論文紹介清水建設が発表した論文をご紹介します。

Analysis of the Damage to the Pile Foundation of a Highway Bridge Due to the 1995 Great Hanshin Earthquake and Study of Effective Countermeasures

by Masaki Fuchimoto, Takashi Tazoh and Akira Ohtsuki

Serious damage to pile foundations was caused by the 1995 Great Hanshin Earthquake. The extent of the damage was made infinitely worse by soil liquefaction and the lateral spreading it induced. This paper presents the condition of the damage to the pile foundation of a bridge on the Hanshin Expressway Route No. 5, and examines the cause of the damage by means of the three dimensional finite element method taking into account soil liquefaction and the lateral spreading of the liquefied soil. The maximum bending moments at some points, the pile-head and -inground obtained by soil liquefaction analysis, exceeded the yield moment of the pile, and the positions of the observed cracks on the piles corresponded to these points. The damage to the pile was mainly caused by the inertial force of the superstructure and the ground motion during the earthquake. It 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. Countermeasures 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. It was found that 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.