The liquefaction phenomenon is usually accompanied by a large amount of settlement. Based on the observations made in past earthquakes, ground improvement by densification is one of the most useful approaches to reduce the liquefaction-induced settlement. Currently, there is no analytical
solution for evaluation of the amount of settlement and tilting of footings that are constructed on densified ground surrounded by liquefiable soil. A number of factors, such as underlying soil properties, dimensions of the footing and earthquake loading characteristics, cause the problem to become complicated. In this paper, the dynamic response of shallow foundations on both liquefiable and non-liquefiable (densified) soils is studied using a 3D fully-coupled dynamic analysis. A well-calibrated critical state two-surface plasticity model has been used in the numerical analysis, which is capable of accounting for the volumetric/shear response of the soil skeleton at a wide range of densities (void ratios) and confining pressures. The OpenSEES platform is used to conduct the numerical simulations. The proposed numerical model has been applied in simulating a series of centrifuge experiments. Comparison of the numerical results and the centrifuge experiment measurements reveals that the numerical model is capable of capturing the important aspects of the dynamic response of footings on liquefiable and densified subsoils, and can be
used as a valuable tool for investigating the amount of liquefaction-induced settlement, tilting of footings and their reduction due to densification.