Undrained loading and collapse of unsaturated soils during centrifuge testing. An experimental and numerical study

The paper presents the results of a centrifuge model of a shallow foundation relying of a layer of unsaturated soil and submitted to axial load for different water level. The objective of the work was to represent a foundation of 1.5 m in diameter on a 15 m soil layer. The model of foundation was a circular disk of 30 mm in diameter and the layer was a cylindrical container of 300 mm in diameter and height. In order to maintain similitude between prototype and model the tests were carried out at 50g. The tests were carried out at the LCPC facilities in Nantes (France). The tested material is an eolian silt from Jossigny, East of Paris. In order to decide the initial conditions of the model in terms of water content and void ratio it was performed a preliminary laboratory investigations. As the intention of the study was to examine the behaviour of a collapsible soil therefore it was decided to prepare the model with a low dry density (14.5 kN/m3 ). The evolution of pore water pressure during the tests are compared with the numerical simulation of the prototype with code brigh