Full-Scale Loading Test on Pre-bored Precast Pile with Enlarged Base in Shanghai

The pre-bored precast piling method is an efficient and environmental measure to construct precast piles to avoid squeezing effect, noise and vibration pollution. Although this pile has been increasingly used in China, the true ultimate bearing capacity and load transfer mechanism are still unclear. In this study, three full-scale ultimate static loading tests on instrumented pre-bored precast piles were conducted in Shanghai, China. The tests results indicated that the load-displacement curve increased slowly at the beginning, and tumbled sharply after reaching the ultimate resistance of the test piles. The pre-bored precast pile with enlarged base pertained to the type of typical end bearing friction pile. Axial force could be directly transferred to the pile toe at initial loading and the toe resistance accounted for about 25% of the pile capacity when applied ultimate load. It is concluded that the pre-bored precast pile with enlarged base in soft clay has a good axial bearing performance, and the ultimate static loading tests provide guidance and technical support for the theoretical research and engineering practice of these piles in Shanghai.