The project, Monitoring systems and geological structure assessment leading to improved management of mining conditions, has given researchers the opportunity to investigate issues associated with the operation of modern high capacity longwall systems in weak mining conditions. The Australian Mining Consultants project headed up Terry Medhurst was given ACARP funding in the December 2003 round.
Recent work by the research team revealed a fundamental link between coal seam conditions and longwall support setting and stiffness characteristics. Detailed leg pressure monitoring and leg loading rate analysis can be used to detect immediate roof and overlying roof weighting effects. More importantly however, is the value of support monitoring to establish ground response and its relationship to support performance.
A new approach has been developed to assess convergence driven roof
behaviour, which uses the Ground Response Curve (GRC). The GRC shows the
relationship between roof convergence and the support pressure applied, allowing for difficult or unique mining conditions to be characterised and assessed.
Under the project, analysis of longwall support monitoring and on-going underground
microseismic monitoring data will be undertaken. The microseismic data will
essentially provide a picture of the damage profile and allow an assessment
of the volume of rock associated with support loading. A practical in-mine
system, Goafwarn, will be used in conjunction with support pressure
monitoring to provide an integrated assessment of support behaviour and
dynamic ground conditions while mining is underway.
Researchers will also look at actual past cases of mining through faults to identify particular strata-support interaction characteristics that can be used to form successful "mining-through-fault" strategies.
By the end of the project, researchers will have a record of ground control/operational actions and actual longwall performance while mining through faults; a better understanding of the geological fault systems likely to cause face stability problems and needing of additional support and conditioning whereby a set of operational actions can be formed; and a demonstration of the use of practical, in-mine logging systems that allow face and ground conditions to be continuously monitored, thus aiding appropriate mining decisions.
