Mechanism and control technique for inhomogeneous deformation of rock surrounding a mining roadway

In a roadway affected by the superposition of in situ stress and mining-induced stress, inhomogeneous deformation and even roof accidents may occur. The stability control of rock surrounding a mining roadway is the key to realizing safe and efficient mining. A track roadway of the No. 152106 working face in Changling No. 1 Coal Mine was severely deformed under the influence of mining. In view of this, deformation characteristics of rock surrounding a plastic zone in the mining roadway were investigated by field monitoring, theoretical analysis, and numerical simulation. The results demonstrate that deformation of rock surrounding the roadway is inhomogeneous under the influence of mining. The deformation of rock surrounding the roadway in rear of the working face is greater than that in front of the working face and deformation of a coal pillar in the roadway is larger than that of solid coal. Furthermore, bed separation occurs on the roof and the floor heave near the coal pillar is greater. The maximum principal stress, ratio of the maximum principal stress to the minimum principal stress (hereinafter referred to as principal stress ratio), and range of the plastic zone in front of the working face are smaller than those to rear of the working face, and the displacement and range of the plastic zone in rock surrounding the roadway are consistent in terms of trend. Affected by secondary mining, the plastic zone changes from an elliptical to a butterfly shape. On this basis, reinforcement support schemes for the mining roadway were proposed, namely adding anchor cables to the roof, applying thru-anchor cables to coal pillars, and setting single hydraulic props in a roadway affected by primary mining. The field test results show that deformation of rock surrounding the track roadway decreases significantly.