Adjustment of a numerical model for pore pressure generation during an earthquake

This article proposes methodology for evaluating the accuracy of the pore pressure generation model devised by Byrne, as implemented in a commercial software program using a Mohr-Coulomb-type failure criterion and a Finn constitutive model. The different empirical formulas of liquefaction developed by Seed and Idriss are reviewed, as well as various constitutive models specified in the literature, emphasizing the selection of the Finn model for the liquefaction study. In the analysis a comparison is carried out using the factors of safety against liquefaction (FSLs) devised by Seed and Idriss and the adapted formula by Boulanger and Idriss. The analysis assumes a hypothesis to verify whether a soil element is liquefied. The results are then compared with those of a numerical model that simulates a soil column, the base of which is subjected to the same seismic inputs of varying magnitudes, Mw, and peak ground accelerations, Pga, to which the empirical model was subjected. Adjusted equations are provided on the based on that comparison to allow for the calibration of the Byrne equation using the (N1)60 value obtained via a standard penetration test (SPT), for the study of liquefaction problems in situations in which there are earthquakes of varying magnitudes.