Behaviour of soft ground improved by conventional and geogrid-encased stone columns, based on FEM study

Abstract

ABSTRACT: Construction of embankments on soft natural soil may be a challenge, owing to its low shear strength and high compressibility. Stone columns, which depend on lateral support from the soft ground, have been utilised to accelerate foundation consolidation, and to increase foundation bearing capacity. To keep the drainage function, and to improve the stone columns as reinforcing elements, geosynthetics are used for column encasement. In this research, the behaviour of full-scale unreinforced and reinforced Bremerhaven clay with conventional and geogrid-encased stone columns under embankment loads is analysed numerically. The consolidation analysis is applied to investigate the long-term behaviour of the clay. The results show that the stone columns in the Bremerhaven clay increase the bearing capacity and accelerate the reduction of excess pore water pressure of the foundation. Once the stone columns are encased, more improvement occurs in their performance in soft soil. The analyses also indicate that stress concentration generation in the stone columns contributes significantly to the acceleration of soil consolidation.