The most frequent cause of injuries and fatalities in underground mines is ground instability. When rocks or walls of earth become displaced as a result of mining activity, they can cause the ground or walls in the underground mine to shift and move, sometimes resulting in a partial or complete collapse. As underground mines age and are dug deeper into the earth, the walls and ground become less stable.
Ontario alone has around 40 underground mines with nearly 25,000 workers—this translates into thousands of opportunities for ground control injuries. Also, several of the mines in Ontario have already reached depths of almost 3,050 metres (around 10,000 feet), making them even more dangerous for workers.
Controlling ground stability calls for a combination of well-thought-out engineering and operational procedures to prevent worker injury or death.
Safe Ground Control
In order to mitigate the risk of injury from ground instability, share the following safety recommendations with workers:
- Keep a check in/check out log so that each employee’s whereabouts are known at all times. This will also prevent unauthorized people from entering the mine.
- Make a list of all potential risks and plan accordingly. This should include a review of the mine’s geology and the effects excavation will have on the ground and walls of the mine.
- Continually measure seismicity, stress levels on rock and displacement of the ground.
- Set up support systems at portal openings and access areas with shoring, head walls, fencing, shotcreting or other comparable protection.
- Plan how tasks are going to be carried out and in what order so that stress on the ground is kept to a minimum.
- Backfill areas that are no longer being mined, or set up barricades and warning signs in places that will not be excavated for an extended period of time.
- Have a competent person thoroughly examine all underground areas before, during and after each shift.
- Replace any damaged ground supports. New supports must be installed before old supports can be removed.
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