Modeling on pile-tip performance in sandy soils

Based on the spherical cavity expansion solution developed by Vesic(1972),a model was proposed for the analysis of long piles embedded in sandy soils.Unlike the Vesic’s model,the reduction of strength under high stress and the increase of strength under high density were both taken into account in the tip present model.The strength parameters could be derived from the effecitive overburden pressure and SPT-N value at the pile tip.The mean volumetric strain in the plastic zone was determined analytically by adopting the finite strain theory,and therefore,it was no longer necessary to estimate such strain from laboratory test results.By incorporating the energy conservation principle,the model was further extended to allow prediction of the load-settlement behavior of piles.The accuracy of the model was assessed by using two case histories.It had been demonstrated that the present model could provide fairly accurate prediction of the end-bearing capacity and the settlement of long piles.