Damage of geotextile due to impact of stones

Abstract

Impact tests of stones on a geotextile or two loosely connected geotextiles (composites) have been performed and analysed to investigate the mechanisms that lead to perforation. The geotextiles were mounted on a concrete cylinder of 0.8 m internal diameter, filled with uniformly graded dry sand. Drop tests were performed with concrete blocks of different shapes weighing approximately 40 kg. The drop heights varied between 0.25 and 5.5 m. Results show that the shape of the stone has an important influence on the critical drop height at which the geotextile is perforated. Furthermore, it appeared from image processing that the tensile strains in a woven geotextile develop in the direction of the yarns, starting from the point of impact. However, in a nonwoven geotextile, the tensile strains develop rather uniformly centred at the point of impact. An important result for composite material consisting of a woven and a nonwoven geotextile was that the lower geotextile was always the first to be damaged. This was also found in the field tests. A possible explanation is the friction between the sand and the lower geotextile, resulting in an additional tensile loading on that geotextile. This explanation is confirmed by numerical simulations.