Abstract: Based on the connecting line project of Zhoushan Island-Mainland Link Project, the experiment of a friction pile was developed to study the application of self-balanced test method in soft strata,and it was verified with the traditional piling-up weights method. The paper introduced the whole process and design points of the method in design, field test and data analysis stage. And an improved method for the use to measure the displacements of the upper and lower shaft was put forword. This new method can avoid the influence of the latent concrete defect in the cell position. The coefficient of negative skin friction in soft strata and the bearing capacity of the test pile was also measured in the experiment. The test results fit the designed requirements, while the bearing capacity of the test pile also meet the designed requirements. This design and the coefficient can be a reference for the soft strata, and the self-balanced test method has its rationality and accuracy in engineering application.

Key words: self-balanced test method, soft strata in the coastal area, bearing capacity of the test pile, experimental study