A Review of Methods to Determine Panel and Pillar Dimensions That Limit Subsidence to a Specified Impact

Coal mine subsidence can be separated into subsidence that develops above the pillars and the sag that develops in beams above extraction panels. Such a separation allows the use of engineering analytical methods to predict vertical subsidence. The subsidence above pillars can be considered to result from compression of the coal pillars and the immediately adjacent roof and floor strata. Estimation of the coal compression needs to consider the difference between yield and failure of coal pillars. Elastic solutions to the settlement of rigid footings may be used to estimate roof and floor compression. Stability and centreline sag of rock beams above extraction panels can be analysed using voussoir beam concepts. Appropriate factors of safety to use in designs needs to be developed and in the meantime a conservative application of methods is required. So that the development of analytical methods is not restricted, there is a need to redesign the databases being used to report mine subsidence.