| Popis: |
Construction of bridge approach embankment in soft ground experiences soil settlement due to different support condition of the approach embankment and the abutment. At the bridge-embankment transition zone, this difference will result in formation of bump at the bridge end. Hence, the present study focuses on developing and efficient foundation system that can minimize the bump at the bridge end. Ground improvement techniques using composite piles can be adopted to improve the soft ground. A series of numerical analysis is carried out to compare embankment system without and with composite pile made of cement-fly ash-gravel (CFG) and lime in reducing settlement. The analysis results show that settlement at the transition zone is reduced by 45% when composite piles are used as ground improvement. Performance analysis of CFG and lime pile shows that the stress carrying capacity of CFG piles is higher than lime piles. Meanwhile, the parametric study results show that pile spacing of 6 times diameter, pile length of 25 times diameter and sand as cushion material are the most optimum design parameters that can effectively smooth the bridge-embankment transition zone. Further, the effect of constant and varying pile length in the foundation system is studied. It is observed that varying length piles reduce soil settlement by approximately 25% compared to constant length piles. |
