Analysis of a Bridge Substructure Subject to Falling Rock Impact

As a critical failure mode of the precipitous slopes, rockfall is one of the frequent geological hazards in mountainous area. Meanwhile, bridges are absolutely necessary in the mountainous transport networks due to the challenging topography and geological conditions. In recent years, the rockfall has posed serious threat to safety of bridges while such kind of researches and studies have nearly been reported. In this paper, a series of static and dynamic numerical simulations is conducted to investigate the behavior of the bridge substructure subject to a falling rock impact. Based on the analysis results, the damage degree of the RC columns are categorized into four levels with increasing impact intensity. The effects of impact direction, striking location and impact energy on the behaviors of the bridge piers are examined through a parametric study. The research result shows that the damage of RC piers caused by falling rocks impact has local characteristic and that the main failure mode of the bridge piers is shear mechanism. Even the maximum impact load induced by a 20-tons rock at a velocity of 5m/s is twice higher than the bearing capacity of piers. Thus, some active protection measures should be taken to protect bridges from falling rock impact