SETTLEMENT OF PILED FOUNDATIONS

A numerical code for the prediction of the settlement of pile groups a nd piled rafts is presented. The code is based on the interaction fact ors method; the non-linearity is simulated as suggested by Caputo and Viggiani, that is, concentrating it at the pile-soil interface. In the linear range, the accuracy is checked against known benchmark solutio ns. A standard procedure, based on the results of load tests on single piles, is suggested for the evaluation of soil properties and for the implementation of the analysis in real cases. Nineteen well-documente d case histories are then analysed, calculating for each of them a lin ear elastic, an equivalent linear elastic and a non-linear solution. F ive out of the 19 cases are illustrated in some detail, to allow a dee per insight into the procedure. In all but one of the analysed cases t he predicted values of the average settlement are within +/-20% of the observed values. The maximum differential settlement is predicted wit h slightly lesser accuracy. For foundations characterized by a relativ ely high safety factor, linear and non-linear analyses are essentially equivalent. Some evidence suggests that the low-strain shear modulus, obtained by in situ shear wave velocity measurements, can be successf ully employed in the prediction of the settlement. When the safety fac tor is low, the consideration of nonlinearity becomes mandatory.