3-D seismic response of liquefaction-susceptible improved-soil deposits
Numerous earthquakes occurring over the last five decades have illustrated the significant hazards posed by soil liquefaction. Recent observations have also illustrated the potential hazard mitigation that can be achieved by reducing soil liquefaction potential via ground improvement technologies. Despite these observations, there remain many challenges in ground improvement, both in innovative improvement technologies themselves, and also in prediction of the seismic performance of improved soil deposits. This paper presents the results of an investigation into the seismic response of liquefiable soil deposits which utilize various configurations of soil improvement using seismic effective stress analysis. The particular problem considered is based on the soil stratigraphy of the downhole seismic array at Port Island, Kobe, and the input ground motion used is that which was recorded at this location in the great 1995 Kobe earthquake. Firstly we compare the observed ground motion during the 1995 Kobe earthquake with those obtained based on 1 dimensional (1-D) analysis. Secondly, we present the salient results of 3-D finite element analyses using various soil improvement configurations. Finally, comparison is made of the results of the set of analyses as a function of improvement area ratio in an effort to identify which types of improvement configuration is most effective at mitigating the consequences of soil liquefaction.