According to the analysis results of the maintenance monitoring which are located on the 5, 6th subway line, they are analyzed that the stress of concrete lining and reinforced bar are converged gradually after 45 months. Therefore Monitoring of measurement and analysis frequency is conduct more often within about 4 years after the measuring instrument installation. Four years later, slowing the frequency of measurement is considered reasonable.

• 우종태(경복대학교 건설환경디자인학과 교수, 정회원) | Woo, Jong-Tae