With technology moving so rapidly, mining is much safer than ever before, thanks to automation,workforce tracking, GPS, and digital twins.
The earliest known mining endeavor can be traced back to the continent of Africa when southern Africans mined coal up to 40,000 years ago. Despite its long history, it didn’t become a significant human industry until around 10,000 years ago.
For many years, the mining process began with exploration, and once an area was discovered, development could begin, which invited production and reclamation.
Sinkholes
A sinkhole is generally a failure in the process, whether it is due to weak overburden, extraction, or discontinuities in the geological makeup.
Overburden is a result of cavities developing in the rock or subsoil. These cavities result in infill from the soil or sand in the adjacent strata. This results in a potential overburdening of the cavity, which can create a cave-in, thus forming a sinkhole.
It is a severe hazard to property and life because it can happen suddenly without warning and create a significant surface depression. In addition, a sinkhole causes weakness in the ground – this can disturb the soil in the surrounding area, which can cause more danger.
Sinkholes can also result in mine fires. For example, in coal mines, there have been cases of spontaneous ignition when water and air made their way into a sinkhole. This is risky enough, but more cavities are created as coal burns, leading to deeper cracks and increasing the risk of collapse.
In the event of a total collapse, coal burning is accelerated by the rush of air. This doesn’t just risk life. It also destroys the resource, pollutes the air, and can kill nearby animals and vegetation.
Preventing sinkholes
You can mitigate the risk of sinkholes. One of the most effective ways to do this is with proper infrastructure design regarding wall construction and mining supports. In the event of a collapse, a wall can be constructed to provide a barrier for the collapsed area.
This is a particularly successful method of maintaining a sinkhole. You can also use backfilling as a technique to stabilize an abandoned underground mining effort. The most effective measures for preventing sinkholes include:
- Controlling drainage to maintain water levels.
- Controlling gas pressure.
- Sealing cavities in surface soil.
The ability to predict a sinkhole is the key to preventing sinkholes. Unfortunately, mining causes sudden terrain alterations; in this case, some sinkholes are so rapid there are no warning signs. However, there is time to evacuate people and property in a gradual collapse. If there are cracks, vegetative stress, and gradual localized ground settlement, these are signs of potential imminent sinkholes.
Managing Sinkholes
Larger sinkholes require excavation and 3D mapping before you can begin the filling operation. The first step is to determine its depth and whether it is stable. You can monitor it to ensure it does not expand. If the edges are unstable, you can shovel them.
Create a solid base for the sinkhole with a concrete plug. Sand can be added on top, ideally a clay-like texture to retain water, preventing the issue from growing. If you can’t find clay-like sand, rocks in standard sand will suffice. Pack the soil and thoroughly water the area to help it settle.
When dealing with a super-sized sinkhole, you must deploy local guidelines. In most cases, rocks and cement are used to fill a sinkhole. The process is much the same as outlined above, but in this case, a graded filter technique is necessary to create layers for additional support that allows for water drainage.
Summing up
The potential sources of sinkholes in mining are many, from geological disturbances, method of working, the thickness of or multiple working seams, overburden, and extraction depth. Sinkholes’ impact varies from surface structure to agricultural effects to surface structure, water, and the mine.
Depending on size, there can be many disruptions, whether there was a prior warning or the surrounding area. But you can avoid a serious disaster by using various measures to prevent and maintain sinkholes. Backfilling, grouting voids, and quickly addressing sinkholes will help protect life and prevent property loss.
