Research on the evolution mechanism of spatial structure of overlying strata and rockburst inducing in coal mine

Abstract：The overlying strata fractures and moves as the result of coal seam exploitation,and in this process both stat- ic and dynamic load apply to the roadways and workfaces, inducing roof and rockhurst disaster. The movement of the o- verlying strata is not only the result of a single workface, but also the interaction of more workface. The traditional spa- tial structure of overlying strata in coal mine is usually plane model focused on the independent single workface, and few researches concern on the structural morphology and evolution mechanism that continuous exploitation of more workfaces. Microseismic monitoring results show that the rockburst sources are mainly concentrated in the adjacent gobs expecially when thick and hard key strata above the workfaces with small or none coal pillar between each other, which indicates spatial structure of overlying strata existed in the coal mine and the spatial structure evoluted dynami- cally with the boundary eontitions changes. The evolution and instability of the spatial structure induce various foms of strata behaviors, especially dynamic disasters of which roekbursts are most serious,was entitled spatial structure insta- bility roekburst. To reveal the mechanism of this new type rockburst, the spatial structure evolution model of overlying strata was putforward, and integrated approaches were adopted for deep research including laboratory physical simula- tion experiment, FLAC3D numerical simuliation, theoretical analysis and engineering practice.