Research on the movement law and traffic safety zoning of spalled blocks in the linings of high-speed railway tunnels

Abstract

Recent years have brought to notice the spalling and falling off problem of the lining of high-speed rail tunnels, which is dangerous for traffic safety. In this study, a three-dimensional spalled block–train–tunnel–air gas–solid coupling calculation model was built using FLUENT numerical simulation software. This model was used to simulate the trajectory characteristics of the spalled blocks under the operating condition of a high-speed rail at a speed of 300 km/h. The spatial movement characteristics of the block falling from the lining under four influencing factors, namely, block's geometric size, density and positions and train's speeds were analyzed. During the operation of the train, the lateral displacement of the spalled block decreases with the increase of the density of the spalled block, increases with the increase of the vehicle speed, and first increases and then decreases with the increase of the geometric size of the spalled block. Considering the above influencing factors comprehensively, the safe area and dangerous area in the tunnel are divided depending on whether the traffic safety was threatened by the falling of the spalled blocks from tne tunnel lining. The results show that the area 4.5 m away from the ground is a dangerous area where the tunnel operation and maintenance need to be paid attention to. Meanwhile, it is recommended to install the auxiliary equipment in a safe area to avoid the peeling off of the surrounding lining and thereby threatening train-driving safety.