Investigating characteristics of strata movement due to multiple-seam mining using a sand-plater physical model

Field observations and experience show substantial increase in the subsidence factor and other subsidence parameters due to multiple-seam longwall mining under a currently mined area. These observations depict a different subsidence mechanism for multiple-seam mining. The mechanism is largely unknown and currently used prediction methods are rather inaccurate or unable to predict the multiple-seam subsidence reliably. To be able to modify the prediction methods to suit the multiple-seam coal mining, the subsidence mechanism needs to be fully studied and understood. Physical modelling is one of a number of useful methods for this purpose. A physical model has been developed to investigate the mechanism of the surface and sub-strata movements due to multiple-seam coal mining. This paper outlines findings from the physical modelling and the subsequent analysis. The results of this study can be used to improve the current prediction methods for multiple-seam subsidence to a reasonable accuracy.