Model shaking table test on the damage to pile foundation in earthquake-induced lateral flow of ground with non-liquefied surface layer

Several types of structures may suffered from liquefaction associated structural damage in destructive earthquakes. Since the flow slide of liquefied ground sometimes induces extraordinary thrust to underground structures, pile foundations for bridges and buildings and pipeline networks have been severely damaged. The aim of this study is to investigate the mechanism of the damage to structural pile foundation induced by the flow slide of liquefied ground, and a series of model tests were conducted. Three types of model sloping ground with a pile foundation were shook on the shaking table. In the standard case the sloping ground with a surface non-liquefaction layer was prepared; the flat ground with surface non-liquefaction layer and the sloping ground without non-liquefaction layer were also prepared. The vibration behaviors of the ground and pile foundation were observed and the thrust on the pile foundation from the liquefied ground were monitored through the measurement of bending moment along a pile. As a result of comparative examination of the observed behaviors, the significant combined effect of surface non-liquefaction layer and flow slide of liquefied ground on the damage to pile foundation was clarified.