Numerical modeling of a rock fall mesh perforation upon impact

Rock fall barriers are usually designed considering the possible range of boulder energy upon impact. Different combinations of mass and speed can result in the same impacting energy but this phenomenon is not really accounted for during the design. Yet, it can lead to different barrier responses: it is the so called bullet effect. This phenomenon was studied experimentally and numerically. The tests have evidenced the bullet effect in a limited extent so that the study was pursued numerically by means of dynamic explicit simulations with Abaqus. The admissible energy of the mesh was determined under well defined boundary conditions and it is shown that a stress concentration phenomenon takes place, i.e. the admissible energy is a function of the block size and does not follow the lines of constant energy. This outcome questions the use of the kinetic energy as a design criterion. The geometry of mesh has been modified in order to investigate if the bullet effect could be addressed.