February 1, 2008 Industrial hygienists, applying geology and engineering, can test mine support systems with the only mine roof simulator of its kind. Using up to 3 million pounds of vertical force and 1.6 million pounds of horizontal force, it offers researchers the chance to test integrity, stability, and performance under simultaneous loads in the vertical and horizontal directions.
Coal miners provide the raw material for nearly half of America's power. Every year, there are an estimated 14-hundred roof collapses and cave-ins at coal mines -- making it essential to provide supports that can keep escape routes open. Now, scientists are using a one-of- a-kind machine to improve safety.
Miners go underground each day -- each day putting their lives at risk deep below the earth's surface. Chuck Urban's father and grandfather spent 50 years working in the mines.
"They always worried about fires and explosions. But their main concern was roof falls," Urban said.
"What happens in mining, we go deeper and deeper into the ground. There's more and more weight of the rock above us," Tom Barczak, Senior Research Engineer at the National Institute for Occupational Safety and Health told Ivanhoe. Not only do miners face the threat from the sheer weight of the ground above, but also from the many layers of shifting rock.
Inside a government laboratory, industrial hygienists apply geology and engineering to put a massive machine through its paces. The mine roof simulator is designed to test mine support systems -- structures to prevent the roof from collapsing.
"The real value of this machine is not the amount of load or pressure that it can apply -- but it's really the movement of the machine that recreates the closure of the mine opening," Barczak said.
The bottom of the machine sits in oil like a big skating rink. The floor can move in a number of directions, simulating the natural shifting of the rock layers. Engineers monitor the pressure and movement to see how much a structure can withstand.
"Before we had the machine, we would have to take the supports underground, and expose the miners to risks in case it didn't work," Barczak said.
A dangerous job made safer by science.
WHOSE FAULT IS IT ANYWAY? Wherever plates meet, there will be faults at the boundaries: breaks in the earth's crust where the blocks of rock on each side are moving in different directions. There are many different kinds of faults, but in all of them, the various blocks of rock push together tightly and produce a lot of friction.
If there is a large enough amount of friction the plates can become locked, increasing the pressure until the plates suddenly give way and snap forward suddenly, sending out a series of seismic waves. These fault lines are the main source of earthquakes.
The American Physical Society and the American Industrial Hygiene Association contributed to the information contained in the video portion of this report.