Research Projects

As near-surface coal deposits continue to be depleted, underground mining in India will transition to deeper subsurface levels, where pre-mining stresses are significantly high. Fracturing and collapse of pillar walls and associated injuries/fatalities are expected to increase unless appropriate risk mitigation measures are undertaken. Development of pillar support guidelines is central to solving this problem, but there is a notable absence of such guidelines around the world. Accordingly, the primary goal of this research is to develop robust and easy-to-use support guidelines that are applicable to Indian coal mines. To achieve this, a coupled continuum-discontinuum numerical modeling approach will be implemented that simulates the mine-scale stress redistribution process using continuum numerical software, and the local pillar behavior and support response using discontinuum numerical software. Continuum models are often inadequate in capturing large deformation processes, such as coal pillar bulking, and tend to underestimate the impact of support elements. On the other hand, discontinuum models, while more accurate in representing these complex behaviors, are computationally expensive and impractical for mine-scale application. A synergy of the two is therefore necessary to allow for a detailed analysis of individual excavations and support effect without the need to simulate multiple adjacent excavations or the entire mine using a discontinuum model. The predictive capability of the numerical models will be established through a rigorous comparison of model response and field attributes (such as deformations) measured at an underground coal mine in India. Instrumentation and monitoring of pillar deformation will be undertaken as part of this research. Since the model parameters obtained through this calibration procedure will be representative of typical coal masses in general, alternative geo-mining conditions relevant to Indian coalfields can be evaluated. Accordingly, a parametric analysis considering variables such as mining depth, coal strength, support patterns etc. will be undertaken, and the model results post-processed to develop broad support guidelines. Finally, the reliability of the support charts/guidelines will be established by comparing ground conditions existing at a few other coal mines in India with the design predictions. This research will scientifically advance our understanding of the capabilities of discontinuum models and extend its application to large structure analysis, which to date has been limited mostly to laboratory-scale problems. From a practical standpoint, the coal mining industry will greatly benefit in terms of extracting deeper deposits in a safe and economical manner. The research outcome also has added implications in that a similar approach can be used to develop support guidelines for non-coal mines (e.g. lead, silver, zinc etc), which are also steadily transitioning to deeper extraction depths.