Geogrid Reinforcement Cushion for Special Ground Treatment

Two multi-story buildings are built at soft ground conditions. PHC pipe pile foundation is proposed in the original design. The installation of PHC pipe piles are blocked by boulders and strip stone foundation of the old port relic. After further investigation and study, an alternative design using of Deep Cement Mixing Columns with geogrid reinforced underlying layer was proposed to replace the PHC pipe piles. One of the two buildings is constructed. The plat loading test and settlement monitoring results show that the bearing capacity of the composite foundation and the building settlements satisfy the design criteria and specifications. Comparing to original design, the alternative design is more cost-effective.