| 摘要 |
FIELD: mining, particularly underground thick flat-laying coal bed mining. ^ SUBSTANCE: method involves dividing coal bed into two layers; cutting each layer by long faces in descending order along with full rock roof caving in goaf; determining pitch of difficult-to-caving roof rock in long face goaf of upper layer and locations of front and rear break cracks, which define difficult-to-caving roof rock blocks; leaving protective coal under difficult-to-caving roof rock blocks as long face advances in lower layer, wherein distance between front break cracks and the protective bed exceeds direct coal bed roof rock thickness. Protective coal thickness is greater than minimal possible protective coal thickness selected so that protective coal thickness reduction below said minimal possible value leads to protective coal caving. As long face passes under difficult-to-caving roof rock blocks spaced a distance less that direct coal bed roof rock thickness from front break cracks, lower layer is cut without leaving of interlayer protective coal in long face roof. ^ EFFECT: decreased coal losses and fire hazard. ^ 2 cl, 1 dwg |
