Research on the Control Technology and Key Parameters of External Anchor-Internal Unloading of Surrounding Rock During Gob-Side Entry Driving Under Severe Mining of 1000-m-Deep Mine

The continuous large deformation of the surrounding rock during gob-side entry driving in a 1000-m-deep mine requires frequent renovation of the mining roadway, seriously restricting the normal mining operations at the coal face. Taking 11,216 headgate of a coal mine as the engineering background, this paper expounds that the large deformation factors of the gob-side entry driving of a 1000-m-deep mine are stress-field factors dominated by high in-situ stress, side abutment pressure, front abutment pressure and tectonic stress, and stress-related factors dominated by coal body crushing, unreasonable support, large section size and broken narrow coal pillar. The two-stage pressurization of the surrounding rock of the section roadway of the mine is governed by the following fundamental law: After pressurization, the peak area of the original abutment pressure of the roadway transfers to the lower parts of the surrounding rock, resulting in an increased stress in the surrounding rock at the side of the roadway. A targeted cooperative control involving external anchor-internal unloading of the surrounding rock of the roadway during gob-side entry driving is proposed, and the pressure relief mechanism in the surrounding rock during the static and dynamic pressure stages of the hole-making process is elucidated: the hole-making space transfers the peak stress to the deep during the static pressure stage, and it transfers the high stress to the deep during the dynamic pressure stage. The pressure relief laws of the surrounding rock were analyzed for different hole-making parameters during the static and dynamic pressure stages of deep gob-side entry driving, the hole-making parameters of the 11,216 headgate were as follows: the hole-making depth, length, and spacing were 8, 4, and 3.2 m. A “four-in-one” double space monitoring method was developed to evaluate the control effect of the support structure on the surrounding rock. The results indicated that the surrounding rock deformation remained within a controllable range, the support structure did not experience any breakage or detachment throughout the service period, and the hole-making space played a pressure relief role. The successful application of this technology to control the large deformations in the surrounding rock of coal roadways in deep mines via gob-side entry driving is of great scientific significance.