Design and analyses of floating stone columns

Two-dimensional (2D) finite element analyses were performed on floating stone columns using the unit cell concept to investigate the settlement and the consolidation characteristics of an improved foundation system. Undrained analyses, followed by consolidation analyses, were conducted throughout the study. The computed values for settlement and excess pore pressure distribution over time are compared for different area replacement ratios. Based on these coupled consolidation analyses, a simple approximate method is developed to predict the degree of consolidation for floating stone columns. In addition, a simple method to calculate the settlement improvement factor for floating columns is proposed. The proposed method may provide more realistic answers than other design methods in view of the yielding characteristics and the influence of key parameters that are considered in the analyses. The key parameters relevant to the design of floating stone columns include the area replacement ratio, the friction angle of the column material, the loading intensity, and the post-installation earth pressure. Closer agreements are obtained with the proposed method than with the established Priebe׳s method or α–β method.