Subterranean Concrete Workings

Underground mining in the United States is some of the safest work in the world.  Headline grabbing stories concerning mine accidents are always tragic but in reality you are safer mining than working in most jobs and yours truly intends to ensure that trend continues :)  

So, how do we keep things safe?  Screening is one of the many ways and helps keep the blasted rock in place.  The photo below shows a typical stack of steel reinforcement screening---the grid is approximately 3"x3".

Shortly after a tunnel has been blasted, the screening is attached to the walls with large spring steel roll pins.  The "spring" in the pins force the rock to stay in place forming arches to help support the tunneling.


A large articulating platform combines the placement of the screening, drilling and installation of the pins.  A good shift can install over 100 of the screen sections.  At no time during this installation is anyone under unsupported rock as the installation is being performed along the leading edge of the platform.


Here is a close-up photo of a pin and plate securing a section of screening.  Note the reduced gap in the pin compared to the earlier photo that is placing pressure on the inside of the drill hole.

All corners, intersections, high traffic areas and any areas of concern are "shot-creted".  This sprayed-on application on the screening greatly increases the safety factor.  These guys could get work building pools back home :)

The photo below shows a large ceiling area with the steel screening in place.  The yellow tube is a ventilation duct.  These run along the ceiling in most areas to ensure air movement.

While cave-ins always grab the headlines, it is nearly always the smaller rocks that fall and injure miners.  The few rocks caught in the screening is very typical and demonstrates the why this safety feature is so important.

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