Movement law of overburden in upward fully mechanized working face and determination of support working resistance

The overburden movement law of the upward fully mechanized working face is different from that of the horizontal working face. The roof collapses frequently, which brings a great test to the stability of the working face support. The existing research on the safe mining of the upward fully mechanized working face mainly focuses on the influence of the change of the mining angle on the overburden movement law, and there is a lack of systematic research on the force characteristics of the roof and floor. In order to solve the above problems, taking the 8102 upward fully mechanized working face in Ruilong Mine as the background, the UDEC numerical simulation software is used to analyze the overburden movement law and roof fracture characteristics at different advancing distances of the upward fully mechanized working face. In the upward working face, affected by the inclination angle and mining method, the bottom coal stress is most concentrated, and the working face has obvious characteristics of initial pressure and periodic pressure. Compared with the nearly horizontal fully mechanized working face, the periodic pressure step is obviously reduced, the peak strength of the overburden is relatively low, the roof is not easy to form a structure, the pressure is more frequent, and the mine pressure appears more intense. The step distance of the first collapse of the direct roof of 8102 working face is 25 m, the step distance of the initial pressure of the basic roof is 40 m, and the step distance of the periodic pressure is 10-15 m. The existing calculation methods of using the roof-support mechanical relationship to determine the working resistance of support are relatively cumbersome. Many methods are not practical when applied to the engineering site. By comparing the advantages, disadvantages and practicality of several commonly used support working resistance calculation methods, it is concluded that the dynamic load calculation method is the most suitable method for calculating the working resistance of the support according to the actual working conditions of 8102 working face. The method has the characteristics of accurate calculation results and easy selection of parameters. It is determined that the maximum working resistance of the support of this working face is 6 359 kN/frame, and the support of this working face with a working resistance greater than 7 066 kN can meet the support requirements. The results of engineering application have proved the correctness of using dynamic load calculation method to calculate the working resistance of the support of 8102 working face.