NUMERICAL ANALYSIS OF STRUCTURAL HEALTH EVALUATION OF SHIELD TUNNELS BASED ON INFLUENCE LINES

Abstract

 The shield tunneling method has been widely adopted for constructing underground tunnels in Japan. However, with their increasing service life, deterioration phenomena such as water leakage and cracking have become significant maintenance concerns. Previous research has proposed methods for measuring displacement and calculating influence lines from the dynamic response of tunnels under train loading, utilizing MEMS accelerometers. The present study conducted a numerical analysis using Finite Element Analysis (FEA) to investigate the feasibility of an influence line-based health evaluation for a shield tunnel's segments and the surrounding ground. The results demonstrated that this approach has the potential to detect an anomaly. Specifically, a discernible change in the influence line was observed in a case where the stiffness of the segments in the lower part was reduced. Furthermore, the analysis also confirmed the potential to detect an anomaly in a case simulating a defect in the surrounding ground below the shield tunnel.