Enhancing the seismic performance of highway embankments on soft soils: a comparative study of conventional and T-shaped deep cement mixing columns

Weak soils globally pose significant challenges in highway construction under seismic conditions, causing instability issues such as settlements and slope failures. This poses challenges for geotechnical engineers to design safe, effective, and economical construction methods for stable slopes. Despite the critical nature of embankment stability under dynamic conditions, there is a lack of research investigating the effects of foundation soil reinforcement in such scenarios. This paper aims to study the seismic behavior of two soil improvement techniques: conventional Deep Cement Mixing (DCM) columns and T-shaped Deep Cement Mixing (TDM) columns. A three-dimensional numerical model was used to investigate the dynamic behavior of DCM and TDM column-supported embankments using PLAXIS 3D software. After validating the numerical model, a parametric study was conducted to understand the seismic performance of embankments with DCM and TDM columns over soft soil. The obtained results demonstrate that, under seismic loading conditions, both DCM and TDM columns substantially enhance embankment stability. However, TDM columns exhibit superior performance, consistently achieving greater efficacy in mitigating settlement and controlling displacement compared to their DCM counterparts.