Prediction of non-linear soil behaviour in saturated sand: A loosely coupled approach for 1d effective stress analysis

Since the catastrophic failures due to soil liquefaction occurred during Niigata (Japan) and Good Friday (Alaska) 1964 earthquakes, increasing efforts have been devoted to the understanding and modelling the phenomenon as well as to the development of effective methods for predicting non-linear soil behaviour at large strains. In this paper, a simplified constitutive model, implemented in a one-dimensional code, is proposed, following a loosely coupled approach. The most important advantage of the adopted approach is that it is at the same time easy to be applied as a semi-empirical method and reliable as an advanced constitutive model. The performances of the proposed procedure, are validated on a well-documented test-site in the north-east of Japan where acceleration records along a vertical array are available. The site was chosen because its geological soil configuration is essentially 1D and detailed site and laboratory investigation are available. Both the accuracy and effectiveness of the procedure are assessed by comparing calculated predictions and field records, in terms of acceleration time histories and spectral accelerations at surface. Moreover, the results of the above simulations were compared with those obtained carrying out total stress analyses and several constitutive models, showing the importance of a coupled approach for a reliable prediction of seismic response of saturated sand.