Proactive Engineering Controls for Highwall Stability
CIM Montreal 2015
Trevor B. Ames (GeoStabilization International)
Highwall instability and ground failures have historically been a consistent contributor for mine injuries and fatalities within surface mines. To combat this, we’ve seen several efforts including those from NIOSH (CDC) educating the mining community with insightful literature focused on hazard recognition and advances in ground monitoring systems. Can more be done or is this our last line of defense to manage potential dangers? Is there a more effective method to mitigate against ground failures or risks against rockfalls?
The more effective control to guard against rockfalls, unstable ground and challenging geohazard conditions are engineering controls. There is a balance between safety and the economic viability as mines get deeper and continually experience slope stability issues throughout its mine life. Mines must consider ongoing geological and geotechnical data available beyond the initial mine plan and continuously improve the design strategy to guard against slope and ground failures.
When we look at contributing factors to ground instability and what we need to isolate hazards, we find that most are manageable with an effective ground control plan. These factors would include;
1) Modifications to mine designs and planning may need to account for updates in rock mass properties, highwall geometry and its orientation to control against joint plan failures. Modifications should be undertaken to continually improve the integrity of the final design standards at operations as mining advances.
2) Vibrations from blasting activity can adversely affect ground stability over time, as operations expand blast sizes and production limits. Adequate vibration limiting techniques along with final wall protection blasting practices need continuous design reviews to minimize adverse effects from blasting operations on wall integrity.
3) Compounding ground stability issues, including precipitation, ground water and freeze thaw cycles accelerate ground movement and induce raveling ground along highwalls. Ground reinforcement methods, catch bench maintenance and advances in barrier fences are also effective engineered solutions to extend mine life and reduce the risk of ground failures at open pit mines.
Engineered controls can be incorporated as part of every operation’s ground control management plan. A continuous assessment into mine designs and operational planning have an impact on highwall safety and can mitigate against geohazard events as an economically viable solution to safeguard your operation.
Mots clés :
Highwall reinforcement, Catchment benches, highwall drilling, rockfall barrier, Highwall scaling, Slope stability, highwall failure, Rockfall mitigation