Study on failure mechanism and energy dissipation law of single fissured coal in different tectonic stress areas.

To study the failure mechanism and energy dissipation law of fissured coal in different tectonic stress areas, the No.9 coal seam of the Limin coal mine was taken as the research background. The hollow inclusion stress relief method is used to measure the in-situ stress, reveal the distribution law of mine in-situ stress, and divide it into different tectonic stress areas. The UDEC numerical simulation software was used to analyze and study the failure mechanisms and energy dissipation characteristics of coal containing single fissures with different dip angles in high stress areas and stress gradient areas. The results show that: ① When in the same stress area, the stress concentration area at the end of the fissure dip angle 45° is the largest, and the macroscopic mechanical properties are the worst. The fissure dip angle is deflected from 45° to both sides, and the stress transfer effect and macroscopic mechanical properties are gradually improved. When it reaches 0° and 90°, the stress distribution of coal is the most uniform and the macroscopic mechanical properties are the strongest. With the increase of the fissure dip angle, the total energy and elastic strain energy of the system decrease first and then increase. The greater the fissure dip angle, the more severe the fissure damage inside the coal, which leads to the weakening of the total energy of the system and the strengthening of the dissipation capacity. ② When the fissure dip angle is the same, with the increase of stress level, the stress around the coal fissure in the high stress area is larger than that in the stress gradient area, and the stress concentration area at the fracture end is also larger, which is more prone to shear dilatancy and form dilatancy effect. At the same time, the total energy of the system gradually increases with the increase of the stress level, and the coal is prone to energy accumulation, which aggravates the occurrence of dynamic disasters.