Analysis of Bearing Capacity of Pile Foundation under Cyclic Tensile Load

Pile foundations are commonly employed as load-bearing structures in loess regions. This study sought to investigate the bearing capacity characteristics of cyclic uplift piles in the northwest region by conducting on-site model tests. These tests examined the axial displacement and lateral friction performance of uplift piles under three different working conditions and varying cyclic loads. The findings revealed that the axial displacement at the pile top during pile failure under cyclic loading was merely 30% of that observed under conventional loading. There exists a significant relationship between the axial displacement at the pile top and the bearing capacity of the pile foundation. During the loading-unloading process, the pile-soil interaction leads to yield as the number of cycles increases, signifying repeated shear between the pile and soil. While the decline in frictional resistance strength of each layer in conventional pile foundation tests typically manifests during the ultimate load stage, this weakening is observed during the cyclic process prior to reaching the ultimate load in cyclic loading conditions. These insights can inform the application of pile foundations.