Mining Publication: Evaluation of New Methods and Facilities to Test Explosion-Resistant Seals

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments to evaluate the strength characteristics of several seal designs for isolating worked out areas in underground coal mines. The PRL is currently pursuing the development of improved seal evaluation methods and facilities based on pneumatic and hydrostatic testing that would lend themselves to in-situ seal testing in an operating mine. Two chambers were constructed and instrumented within PRL’s Lake Lynn Experimental Mine (LLEM) for the evaluation of seals. Two solid-concrete-block seals, 13.5 and 40.3 square meter cross-section and 406 mm thick with a central pilaster, were constructed in both the small and large chambers and tested to failure with a series of methane explosions producing loading pressures ranging from 386 to 688 kPa.

A preliminary size-scaling relationship is presented for estimating the ultimate strength of masonry block seals built with rib and floor hitching. Testing seal designs in the chambers shows promise as an alterative evaluation method to that of full-scale explosion testing within the LLEM.