Published in March 2008 Australian Longwall Magazine

Real-time information was vital to ensure rapid remedial action could be taken in the event of excess weight from the roof and floor heave.

The mine needed a system that would monitor continuously any movement in the longwall roof or floor and relay this data back to the surface. With that in mind, Tahmoor contacted mining supplier Austdac to assist.

Using the Austdac Roof Convergence Monitoring package tailored to site specific needs, Austdac and Tahmoor were able to come up with a system that would monitor for convergence providing early indication that fractures formed at the goaf edge were extending to the face area.

Any deformation at the face would cause problems and delay start-up of the longwall.

Output from monitoring in conjunction with a Trigger Action Response Plan (TARP) process allowed early intervention with secondary support.

The Austdac system was also adapted at the mine to monitor heave giving a total picture of roof and floor convergence.

Using data collected the mine has elected to inject polyurethane into areas of concern on the longwall face. Subsequent monitoring showed minor change and stable conditions.

For Austdac, Tahmoor is the second longwall where continuous monitoring of convergence has been used for strata management. Soon the system will be used to monitor the next longwall face road prior to installation. It will then be integrated with manual monitoring in the maingate forming part of the ongoing strata management process.

The Austdac system allows the site to be continuously monitored and conveys the data from the underground face to the surface computer network, giving the site an early warning system and allowing corrective action through a TARP.