Development of earthquake disaster simulator for railways

Abstract

1 Purpose and background After the Southern Hyogo Prefecture Earthquake in 1995, Japan has frequently been hit by large-scale earthquakes across the country. It is said, therefore, that Japan is now in a high seismic activity age. Railways are strongly associated with public interests and it is very important for them to continue to function even after earthquakes. The railway system features long routes and diversified component elements and it is difficult to imagine what sorts of disaster risks exist at any particular location. However, it is important to be prepared for earthquakes by doing the following. (1) Determine potential earthquake disaster scenarios and earthquake risks to appropriately implement measures against earthquakes in order to protect the railway system. (2) Establish common recognition against earthquake disaster risks among railway promoters, users and the Railway Technical Research Institute (RTRI) and construct a mechanism for these parties to evaluate and quantify earthquake disaster risks. RTRI has been developing a " railway simulator " under its five-year plan since 2010. As a part of this overall program, RTRI is developing an " earthquake disaster simulator " to evaluate the safety of the total routes during earthquakes and, to use as an effective tool to appropriately visualize and mitigate earthquake disaster risks. Figure 1 shows the primary features of the earthquake disaster simulator for railways and Fig. 2 a visual depiction of the simulator's capabilities. This system can broadly be divided into four components: (1) a " database " , (2) a " simulator of earthquake motion " , (3) a " software to construct a model of a group of railway structures (hereinafter referred to simply as structures) " and (4) a " simula-tor of the behavior of railway structures. " The " database " stores the data on the ground and structures. It consists of data possessed primarily by RTRI at the moment and will be updated in the future. The " simulator of earthquake motion " calculates the propagating process of the earthquake motion generated at faults. The seismic motions in hundreds-kilometer square are calculated. The simulation is conducted not by the conventionally-used finite difference method (FDM) but by the voxel finite element method (FEM) that enables sophisticated calculations for mountain and ground-surface profiles. This method is considered appropriate to accommodate the required speed and data volume of the calculation. See Fig. 3 for the results of a simulation conducted to …