Experimental investigation on a single stiff pile subjected to long-term axial cyclic loading

Stiff pile-supported low embankments have been widely adopted in high-speed railway lines in China. Large-scale model tests are carried out to investigate the response of a single stiff pile subjected to axial dynamic loading in silts. Tests are conducted by means of the large foundation and slope engineering simulation system in Zhejiang University. Various combinations of static and cyclic loadings are applied in tests. The pile used in the tests are instrumented with load cells, pore pressure probes and pressure cells. The accumulated settlement, axial force, pore pressure and radial total stress along the pile are monitored. The test results indicate that the cyclic loading causes soil particle rearrangement, which leads to a change in stress state at soil-pile interface. The accumulated settlement and stresses acting on pile shaft are greatly influenced by the cyclic loading ratio (CLR). The development of the accumulated settlement with different CLRs is summarized and presented. The possible mechanisms responsible for stress changes at soil-pile interface are discussed.