Reduction of rockfall impact on protection galleries by using EPS geofoam.

Rockfall hazard is a major problem especially in mountainous regions where steep rock slopes are present and the properties of the surficial rock masses are suitable for fragmentation. Highways, railroads, and other infrastructural elements built in the trajectory of the rocks need to be protected. In critical locations that are under constant risk of rockfall hazard, protection galleries can be a good choice for shielding highways, railroads, and other lifelines. In order to reduce the damage induced by rockfalls to an acceptable level, damping and absorption of the impact energy at the collision have a significant importance. Within the scope of this study, displacements, stresses, and strains on a reinforced concrete protection gallery located at the toe of an actual rock slope during rock fall impacts were investigated by numerical analyses performed using RocFall and ABAQUS codes. In the light of analyses results, it is anticipated that the use of expanded polystyrene as a compressive layer on protection galleries can be beneficial to reduce the transmission of the impact forces caused by a rock collision. Impact analyses for a 1000 kg mass were carried out using explicit dynamic analysis module of finite element method-based ABAQUS software. Results indicate that use of EPS geofoam significantly reduces the destructive effect of the rock falls on the reinforced concrete protection galleries. Structural displacements are significantly less when EPS is used as cushion material instead of granular fill. A percentage reduction of 85% is observed in the maximum value of sectional displacements. An approximate reduction of 76% is observed in the maximum values of stress on the protection structure in the vicinity of the impact zone. Results indicate that the use of geofoam compressible layers may protect the structure from taking significant damages therefore increase the useful economic life of the concrete structure. [ABSTRACT FROM AUTHOR]