Seismic response and failure modes analysis of pile foundations in liquefiable soils using various design criteria

Pile foundations may fail by bending, shear forces and buckling etc., if soil surrounding the pile liquefies during earthquake. In this paper, a detailed 3D numerical model was developed based on the Showa Bridge that collapsed during the Niigata earthquake, estimations have been made of the times that the Showa Bridge collapsed based on a soil and pile seismic response. Then, seismic design criteria of pile foundations corresponding to different failure modes are selected, it is found that the pile of Showa Bridge may have fail by buckling. Furthermore, the effects of the pile flexural rigidity, earthquake type, peak ground acceleration, and degree of soil layer liquefaction on the ground and pile response in liquefiable soil are examined. The peak bending moment of pile and pile top displacement increases with increasing degree of soil layer liquefaction. Finally, evaluates those criteria by comparing and contrasting the results in various conditions. Nonlinear discriminant methods considering the effect of pore pressure distribution can identify different failure modes with higher reliability compared to those obtained by linear theories., and suggested flowchart of evaluating bearing capacity of pile in liquefiable soils was purposed It is recommended that develop a more comprehensive theory of pile foundation failure discrimination.