Rockfall barrier service loads for rock impacts with spin. Theory and experiments

The specification of realistic service loads for flexible rockfall barriers is an on-going concern in rockfall engineering. The purpose of this document is to present results of full-scale experiments of rockfall barriers in natural terrain. Full scale experiments are performed in-situ at the Chant Sura test site located at the Flüela Pass, Canton Grisons, Switzlerland between 2018 and 2021. The tests were performed with instrumented blocks in order to quantify how blocks decelerate at barrier impact in real conditions. A total of 30 blocks were released - 25 of these blocks impacted the barrier. The barrier absorbed a total of 12'100 kJ of impact energy. The boulder masses varied between 840 kg and 3200 kg and both equant and platy shaped blocks were used in the experiments. Forces in the barrier components are measured and quantified in terms of incoming translational and rotational block energies. [...]