Compiled statistics show that the fall of roof is one of the major causes of coal mine accidents, contributing 44.6% of total underground accidents in India. 136 major accidents resulted into fatalities of 840 persons during 1901 to 2007. Most accidents occur in pillar mining districts, adopting Bord & Pillar (B&P) mining method (globally known as Room and Pillar mining with specific variations). This method shares about 90% of total underground coal production in India, employing about 57% of total workforce. Understanding ground control and related rock mechanics have been primordially the greatest challenge while undertaking exercises of rock excavation (primarily by blasting). In an effort to phase out timber supports usage, roof bolting occupies a pride of place. However, the application of cement bolting in India has been fallen short of planned targets of safety and productivity. The geotechnical issues are largely compounded by inventories and reinforcement procedures put in place. Keeping above aspects in view, this paper takes into account the prevailing geo-mining conditions. A simplified approach to deal with the roof control problems, presented here, consists of roof support design methodology using three dimensional numerical modelling, estimating the extent of a roof failure zone and respective rock load and finally linking with adequate support-safety factor. The approach is site-tested in many coal mines. Two representative case studies (moderate and high depths) are briefly cited, where suggested patterns of bolting were implemented. Fortuitously, the economics presented also suggests that resin reinforcement is need of the hour for Indian Coal Mines.
To improve the safety and to reduce fatigue of human beings, it was agreed upon in the recently concluded 10th Conference on Safety at New Delhi, India, that manual loading operations should be phased out in coal mines by identifying and introducing appropriate technologies in each locales, subject to understanding geo-mining conditions [1]. However in steep deposits, it is difficult to go for mechanisation with Bord & Pillar (B & P) pattern. Roof bolting with mechanised roof bolting machines will not only prevent workers to be exposed to hazardous conditions during supporting, but also will pave the way for mechanisation belowground in India. Expectedly, it will reduce the likely-occurrence of accidents. The productivity is very low, cost of coal production is high and majority of underground coal mines are incurring financial losses. Because of compelling socio-political reasons and sometimes because of technical reasons also, underground mines have to be run or to be planned for production. We need to plan coal extraction safely and economically to make underground mines viable in India. The key issue will be improving productivity which is dismally low. To meet the demand of energy and the aspirations of India's teeming millions, the coal industry has to achieve a growth rate of above 9%. The emphasis now is laid on underground winning of coal deposits in India to meet the ever-increasing energy demand. Roof bolting can be used gainfully to mitigate many ground control problems.
