Effect of stress level of surrounding soil on bored pile capacity in sand

Abstract EN

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.