Mitigation of seismic damage of transportation facility to fault induced distlacemelts

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Since there are a number of faults which could result in a rupture of surface ground, it is very difficult for transportation facilities such as highways and railways not to cross faults at all. This may results in a critical failure of the transportation facilities by the fault activity in the near future. However, due to the difficulty of the problem involved in this countermeasure, few research have been conducted to develop a rational technology for mitigating the damage of transportation facilities to fault displacement. This research was conducted between 1990 and 1992 to develop an appropriate countermeasure of transportation facilities to fault displacements. The following conclusions were deduced from the study.1) Based on an analysis of fault lengths of the past seven earthquakes (Nobi, Kita-Tango, Kita-Izu, Hyougoken nanbu, Izmit and Duzce (Turkey), and Chi Chi (Taiwan)), it was found that a fault is shorter than 3 m in length for the earthquakes with a moment magnitude Mw l … More ess than 7, and that about 70% of the earthquakes with Mw larger than 7.5 have a fault shorter than 3m in length.2) Based on a strong motion record measured at Kasho Dam during the 2000 Totori-ken Seibu earthquake, it was revealed that the dam body settled about several tens centimeters, and the level of reservoir dropped sharply. It was revealed from the numerical analysis for the settlements than the settlements were resulted from a rupture of a hidden fault under this dam.3) Damage of piles in the Bolu Viaduct, which suffered damage by a fault displacement during the 1999 Duzce, Turley earthquake, was analyzed. It is found from an analysis that the critical damage of piles occurred at approximately 3 m above and below the level where a fault crossed the foundation. The damage was destructive that the pile failed in shear and flexure.4) A foundation isolation using expanded poly-sterol (EPS) was proposed, and this was extended to a pile foundation. It was found that by providing a soft layer by EPS around the footing and piles, the plastic deformation of the piles which are subjected to a fault displacement can be mitigated. However an isolation effect cannot be fully activated unless the isolated layer is thick enough to mitigate and isolate the deformation of ground resulted from the fault displacement.5) A damage of a viaduct resulted from a tectonic surface ground movement during a volcanic eruption of Mt. Usu was analysis because of similarity of the tectonic ground movement and a fault displacement. It was found from a pushover analysis which takes account of the lateral confinement effect of concrete that the real damage developed during the tectonic sound movement can be predicted by the pushover analysis with a satisfactory accuracy. Less