Laboratory Studies on Soft Clay Improved by Floating Stone Columns

To have construction on soft soil, it is essential to apply proper ground improvement technique owing to low bearing capacity and high compressibility of soft clay. Among the available techniques, vibro-replacement also called as Stone Column technique is widely used. However, to determine the improvement of soft clay improved with floating stone columns, a load transfer mechanism needs to be explored among soft clay and column. The load-bearing capacity of column is function of lateral resistance provided by adjacent soft clay. When load is applied, it is anticipated that shear strength of soil will get mobilized, because of rigid walls of unit cell this may not happen. This study presents a laboratory investigation of unit cell studies on floating stone columns considering three different loading cases, viz., only column area, complete unit cell, and whole column with partial soil. The study highlights the whole column area loading with partial clay area is the appropriate method to investigate the performance of ground improved with stone column. Additionally, the effect of preloading is also studied in minimizing the post-construction settlement. Because of the preloading, soil state gets shifted to over consolidated state, and plastic strains gets developed. Preloading offers the increased lateral resistance of soft clay to the stone column.