OPTIMIZATION PLAN OF REINFORCEMENT ON DEEP DREDGER FILL OF SOFT GROUND

Dredger fill of soft ground can't be put into engineering until foundation treatment is finished. Shallow foundation treatment such as vacuum preloading is generally utilized to improve the strength of foundation.But for a large area loading ground, shallow foundation treatment is not sufficient to ensure the stability of the foundation. Therefore, a deep foundation reinforcement is needed. Three plans of deep foundation reinforcement are the mixing pile foundation, micro-pile foundation and the mixture of the two piles. They are proposed after vacuum preloading treatment for the dredger fill of soft ground of the shipbuilding base in this paper. Besides, the finite element method software PLAXIS is utilized to simulate the proposed plans in the framework of the Biot's consolidation theory and the effective stress theory. Soft Soil Model based on the modified Cam-clay Model is selected for muck and mucky soil. Mohr-Coulomb Model is selected for sand, clay and silty clay. Linear elastic model and elastic model are respectively for mixing piles and micro piles. Settlements of different plans are obtained by the calculation. Further analysis on the different types of foundation reinforcement is made with different mechanism. For this deep dredger fill of soft ground, the mixing pile foundation is better than the micro-pile foundation with the same length in improving the ground strength. Additionally, settlements of mixing pile foundation with different lengths are calculated. The mixing pile foundation with the length from 10m to 15m can improve the ground strength. However, the effect is not improved obviously as the length increases. The results can provide some basis for the design of a deep dredger fill of soft ground reinforcement.