1. Field of the Invention
The present invention relates to a reinforced seal cast from a structural material and anchored with steel dowels into the floor and ceiling of a mine passageway. The seal is capable of bidirectionally withstanding an overpressure substantially greater than 20 psi.
2. Brief Description of the Prior Art
Seals are required in U.S. mine ventilation plans to protect against explosions and are used extensively in mining to isolate worked-out areas. Over the years, tens of thousands of seals have been erected in underground coal mines in the United States. In the 1990s there were a number of explosions of methane and/or coal dust within sealed areas of underground U.S. coal mines. These explosions, believed to be initiated by lightning strikes on the surface, destroyed numerous seals and did considerable damage in the active workings.
A response to the above-mentioned disasters was to require that abandoned areas of a mine must be either ventilated or isolated from active workings through the use of seals capable of withstanding a static horizontal pressure of 20 psi. More recently, in response to other mine disasters with fatalities, the standard for mine seals has been substantially increased to require seals to withstand static horizontal pressures of 50 psi or even 120 psi in some instances.
Prior art mine seals formed from masonry or concrete are not designed to meet such blast criteria even when hitched into the passageway with roof bolts or grooves into the ribs. There is a need, therefore, for a cost effective and efficient way to construct a mine seal meeting the higher standards for explosion resistance.