DETERMINATION OF REASONABLE FORCED CAVING INTERVAL IN SHALLOW-BURIED SEAM WITH HARD AND THIN BEDROCK
FANG Xinqiu1，2，HAO Xianjie1，LAN Yiwen1
(1. School of Mining Engineering，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；2. State Key Laboratory of Coal Resources and Safety Mining，China University of Mining and Technology，Xuzhou，Jiangsu 221008，China)
Abstract：During mining of shallow-buried seam with loose topsoil and hard and thin bedrock，in order to avoid support break-off and sand inrush happening，forced caving is often adopted in practical engineering in order to avoid support break-off and sand inrush happening. But how to determine the reasonable forced caving interval lacks rational basis. Combining the practical condition of Liangshuijing coal mine，according to rock strata control theory，the reasonable forced caving interval is studied by using methods of theoretical analysis，numerical simulation and in-situ measuring. The results indicate that when the working face advances 20 m far away from cut-hole，namely，between the periodic weighting step distance and first weighting step distance of basic roof，forced roof caving can successfully avoid first weighting，which has less influence on supports and can also avoid support break-off. The conclusions have been proved successfully by in-situ experiment.
