Abstract

Recently, as tunnel structures are getting older and decrepit, many tunnel inspections are carried out for evaluatingthe tunnel state and safety. But, because there is no exact sta ndard for tunnel state and safety, depending on subjectivedecision, the new standard to assess the tunnel state is requir of the state of tunnel lining is not considered the characteris tics of tunnel as underground structures. Also, the item ofassessment and process of grading and classifying the state of tunnel is not objective and systemetic. In this study, newstandard for assessment of tunnel state is presented for improv safety. In the new standard, the new items of assessment includ ing geotechnical condition were selected and graded, theprocess in classifying the tunnel state is quantitative for ob jective assessment for tunnel state. This new standard andmethod is practically used in effective safety inspection and d iagnosis and tunnel maintenance.