Single Pile Dynamic Characteristics Under Unidirectional And Bidirectional Cyclic Loading

The force analysis of pile foundations under the effect of dynamic load is quite complicated, especially when pile foundations subjected to biaxial dynamic load, the rapid development of our high-speed rails, highways and high-rise buildings in recent years requires better and better pile foundation projects. In addition, the disastrous consequences of the previous earthquakes also make us have a comprehensive understanding of the seismic performance of pile foundation, domestic and overseas scholars are seeking more secure and reliable design methods of pile foundation.This paper was wrote on the basis of the comprehensive analysis of domestic and overseas related literatures, combined with the laboratory model experiments, Ansys numerical analysis and other primary means, studied the mechanism of single pile under horizontal, vertical, horizontal and vertical two-way cyclic loading, and discussed the effects of one-way load and bi-directional load on pile traits. The analyzed results show that for sandy soil:First, under the effect of horizontal cyclic loading, the horizontal ultimate bearing capacity will decrease; the maximum bending moment pile has increased. Under the effect of vertical cyclic loading, cycles times will lead the vertical bearing capacity of pile body decrease. Under the effect of two-way cyclic loading, the horizontal ultimate load of pilebolck, bending moment and axial force of pile body has increased compared to uniaxial loading, and the maximum bending moment point of pile body go down along pile body.Second, the results of contact elements selected by the paper have certain disparities with test results, especially under the circumstance of high displacement, some results are distorted. From the results of numerical simulation, the distribution laws of pile body horizontal displacement, pile body stress and pile top P-S curve are relatively close to test results, but they are still different, this is because the numerical model contains the nonlinear of soil material and contact elements, which proved that numerical analysis has some defects when deal with pile-soil nonlinear.