Forced Roof Caving Technology of Hard Roof in Shortwall Coal Mining Face

In order to solve the long free support distance of a hard roof in a shortwall coal mining face of Yujialiang Mine, based on analysis on the roof movement law of the coal mining face, the forced roof caving technology combined with a deep borehole blasting and a shallow borehole blasting was provided. The application re sults of the combined technology in No. 42209 Coal Mining Face of Yujialiang Mine showed that the technology not only could reduce the explosive quantity applied to t he blasting, but also could highly reduce the labor intensity of the miners. The technology could realize deep boreholes in the connection gateway, the waste rock after t he blasting could backfill the goaf under the blasting boreholes and thus the production coal mining face and the goaf could be isolated. The roof mechanics structure W ould be changed after the blasting. Therefore, the hard roof in the goaf of the shortwall coal mining face would be fallen naturally, the free support distance of the previo us roof could be reduced and a safety and high efficient mining of the shortwall mining face could be ensured.