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Assessment of Stability of Slopes Subject to Blasting Vibrations at Savage River Mine: Evaluation of Blast Design with Focus on Wall Control
2015 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

There is a very strong focus on achieving high levels of control over fragmentation, wall stability and environmental impacts in modern mines. Many factors influence the stability in hard rock metal mines and the economic pressure has driven the production at Savage River Mine to have steep walls. Mining at Savage River Mine has always been challenging from a geotechnical perspective due to highly sheared nature of the orebody and surrounding rocks. There has been a real need in the last few years to develop system that can allow safe mining system for high walls. This project was conducted both at Monash University civil engineering department and Savage River Mine of Grange Resources Limited, during a limited time of 20 weeks. The main object was to assess the dynamic effects of blasting in the eastern wall at Savage River Mine. To minimise blasting damage to eastern wall, an optimal drill and blast design was developed by evaluating the PPV and dominating frequencies for the site-specific rock mass, 70 metres away from the blast. The eastern wall is located in the North Pit which has reached a depth of 330 metres today. The current design for the cut backs at Savage River Mine in the east wall is a double bench geometry consisting of two 15-metre high benches and a 30 metre pre-split with a 90° batter. Grange Resources use electronic detonators, the delay time is 54 ms inter-hole, 99 ms inter-row. To provide an accurate prediction model a series of vibration tests for eastern wall were carried out in 2011. By using linear regression techniques and the scaled distance method, a site vibration equation was developed to predict the PPV. A full-scale single-hole trim shot was then tested in November 2014 to collect a trace. A linear super-positioning model was used to analyse the trace from the trial. The raw data of the collected trace from the seed wave was plotted in Excel to generate three waveforms; transverse, vertical and longitudinal. A new optimal timing was analysed from the linear super-positioning model. When the design with an optimized delay time was determined, two new trials were made on the east wall in North Pit. at the same cut-back as the single-hole trim test shot. The new delay time was 31 ms inter-hole, 52 ms inter-row and PPV for the new timing reduced 60% at a distance 70 metres away.

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URN: urn:nbn:se:ltu:diva-49432Local ID: 6c3c9747-58db-4c89-8347-bc5ba323350dOAI: diva2:1022779
Subject / course
Student thesis, at least 30 credits
Educational program
Civil Engineering, master's level
Validerat; 20151218 (global_studentproject_submitter)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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