Abstract
Roadway deformation and rock burst are the two key challenges faced by the safe operation of coal mines. Aiming at the issue of large deformation of the gob-side roadway under coal pillars in multiseam mining, this study has considered the case of the 8308 panel of Xinzhouyao coal mine in China. Based upon a combination of theoretical analysis, numerical simulations, and engineering practices, the mechanical model of “stress and deformation quantitative calculation of gob-side roadway under overlying coal pillars” was established in this study. The analytical solutions of the vertical stress distribution and the plastic zone of the gob-side roadway under overlying coal pillars were obtained. Finally, the accuracy of the mechanical model was verified using numerical simulations. The results showed that the coal pillar, upright above the gob-side roadway, and the cantilever roof around the gob-side roadway were the main factors leading to stress concentration and deformation around the gob-side roadway. For the particular cases considered in this study, the peak stress of the gob-side roadway could reach 1.8 times of the self-weight stress of overlying strata. The rates of the contribution of the gob-side roadway’s overlying pillar and the cantilever roof around the gob-side roadway to peak stress were 78.3% and 16%, respectively. The obtained results have an essential reference significance for stress calculations and rock burst prevention design of gob-side roadway under overlying coal pillars in multiseam mining.
Highlights
In the few years, coal will still be the basic energy in China [1,2,3]
Large deformation of roadway is a feature of deep mining, and it will be encountered in multiseam mining
In the close multiseam mining, the residual coal pillar and goaf in the upper seam will cause the redistribution of stress in the lower seam, which will lead to higher stress concentration under the overlying coal pillars
Summary
In the few years, coal will still be the basic energy in China [1,2,3]. With the decrease in coal reserves in the first mining coal seam, the number of coal mines mining under the upper mined coal seam is rapidly increasing [4,5,6]. Erefore, it has become an urgent task to establish a quantitative calculation method for determining the deformation and failure of roadways under the effect of the overlying coal pillars. Erefore, it is of significant theoretical and practical value to establish a quantitative calculation method to determine the stress concentration and roadway deformation and failure in multiseam mining. Considering the width of the overlying coal seam goaf and coal pillar, the interval between coal seams, whether the adjacent working face of the roadway is mined out, the nature of coal and rock, and other factors, we established the model of “large deformation mechanism of the gobside roadway under overlying coal pillars,” which can realize the quantitative calculation of the deformation and failure of the roadway in the near-empty area under the overlying pillar in multiseam mining. Considering the width of the overlying coal seam goaf and coal pillar, the interval between coal seams, whether the adjacent working face of the roadway is mined out, the nature of coal and rock, and other factors, we established the model of “large deformation mechanism of the gobside roadway under overlying coal pillars,” which can realize the quantitative calculation of the deformation and failure of the roadway in the near-empty area under the overlying pillar in multiseam mining. e research results will have important guiding significance for evaluating support effect and formulating reasonable support measures
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