Underground » Ventilation, Gas Drainage and Monitoring
The test programme of 4 consecutive blasts and 1 further `inadvertent' blast, conclusively demonstrated that the overcast design can successfully withstand the target rating of 5 psi. The level of blast intensity applied, the deformation response of the structure and the basic requirement to withstand a `single event' only, prompts the revision of the design for greater commercial suitability. Refinement of the design to reflect a more general application for personnel trafficability only, provides commercial and practical advantages in many mine applications.
Design modifications to suit variations in size or specific application can be facilitated by the graphical output of the transducers mounted on various test structures.
Introduction
In 1997, Barclay Mowlem Construction Limited entered into a contractual agreement with the Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health (NIOSH), for a test programme for mining ventilation structures to be undertaken at the Lake Lynn Laboratory Experimental Mine.
This initiative into the determination of design parameters for underground ventilation structures was supported by ACARP particularly in respect of the overcast evaluation.
The test programme was structured to practically examine the behaviour of various structures designed for ventilation applications in underground coal mines, when subjected to an explosion.
The overall test programme involved the testing of a yielding stopping, 20 psi (140 kPa) and 50 psi (345 kPa) seals and an overcast intended to withstand at least 5 psi (35 kPa).
The test programme was conducted in the early months of 1998 at the underground test facility at Lake Lynn, following established practices involving explosions of varying intensity achieved through the detonation of methane gas and gas and coal dust mixtures.
This report is only intended to be an over-view of the test programme, and should be read in conjunction with the exhaustive and finely detailed report by NIOSH - "Evaluation of Barclay Mowlem Cementitious Seals, Stoppings and Overcast".
Readers of this report should also be aware of an earlier series of tests conducted by another Australian company - Tecrete (Fosroc VentMine), that will provide a wider perspective on the range of tests on ventilation structures conducted at the Lake Lynn facility. Finally, reference should also bem ade to US tests conducted at the facility, particularly in the area of 20 psi seals constructed with cementitious blocks.