Laboratory Testing and Numerical Modelling of the Dynamic Behaviour of Tagus River Sand

Abstract

In this paper, an immersed tunnel case-study, corresponding to a third Tagus river crossing, supported on liquefiable alluvial sands, is presented. Laboratory testing, namely monotonic drained triaxial tests and cyclic undrained torsional tests, is described. Moreover, a constitutive model, as well as the numerical work, essential to its calibration and to 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, is defined. Furthermore, a parameter sensitivity analysis through numerical simulation 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.