Roof Fracture Characteristics of Deep Mining-pause Space Without Pre-excavation Roadway

In view of roof fall and supports retracement accidents existed in deep miming-pause space without pre-excavation roadway, the most dangerous roof failure mode was theoretically analyzed．The studies show that enlarging coal wall and withdrawing hydraulic supports would cause persistent disturbances to the mining-pause space．Under high ground pressure, the tensile zone and compression-shear zone of immediate roof gradually evolved．The immediate roof was easy to collapse when the two zones were interpenetrated by through crack．With continually retracing supports, the basic roof gradually forms lateral rotary structure, which will induce hydraulic supports instability by exert lateral force．Through shortening the width of mining-pause space，utilizing additional supports to protect the dangerous zone of roof，as well as alternately withdrawing the supports, the roof fall problems can be effectively controlled．