Numerical simulation analysis of damage and detachment of lining blocks with cold joints under aerodynamic fatigue loads

Researchers have been widely attracted by the lining block falling accident of Fukuoka tunnel in Japan, with the main reason that the cold joints have cause the lining blocks falling. This article constructs a numerical calculation model of the Fukuoka tunnel lining, which is based on cohesive fatigue damage units. It analyzes the damage and deformation of lining blocks with cold joints under aerodynamic fatigue loads. The study also explores the extents of aerodynamic load amplitude, pouring intervals, and block positioning on the damage to cold joint units. The study shows that this method is suitable for analyzing the damage process of lining blocks with cold joints under aerodynamic fatigue loads. The discrepancy between the predicted detachment time (40 years) and the actual time (25 years) is attributed to unclear design parameters, the exclusion of train vibration loads, and the deterioration of concrete performance. The timing of cohesive unit damage is accelerated with increasing aerodynamic load amplitude and pouring intervals, while it is delayed when the block position is lower. The greater the normal force on the lining block with cold joints, the more likely the cold joint interface elements are to be damaged.