Document Type

Conference Paper

Publication Date


Publication Details

B. Shen, X. Luo, A. Moodie and G. McKay, Monitoring longwall weighting at Austar Mine using microseismic systems and stressmeters, 13th Coal Operators' Conference, University of Wollongong, The Australasian Institute of Mining and Metallurgy & Mine Managers Association of Australia, 2013, 50-59.


Cyclic weighting is a major hazard for longwall operations in many deep mines with strong roof strata. Significant cyclic weighting events had been experienced at Austar Mine, resulting in production delays. Early warning of imminent weighting events by means of geotechnical monitoring will help to minimise the risk associated and to develop preventative solutions. This paper describes a study undertaken by CSIRO and Austar Mine in which an integrated stress and microseismic monitoring system was trialled to detect strata responses to the mining processes. The main objectives of this study were to understand the caving mechanics and develop an effective early warning system for roof weighting management. The field monitoring results clearly demonstrated the effectiveness of using both stress and seismic signatures to infer longwall caving and weighting events. Stress changes recorded by stressmeters in shallow surface strata and underground roadway roofs showed a strong correlation with the chock pressure increase at the longwall face. The same phenomenon had also been observed from the recorded microseismic events. In order to develop an automated early warning system for longwall weighting, a trigger index method, which integrates the warning signs from different sensors, was developed and tested against the mine weighting observations and chock pressure data. A remarkably good agreement was achieved. For a limited number of cases examined, the warning signs from the monitoring system mostly occurred at least several hours before the roof weighting events and the major increase in chock pressure. This has demonstrated that the integrated stress and microseismic monitoring system, together with the analysis method developed, is capable of providing sufficient early warning for imminent underground weighting events.