Research on dual pressure relief and outburst prevention model for deep floor rock roadways

Abstract

The mechanism of coal and gas outbursts tends to be more complex after entering the deep part of a coal mine from the shallow ground. As deep coal roadway outbursts change from gas-dominated to geostress-dominated, it is imperative to explore how to prevent outbursts of deep geostress-dominated coal roadways. Because the fracture zone of surrounding rocks in deep roadways is far larger than that in shallow roadways, this research considered the pressure relief field for a deep roadway. The first pressure relief field in the horizontal and vertical directions was 1.3 times and 2.05 times, respectively, greater than the roadway diameter based on data analysis, while the second pressure relief field in the horizontal and vertical directions was 1.8 and 2.8 times, respectively, greater than the roadway diameter. The range of the pressure relief of the second pressure relief field was 1.4 times greater than that of the first one in both the horizontal and vertical directions. With the action of the pressure relief field, the strip of the overlying coal roadway would produce a pressure relief area, a stress concentration area and the original coalbed area. Then, we proposed a dual pressure relief and outburst prevention model and applied it in the Qujiang Coal Mine. With the supplementation of hydraulic technology, this model released pressure from the floor rock roadway and drilled boreholes across beds to extract gas. The application showed that releasing pressure in the strip zone of the coal roadway was very effective in preventing an outburst. The hazards produced by both the geostress of the roof and floor rocks and the coalbed gas were removed so that the coal roadway could be excavated in a safe and rapid manner.