Numerical modelling of the effect of horizontal drains in centrifuge tests on soil-structure interaction in liquefiable soils

The research presented herein was carried out in the framework of the H2020 LIQUEFACT project (http://www.LIQUEFACT.eu/). This paper presents the results of a set of numerical analyses performed to study the soil-structure interaction in presence of a liquefiable soil. In the first part of the paper, the attention was focused on the ability of some advanced soil constitutive models to simulate the centrifuge tests carried out within the project. Two finite element codes, Plaxis 2D and OpenSees, were used for the computations. The results were analysed in terms of accelerations, displacements and pore pressures build up. In the second part of the paper the effects of the introduction of horizontal drains, as mitigation techniques against liquefaction, were shown and discussed in terms of their ability in reducing pore pressure build-up and building settlement. All the numerical predictions confirmed the experimental evidence that horizontal drains are able to reduce the excess pore pressure during shaking and the structural settlement. The amount of reduction depends on the water boundary condition at surface: a free seepage surface generally allowed a larger mitigation than where the liquefiable layer was topped by clay.