A new rockfall hazard assessment methodology for open-pit coal mines

Rockfalls represent a serious hazard in open pit-mines, threatening human lives, machinery and portal structures located at the toe of highwalls. This hazard can have signiicant inancial consequences should the production be temporarily stopped for safety issues. Results from the ACARP C19026 rockfall netting project and field observations suggest that a more effective approach to rockfall hazard management is required for safe mining operations. In this paper, a new qualitative rockfall hazard procedure speciically designed for coal mining environments developed within the current ACARP project C23026 is presented. The methodology intends to be a simple and quick tool for identifying the most dangerous highwall sections. The use of this methodology provides practitioners with a more rigorous guidance on rockfall management strategies, and the industry with the ability to generate hazard zoning maps that can be updated on a regular basis. The methodology uses in situ observations (and records of past rockfall events when available) for the deinition of three hazard levels (i.e. low, medium and high) deined on the basis of the expected rockfall energy at the base of a highwall and the rockfall frequency, evaluated through the state of activity of the highwall. As a result, the sections with a high level of hazard, which require a further strict quantitative assessment, are quickly identiied. The methodology will provide greater conidence in locating personnel, machineries, and structures over the working areas at the toe of highwalls.