The small deflection theory of elastic thin plate were used to analysis the roadway floor stress condition and the main influence factors of floor rock burst were cleared. Both of the theory analysis and numerical simulation were used to study on the rock burst prevention mechanism and optimization scheme about deep hole floor-break blasting and the control effect were tested in practice. It's found that the mining horizontal stress was the key reason for floor heave and the layer thickness of floor, mechanical properties and the supporting intensity of roadway surrounding rock were the main influence factors of floor heave. If the floor strata were dense thick mudstone, the rock burst will happen for the elastic deformation energy released in the process of floor layer broken. The essence of deep hole floor-break blasting was the combination of borehole pressure relief and blasting vibration method for rock burst prevention. When the position of blasting holes in the middle of the floor and roadway center line, not only the high elastic deformation energy accumulated in the floor was released and the ability of continuously transfer stress/ energy was destroyed, but also the high stress in the roadway side was released, the prevention effect was more apparent.
Due to the influence factors such as mechanical properties and stress state of surrounding rocks in deep roadway and complicated geological conditions of coal-rock mass, the mechanism of floor heave had not been really understood, leading to the floor as the center of floor heave control method (Afrouz 1988, Stankus 1994) The main influence factors of floor rock burst were cleared based on the analysis of roadway floor stress condition in this paper. Both of the theory analysis and numerical simulation were used to study on the rock burst prevention mechanism and optimization scheme about deep hole floor-break blasting and the control effect were tested through rock burst prevention practices in typical hazardous roadways.
Much field practice shows that, the floor rock burst mainly occurs in the "hard roof - hard coal - hard floor" structure. Analysis on stress state and structural characteristics of deep roadway floor under the condition of "three-hard" structure were the pre-requsites for realizing mechanism of floor rock burst. Due to the influence of layered structure occurrence characteristics and multiphase tectonic movement of coal-bearing sedimentary layers, the surrounding rocks were not only divided massive fissures and joints, but it also arose bending deformation in different degrees and accumulated elastic energy under the external force of difference in floor lithologic and thickness. Loading process of layered strata due to the excavation was shown in Figure 1.
