Pile Installation Effect on Dynamic p-y Curves in Dry Sand

摘要

The p-y method, which can account for the non-linear behavior of soil, is widely used for modeling pile foundations under dynamic loads in pseudo-static analysis. Recently, Yang et. al. (2009) suggested the dynamic backbone curve for sand based on the 1g shaking table tests. However, the suggested p-y curve did not factor in the confining stress effect of a prototype and the pile installation effect on the p-y curve. Despite the importance of soil-pile interaction, no studies have been carried out on the pile installation effect on dynamic p-y curves during earthquakes. In this study, dynamic centrifuge tests with different types of piles in dry sand, pre-installed pile, a 1g jacked pile and a 40g jacked pile, were carried out in order to analyze the effect of pile installation on the dynamic p-y backbone curve. From the tests results, the modulus of subgrade reaction of the 40g jacked pile and 1g jacked pile were 164% and 56% greater, respectively, than that of the pre-installed pile at 0.5D (D: pile diameter) depth. Moreover, it was also found that the modulus of subgrade reaction of the 40g jacked pile and 1g jacked pile was 52% and 12% greater than that of the pre-installed pile at 2D depth. The installation effect was shown to be within less than the depth at 3D.