Improving the impact behavior of pipes using geofoam layer for protection

In scope of this study performances of protective layers, proposed to protect the pipes from sudden impact loads such as rock falls, are aimed to be compared. In this study, performance, strength and energy absorption capability of geofoam structures against impact forces are investigated by using drop weight impact testing apparatus. Pipes that are manufactured from steel and composite materials are tested with only 130 mm thick sand protecting layer without any geofoam structure, and with two different geofoam with different thicknesses. Results are presented in a comparative form and the effect of geofoam on the impact behavior of sand layer is investigated. Impact load and accelerations on the pipes are measured with respect to time during experiments. Absorbed energy by the pipes are calculated and compared with each other for determining performance of the different protective structures. From the study, it was observed that the sand and geofoam layers used as protective layers were generally successful by reducing the detrimental effects of impact loads in terms of dissipating impact effects on the pipes and the measured acceleration and displacement levels. The best result is obtained from the 50 mm thick geofoam with sand layer. Finite elements analyses are performed by using ABAQUS software and both test and analysis results are compared to obtain a model that can give an idea to designers. - Highlights: • Protective layers reducing acceleration, displacement and energy absorption values significantly. • Energy absorption capacity is the most important criteria for the impact behavior of the specimens. • The most effective result is obtained from the 50 mm thick geofoam with sand layer. • Results of the finite elements analysis that are made by using ABAQUS software and the test results are consistent with each other