Buckling Behavior of Piles in Liquefiable Soils

In the realistic manner، piles are similar to the slender columns that soil around them acts as a lateral support. The piles situated in the liquefiable soil layers، loss their lateral supports due to the liquefaction resulted from the seismic ground motion. In this case، pile has the potency of axial instability similar to the unsupported columns. This instability can lead to the lateral buckling of the piles in the eak direction and creating the plastic hinges in the pile’s badly. Many failures that acurr in the piles and their supported structures، due to the lique faction of soils after earthquakes has been reported. These piles ere designed based on the credictable codes such as JRA and NEHRP. So it seems that the behavior and analysis methods of piles are still unknown. This research attempts to predict the buckling capacity of the piles in layered liquefiable soils، using a numerical method in which Rayleigh-Ritz approach was employed to minimize total potential energy. Furthermore، a new practical approach has been presented to calculate effective buckling length of pile in liquefiable soils. By the means of this approach the buckling capacity of pile could be obtained while the stiffness of pile and soil are accessible. This method can be also applied to the extended pile shafts in the bridge piers