Dynamic finite element analysis of interceptive devices for falling rocks

The widespread use of net barriers, which are flexible, as opposed to rigid, devices for intercepting falling rocks has led to the need for rigorous design criteria based on safe and sound theoretical methods. Consistently with current practice, full-scale experimental tests are necessary in order to assess the reliability of any such barrier. Here, a new simulation approach based on numerical methods is presented: the analysis of a complete typical falling-rock event has been performed, to study the response of these interceptive devices. A commercial finite element code featuring explicit dynamic capabilities, particularly useful when modelling high-speed phenomena has been used. The simplifying assumptions along with the model geometrical and mechanical data are discussed. Both single net panel and complete barrier simulations are presented. In the latter case, the results are compared with some experimental data obtained from in situ testing. The results of the numerical simulations highlight some limitations in the testing methods which are currently accepted, and suggest the use of new parameters to more precisely characterize the behaviour of such interceptive devices for falling rocks. The benefits of numerical simulations as supplements to or substitutes for full-scale crash tests are emphasized particularly for design or parametric studies.