Increase in SPT <i>N</i>‐Values Due to Displacement Piles

Abstract

A technique that was used to estimate the safety factor against liquefaction by predicting the increase in SPT N-values due to driving of displacement piles in sand is presented. The prediction method involved applying previously-developed relations between relative density, grain-size distribution, overconsolidation ratio, effective stress and N-values to evaluate the relative density of site sands prior to pile-driving. Similar relations were applied to calculate increased N-values from increased relative density due to volume displacement and lateral stress increase from pile-driving. The predicted N-values were subsequently verified by carefully-controlled field penetration testing.