Liquefaction characteristics of coarse silt-graded A50 silica flour

Centrifuge modelling is used for testing physical scale models under increased gravitational acceleration, in order to match model stresses to a model prototype. In geotechnical centrifuge testing, the model is usually prepared by the same soil as the prototype. However, the latter cannot always be supported in cases where particle size play a role. Thus, the used soil must be scaled down but, at the same time, behave as the prototype soil during shaking. This paper shows that silt – graded materials can be liquefiable and hence usable as a model material for liquefaction centrifuge testing. The soil chosen for further investigation was coarse silt A50 Silica. Since many case studies support that silts could be liquefiable, the sample was examined in the lab to determine its main mechanical and geotechnical properties. Liquid limit value was found within a range that could show preliminary signs of soil liquefiability. Moreover, cycling simple shear tests were performed which clearly showed a contractive behaviour of the coarse silt during shearing. Finally, the fine material was tested in the geotechnical centrifuge of Dundee University. Pore pressure rise was observed, in addition to soil densification which confirms that the coarse silt is a liquefiable soil and thus suitable for modelling coarser prototypes.