Underground » Ventilation, Gas Drainage and Monitoring
This project set out to determine the feasibility of using non-destructive testing methods to evaluate the strength of ventilation control devices to withstand the required overpressures.
The project set out to assist the evaluation of ventilation control devices for the purposes of compliance with the Queensland regulations and to ensure maintenance of the structure's integrity. Testing of ventilation control devices was done at significant cost and effort on the behalf of manufacturers. There was no established methods whereby the integrity of devices already installed in the mine could be tested.
Due to the changes in the legislation as well as the development of newer destructive methods, the paradigm under which this project started, changed significantly from March 2001. This led to various methods of destructive testing being considered as well as, non-destructive testing methods for testing the strength of underground structures. During the period of the project the need arose for different performance criteria for additional ventilation controls devices to be investigated. These studies led to a draft standard that specified different post explosive performance criteria from those originally specified. This reduced the need for the non-destructive testing of ventilation control devices.
The most suitable method of non-destructive testing was found to be one that provided an image of the internal conditions of the structure as well as one that would give a comparative estimate of the materials strength. Such methods are capital intensive and require a high level of operator skill. At the same time simpler and more cost effective methods were identified that could be used to determine the condition of a structure although not at the same level as the imaging methods.
An important aspect of using non-destructive testing is the need to correlate the non-destructive testing parameters with the physical parameters of the structure and then to compare these characteristics with the ability of the structure to comply with the regulatory requirements. These tests are expensive in terms of the resources required especially when considering the number of alternative designs that would have to be considered.
New and innovative methods for destructively testing seals and other ventilation structures have proved to be viable low cost alternatives to the non-destructive testing of ventilation control devices. With the very high cost of establishing these non-destructive testing methods, it has to be concluded that non-destructive methods are not the most appropriate method for testing innovative prototype structures.
The use of non-destructive testing has application and merit in determining the state of ventilation structures in mines as well as determining the quality of installation. If the mining industry requires a higher level of certainty, resources will have to be expended to establish alternative testing galleries to facilitate the testing of new designs. Work will have to be conducted to develop the required relationships that will enable the determination of the non-destructive parameters that will allow structures to be tested in the underground environment.