Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Stress level


Effect of Stress Level on Behavior of Bored Piles Embedded in Medium Sandy Soil

Kais T. Shlash; Mohammad A. Al-Neam; Saif I. Akoobi

Engineering and Technology Journal, 2013, Volume 31, Issue 19, Pages 29-43

In this paper investigation in the end bearing and shaft resistance of bored piles embedded in medium sand and subjected to axial load for wide rang of stress levels starting from laboratory dimensions and go toward field dimensions were made by utilizing the finite element method. The soil is modeled using hyperbolic soil model with empirical equation account for reduction of angle of internal friction Ø with increase in stress level while the bored pile assumed as a linear elastic material. It was found that the stress level has a significant effect on pile’s behavior and the small scale model in laboratory dimension not represent the real behavior of pile in field dimensions and if the results from such dimensions are adopted, it will lead to overestimate of bearing capacity factor Nq. Also, the effect of embedment ratio (L/D) on pile’s behavior is examined in this study and the results showed that the embedment ratio (L/D) increases the bearing capacity factor Nq up to a certain length beyond it the effect of embedment ratio (L/D) diminished.

Effect of Stress Level of Surrounding Soil on Bored Pile Capacity in Sand

Kais T. Shlash; Mohammed A. Mahmoud; Saif I. Akoobi

Engineering and Technology Journal, 2013, Volume 31, Issue 15, Pages 2839-2859

This study deals with assessing the effect of stress level on bearing capacity
factor , distribution of shear stresses at soil-pile interface along pile shaft, and
presence of critical depth concept for bored piles axially loaded in compression and
embedded in dense sand. These investigations are made using finite element method
with the employment of a wide range of stresses by using piles with dimensions
starting from laboratory dimensions and goes towards field dimensions with
embedment ratio range from (15-40). The soil and the interface behavior is
modeled using Duncan-Chang hyperbolic soil model with empirical equations
account for reduction of angle of internal friction ø with increasing in stress level.
Bored pile is modeled as a linear elastic material. The results showed a dramatic
decrease in bearing capacity factor as length of pile increase. It was also found
that the embedment ratio has a significant effect in increasing bearing capacity
factor , and the distribution of shear stresses at soil-pile interface is not linear and
does not tend to take a constant value beyond a certain depth of pile nor decreases
after a certain depth along pile shaft. The fallacy of critical depth also noticed and
discussed in this paper.