LIQUEFACT PILOT SITE AT THE GREATER LISBON AREA: PRELIMINARY MICROZONATION OF LIQUEFACTION SUSCEPTIBILITY

Earthquake-induced liquefaction is a subject of great relevance since it can be the cause of great structural damage, economic and human losses, resulting from a seismic event. As part of the European project H2020 LIQUEFACT, an area was selected for the first experimental pilot field located in the Lezíria Grande of Vila Franca de Xira, located in the region of Greater Lisbon. A vast amount of information, historical data and geological-geotechnical reports were collected in order to characterize the studied area, namely in terms of the susceptibility to liquefaction. The data collected was complemented by an extensive field testing campaign carried out under the project, including the collection of undisturbed samples for further study and characterization in the laboratory. The in situ tests included standard penetration tests (SPT), piezocone penetrometer (CPTu) tests, Marchetti dilatometer tests with seismic velocity measurement (SDMT) and geophysical tests, including seismic refraction and HVSR tests. The careful analysis of all these tests and their results, using the most recent methods to evaluate the susceptibility to liquefaction, allowed the definition of a preliminary microzoning of the area in relation to its liquefaction potential, based on the Factor of Safety against liquefaction (FSliq), Liquefaction Potential Index (LPI) and Liquefaction Severity Number (LSN). The present work intends to present this preliminary microzoning, as well as a summary of the objectives and contributions of the project to the evolution of the study of liquefaction in Portugal.