1. Method for estimating probability of vehicle derailment damage on structures during seismicity

An analysis method was developed to effectively examine train running safetyon groups of structures along whole lines during seimicity.
This method can be used to evaluate the influence of various parameters, such as vehicle speed, structure characteristics, countermeasure techniques, etc. on the probability of damage occurrence.

In order to comprehensively examine train running safety and the effect of seismic countermeasures on continuous railway structures during seismicity it is essential to obtain a risk assessment method which gives accurate estimations of damage occurrence probability for the whole line in question.

The present research led to the development of an analytical method which divides large civil structures spanning several tens of kilometers into analysis sub- sections using pseudo boundaries which are computed in parallel by multiple CPUs (Fig. 1).

This method makes it possible to analyze the effect of various parameters such as structural or vehicle specifications, vehicle running speed, type of seismic motion, direction of the hypocenter, and countermeasures, etc.

The damage occurrence probability during seismicity was examined for a 20 Km model section, including viaducts, embankments and tunnels (Fig.2). The result of this examination clarified that vehicle derailment in the tunnel or on the embankment would be highly unlikely during an earthquake, whereas there were vulnerable points on underpasses and groups of viaducts.

An additional method was proposed for obtaining approximate estimates of damage occurrence probability using a simple function based on the analytical output of the method described above.

Fig.1 Outline of analysis method
Fig.2 Example of analytical result for model section