Fast prediction for outburst risk before coal un-covering in shaft and cross-cut

In this paper, we describe the principle, technique, and steps of fast predicting the outburst risk before coal un-covering in shaft and cross-cut, including the selection of indexes for the prediction, fast test of gas pressure, coring technique for obtaining an whole coal core, and the determination of outburst parameters. Using this technique, we can finish testing the original gas pressure of coal within 20 h, making it possible to accurately predict the outburst risk before coal un-covering in shaft and cross-cut in 3~5 days. In addition, we can, according to the prediction result, give out the residual pressure and the smallest pre-drainage rate of gas. The comparison of prediction data among more than 10 shafts and cross-cuts shows that the index of initial gas relief expansion energy can more accurately reflect the outburst risk of coal seams.