Damage assessment of tunnels caused by the 2004 Mid Niigata Prefecture Earthquake using Hayashi's quantification theory type II

Mountain tunnels, being underground structures and situated deep within rock layers, are generally considered to suffer appreciably less damage from earthquakes than surface structures. However, it has been reported that many tunnels were damaged by the 1923 Great Kantou earthquake, the 1995 Great Hanshin Earthquake, the 1999 Taiwan Chi-Chi Earthquake, the 2004 Mid Niigata Prefecture Earthquake and the May 2008 Great Wenchuan Earthquake in China. In this study, the damaged tunnels resulted of the 2004 Mid Niigata Prefecture Earthquake are the study objects. The damage patterns are analyzed, and the information which is considered to be of influence, such as the distance to epicenter, the completion time, the geological conditions, etc., are collected. A database of the damaged tunnels has been created using a Geographic Information System (GIS). The influence ranking for these factors has been analyzed using Hayashi's quantification theory II. The degree of the tunnel damage has also been assessed using GIS and Hayashi's quantification theory II. The field investigation is in close agreement with the assessment results following Hayashi's quantification theory II.