Abstract:
In the framework of a third Tagus River crossing, through an immersed tunnel, advanced
laboratory tests were performed on its highly liquefiable foundation sand, namely cyclic
undrained torsional tests. The Manzari-Dafalias model, which allows simulating liquefaction
on the Tagus River sand and is, therefore, central in the tunnel design, as well as the
numerical work to calibrate the model and identify its most relevant parameters, are
presented. Model parameters, their respective reference values and tests performed to
determine directly most of the parameters, are introduced. A parameter sensitivity analysis,
conducted through numerical simulation of triaxial monotonic drained tests and of cyclic
undrained torsional tests, implemented both for the pre-liquefaction and liquefaction phases,
is described. Finally, some parameters are determined by fitting the model to the laboratory
results.
