A p-y curve-based approach to analyze pile behavior in liquefied sand under different stress states

In general, p-y curves that represent the soil resisting force per unit length of pile as a function of soil displacement are used to model the interaction behavior of soil and pile. However, there are significant uncertainties about how to model soil-pile behavior in liquefied sand, especially for the different softening effect of liquefied soil under different states of soil-pile interaction. A new p-y model, which is capable of reflecting the dilative behavior of soil and the gap effect under different soil stress states, is presented in an attempt to develop a practical approach for soil-pile interaction behavior. This p-y model incorporates an upperbound p-y curve calculated from the improved p-multiplier and y-multiplier and a lower-bound p-y curve regarding the residual state of the soil-pile reaction in liquefied sand. Also, for the stress state between the two boundaries, the p-y curve can be approximately obtained from linear interpolation. The comparison between calculated results and the results of pile lateral-load test, which was taken in medium dense sand liquefied by blast load, indicate that the proposed p-y model provides reasonable estimates of response for piles in liquefied medium dense sand while pile-head displacements were less than 150 mm.