Numerical and Field Investigations of Rockburst Mechanisms Triggered by Thick-Hard Roof Fracturing.

Mine tremors and rockbursts triggered by thick-hard roof fracturing are major problems in safe production of coal mines, and the corresponding numerical simulation is also a great challenge due to complexity of rock failure and wave field characteristics radiated from sources. In this paper, based on the engineering background that strong mine tremors frequently occurred in the 7301 working face of the Baodian coal mine due to thick-hard stratum fracture, a novel method is used to successfully simulate the whole process of tremor generation caused by thick-hard roof fracturing and triggered rockburst in a roadway. Much interesting information is studied in detail, including the characteristics of the source radiation wave field, the variation of the stress field caused by seismic wave diffusion, and the changes in stress, crack and displacement throughout the process of the roadway rockburst from inoculation to explosion under the disturbance of seismic waves. The effects of tremor disturbance intensity are studied based on the relationship between the relative spatial orientation of the roadway and fault plane. The disturbance to the roadway is largest in the direction of 45° of the fault plane. The research results provide a useful reference for understanding the mechanisms of rockburst induced by mine tremors. The simulation method gives a valuable insight into the disturbance effects and focal mechanism of mine tremors. Highlights: Characteristics of source radiation wave field of mine tremors induced by shear fracture are numerically simulated. Influences of fault plane geometric properties, radiation wave field, and relative position between roadway and source on rockburst are discussed. Rupture types of thick-hard stratum in different areas are investigated by moment tensor inversion. [ABSTRACT FROM AUTHOR]