Impact protection of bridge piers against rockfall

Abstract

The Dujiangyan-Wenchuan highway serves as a vital passage to and from the region severely damaged by the 5.12 Wenchuan Earthquake in China. Chediguan Bridge is located on the highway and spans the Minjiang River. During the earthquake, the bridge was severely destroyed by rockfalls. Although the bridge was subsequently rebuilt and opened to traffic on May 12, 2009, it was destroyed again on July 25, 2009 by rock avalanches that had been located perilously high on the right bank of the Minjiang River, and caused deaths, casualties, and roads being cut off. A subsequent investigation revealed multiple perilous rocky areas on the massif along the Minjiang river bank, indicating an extremely high risk of another rockfall hazard, which could, again, lead to damage to the bridge and a further disastrous outcome. To mitigate the rockfall hazard to the bridge, a new flexible, energy-dissipating crashworthy device for bridge piers is developed to withstand the impact of rockfall. Numerical simulations using nonlinear finite element analysis was carried out to simulate the rockfall impact process on bridge piers. The following influencing factors during the impact process were taken into account: material nonlinearity, geometric nonlinearity, as well as contact nonlinearity. The results show that the new protective structure of bridge piers can effectively buffer rockfall impacts and significantly improve the anti-impact capability of the bridge piers.