Instability mechanism and control technology of surrounding rock of gob-side entry with narrow pillar by fully-mechanized caving mining

In order to probe the deformation and failure and control problems of rock masses around the gob-side entry by fully-mechanized caving mining with a narrow pillar, a comprehensive method including field monitoring, theory analysis, numerical modelling was employed to study the deformation and failure characteristics, instability mechanism and control measurements of the rock mass surrounding the gob-side entry, based on the engineering background of No.103 lane mining face in a coal mine. The results suggest that: ① With the influence of movement induced by unstable overlying strata, the roof coal masses on the coal pillar side was seriously damaged, and the virgin coal pillar and coal pillar were damaged seriously. ② The deformation and instability of No.103 lane was a result of multi dynamic loads, soft and weakness coal mass, a narrow coal pillar, large cross-section and horizontal movement, and the evolution process of deformation and failure of gob-side entry was deduced. ③ A combined control technology including high strength bolts, asymmetric cable beam and cable truss was put forward, and its control mechanism including controlling fractures evolution and improving the bearing capacity and integrity of the surrounding rocks was clarified. Its validity was verified by the field application.