Estimation of Optimum Line of Extraction for Continuous Miner Workings and Development of Continuous Miner Stability Index (CMSI) using 3D Numerical Modeling and Statistical Approach

The continuous miner method is the emerging extraction technology for mining the deep-seated coal seams with low investment. This technology is used for the development and depillaring of the pillars/panels in the form of slices and ribs. During the depillaring of coal pillars, the stress and strain development will be higher on the workings, and the ribs and snooks deteriorate and may fail after just extraction. This condition of the workings depends on the line of extraction, either a diagonal line or a straight line. Field experience also concludes that a straight line along a dip-rise direction will be a favorable method compared to diagonal line extraction since it ensures fast rate of extraction. It is an imperative that the optimum line of extraction technique must be required to create safe workings and extract the coal panels safely. Hence, in this study, three emerging lines of extraction techniques, such as diagonal line, straight line along strike, and dip-rise directions, are taken for detailed stability analysis considering three different stages in each technique. Results of numerical investigation also concluded that the straight line along dip-rise extraction technique may have more stability than other techniques. Therefore, this technique is considered optimal to exploit the coal from a deeper depth. In addition, a sensitivity analysis is undertaken by varying mining depth, working stages, and mining height, and a continuous miner stability index is developed to forecast the stability of the underground workings of similar geo-mining conditions using statistical techniques.