Rockfall nets are often tested in unrealistic, academic conditions that ignore common load cases. Naturally occurring important load cases are missing in certification norms: (1) fast rotating rocks bear the potential, depending on their rock size, impact location and mesh geometry, to over climb the nets; (2) non-ideal, eccentric net impacts including direct column or (3) border field hits are inexistent as well.
In order to approach real-world conditions, we present a novel full scale rockfall net testing site in natural terrain. The shift towards realistic impact conditions imposes the use of internal measurement devices, not only to the net but also to the impacting block, in order to have a fully determined impacting system. We exploit recent advances in sensor technology and progress made in rockfall reconstruction methodologies. In-situ accelerometer and gyroscope data are combined with videogrammetric and unmanned aerial systems mapping techniques to understand the role of rock rotations, ground penetration and translational scarring in rockfall motion. The exhaustive target tracking and succeeding trajectory reconstruction provides information over the complete flight path such as translational velocity vectors, angular velocities, impact duration and forces, ballistic jump heights and lengths during its downslope travel as well as upon impacting the mitigation structure.
The experimental data provides insight into the basic physical processes detailing how rotating rocks of general shape penetrate, rebound and scar ground terrain and consequently rockfall nets. The adequate simulation of change of kinematics during the impact becomes of key importance in order to match realistic mitigation structure behaviour.
The presented methodologies pave the way to a comprehensive understanding of rock-ground and rock-net interaction, a key requirement to develop numerical models and loading procedures that account for the role of rock shape, spin and eccentric impacts in rockfall protection.