile-soil interaction problem of negative skin friction. The soft clay was simulated by the double hardening model, and the pile was represented by a plate element. An extensive parametric study was carried out to investigate the effect of different factors on the behavior of a floating pile subjected to downdrag. The studied parameters are: surcharge value, surcharge radius, and clearance between pile toe and a stiff stratum. Also, a comparison between the effect of negative skin friction on both end bearing, and floating piles was carried out. The comparison incorporated the following points: shear stress distribution along pile, neutral plane location, dragload, and pile movement.