Abstract
The seriousness of the phenomenon of negative skin friction on piles penetrating Basrah soil in Iraq is investigated via the finite element method. The most common (0.285×0.285 m) precast driven and (0.8 m diameter) bored piles, are analyzed under the structural loads and down drag forces due to recent fill. A two-dimensional program adopting nonlinear constitutive relations for soil layers is utilized. The results revealed a great decrease in negative skin stress and pile length on which the phenomenon is to act upon, due to the application of structural loads. Reductions in drag forces as much as (86%) for driven piles and (96%) for bored piles are recorded in some sites. It is also concluded that, overlooking the negative skin friction does not result in failure and that more economical pile capacities could be adopted.
Highlights
Piles penetrating soft soils and resting on/into rock/dense sand are subject to loads in addition to the structural loads if the surrounding soil settles relatively to pile
The results revealed a great decrease in negative skin stress and pile length on which the phenomenon is to act upon, due to the application of structural loads
Comodromos and Bareka (2005) utilized a nonlinear three-dimensional finite element analysis to study the effects of negative friction on a single pile embedded in a layered soil system
Summary
Piles penetrating soft soils and resting on/into rock/dense sand are subject to loads in addition to the structural loads if the surrounding soil settles relatively to pile. The analysis was extended to investigate the combined effect of negative skin friction and the pile's working load application. It was realized that a considerable reduction in negative skin friction could be achieved when the construction of the embankment preceded the structural load application, compared to the reverse construction sequence. Constructing the embankment after structural load application produced a negative friction force of about (50%) of the working load whereas, the reverse scenario produced an additional load of around (10%) of the working load. Leung (2009) carried out an extensive experimental study by conducting centrifuge model tests at the National University of Singapore, to examine the behavior of single piles and pile groups subjected to simultaneous negative skin friction and working loads. It was demonstrated that the application of large structural loads neutralized the negative skin friction when soil settlement ceased under working conditions. It was demonstrated that the application of large structural loads neutralized the negative skin friction when soil settlement ceased under working conditions. Hong (2013) studied the negative skin friction on single piles
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
