An integrated approach for rockfall analysis with drapery systems

Klaus Thoeni, Cédric Lambert, Anna Giacomini, Scott Sloan, John Carter
2013 Proceedings of the 2013 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering   unpublished
The rockfall hazard in mining environments needs to be rigorously managed in order to ensure safe mining operations, in particular when designing portal entries for punch longwalls. The installation of drapery systems is a common practice to mitigate the rockfall hazard at the base of highwalls. However, the hazard is not completely eliminated since blocks can still detach and fall in between the drapery and the highwall. This contribution shows how geostructural modelling and 3D rockfall
more » ... is can be combined in order to accurately map and assess the rockfall hazard at the base of such highwalls. The study entails the estimation of the size distribution of unstable blocks and the simulation of their trajectories and velocities for highwalls without and with drapery. First, 3D photogrammetry is combined with discrete fracture network modelling in order to generate polyhedral models of the rock mass structure. Polyhedral modelling and kinematic analyses are combined to estimate the volume and shape distribution of unstable blocks. Unstable blocks are then classified according their shape. Second, a 3D discrete element rockfall model is presented which allows for an accurate prediction of velocities and run-out distances for rock slopes with and without drapery. The 3D model is used to predict trajectories and velocities for blocks representative of a highwall, i.e. block size and shape according the results from the polyhedral modelling. The focus is to investigate the efficiency of the drapery and to quantify the residual rockfall hazard at the base of a highwall. Rockfall hazards pose significant problems worldwide because they are responsible for major damage to infrastructure and for severe accidents including fatalities. In mining environments rockfall events can also have financial consequences in cases where the production must be temporarily stopped for safety reasons. Rockfall phenomena have been widely studied for roads and highways (Pfeiffer and Bowen, 1989; Giani, 1992; Agliardi and Crosta, 2003; Dorren, 2003; Turner and Schuster, 2012) but it is only recently that they have been accounted for in the context of quarries (Alejano et al., 2007 (Alejano et al., , 2008) ) and open pits (Giacomini et al., 2012a) . Several areas with significant rockfall hazards exist in a mining environment. Areas which are particularly vulnerable to rockfall events are portal entries for punch longwalls in underground mining which can be found along a highwall. For Australian punch longwall operations, the standard approach has been the use of draperies combined with face bolting of potentially large blocks (Giacomini et al., 2012b) . However, this protection system does not totally eliminate the rockfall hazard as blocks can still detach and fall in An integrated approach for rockfall analysis with drapery systems K. Thoeni et al.
doi:10.36487/acg_rep/1308_81_thoeni fatcat:hfsqkj23l5cktivqhcgbzjm76u