Coal Bumps Prediction in Longwall Coal Mines

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DESCRIPTION (provided by applicant): Coal bumps are sudden violent bursts of coal from a pillar or pillars. The successful application of yield pillars in deep coal mines of Utah coal field does not mean that coal bumps are no longer a problem. Recent investigation by the principal investigators have found that longwall face bumps, especially at the tailgate and sometimes at the headgate corners, occur routinely in the Utah coal field, causing injuries or sometime fatalities. And yet, no research has been performed to address this issue. The main objective of this proposal is to predict the coal bumps in the longwall coal mines. The preliminarily study and previous researches conducted by the principal investigators show that this objective can be accomplished in three stages. In the first stage, a rock/coal interface friction model will be developed since the characteristics of rock/coal interface can be the prime cause of coal bumps in coal mines. In the first stage a series of direct shear tests will be conducted to identify the appropriate rock/coal friction model by comparing the available friction models with the experimental results. In the second stage, a coal bump prediction model will be developed. The rock/coal interface friction model obtained in the first stage associated with modeling technique developed by the principal investigator (Morsy, 2003) will be used to estimate the coal bumps. A series of uniaxial compression tests simulating the loading conditions associated with coal bumps will be conducted to verify the developed coal bump prediction model by studying the damage processes of rock/coal interface and the potential of coal to store the elastic strain energy. In the third stage, a parametric study will be conducted using the coal bump prediction model developed in the second stage. The most influential parameters on coal bumps and stress transfer between the gateroad system and longwall face will be considered, such as; characteristics of rock/coal interface, overburden depth, width of gateroad system and stiffness of immediate roof and floor.