Vehicular impact loading on the barrier of a retaining wall system and its effect on the system foundation

When a vehicle collides against a traffic barrier which is integrated into a retaining wall below, the impact load must be resisted by the barrier and the retaining wall system, and the concomitant effects will be eventually transmitted to the system foundation. Although the collision is a very short transient dynamic loading over an initially small impact zone, it has implications on the stability, hence design, of the barrier, the retaining wall system and its foundation. Little information, however, is available on how the impact loading transmits from the small impact zone over time to the broader structural system, and on how the effects of impact eventually interacts with the foundation soil. In this paper, numerical simulation of a Test Level 4 (TL-4, corresponding to regular traffic in Australian Standard (AS) 5100.2) vehicle crash on a 1.2 m high traffic barrier integrated into a 3 m high concrete retaining wall was performed and the effects of the impact loading on such an integral barrier-retaining wall system studied. The speed and impact angle of vehicle crash against the barrier in the model was calibrated so that the impact resulted in maximum loads in the transverse, longitudinal and vertical (downward) directions in the local area of impact which correspond to the design loads specified in AS 5100.2:2004. The soil-structure interactions at the base of the wall due to effects of the impact loading were then established for the calibrated vehicle collision, and results are discussed in this paper.