Authors: Graf, CC; Peryoga, T; McCartney, G; Rees, T


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Graf, CC, Peryoga, T, McCartney, G & Rees, T 2013, 'Verification of Trajec3D for use in rockfall analysis at Newmont Boddington Gold', in PM Dight (ed.), Proceedings of the 2013 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 1231-1241,

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The Boddington gold mine is owned by Newmont Asia Pacific and is located approximately 130 km southeast of Perth in Western Australia. Operations officially commenced in 2010 with production from two large pits. At full capacity Boddington will become the largest gold mine in Australia. Boddington is located within the Saddleback Greenstone Belt and the pits are being developed in a largely hard rock environment. In open pit mining generally, isolated falls of individual or small clusters of rock pose a risk to personnel and equipment. The aspects of interest in modelling the rockfall behaviour includes the rock trajectory path, landing distance from the bench and the lateral spread from the point of origin that have detached from the slope. Readily available software for the modelling of rockfalls simplifies the problem to two-dimensions that does not account for the three-dimensional pit surfaces, and does not represent the rock geometry. This makes rockfalls difficult to model accurately and does not address all the aspects that are of interest in the modelling of rockfall behaviour. These shortcomings were addressed in a three-dimensional rigid body rockfall analysis program software program Trajec3D (BasRock, 2013). Trajec3D is able to simulate the trajectory of rocks during free fall, rolling, bouncing and sliding. A project was undertaken at Boddington to verify the use of Trajec3D to model rockfall events, and understand rockfall behaviour. The project involved completing a series of tests to determine the coefficient of restitution on different floor surfaces within the pit, and undertaking rockfall experiments in the pit. The experimental rockfalls were then back-analysed with Trajec3D to determine appropriate physics interaction properties. It was found that there were some limitations to the model, however the model did aid in understanding rockfall behaviour, and potential rockfall motion paths. It is believed that the Trajec3D model provides a fair representation of the rockfalls, and is able to be used to establish a procedure whereby potential rockfall areas can be identified, and effective rockfall mitigation techniques determined.

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