Numerical Modelling of Reinforced Stone Columns and Bamboo Mattress for Supporting Causeway Embankment on Soft Soil Bed

Abstract

This paper presents numerical model of reinforcement of causeway embankment over soft soil deposit using bamboo grid mattress and stone columns. A series of experimental tests were undertaken to obtain several mechanical parameters of stone columns, and mechanical characteristics of bamboo grid. The soft soil is silty clay in deep layer in which its index and engineering properties derived from oedometer tests. FEM model of a causeway embankment over bamboo grid mattress overlying deep soft soil reinforced by a group of granular columns encased with geotextile, was developed. To validate the FEM model, full scale experimental of similar model was conducted. It was found that FEM model is well agreement with the experimental model. The result explains the stress-strain behavior in bamboo grid mattress and stone columns, interacted with the soft soil as response to increasing embankment height. Bamboo grid mattress enhances the bearing capacity of the soft soil in supporting embankment leading to the decrease of settlements, while stone columns affect the acceleration of consolidation of the soft soil. The results would be beneficial for application of local natural materials such as bamboo for soft soil reinforcement as bamboo is widely available in developing Asian countries.