Longwall panel width design with prediction of the corresponding maximum induced ground surface subsidence

Longwall mining is one of the most commonly used methods in underground coal mining. With advancing the coalface, the created flexural cracks at panel roof gradually transmit upwards, towards the ground surface that may induce ground surface subsidence. Since the resulting subsidence depends upon the bulking factor of the goaf materials, a new equation to estimate the initial fractured bulking factor has been first proposed. Then, the paper continues to present two more new analytical methods for a suitable longwall panel width design and subsequently to predict the corresponding maximum induced ground surface subsidence. To investigate the impact of the parameters incorporated into the new developed methods, a sensitivity analysis was carried out. The effects of parameters including; extracted coal seam thickness, depth of cover, angle of draw, initial and ultimate bulking factors have also been examined and evaluated. The present proposed methods have been compared with the current comparable methods and then verified with the results of in-situ measurements for both subcritical and critical/ supercritical panel widths. Finally, it has been concluded that the present proposed analytical methods can reliably be used to design a longwall panel width and to predict the corresponding maximum induced ground surface subsidence.