Evolution of mining stress field and the control technology of stress relief gas in close distance coal seam

Abstract

The prevention and control of stress relief gas have crucial influence on safety of coal mine, it is not only the inevitable requirement of safe production, but also an effective way to realize reasonable utilization of gas. Taking the 1103 working face of the Weijiadi coal mine as the background, the mining stress field was analysed by means of numerical simulation, theoretical analysis and field practice, and the control technology of stress relief gas was studied. The results showed that scope of stress relief zone drops gradually associated with an increase of distance from the roof (or floor) to the working face. Additionally, the shape of the stress relief body exhibited a ring-shaped distribution, while four corners of the goaf roof and floor underwent high permeability zones due to a deep stress relief body, where the permeability of two corners near the transportation roadway of the floor was higher. The results provided good information for W-shaped ventilation mode with two inlets and one return which was adopted in the working face. More importantly, the optimized layout of boreholes was put forward, which eventually were useful for solving the gas overrun of the working face. The technology used in 1103 working face has an attractive and practical background with other extensive applications for the prevention and control of relief gas.