Laboratory and numerical based analysis of floating sand columns in clayey soil

Abstract

The inclusion of sand columns results in enhancing the bearing capacity of clayey soil, increase the rate of consolidation, presentation of liquefaction in loose sandy soils and provide lateral resistance against the horizontal movement. This research aims at investigating the effects of floating columns in clayey soil with silty deposits by developing small scale laboratory models. The effects of sand columns on soils of different shear strengths, slenderness ratio (L/D) of columns were investigated. Group effect was also investigated by varying spacing between the columns. Experimental results were compared with the numerical analysis results. A 15-noded triangular mesh was generated using a finite element tool PLAXIS 2D. Finite element analysis was performed using Mohr’s Coulomb’s criterion considering undrained analysis for soft clayey soil and drained analysis for sand columns. It was concluded that the sand columns can significantly increase the ultimate loading capacity of soft soils. Results show that critical length for floating column ranges from 4 to 5.5 times the diameter of the column, beyond which bulging occurs and loading capacity decreased. The effect of group was also investigated and observed that with high spacing between the sand columns, the group efficiency decreased. The axial capacity of sand columns decreases while increasing spacing between the columns.