Influence of Load Transfer Platforms on the Performance of Embankments on Soft Soils Reinforced with Stone and DCM Columns
摘要
The embankments constructed for highways, railways, airfields, etc., resting on soft soils, are often reinforced with columns to restrict total and differential settlements. The performance of columns in soft soil can be enhanced further by providing a load transfer platform (LTP) at the embankment base. The provision of LTP prevents the punching of columns, increases column spacing, and enhances soil arching. In this study, the performance of geogrid and soil cement mixed (SCM) as LTPs and their compatibility with stone and deep cement mixing (DCM) columns was assessed. The present study was validated and compared with the previous literature on numerical modeling and large-scale studies from the case history. The responses were expressed in terms of the maximum settlement, settlement at the center, stresses at the stone or DCM column and soft soil, variation of stresses along the depth of the columns, and lateral displacement at the toe. Further, the significance of LTPs was evaluated by analyzing parameters such as stress concentration ratio (SCR), settlement ratio, and lateral displacement ratio. The stone or DCM columns with SCM LTP were more effective in restricting the maximum settlement and lateral displacement. The maximum settlement and lateral displacement at the toe for the stone columns with SCM LTP were reduced by 11.3% and 65%, respectively, while for the DCM columns, the reduction in maximum settlement and lateral displacement at the toe were 29.5% and 76%, respectively. The SCR for the soft soil reinforced with stone and DCM columns with SCM LTPs at the base were 1.7 and 5.5, respectively. The use of geogrid at the base with stone columns is more effective than the DCM columns as LTP for increasing the stresses at the columns compared to the isolated columns.