ANALYSIS OF THE DAMAGE TO THE PILE FOUNDATION OF A HIGHWAY BRIDGE CAUSED BY SOIL LIQUEFACTION AND ITS LATERAL SPREAD DUE TO THE 1995 GREAT HANSHIN EARTHQUAKE

摘要

The damage to the pile foundation of a bridge on the Hanshin Expressway caused by the 1995 Great Hanshin Earthquake was studied, and the cause of the damage was examined by means of the three dimensional finite element method taking into account soil liquefaction and the lateral spreading of the liquefied soil. A pier of the bridge moved about one meter laterally toward the river; the revetment moved about three meters laterally in the same direction and subsided by more than one meter. It was determined by the analyses that the damage was mainly caused by the inertial force of the superstructure and the ground motion during the earthquake, and the damage was expanded by the lateral spreading of the liquefied soil which occurred in succession after the main shock, causing large residual deformation to the piles. Remedial measures involving the adoption of sand-compaction piles or steel-pipe-sheet piles were investigated in order to assess analytically the level to which the damage could be mitigated. The steel-pipe-sheet piles constructed between the foundation of the pier and the quay wall can withstand strong motion, liquefaction, and the lateral spreading it induces.