Study On Safe Mining Technology In Shallow Coal Seam With Thin Bedrock

With abundant coal resources, the Shendong Mining Area is an important commercial coal base of China.Coal seams are buried in characteristics shallow burial and thin bedrock, covered thick loose rock.The production practice shows that strata behaviors appear violent inlongwall coal mining process. The working face easily appears to such disasters as sinking of roof step and inrush of water or sand in Shendong Mining Area.Based on special geological conditions of the Shendong Mining Area and Daliuta mine, this paper summarizes characteristics of strata behaviors of shallow seam and analyses the causes by site investigating and observing. Through further study of the shallow burial mining coal seams intermixed security boundaries, forecasting assessment about supports'type and rational working resistance of this geological condition are made. A length theoretical model of working face is established to optimize the length. After the study, this dissertation draws conclusions as follow:1)Through field observation of 22614 working face in Daliuta coal mine, the strata behaviors of working face and influencing factors are summarized in shallow seam under thin base rock, the strata behaviors in special areas where the violent changes of bedrock thickness is thin are analyzed.2) Based on the thin bedrock, theoretical model of critical thickness of roof disaster and water or sand bursting disaster is established, safety mining boundary and measures is divided and raised. We provide reference to similar geologic conditions of safety mining.3) According to various thickness of bedrock,4 mechanical models of 'support --surrounding rock" are set up. We forecast reasonable working resistance of 22614 working face and adjacent working face, and evaluate models with observation results. It is expected that it can provide the foundation for selecting support's type and confirming working resistance.4) Based on the length theory of working face in large mining height, length parameters of thin bedrock workface is calculated and the evaluation is verified practical mining conditions. References to the length optimization of thin bedrock workface are provided.