Reliability based design for rock fall barriers

Rock fall phenomena are widely distributed and commonly encountered in mountain regions, and flexible barriers are often installed as countermeasures to minimize the resulting hazard. In Europe, such barriers are generally produced and tested according to ETAG 027 (2013) “Falling Rock Protection Kits”. However, since 2010, EN-1997 Geotechnical Design (CEN, 2004) – referred to here as EC7 – has been the reference design code for construction in the EU and, in particular, it applies to rock engineering design. Thus, such barriers should perhaps be designed following EC7. However, the applicability of EC7 to these structures is not obvious, since EC7 uses partial factors in design calculations and the factors associated with rock fall are not given in the code. Nevertheless, the underlying code philosophy of reliability-based design as presented in EN1990 (CEN, 2002) suggests an appropriate alternative to the use of partial factors in the design of such barriers. This paper reports an example of barrier design with RDB, using a sensitivity analysis to analyze ruling factors and discusses the applicability and the limitations of EN1990 and EN1997 in the design of such rock engineering structures.