Liquefaction evaluation in stratified soils

The Canterbury Earthquake Sequence of 2010-2011 (CES) induced widespread liquefaction in many parts of Christchurch city. 55 case history sites around Christchurch have been studied to assess the liquefaction characteristics of Christchurch soils. Initial studies identified a correlation between soil stratification and liquefaction manifestation during the CES. Furthermore, comparisons with the simplified method show an under-prediction of liquefaction at sites that manifested liquefaction and an over-prediction at sites that did not. To further investigate these observations, an effective stress analysis was employed to study the effect of soil stratification on the development and manifestation of liquefaction, and to investigate the impact that neglecting these effects has on the predictive capabilities of current simplified methods. The analysis showed that the system response of soil deposits (i.e. the dynamic interaction between soil layers) is a key component in the development and manifestation of liquefaction.