HAMADA MASANORI - Professor, Tokai University, Shizuoka, Japan

Liquefaction-Induced permanent ground displacement and it's caused damage to in-ground structures such as foundation piles and buried pipes during ۱۹۶۴ Niigata and ۱۹۸۳ Nihonkai-Chubu earthquakes were surveyed. The permanent ground displacements were measured by aerial photographs taken before and after the earthquakes. The maximum gro and displacement reached over ۵' m in Noshiro City during the NihonkaiLChubu earthquake as well as over ۱۰ m in Niigata City during the Niigata earthquake. These large ground displacements caused severe damage to in-ground structures. It was found that all foundation RC piles of diameter ۳۵ cm had been broken in Niigata City ۲۵ years after the earthquake when the building was reconstructed. The causal relationship between the ground displacements and the damage to piles was studied by numerical simulations