Numerical simulations of liquefaction phenomena after Emilia Romagna (20 May 2012) earthquake.

Soil liquefaction has been observed worldwide during earthquakes with induced effects responsible for damage, disruption of function and considerable replacement expenses for structures. The May 20, 2012 M5.9 shock in Emilia Romagna (Italy), is one example of moderate earthquakes yielding extensive liquefaction-related phenomena. The paper provides an attempt to simulate the observed ground effects using a finite element (FE) approach. The study adopts a FE computational interface (OPENSEES PL) implemented in OpenSees and able to analyze the earthquake-induced threedimensional pore pressure generation. Credited non-linear theories are applied in order to take into account appropriate flow rules as to reproduce the observed strong dilation tendency and resulting increase in cyclic shear stiffness and strength. The interface simplifies the 3D spatial soil domain, boundary conditions and input seismic excitation definition with convenient post-processing and graphical visualization of analysis results including deformed ground response time histories. The possibility to simulate wave propagation adopting realistic boundaries is of particular importance and significance in order to realistically reproduce liquefaction behaviour.