Most of liquefaction countermeasures for the grounds under airport pavements are constructed during service of the airport facilities. Therefore, liquefaction countermeasure methods which can be applied to the ground under airport pavements are limited because they have to be conducted under various restrictions. There are few applicable countermeasure methods in case of the soil restriction, for instance, against high fine content soil, near existing structures and/or under thin surface soil layer.
　The grid-type ground improvement method is subjected in this research. This is different in a mechanism preventing liquefaction, from the other countermeasure methods generally used for the ground under airport pavements. The grid-type improvement method can be applied to high fine content soil and ground near existing structures. Seismic behavior of the asphalt pavement applied the grid-type improvement is clarified to apply this method to airport pavements. In this paper shows results of model tests and numerical analyses conducted to evaluate influence of a grid interval and thickness of surface non-liquefiable soil layer and to propose deformation prediction method for practical uses.