坚硬顶板来压控制的探讨

DISCUSSION ON CONTROL OF HARD ROOF WEIGHTING

The paper considers the overlying main roof over a longwall face as a Kirchhoff plate on the Winkler elastic fundament. Based on analysis of loading, movement and balance of the main structural block, the authors point out that the main characteristics of ground pressure manifestation of hard roof face is intensive impact loading when weighting,which makes the nether roof collapse over large area and brings about severe damage of the roof support. And the intensity of the impact is related to the relative distance between the fracture Line in the main roof and coal rib at face. The deeper the fracture penetrates into the coal rib, the more the impact loading is released,and the main roof becomes more stable. On the other hand, according to the discovery of the study of rules of fracture developed in Kirchhoff plate on Winkler elastic fundament, the relative distance from the fracture line in the main roof to coal rib is related to elastic coefficient of the supporting coal rib and the nether roof. The smaller the elastic coefficient, the deeper the fracture penetrates into coal rib. Therefore, the paper proposes a blasting method for loosing the coal rib in front of face to release weighting of the main roof. This method has been proved in Yungang Colliery, Datong Mining Administration to be satisfactory technically and economically.