Seismic Liquefaction Potential Assessment by Means of Automated Numerical Modelling

Abstract

The state of the practice to evaluate the seismic liquefaction potential of a soil column entails the use of semiem-pirical methods that compare the cyclic stress ratio (𝐢𝑆𝑅) with the cyclic resistance ratio (𝐢𝑅𝑅). These methods are useful in practice because they are calibrated from limited real liquefaction cases, and are routinely employed although there is limited insight in the fundamentals behind them. 

In this work, an extensive numerical modelling exercise is performed to determine which are the main aspects of the soil and the earthquakes that control the liquefaction phenomenon and understand why these methods work so well. 

A total of 6500 realizations of a soil column are performed, using the PM4Sand constitutive model implemented in Plaxis 2D. Real ground records are propagated through layers of liquefiable and non-liquefiable soils, and the results are compared with conventional linear and equivalent-linear site response analyses. 

The results from both analyses are compared in terms of 𝑃𝐺𝐴 and 𝐢𝑆𝑅 at the liquefiable layer. Finally, a discussion is presented regarding the predictive capabilities of the simplified methods and the value added by modern numerical modelling of soil liquefaction.