Study On Optimum Thickness Of Covering Layer During Turning Open Pit Into Underground Mining

There is a common problem existing in many of the open-pits mining in our country: along with the digging extend of the open pit, the high sharp side slope brings a serious threaten to the mining safety. Therefore the open pits will be transferred from the present open pit to the underground mining. The appropriate determination of the coving layer thickness plays a very important role during the transfer process, which will have a practical significant effect on the safeties of mining production and the full usage of the mining resources.The understanding about the function of the covering layer is unclear. According to the systematical research of factors that influenced thickness of covering layer, the minimal thickness of covering layer that satisfy the produce requirement can be found. The firm confirmation of the reasonable thickness covering layer should be made on the basis of the principle: safe production and waste-avoiding. The experiment model and computer simulation have been used to do the study on the proper thickness of the transferred covering layer. The simulation experiments of different thickness of the covering medium are carried on through the model experiments. The computer simulation program is generated on the basis of the analysis of the covering interface. The computer simulates the covering interface moving and analyzes simulation results of different covering layer. Meanwhile, the contrast is made between physical experiment and computer simulation. The thickness of the cover layer can be studied based on the incident spray disaster. The leaking experiment of different granule and thickness is taken by virtue of the model experiment. During the process of the transfer, the empirical formula between cover leak depth and leak time will be made as well as the relationship between granule and leaking time. The experiment data analysis is carried on and making use of the direct flux experiment chart. The formula is also used to relate with the production reality, so that the conclusion is obtained that 32 meters of the protruding shaped covering layer can theoretically meet the exploitation requirement during the turning open pit into underground mining process.