STUDY ON IMPROVEMENTS OF EVALUTATION AND CALCLATION OF TUNNEL-LINING CRACK INDEX (TCI) FOR ASSESS THE HEALTH MONITORING OF TUNNEL LINING

The health monitoring for tunnels, especially over 50 years old, became a serious issue after the ceiling panel collapse accident at Sasago highway tunnel occurred in 2012. Following this accident, MLIT (Min-istry of Land, Infrastructure, Transport and Tourism of Japan) required administrators to conduct periodic inspections of road tunnel. One of the authors has already proposed Tunnel-lining Crack Index (TCI) to assess the health monitoring for tunnel lining quantitatively. Periodical inspection data of twin road tunnel were applied for the estimation of TCI. However, health monitoring by using TCI is usually performed focus on each span or each tunnel. In this study, the effectiveness of TCI separating the section of tunnel lining become clear by comparing the difference of area by four patterns. Thus, benefits of employing TCI become clear for quantitative priority health assessments of tunnel lining.