A three-dimensional finite element seepage-coupling numerical modeling is performed on a 6m thick soft foundation reinforced by geosynthetic-encasement stone column (GESC) with diameter of 0.8 m. The load transfer mechanism and deformation characteristics of GESC composite foundation subjected to vertical loading and excess pore pressure dissipation are analyzed using the numerical model. Compared to conventional stone column (CSC) composite foundation

the stress concentration ratio (SCR) in GESC composite foundation apparently increases while the excess pore pressure

settlement and column shaft bulging apparently decrease. The performance of GESC is further improved with an increase of geosynthetic stiffness. An apparent differential settlement between column and surrounding soil emerges to form a soil arching during consolidation of the surrounding soil

which leads to little change in SCR values after loading. Reinforcement length is found to have a significant influence on SCR and settlement in GESC composite foundation. Full length reinforcement is required for GESCs in composite foundation to assure their entire stiffness and less settlement.