Comparative Analysis of the Compression and Uplift Bearing Characteristics of PHC Pipe Pile on the Same Site

The analysis of single pile behavior is an important foundation for the analysis of group pile foundation and other complex pile foundations.

Based on the analysis of the load transfer of the compression pile and the uplift pile, the DoseResp model is used to fit the normalized load transfer function.

The results show that the load transfer function of the uplift pile and the compression pile has similar characteristics, the goodness of fit of the DoseResp model to the test data is greater than 0.99, which can better reflect the load transfer law of the pile. The fitting parameters in the DoseResp model mainly depend on the end resistance sharing ratio, A₂ (Top asymptote)is independent of pile type and soil property parameters and is close to 1. The DoseResp model is applied to the PHC pipe pile, and the method to determine the parameters of the model fitting is proposed, which can accurately determine the side resistance distribution of PHC compression and uplift pipe pile along the pile body. Under the same load, the amount of uplift on the top of the uplift pile is significantly greater than the settlement on the top of the compression pile.

The end resistance sharing ratio of the compression pile and the uplift pile is between 5.76 and 12.80. The ultimate bearing capacity of the compression pile is 3.61 ~ 3.81 times of that of the uplift pile under the same geometric parameters.