| During period of transition from open-pit to underground, it is necessary to build a reasonable overburden layer to ensure the safety of mine transition.Therefore,the study related to granular rock has an important influence on the formation of overburden layer,the most important of all, it will promote the progress of research about overburden layer and perfect the theory system.Through the transition from open pit to underground living example of Miaogou iron mine, the physical ore-drawing similar experiment is developed according to physical law. The best ore-drawing structure parameters are determined by contrasting and modifying various parameters. Exploring the water retention ability, specific yield and the process of seepage on overburden layer by means of permeable research. Finally,studying the movement and loss destruction on granular rock with different graduation ratios by establishing PFC numerical model based on physical experiment. The results provide theoretical guidance for the formation of overburden layer.The best ore-drawing parameter are determined by means of physical similar experiment, sublevel was 20 m, drift interval was 18 m, ore caving interval is 1.8m and the range of ore wall inclination is between 87.5 degree and 90 degree.Numerical experiment model is established according to the physical experiment,the results of numerical experiment show that the velocity and displacement vector of particle decayed with ore drift for the center, the velocity of particle is inversely proportional to its grain diameter. The process of the loss increase,then reduce, finally soar.Therefore, the diameter proportion of overburden should be selected reasonably, if the small particle content is too large, the structure of layer will be destructed. At the same time,setting arch will produce a bad influence on the process of ore-drawing.The suggestion is that small particle content should between 4.34%and 26.04%. |
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