Research on deformation and failure law and control of roof in deep gob-side entry retaining

In order to solve the problem of severe deformation of the roof in deep gob-side entry retaining, the combination of FLAC3D numerical simulation and engineering practice were applied to study the evolution law of the basic top of the track roadway of the 1115 working face in Guqiao Coal Mine from the excavation to the secondary mining stage. The results showed that: ① The deformation of the roof is symmetrically distributed during the excavation stage. The slope of the intersection of the roof sinking curve is 7.25×10-4 during the first mining influenced stage, the slope of the intersection point has increased by 6 times during roadway retaining, and the skew effect is significantly enhanced. The slope of the intersection point of the roof sinking curve of the secondary mining stage is 3.2 times bigger than that during the roadway retaining. The skew effect is increased, but mainly due to translational subsidence; ② The deformation of the roof is gradually increased, and the maximum subsidence of the roof of the roadway during the excavation is 69.2mm. In the future, the deformation of each stage increased by 0.99 times, 0.82 times and 2.13 times compared with the previous stage. The deformation of the roof along the roadway is gradually becoming more and more severe, and the difficulty of support is significantly increased. The support design of the roadway along the gob should be coordinated. ③ The principle of roof control for deep mine along the roadway is proposed by the principle of ensuring the completeness of the immediate roof, step-by-step strengthening of each stage and weakening deformation of the roof. The engineering verification can achieve the strong deformation of the roof of the roadway along the deep roadway.