Impact Response Behaviour of Gabion Cells Filled with Different Cushion Materials

Dwellings constructed in mountainous areas can be vulnerable to rockfall hazards. Reinforced concrete barriers and rocksheds can be used to offer protection from falling boulders. Gabions (which refers to manufactured steel nets filled with geo-material) can be used to strengthen the protection. Mitigation of localised damage to the barrier due to the high impact force developed at the point of contact is particularly important in a design featuring the use of a slender stem wall forming part of the barrier. Vertical impact tests have been conducted with the core purpose of studying the total amount of force imposed onto the barrier as a whole. The distribution of pressure on the transmitting surface is also an important consideration when it comes to predicting localised damage that is inflicted on the frontal surface of the barrier. Experimental study is warranted to investigate the efficiency of the gabion in distributing the impact pressure. A series of small scale drop tests involving the use of two types of cushion materials has been conducted to study the pressure distribution behaviour. The volume of cushion materials that contribute directly to the transmission of force has also been studied for two different materials. The influence of friction between particles (which is dependent on many factors including the shape of the individual particles) is relevant to the performance of the cushion. This study is aimed at making recommendations on the selection of cushion materials for filling the gabion cells and developing simple calculation methodology which has been validated by comparison against experimentally recorded results.