Coupled influence of geosynthetic reinforcement and column configuration on failure dynamics in deep mixed columns under embankment loading

Abstract

The design of column-supported embankments requires a comprehensive evaluation of overall stability and failure mechanisms. Previous research has investigated stress characteristics and failure modes of deep mixing (DM) columns under embankment loads. Depending on column configurations, those near the embankment toe experience flexural potential bending or tilting failure, while those closer to the centre are prone to shear failure. As column spacing decreases, a shift from bending to tilting failure occurs. Inadequate column bending capacity increases the risk of tilting-induced embankment collapse. This study initially showcases the efficacy of geosynthetics in mitigating tilting failure in columns with smaller spacings. The interaction between geosynthetics and diverse configurations on the failure mechanisms of DM columns is meticulously examined. A crucial shift in the failure mechanism from tilting to bending is facilitated by the application of conventional geosynthetics with tensile stiffness, particularly in scenarios with restricted spacing. Geosynthetics effectively mitigate lateral soil displacement, enhance column bending capacity, and intricately redistribute lateral pressures exerted on the columns. Ultimate load, shear strain, and stress are analysed both with and without geosynthetics. Lastly, the influence of geosynthetics on soil reaction distribution and internal forces within columns is deliberated.