Stability and its control of top-coal in the longwall prop-free area

Based on quantities of field observations on supports and surrounding strata at fully-mechanized longwall top-coal caving mining face No. 7506 in Wuyang coal mine, the relationship between the top-coal caving in prop-free area and its influential factors is analyzed by use of the numerical calculation soft-ware UDEC and mathematical method, and the reasonable range of monitoring indices is decided in accordance with the productive and geological conditions. The fine effects on technology and safety and economy have been achieved in Wuyang coal mine since the monitoring system of supports and surrounding strata was put into practice at the face.