Subsidence due to coal mining in India

In India, every year loss of life occurs due to subsidence of land in coal mining areas. Subsidence is very prevalent in the Raniganj coal field which is a major coal producing area. The occurrence of thick coal seam at shallow depth is the main reason for the subsidence and as a result collapses have occurred in many coal mines in recent years. In the present paper, a review of coal mining subsidence in India will be presented. The Indian scientists have made efforts to predict the subsidence using empirical relations but it was not found to be successful since the geology of the coal mining area is found to be quite variable. We have made efforts to predict the subsidence occurring in the Indian coal fields in general and in particular in the Raniganj coal field using a visco-elastic model. Computed subsidence profiles of Ratibati and Shivadanga coal mines of the Raniganj coal field have been compared. The results show a reasonable match of the predicted and observed subsidence in the case of the Ratibati coal mine. In the case of the Shivadanga coal mine the predicted subsidence profile is found to be larger than the observed profile. However, the bottom of the observed troughs is found to match with the predicted troughs. Detailed analyses have been carried out to investigate the effect of mine parameters on the subsidence.