All mechanical factors of the floor heave in roadways, such as rock dilatancy, creep and buckling failure, are analysed here. The mechanism and rational parameters of two new kinds of stress relief methods are discussed by means of FEM. The stress relief method for roof was applied to a belt chamber in Yanzhou coal mining area, and serious floor heave was eliminated.
Floor heave has been a difficult problem in many underground coal mines for a long time. It shows more and more serious as the depth of extraction increases. However, the control of the floor heave has been considered less important than roof support over a long period of time in China, so the mechanism of the floor heave has not been clarified, there has been great blindness in selecting the control methods. The intense floor heave has made roadway support costs obviously rise, what is more, seriously hindered coal mining rate. The floor heave is a very complicated process. It not only relates to the physical and mechanical properties of surrounding strata, but also depends on the stress distribution around the roadway. The mechanical factors of the floor heave are studied in this paper, and the mechanism and effectiveness of the stress relief methods are analysed.