Analysis of coal mining dynamic disasters and study on prevention countermeasures

In order to further study the mechanism of coal mining dynamic disaster,prevent and reduce coal mining dynamic disaster accident, through the analysis of relevant technical parameters and field investigations of three coal mine gas and coal rock impact dynamic disaster accidents ,combined with the measurement result s of stress transfer change distribution of No.1152( 3) return air entry roof in Zhangji Coal Mine,the relationship between coal and rock structure characteristics,fault str ucture belts,multi-factor coupling,redistribution of mining stress and the occurrence of dynamic disasters were analyzed.The results show that the combined effect of in- situ stress and tectonic stress is the leading factor of energy accumulation and in-situ stress concentration. The elastic energy is abundant and the stress is concentrate d in a certain range on both sides of the structural failure zone,which is especially prone to dynamic disaster accidents. The hard roof is the distribution carrier of stress transfer. The complete roof will increase the formation of concentrated stress and aggravate the expansion of accidents. The mining stress concentration areais 5 to 10 m in front of the development work. Under the condition of soft and hard alternating coal rock structure,the elastic energy of local soft coal body under compression defo rmation is accumulated and the coal body is coupled with rich gas,which reduces the initial outburst energy. The redistribution of mining stress will induce the occurrenc e of coal or coal and gas dynamic disaster accidents,most of which form secondary or multiple concentrated stress( energy) release and transfer,resulting in energy exp ansion and superposition,leading to the expansion of the scope of dynamic disaster or hazard. In order to avoid stress concentration and cut off the stress transmission path,the impact dynamic parameters such as in-situ stress,gas pressure. drilling cuttings index method and other impact dynamic parameters should be measured. The hard roof can be cut off manually by pressure relief or pre-splitting blasting to avoid stress concentration and cut off the stress transmission path,which can effectively p revent the impact dynamic disasters and achieve the goal of reducing the occurrence of impact power accidents.